CHAPTER ONE

1.1 INTRODUCTION

Camels are in the taxonomic order Artiodactyls (even-toed ungulates), sub

order Tylopoda (pad-footed), and Family Camelidae (Wilson, 1984).They are

pseudo-ruminants that possess a three-chambered stomach, lacking the omasum

that is part of the four-chambered stomach of the order ruminantia (Hegazi,

1950).

Camels are important animals especially to the people of arid and semi arid

zones for many economic and agricultural purposes. They have been

traditionally used for transportation of people and goods, to supply hides and

skin, meat and milk products (Reece, 1997). One of the most advantageous

attributes of the camel in drought areas is its ability to utilize plants that grow

well under arid conditions which are unacceptable to other grazing animals

(Fowler, 1998b). Camelids evolved in North America and were separated from

primitive artiodactylids in the Eocene epoch period, approximately 40 million

years ago (Wilson, 1995; Wilson, 1997).

Though camels ruminate, they are not true ruminants, as they lack the

four well-defined stomach of the ruminants; the rumen, reticulum, omasum and

abomasum (Arnautovic, 1997). The role of the camel in the modern world is

changing with increases in human population, coupled with poor economic

potentials of some countries have transformed the traditional use of camel as

milk and meat source (Mukasa-Mugerwa, 1981; Khanna, 1990). The anatomical

development of all members of the Camelidae is considered to be similar but

most of the available data on the anatomy of the alimentary canal have been

obtained mainly from the Llama (Bustinza, 1979). From the anatomical

differences between the Camelidae and Bovidae, it was hypothesized that the

physiological processes in the alimentary canal would also differ (Bohlken,

1

1960). This was further emphasized by the difference in rumen protozoan

population between the camel and the sheep (Farid, et al., 1979).

In Northern Nigeria, where camels are slaughtered for human

consumption, the meat was found to rank second to that of cattle (Mustapha and

Oluyisi, 1993; Agaie et al., 1997; Sonfada, 2008).In East Africa, (Kenya,

Ethiopia, Sudan, and Somalia), camel, are bred for meat (Mukasa-Mugerwa,

1981) and are used mainly as traction animal, even though cattle are the most

predominant (Tukur and Maigandi, 1999).

1.2 Statement of Problem

There have been many studies on the quantitative value and histology of

digestive system in adult camel, (Asari et al., 1985; Wilson, et al., 1990; Reece,

1997; Bustinza, 1979; Franco et. al., 2004a) but similar studies have not been

conducted on the developmental changes of the entire digestive tract of the

camel fetus. There is thus, paucity of information on the developmental changes

of the digestive tract of dromedarian camel.

1.3 Justification of the Study

Since the importance of camel in its adaptation to its environment proves to

have so many relationships to the digestion and utilization of its food, there is,

therefore, need to study the anatomical development of the digestive tract for

better understanding of the animals habitat and management system so as to

enhance camel production in Nigeria.

There is also need to establish anatomical base-line information on the

development of gastrointestinal tract of the dromedarian camel fetus. The

information so generated will complement available literatures that were mostly

on Llama. The data obtained from this study will help to bridge the existing gap

on the morphology, morphometry and histology of the digestive tract of the

developing dromedarian camel.

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1.4 General Objectives

The general aim of this work is to study the Gross anatomy, morphometry and

histology of the digestive tract of dromedarian Camel fetuses.

1.5 Specific Objectives of the Study

The specific objectives of the study are:

To provide an information/data on gross anatomy of digestive tract (D/T) of

the developing dromedarian fetus.

Provide Morphometric data of the fetal digestive tract at different

developmental stages.

Determination of the microscopic features of various segments of the

digestive tract of one- humped camel fetuses.

To relate the structural findings to the function of various segments of the

digestive tract.

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CHAPTER TWO

2.0 LITERATURE REVIEW

2.1 OVERVIEW

All the members of the camel family are found in the order of the Artiodactyla

(even-toed ungulates); suborder: Tylopoda (pad-footed); family: Camelidae.

The old-world genus is the Camelus, having the two species of the Bactrianus

(two-humped) and Dromedarius (one-humped). The new-world genus of the

Lama has three species, while the genus of Vicugna has only one species.

Though they chew cud, camels differ from true ruminants in a few anatomical

features (Cloudley-Thompson, 1969). Adult camels have two incisor teeth in

their upper jaws; they lack an omasum, the third stomach division of the

ruminants, which is considered the water reabsorbing portion of the stomach;

they have no gallbladder; and the hooves have been reduced to claw-like toes,

projecting beyond the pads (Zeuner, 1963).

Camel is an important animal especially to the people of Sahel savanna for

many economic and agricultural purposes. They have been traditionally used for

the transportation of people and other commodities, to supply hides and skin,

meat and milk products (Reece, 1997). One of the most advantageous attributes

of the camel in drought areas is its ability to utilize plants that grow well under

arid conditions and are unacceptable to other grazing animals (Dahlborn et.

al.,1987).

There are almost 14 million Dromedary camels alive today that are

domesticated animals, mostly living in Somalia, Sudan, Mauritania and nearby

countries (Malie et. al., 1987) .The Bactrian camel once had an enormous range,

however, it is now reduced to an estimated 1.4 million animals, mostly

domesticated. It is thought that there are about 1000 wild Bactrian camels in the

Gobi Desert in China and Mongolia. Humans first domesticated camels between

4

3,500 - 3,000 years ago (Bulliet, 1975). FDLPCS (1992) estimated a Nigerian

national annual mean population of 87,000 camels, being found most frequently

in the former Sokoto (43,960) and Borno (26,866) states. The same report also

found that 83.93% of all camels are found in the villages, depending on season.

The camel is morphologically, behaviorally and physiologically adapted to heat,

water shortage and poor quality fodder (Yagil 1984).

Unlike other domestic species where differentiation into types or breeds

started soon after domestication, and animals were selected for specific

economic traits that lead to changes in morphology, particularly size, shape and

colour, the camel never had such changes (Wilson, 1984). No breed differences

were recognized even though the camels were identified with the tribes that

bred them (Malie et. al., 1987; Duhan et. al., 1996). Tribal brands (Wasms)

were of particular importance in Arabia, Egypt and Sudan. Types of camel can

often be identified with the help of these marks; other wise even very

experienced camel men have difficulty in distinguishing types. It is more correct

to discuss camels in terms of ecotypes, associated to particular ethnic groups

(El-Amin, 1979; Wilson, 1984).

2.2 Camel Characteristics

Camels are camelids, members of the biological family Camelidae, the only

living family in the suborder Tylopoda. Camels tend to be large and are strictly

herbivorous but differ from ruminants in several ways (Wilson, 1984). Camels

have a three-chambered rather than a four-chambered stomach. They have an

upper lip that is partially split in two with each part separately mobile. Camels

also have an isolated incisor in the upper jaw (Wilson, 1998).The red blood

cells in camels are oval shaped, unlike those of other mammals which are

circular. This is to facilitate their flow in a dehydrated state. These cells are also

more stable in order to withstand high osmotic variation (the diffusion of water

5

through a cell wall or membrane) without rupturing when taking in large

amounts of water (Wilson, 1998).

A fully grown adult camel stands 1.85 metres (6 feet) at the shoulder and

2.15 metres (7 feet) at the hump. Camels can run up to 65 kilometres per hour

(40 miles per hour) in short bursts and sustain speeds of up to 40 kilometres per

hour (25 miles per hour).The life span of a camel is 30 to 60 years (Malie et. al.,

1987).

The kidneys of a camel are very efficient. Urine comes out as a thick syrup

and their faeces are so dry that these can fuel fires (Malie et. al., 1987; Wilson,

1998).Camels are able to withstand changes in body temperature and water

content that would kill most other animals. Their temperature ranges from 34°C

(93°F) at night up to 41°C (106°F) in the day and only above this threshold will

they begin to sweat. This allows them to preserve about five litres of water a

day. Camels can withstand, at least, 25% weight loss due to sweating (Wilson,

1998).

A feature of their nostrils is that a large amount of water vapour is trapped

when they exhale and this is returned to their body fluids, thereby reducing the

amount of water lost through respiration(Alexander and Robert, 1986). A

camel’s thick coat reflects sunlight. A shaved camel has to sweat 50% more to

avoid overheating. It also insulates them from the intense heat that radiates from

hot desert sand (Malie et al., 1987). Their long legs help by keeping them

further from the hot ground. Camels have tough feet so that they can endure the

scorching desert sands. Camels have also been known to swim if given the

chance (Sweet, 1965).

A camel’s mouth is very sturdy and it is able to chew thorny desert plants

(Alexander and Robert, 1986). Long eyelashes and ear hairs, together with

6

closeable nostrils, form an effective barrier against sand. Camels pace (moving

both legs on one side at the same time) and their widened feet help them move

without sinking into the sand (Sweet, 1965 ; Malie et al., 1987).All member

species of the Camelids are known to have a highly unusual immune system,

where part of the antibody repertoire is composed of immunoglobulins without

light chain. Whether and how this contributes to their resistance to harsh

environments is currently unknown (Malie et al., 1987).

2.3 Pregnancy diagnosis

In order to improve the efficiency and increase the economic viability of camel

breeding, it is important to know if and when the females are pregnant. This can

be done by rectal palpation (Chen and Yuang, 1979; Musa, 1979; Skidmore,

2000a) and by biological assay using infantile mice (Musa, 1979). The latter

method is only feasible at certain stages of pregnancy. The surest method is by

radio-immuno assay. Pregnancy determination is important in the care of the

females, the selection of males and in long-term planning.

2.3.1 Methods of pregnancy diagnosis

2.3.1a Tail "Cocking"

Several scholars have asserted that it is possible to detect pregnancy in camels

from as early as 15 days by observing an erected and coiled tail in the pregnant

animal when approached by a male camel (Ibrahim, 1990). This response has

been noted in unmated animals treated with exogenous progesterone and also in

younger animals that maybe alarmed by the male (Malie et al., 1987; Skidmore,

2000b).

2.3.1b Changes in Cervical Mucous

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i) Viscosity - Other studies have shown that changes occur in pH and flow

elasticity of the cervical mucous in pregnant versus non-pregnant camels. The

cervical mucous tends to be turbid in most stages of the ovarian cycle, although

during oestrus it becomes less viscous, but not watery (Skidmore, 2000c). In

pregnant females the mucous becomes whitish and opaque and it decreases

gradually in amount until the second month when it becomes almost impossible

to collect (Ibrahim, 1990).

ii) pH - The pH varies between 6.74 and 7.36 during the follicular cycle in non-

pregnant camels but it becomes more alkaline during early pregnancy,

increasing from pH 7.05 after mating to as high as 8.2 at the beginning of the

sixth week of gestation (Ibrahim, 1990 ; Skidmore, 2000a).

iii) Specific Gravity - This was measured using the copper sulphate method and

was found to vary between 1.004 and 1.008 during the follicular phases in the

non-pregnant animal (Skidmore, 2000c). During pregnancy the specific gravity

also increased, rising from 1.009 after mating to 1.014 at the beginning of the

sixth week (Ibrahim, 1990).

However none of these methods mentioned above are very practical under field

conditions.

2.3.1c Rectal Palpation

Diagnosis of pregnancy using rectal palpation can present some risks to the

females such as rectal tears but it is not considered detrimental to the foetus

provided the examination is carried out by experienced personnel and the uterus

is not over manipulated. The membrane slip test, described in cattle pregnancy

diagnosis, is not possible in camelidae because of the diffuse type of

placentation (Skidmore, 2000b). Therefore positive pregnancy diagnosis can

only be achieved if the CL and foetus are palpated.

8

The earliest sign of pregnancy is the persistence of the CL which continues to

grow until day 35 of pregnancy.It is usually soft, flabby and spherical in shape,

measuring about 25 mm in diameter, but becomes out of reach after about 90

days (Ibrahim, 1990; Skidmore, 2000b).

It is not until about day 45, that uterine changes due to pregnancy can be

detected by rectal palpation and the first sign is an increase in the diameter of

the left horn (Skidmore, 2000c). However, it is not until approximately the third

month of pregnancy that the gravid horn feels obviously bigger and softer than

the non-gravid horn and the uterus becomes more abdominal as the amount of

foetal fluid increases. The cervix is pulled forward and lies just at the brim of

the pelvis at 4 months, and by the fifth month the uterus is completely in an

abdominal position with a small degree of fluctuation, but the foetus is not

always palpable (Skidmore, 2000c).

From 6th month onwards, the foetus can be palpated; first by ballotment,

then the head and legs become easily palpable as the foetus starts its ascent. By

the 9th month, movement can be observed by inspection of the right flank of the

animal and external signs such as an enlarged abdomen and udder are visible

from about the 11th month. Precise estimation of the stage of pregnancy by

rectal palpation in the dromedary is not possible beyond 3 months because of

the absence of structures such as cotyledons and difficulty in reaching the foetus

in this species (Skidmore, 2000a).

Pregnancy diagnosis in the Bactrian camel by rectal palpation is similar to

that of the dromedary as noted by Skidmore (2000c). The first sign indicating

pregnancy is a persistent corpus luteum, but it is not until 45 days that the first

palpable changes in the uterus are noticed. At around this time the left horn of

the uterus increases in size and is almost continuous with the uterine body.

Between 2.5 - 3 months, the tip of the left horn is out of reach but the

bifurcation between the uterine horns can still be felt, and this is also out of

reach by 4 months. By 5 months the uterus is in an abdominal position and the

9

foetus can only be balloted in a small proportion of females. A fremitus can also

be detected on the left uterine artery in 75% of the females. By 8 months, the

foetus becomes more easily palpable and the artery fremitus is felt on both

sides. Foetal activity seems to increase from the 9th month and from 11th

months to term, the foetus is high and always palpable (Ibrahim, 1990).

2.3.1d Ultrasonography

Realtime ultrasonography, using a 3.5 or 5 MHz transrectal linear array

transducer is now regarded as the method of choice for detecting pregnancy and

monitoring early foetal development in large domestic animal species

(Skidmore, 2000b).

In camelids, pregnancy diagnosis by ultrasonography is possible as early as

17 days of gestation. This diagnosis is based on two main criteria: the

visualization of an embryonic vesicle and the presence of a corpus luteum. The

corpus luteum has to be present to confirm pregnancy status unless the female is

getting exogenous progesterone. In the early stages of pregnancy, the embryonic

vesicle is relatively difficult to visualize because it is elongated, the embryonic

fluid is dispersed and the uterus is relaxed. The vesicle is however, almost

always in the left horn and is best visualized at the tip of the horn where it is

likely to have accumulated most fluid (Skidmore, 2000a).

By day 17 of gestation, the embryonic vesicle appears as a star-shaped small

accumulation of fluid within the uterine lumen (Ibrahim, 1990). As the stage of

the pregnancy increases, the embryonic vesicle increases in size and becomes

more visible and elongated in longitudinal view of the uterus (Ibrahim, 1990) or

more round in cross section (Ibrahim, 1990). The embryo then becomes visible

between days 20 - 22 as a small, echogenic speck within the fluid fixed at one

pole of the vesicle (Ibrahim, 1990) and the heartbeat becomes discernible

between days 23 - 25 as a small fluttering within the echogenic speck of the

foetus.

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2.4 Gestation

Yasin and Wahid, (1957) reported a gestation period of 365 to 395 days in

dromedarian camel. It has a range of 370 to 405 days with an average of 388

days.The period of gestation for female calves averages at 390 days, while for

males 385 days.Lower limit for survival of foetus is 350 days. Calves born at or

just before this time may appear weak but otherwise normal for the first 24

hours post partum but then go into irreversible decline surviving only for 2 to 3

days. The gestation period of the Bactrian camel is 402 days (Chen and Yuang,

1979).Average pregnancy duration in the Bactrian is about 400 days.

2.5 Foetal Development

The camel embryo elongates quickly and soon protrudes from the left horn onto

the right uterine horn. Videoscopic studies showed allantochorion to be in left

horn at day 20 which extended into the right by day 25 (Skidmore, 2000a).Chen

and Yuang, (1979) show that, examination at day 44 showed the exposed

surface of the allantochorion to have a roughened and hazy appearance,

presumably due to the development of simple chorionic villi in the process of

implantation and placentation. When examined by the transmission electron

microscope, these villi are present on the trophoblast cells of embryos as young

as 7 days. At 44 days the tail and four limb buds are visible on the foetus and

the head, eye, umbilical cord and heart beat are discernible (Skidmore, 2000a).

At 55 days the allantochorion is thickened and spotty and presses on the internal

os of the cervix. The foetus is clearly seen to have rudimentary bones and a

more camel-like head and neck. Blood vessels are also more developed by now

(Skidmore, 2000a). When the FBL (foetus body length) is 1 to 10 cm, the

allantoic fluid volume is 1.5 litres. When FBL is 90 cm, fluid volume is 5 to 6

litres and finally reaches about 8.5 litres when the FBL is 100 to 107 cm and the

fluid resembles pale urine (Skidmore, 2000a). When the FBL is 0 to 10cm, the

volume of amniotic fluid is 13 ml. It increases to a volume of about 1 litre at 11

parturition. The fluid may be watery or cloudy due to the presence of meconial

debris. The extra close fitting of epidermal membrane becomes apparent when

FBL reaches 41cm. It closely envelops the foetus but leaves the orifices open to

the true amnion. It appears to be a major source for the relative ease of birth in

the camel (Skidmore, 2000a).

2.6 The camel digestive tract

Although camels ruminate, they are not true ruminants, as they lack the four

well-defined stomachs of the ruminants- the rumen, reticulum, omasum and

abomasum. The anatomy of all members of the Camelidae is considered to be

similar but most of the available data on the anatomy of the alimentary canal

have been obtained mainly from the Llama (Malie et al., 1987 ; Sonfada, 2008).

Lesbre (1903) and Leese (1927) stated that the camel has only three

compartments compared with the bovine's four compartments (Phillipson, 1979)

i.e. the missing compartment being the omasum, or third compartment. Hegazi

(1950) describes the camel as having the same four compartments as other

ruminants, but with the external constrictions between the omasum and

abomasum being less well defined in the camel. Sonfada, (2008) stated that the

Llama and guanaco stomachs consist of only three compartments.

The salivary glands of the camel have the same grouping as in cattle, but are

slightly darker in colour morphologically (Malie et al., 1987). The arrangement

of the glands, however, is different. The parotid glands are in the same position

in camels as in cattle, but in camels, the maxillary gland is located under the

parotid gland and jugular vein and over the pharyngeal lymph glands (Leese,

1927). The gland does not extend under the throat as it does in cattle. The

sublingual glands are smaller than those of cattle and are situated along the root

12

of the tongue. The buccal glands are well developed, and have dorsal and

ventral portions.

When comparing the mouth of the camel with that of cattle, the outstanding

differences are the very supple lips of the camel, the long prominent papillae,

and canine teeth. The oesophagus enters the rumen directly (Vallenas, et al.,

1972).

Much has been written about the internal anatomy of the camel stomach. The

stories of camels being slaughtered for water in the stomach (Bohlken, 1960)

led to the belief that the rumen, contained water cells (Leese, 1927). It was

assumed that these water cells were able to store water (Colbert, 1955; Hegazi,

1950; Leese, 1927, Schmidt-Nielsen, et al., 1956). This theory was disputed by

Vallenas, et al., (1972) the sac-like compartments were found in the caudal part

of the first compartment, the rumen. It has been suggested that the main

function of this glandular region of the fore-stomach is the rapid absorption of

solutes and water (Engelhardt and Rubsamen, 1979).

The suggestion that the glandular areas of the rumen contain accessory

salivary glands (Schmidt-Nielsen, et al., 1964) has not been substantiated. The

mucous layer, which covers the surface epithelium, may have a mainly

protective function (Engelhardt and Rubsamen, 1979). The bicarbonate

secretion of these glands (Eckerlin and Stevens, 1972) was not substantiated in

later experiments (Engelhardt and Rubsamen, 1978).

The camels forestomach is quite different. Although it is divided into three

parts, carrying the neutral names; compartments 1, 2 and 3, which are analogous

in function to the rumen, reticulum and abomasum respectively, it differs

anatomically in many respects from the forestomach of the Ruminantia.

Compartment 1 is not papillated nor strongly subdivided by muscular pillars

13

like the rumen, compartment 2 is not lined by the honeycomb structure of the

reticulum, and compartment 3 is not globular nor filled with laminae like the

omasum. Instead compartments 1 and 2 possess many deep and muscular

saccules lined by a smooth mucous epithelium and the tubular compartment 3

has longitudinal folds also lined by a mucous epithelium. Dehydration allows

them to forage in a much wider circle around watering points than cattle or

sheep. (Hoppe et al., 1975)

The surface of most of the first and second compartments is lined with a

non-papillated stratified, squamous epithelium (Vallenas, et al., 1972).

Glandular epithelia can be found in the ventral portions of the first two

compartments and covering the entire third compartment. The glandular area in

the first compartment is restricted to the bottom of the saccules, and this area

was found to be smaller in camels than in llamas. In addition, the pouches in the

camel's rumen are smaller than those in the llamas (Franco et al., 1993a).

In the adult llama, the contents of the first two compartments account for 10–15

percent of the animal's body weight, and the third compartment for a further 1–2

percent. It is therefore clear that the intestines must contain at least an additional

5 percent of the body weight (Engelhardt and Rubsamen, 1979). Then the total

contents of the camel's alimentary canal will account for 25 percent or more of

the animal's body weight. The liquid contents in the alimentary canal are the

source of water for the thirsty camel (Yagil and Etzion, 1979).

The function of the numerous endocrine cells in the stomach wall is

unknown but it is possible that these cells play an important role in the control

of the water and electrolyte balance of the camel during dehydration (Yagil and

Etzion, 1979).

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From the anatomical differences between the Camelidae and Bovidae it was

hypothesized that the physiological processes in the alimentary canal would also

differ (Bohlken, 1960). This is further emphasized by the difference in rumen

protozoan population between the camel and the sheep (Farid, et al., 1979).

Entodinium comprises 70 percent of the rumen protozoan population in both

animals, while Holotricha accounts for 10 percent of the population in sheep,

but was absent in camels. Epidinium is present in camels, but absent in sheep

rumen. The interesting fact was that during water restriction the Entodinium

population and total protozoan count decreased in sheep, but in camels the

Entodinium population increased and the total count remained virtually

unchanged.

2.7 Physiology of the digestive tract

The extremely mobile lips of the camel and the tough mucosa of the mouth

enable the animals to graze thorn bushes. The branches are stripped of their

leaves and the thorns present no problem.

In the mouth, the feed is mixed with saliva. The size and structure of the

salivary glands and the composition and flow of saliva from the glands are all

comparable with what is found in cattle (Engelhardt and Rubsamen, 1979).

Camel saliva is slightly hypotonic and the bicarbonate content is high

(Engelhardt and Rubsamen, 1979). When the animal is dehydrated a quarter of

body weight is lost. The parotid gland secretions then decline to a fifth of the

normal flow (Hoppe, et al., 1974). In the camel, as in all ruminants, the urea

formed from the protein metabolism is recycled to the stomach via the saliva. In

addition, the camel also obtains urea via the rumen epithelium itself (Houpt and

Houpt, 1968; Franco et al., 1992). The urea nitrogen is important as it is

assimilated into microbial protein which is a source of protein for the animal

following hydrolysis in the small intestines (Emmanuel, 1979).

15

Camel saliva was collected by allowing the animals to chew a clean dry

sponge and then examined for amylase content (Nasr, 1959). It was found that

the saliva has less amylase than that of man, pig or rat. This, however, is

different from cattle saliva which has no amylase (Schwart and Steinmetzer,

1924) whereas it is present in buffalo saliva (Nasr, 1959). Of all the glands, the

parotid glands have the most amylolytic activity, the submaxillary glands the

least and the sublingual glands none being mucous glands.

The contractions of the first and second compartments begin with a

contraction of the second compartment (Engelhardt and Rubsamen, 1979). This

is similar to the relationship of reticulum and rumen in cattle. In camels the

contents of the dorsal portion of the rumen are relatively dry. The ventral

portion of the cranial and glandular sacs in the reticulum, contain semi fluid and

watery ingesta (Ehrlein and Engelhardt, 1968; Ehrlein and Engelhardt, 1971;

Vallenas and Stevens, 1972).

Following the first single contraction of the reticulum, there is an immediate

contraction of the caudo-ventral region of the rumen and the glandular sacs

(Engelhardt and Rubsamen, 1979).The caudo-dorsal rumen contracts, followed

by the cranial sacs. This first set of contractions is followed by additional

contractions. The duration of a cycle is 1–2 minutes in the resting llama. The

rate increases when the animal feeds. The contractions and movements of each

cycle begin with a contraction of the reticulum. During contraction of this

compartment contents are moved from the reticulum to the caudal sac of the

rumen. From here part of the contents re-enter the reticulum and part goes into

the cranial sac, when the caudal sac contracts. When the cranial sac contracts,

its contents move back into the caudal sac. The motility of camel's fore-stomach

is radically different from that of cattle (Ehrlein and Engelhardt, 1968).

16

Rumination and eructation occur three to four times during every cycle

(Ehrlein and Engelhardt, 1971; Engelhardt and Rubsamen, 1979). Rumination

begins after the maximal contraction of the cranial rumen sac. Eructation takes

place near the peak of the caudal sac contraction.

In the camel's fore-stomachs, the volatile fatty acids (VFA) produced are

efficiently neutralized, probably by the glandular secretions as reported by

Vallanas and Stevens, 1972. A high concentration of VFA is found in the

Camelidae rumen (Maloiy, 1972; Vallenas and Stevens, 1972; Williams, 1963).

The various proportions of VFA are similar to those found in the rumen of cattle

(Maloiy, 1972). This suggests a great similarity in metabolism in the fore-

stomachs of camels as compared with other ruminants. Motility studies,

however, indicate that there is no precise similarity between the species

(Vallenas and Stevens, 1972) and were verified in comparative studies between

the camel and the Zebu (Maloiy, 1972). It was found that the camel has a lower

digestive efficiency of low quality hay, assumed to be caused by a more rapid

passage of food through the stomachs. Camels fed on straw (Yagil and Etzion,

1980a), however, not only grow better but digest the food better than most cows

(Personal observation). Digestibility of medium quality hay was no different in

the llama and in sheep (Franco et. al., 1992). In the digestive studies, the most

important finding was that the fluid volume of the fore-stomach and the rate of

outflow of fluid from the stomachs to the intestines were far greater in the camel

than in the Zebu (Maloiy, 1972). Water-deprived sheep lost far more rumen

water than camels (Farid, et al., 1979). Water dynamics in the alimentary canal

of the camel allow it to survive and produce during dry periods. The alimentary

water provides a reservoir that is tapped slowly in order to maintain a relatively

unchanged extra cellular volume and provides the fluid which dilutes the milk

(Yagil and Etzion, 1979; Yagil and Etzion, 1980a and b). The anatomical

17

differences between camels and other ruminants could account for the much

slower water turnover in the camel (Macfarlane, 1977).

Sodium chloride and VFA were found to be rapidly absorbed from the

rumen of the llama (Engelhardt and Sallman, 1972 and Franco et. al., 2004a).

The absorption rates in the llama were three times greater than the absorption in

sheep and goats. Absorption occurs mainly in glandular areas of the fore-

stomach. In the third compartment solutes and water are absorbed (Franco et.

al., 2004a; Ali and Wipper, 1979). The absorption rates of sodium, VFA and

water in this tubiform compartment were found to be far greater than the

absorption rate in the omasum of sheep and goats.

According to Engelhardt, et al. 1977 who said that the pH is very low in the

abomasum with an estimated segregation of water reaching 15 percent of the

amount that was absorbed in the omasum.

Comparative experiments carried out at the Desert Research Institute in

Egypt by Farid, et al., 1979 showed that the camel managed far better than

sheep on a low-protein, roughage diet and restricted drinking water regimen.

The sheep were allowed to drink every three days, the camels every twelve

days. The camels needed less water than the sheep for every unit of dry matter

consumed or per unit body mass. The camels also had a lower water intake than

Zebu cattle according to Maloiy, 1972. During deprivation studies, camels lost

far less water in urine and feces than did sheep (Farid, et al., 1979).

The camels digested dry matter and crude fibers better than the sheep. The

sheep, however, utilized crude protein better than the camels. The sheep

increased their feed intake during dehydration. The nitrogen metabolism of the

camel was superior, and this was even more apparent during water restriction

owing to the reduced nitrogen excretion in both faeces and urine. The sheep

18

were only able to reduce the nitrogen excretion in urine. The endocrine cells and

secretory cells in the rumen of the camel could account for the added nitrogen

retention capabilities (Engelhardt and Rubsamen, 1979). These data also

reinforce the theory of endocrine control of the alimentary canal, kidneys and

mammary glands affecting the water, salt and nitrogen metabolism (Yagil and

Etzion, 1979; Yagil and Etzion, 1980a and b), the ADH being responsible for

the flux of water and urea-nitrogen, the aldosterone for the flux of sodium.

The decline of nitrogen in both faeces and urine and the renal loss of sodium

allow the camel to maintain a relatively unchanged extra cellular volume. The

flow of water in the same direction with the urea-nitrogen accounts for the

lower amount of feacal and urinary water in the camel, when compared to the

Zebu steer (Maloiy, 1972) or sheep (Farid, et al., 1979). The camel has thus a

far more efficient nitrogen conservation mechanism than other ruminants

(Emmanuel, 1979). Even on a low-protein diet, nitrogen fixation in the rumen

and constant recycling of urea contribute significantly to a steady protein

synthesis. Twelve days of dehydration in the camel were equal to two days of

dehydration in sheep, as far as recycling of urea was concerned (Farid, et al.,

1979). The most pertinent result of the experiment was that the sheep did not

survive the experiments while the camels were unaffected.

Another important difference with other ruminants is that camels have a

significantly higher blood glucose level (Emmanuel, 1979). This may be

caused, in part, due to the anatomical differences in alimentary canals

(Engelhardt and Rubsamen, 1979), although VFA production was high in the

camel's fore-stomachs (Engelhardt and Rubsamen, 1979; Maloiy, 1972). Other

metabolic factors may play a role in the glucose handling by the camel and also

the hygroscopic properties of glucose may play a significant role as was

demonstrated in glucose-loading trials (Franco et al., 2004a).

19

Salt makes up a very important part of the camel's diet (Hartley, 1979).

Nomadic tribes are especially careful to ensure that the camel obtains sufficient

salty plants to eat. Salt is an important factor in the passage of water and urea in

the gut and the kidneys (Yagil and Etzion, 1979). Inadequate salt diet will lead

to less milk production in camels (Mares, 1954) which becomes even more

important when drinking water is restricted (Yagil and Etzion, 1980b).

2.8 Feeding habits

The camel covers large areas while browsing and grazing, and is continually

on the move, even if food is plentiful. Distance of 50–70 kilometers a day can

be covered (Newman, 1989). Camels in the Horn of Africa still range for their

food even though they are brought to graze on crop residues, such as Sorghum

stover, cotton stalks and sesame waste (Hartley, 1979).

The main forage is obtained from trees and shrubs. The diet is made up of

species of Acacia, Indigofera, Dispera, and Tribulus. The Acacia, Salsola and

Atriplex plants which contain the highest content of moisture, electrolytes and

oxalates are preferred (El-Amin, 1979). It is noteworthy that most of the

preferred plants are not readily eaten by other animals because they are thorny

and bitter. In Africa (Newman, 1989), shrubs and forages make up 70 percent of

the diet in winter and 90 percent in the summer.

2.9 Camel Physiological Adaptation

The physiological mechanisms, which allow the camel to survive periods of

over two weeks without drinking water and to eat the most unpalatable plants,

have to do with the conservation of water. It is of interest that severe desiccation

is tolerated. Up to 30 percent of its body weight can be lost by loss of water -

20

amounts that would be fatal in the case of other farm animals or even man

(Schmidt-Nielsen, 1964). Moreover, this loss can be replenished in a matter of

minutes (Yagil et al., 1974). The camel has the lowest water-turnover of all

animals (Macfarlane, 1977) and is able to regulate water and salt uptake from

the colon and their excretion from the kidneys (Yagil and Etzion, 1979). Camels

do not need to sweat to lower their body temperature, thus conserving water

(Schmidt-Nielsen, 1964). The camel increases its body temperature from 34°C

in the early morning to over 41°C in the late afternoon, at which time the

environment cools greatly. Thus the camel stores its heat during the day and

cools off by conduction and convection in the evening. The water-deprived

camel reduces its metabolism (Schmidt-Nielsen et al., 1956; Yagil et al., 1975)

which also conserves water.

21

CHAPTER 3

MATERIALS AND METHOD

3.1 AREA OF STUDY AND STUDY DESIGN

The study was conducted in Sokoto metropoly through daily visitation to

the Sokoto metropolitan abattoir for a period of six (6) months (January-June,

2010). The study involved an evaluation of thirty- five (35) digestive tract of

dromedary camel fetuses harvested from slaughtered female pregnant camels.

The uteri of female camels slaughtered were examined at post-mortem to

determine pregnancy as reported by Malie et al., 1987. Fetuses from gravid

uteri were recovered and transported to Veterinary Anatomy laboratory. Each

fetus was examined grossly to rule-out any abnormality such as congenital

abnormalities and trimming of fetal membranes; followed by sexing, ageing and

weighing of the fetuses.

3.2 FETAL AGE ESTIMATION

The age of the fetuses were estimated biometrically using a formula [GA

= (CVRL + 23.99)/0.366] as described by El-Wishy et al. (1981), where GA is

the gestational age (in days). This was done by taking the length of the crown

vertebral- rump length which is from the point caudal (posterior) fontanel to the

base of the tail following the vertebral curvature (in centimeters) using

measuring tape (Butterfly brand) to substitute in the above formula.

3.3 DISSECTION OF THE FETUS

Chibuzor (2006) method was used for the dissection of the fetuses. These

were done by placing the fetus on dorsal recumbency and a mid-ventral skin

incision (linear alba) at abdomino-pelvic region across the thoracic region up to

the neck at the inter-mandibular space was made. The entire digestive tract and

22

individual segments of the system (tubular and accessory) was dissected out,

identified and the morphometric values were recorded.

3.4 MORPHOMETRICAL INVESTIGATION

The morphometrical procedures employed in this study involved dividing

the segment of the digestive tract into eleven components, namely; oesophagus,

smooth part of the rumen (dorsal), coarse part of the rumen (ventral), reticulum,

abomasum, duodenum, jejunum, ileum, caecum, colon and rectum (Luciano et

al.,1979). The length and diameter of the oesophagus, duodenum, jejunum,

ileum, caecum, colon and rectum were measured and dissected out. The length,

width and volume of the rumen, reticulum and abomasum were also measured.

Observing and measuring the crown vertebral-rump length (CVRL) in

centimeter. This was done using measuring tape (butterfly brand) by placing the

free-end at the anterior fontanel and running it over the vertebral column to the

base of the tail.

Measuring the weight of the fetuses (FW), weighing the entire digestive system

(D/S), weighing the accessory digestive system (ADS) and weighing the

digestive tract (D/T) using compression spring balance (AT-1422), size C-1,

sensitivity of 20 kg X 50g in Kilogram.

Measuring the length of the various segments of the D/T of each fetus using

butterfly measuring tape in centimeter; and Measuring the diameter of the

various segments of the D/T of each fetus using divider (for smaller segments)

and meter ruler (for bigger segments) in centimeter.

Measuring the volume of the stomach using water displacement technique

(Archimedes’ principle) in cubic centimeter (Luiz and Jose, 2005).

23

3.5 HISTOLOGY

Two cubic centimeters (2 cm3 ) of each segment of the GIT was trimmed

and kept in labeled bottle containing 10% formal saline as a fixative (Barbara

and John, 2000); the tissues were then kept to stay on the table for two days to

allow proper fixation. Thereafter, the tissues were processed using normal H &

E preparation (Drury et al., 1967). (Appendix II).

3.6 PHOTOMICROGRAPHY

The prepared sectioned slides were examined and photographed using

motic camera 2.0 with 1.30M pixel (digital motic cam Camera at different

magnifications of the microscope).

3.7 DATA PRESENTATION AND STATISTICAL ANALYSIS

Data obtained were presented in mean + standard error of mean and

student-t test was employed to analyse the data using SPSS version 17.0

statistical soft ware.

24

CHAPTER FOUR

RESULTS

4.1 Fetal Study

Of the thirty five (35) fetuses at different gestational age used for the

study, twelve (34.3%) were females while twenty three (65.7%) were males.

From the observations, 13(37.14%) fetuses belong to first trimester, 11(31.42%)

belong to second trimester and 11(31.42%) belong to third trimesters of

pregnancy respectively. The mean crown vertebrate-rump length (CVRL)

ranges from 20.06 ± 3.0 cm for fetuses of first trimester, 60.27± 4.0 for fetuses

of second trimester and 103.83 ± 6.0 cm for fetuses of third trimester as shown

in table 1.

The weight of the camel fetus at all three phases of gestation (first, second and

third trimesters) were observed to increase as the animal advanced in age.

The mean body weight of the foetus ranges from 1.40 ± 0.06 kg, 6.10 ±

0.05 kg and 17.87 ± 0.6 cm at first, second third trimester respectively. The

mean weights of the entire digestive system at first, second and third trimester

were 0.80 ± 0.07 kg, 2.13 ± 0.04 kg and 4.86 ± 0.08 kg respectively. The mean

weights of the digestive tract at first, second and third trimester of age were 0.53

± 0.07 kg, 1.03 ± 0.05 and 2.43 ± 0.07 kg respectively (Table I).

4.2 Morphology of the digestive tract (D/T)

Fetuses considered to be in the first trimester (0 -4 months) had physical

features as, the abdomen appeared transparent with some organs appearing dark,

an indentation of the eye buds, ear buds and jugular veins were prominent. The

calvaria were very soft and transparent. The CVRL ranged from 13 – 40 cm,

while the weight ranged from 0.8 kg to 2.3 Kg. (Plate 1)

Fetuses at second trimester (4 – 8 months) have well developed eyes and ears.

Hairs were on the lower eyelid and ear margins. Hairs developed on the lips

25

(upper and lower), the calvarium was hard but soft at the fontanels (cranial and

caudal), Mammary buds and vulva was prominent in female at this stage. The

scrotal sacs became more prominent with structures being palpable. The CVRL

and body weight ranged from 40 to 80 cm and 4 to 9 kg respectively (Plate 2).

The fetuses of third trimester (8 – 12 months) had their whole body covered

with short hair initially except at the inner thigh. The hair continued to grow as

the fetus advanced in age. The skull at this level was strong, on palpation. The

CVRL at this stage was above 80cm (85-120), while the weight of the fetus

ranged from 11 to 29.15 kg (Plate.3).

26

Plate 1: Photograph showing camel fetus at first trimester with transparent abdominal

wall, rudimentary ear canal opening and eye indentation X 75

27

Plate 2: Photograph showing camel fetus at 2nd trimester with thick prominent skin (A)

and hair on the upper eyelid (B) and head region. X 75

28

Plate 3 Photograph showing camel fetus at 3rd trimester with short densely distributed

hair (whitish) all over the body with very small areas of alopecia (black

arrow). X 75

29

The camel digestive tract comprises of the oesophagus, stomach {rumen

(coarse and smooth), reticulum and abomasum}, small intestine (duodenum,

jejunum and ileum), and large intestine (caecum, colon and rectum), (Plate 4,5

and 6).

In the first trimester fetuses, the digestive tract was observered to have all the

component i.e. oesophagus, stomach {rumen, reticulum and abomasum}, small

intestine and large intestine; however, there was no clear demarcation between

segments of the small intestine i.e. duodenum, jejunum and ileum as shown in

plate 7 and 10.

The digestive tract of the second trimester fetuses showed to have clear

demarcation of the small intestine in to duodenum, jejunum and ileum and

prominent demarcation of the stomach in to dorsal smooth and ventral coarse

parts as shown in plate 8 and 11.

As shown in the plate 9 and 12, fetuses of the third trimester had similar

developing structures as in that of the second trimester fetus. In addition, all the

components are highly developed with segment filled with muconeum.

30

Plate 4: Photograph showing abdominal cavity organs of camel fetus at first trimester

insitu X 75

31

Plate 5: Photograph showing abdominal cavity organs of camel fetus at second

trimester insitu X 75

32

Plate 6: Photograph showing abdominal cavity organs of camel fetus at third trimester

insitu X 75

33

Plate 7: Photograph showing the entire digestive tract of camel fetus at first trimester

X 75

34

Plate 8: Photograph showing the entire digestive tract of camel fetus at second

trimester X 75

35

Plate 9: Photograph showing the entire digestive tract of camel fetus at third trimester

X 75

36

Plate 10: Photograph showing the entire digestive tract of camel fetus at first trimester

with no clear demarcation in the small intestine (duodenum, jejunum and ileum) (A),

caecum (1), colon (2) and rectum (3)

37

3

2

1

A

Plate 11: Photograph showing the entire digestive tract of camel fetus at second

trimester with clear demarcation in the stomach and small intestine, oesophagus (1),

reticulum (2), rectum (3), colon (4), abomasum (5), coarse part of the rumen

(6) ,smooth part of the rumen (7), duodenum (8), jejunum (9), ileum(X), caecum (Z).

38

8

4

52

9

z

X

1

3

6

7

Plate 12: Photograph showing the entire digestive tract of camel fetus at third

trimester showing oesophagus (A), ,smooth part of the rumen (B), coarse part of the

rumen (C), reticulum (D), abomasum ((E), duodenum (F), jejunum (G), ileum (H),

caecum (I), colon (J) and rectum (K).

39

H

K

AEF

B

CD

G

J

I

4.3 Morphometric values of the digestive tract (G I T).

From the study, the digestive tract index ranges from 37.86 at the first

trimester to 13.60 in third trimester, while the digestive system index ranges

from 57.14 at the first trimester to 27.20 in third trimester fetus as shown in

Table I.

Morphometrically, the digestive tract was divided into oesophagus,

stomach; rumen, reticulum and abomasum, small intestine; duodenum, jejunum,

and ileum, large intestine; caecum, colon and rectum as shown in plate 10, 11

and 12.

As shown in table II, the mean lengths of the oesophagus ranges from 13.83

± 2.33cm in first trimester to 52.13 ± 2.67cm in the third trimester. The mean

lengths of the rumen, reticulum and abomasum ranges from 7.47 ± 1.67 cm,

1.97 ± 0.43 cm and 12.67 ± 2.33 cm at first trimester to 20.75 ± 1.33 cm, 6.93 ±

0.27 cm and 25.75 ± 0.37 cm at third trimester respectively.

As shown in plate 7 and 10, the small intestine at first trimester were found

not to have any clear demarcation to show duodenum, jejunum and ileum; the

entire small intestine was found to be 76.00 ± 3.00 cm at first trimester and

showed clear demarcation at second and third trimesters; with the duodenum,

jejunum and ileum found to be 66.00 ± 2.00 cm, 139.50 ± 3.00 cm and 75.00 ±

3.00 cm in the third trimester respectively.

There was clear demarcation between the components of the large intestine

in all the phrases of gestation as shown in plate 7-12. The mean lengths of

caecum, colon and rectum ranges from 9.33 ± 0.30cm, 65.00 ± 3.00cm and

8.33 ± 0.30cm at the first trimester to 40.75 ± 3.33cm, 164.75 ± 3.00cm and

30.00 ± 2.33cm in the third trimester respectively as shown in table II.

As shown in the table III, the mean diameter of the oesophagus ranges from

0.30± 0.04 cm in the first trimester to 1.30± 0.80 cm in the third trimester. The

mean width of the rumen, reticulum and abomasum ranges from 1.93 ± 0.17cm,

1.00 ± 0.40cm and 1.33 ± 0.20cm in the first trimester to 11.50 ± 1.00cm, 4.05

40

± 0.20cm and 4.25 ± 0.30cm in the third trimester respectively. The mean

diameter of the small intestine at first trimester was 0.30 ± 0.01cm while at third

trimester, the mean diameter of the duodenum, jejunum and ileum were 1.18 ±

0.03cm, 1.20 ± 0.03cm and 1.23 ± 0.03cm respectively.

The mean diameter of the caecum, colon and rectum ranges from 0.33 ±

0.03cm, 0.33 ± 0.01cm and 0.40 ± 0.04cm at first trimester to 2.55 ± 0.03cm,

1.60 ± 0.03cm and 3.28 ± 0.03cm in the third trimester respectively.

The mean volumes of the entire stomach (rumen, reticular and

abomasum) ranges from 136.67 ± 8.30 cm3 at first trimester to 353.33 ± 6.50

cm3 at third trimester as shown in table II.

Table I: Mean CVRL, Mean fetal weight (FW), Weight of the Digestive system (D/S)

and mean weight of the Digestive tract (D/T), of fetuses at various

trimesters

Parameters First Trimester Second Trimester Third Trimester

Number of sample (N) 13 11 11

CVRL (mean±SEM) 20.06 ± 3.0 60.27 ± 4.0 103.83 ± 6.0

Fetal weight (FW) (Kg) (mean±SEM)

1.40 ± 0.06a 6.10 ± 0.5b 17.87 ± 0.6c

W/DS (Kg) (mean±SEM)

0.80 ± 0.07a 2.13 ± 0.04b 4.86 ± 0.08c

W/DT (Kg) (mean±SEM

0.53 ± 0.07a 1.03 ± 0.05b 2.43 ± 0.07c

D/S index (%) 57.14 34.91 27.20

D/T index (%) 37.86 16.89 13.60

abc: means on the same row with different superscripts are significantly different (P < 0.05).

41

Table II: Mean Lengths of the different segment of the Digestive tract (D/T and

volume of the stomach compartment at various trimesters.

Parameters First Trimester Second Trimester Third Trimester

Oesophagus(cm)

(mean±SEM)

13.83 ± 2.33a 31.83 ± 2.00b 52.13 ± 2.67c

Stomach (cm)

Rumen (mean±SEM) 7.47 ± 1.67a 13.83 ± 1.67b 20.75 ± 1.33c

Reticulum (mean±SEM) 1.97 ± 0.43a 3.47 ± 0.47b 6.93 ± 0.27c

Abomasum(mean±SEM)

Volume (mean±SEM)

( cm3)

12.67 ± 2.33a

136.67± 8.30a

18.33 ± 0.40b

283.33± 6.50b

25.75 ± 0.37c

353.33± 7.65c

Small intestine (cm)

Duodenum(mean±SEM) 44.83 ± 2.67b 66.00 ± 2.00c

Jejunum(mean±SEM) 76.00 ± 3.00 111.67 ± 3.33b 139.50 ± 3.00c

Ileum (mean±SEM) 59.33 ± 2.67b 75.00 ± 3.00c

Large intestine (cm)

Caecum (mean±SEM) 9.33 ± 0.30a 28.00 ± 3.00b 40.75 ± 3.33c

Colon (mean±SEM) 65.00 ± 3.00a 110.33 ± 3.00b 164.75 ± 3.00c

Rectum (mean±SEM) 8.33 ± 0.30a 18.00 ± 2.00b 30.00 ± 2.33c

abc: means on the same row with different superscripts are significantly different (P < 0.05).

42

Table III: Mean widths/ diameters of the Digestive tract segments at various

trimesters.

Parameters

First Trimester

Second Trimester Third Trimester

Oesophagus(cm)

(mean±SEM) 0.30± 0.04 a 0.70± 0.20b 1.30± 0.80c

Stomach (cm)

Rumen (mean±SEM) 1.93 ± 0.17 a 6.43 ± 0.43 b 11.50 ± 1.00c

Reticulum(mean±SEM) 1.00 ± 0.40 a 2.63 ± 0.30 b 4.05 ± 0.20c

Abomasum(mean±SEM) 1.33 ± 0.20 a 3.00 ± 0.23 b 4.25 ± 0.30c

Small intestine (cm)

Duodenum (mean±SEM) 0.80 ± 0.05b 1.18 ± 0.03c

Jejunum (mean±SEM) 0.30 ± 0.01 0.83 ± 0.02b 1.20 ± 0.03c

Ileum (mean±SEM) 0.80 ± 0.03b 1.23 ± 0.03c

Large intestine (cm)

Caecum

(mean±SEM)

0.33 ± 0.03 a 1.13 ± 0.03b 2.55 ± 0.03c

Colon (mean±SEM) 0.33 ± 0.01 a 0.77 ± 0.02 b 1.60 ± 0.03c

Rectum

(mean±SEM)

0.40 ± 0.04a 1.00 ± 0.03 b 3.28 ± 0.03c

abc: means on the same row with different superscripts are significantly different (P < 0.05).

43

4.4 HISTOLOGY

Histologically, observation of the tissues in this study revealed a complete

structure of the tubular organ. The oesophagus was found to consist of four

layers namely: (1) Tunica mucosa, (2) Tunica sub mucosa, (3) Tunica

muscularis and (4) Tunica adventitia /serosa. At the first trimester, only three

layers were identified, that is; Tunica mucosa, Tunica muscularis and Tunica

adventitia. At the beginning of the second trimester, the orientation changed,

resembling that of the adult with all the four layers prominent i.e. Tunica

mucosa, Tunica sub-mucosa, Tunica muscularis and Tunica adventitia. At the

third trimester, the Oesophageal gland appeared prominently in the tunica sub-

mucosa resembling that of the adult camel (slide 1).

The Tunica mucosa epithelium was simple squamous epithelium at first

trimester and began to change at second trimester to stratified squamous

epithelium. At third trimester, the epithelium was keratinized stratified

squamous epithelium with the oesophageal (sub-mucosal) glands appearing to

be prominent and abundant.

The tunica muscularis showed clearly a single layer at second trimester

while at third trimester; both inner circular and outer longitudinal layers

appeared. The tunica adventitia was typical. Blood vessels and nerve fibres

became well visible at the tunica muscularis and sub-mucosa in third trimester

fetuses (slide 1).

The proximal compartment of the camel stomach was the rumen and grossly

is divided into two parts at first trimester; the dorsal smooth part and the ventral

coarse part.

The ventral coarse part showed a progressive fold at the tunica mucosa

and sub-mucosa with advance in gestation. In the first trimester, there was no

clear difference in the tunica mucosa epithelium. At the second trimester, it

showed clearly the appearance of stratified squamous epithelium with numerous

blood vessels in the tunica sub-mucosa. The tunica muscularis showed clear

44

demarcation of inner circular and outer longitudinal arrangement. At third

trimester, the surface of the tunica mucosa showed numerous projections or

elevation and depression resembling the intestine. The tunica serosa was typical

in both trimesters as shown in slide 2.

The dorsal smooth part showed fewer folds than the ventral coarse part

with only three distinct layers in first trimester. Tunica mucosa epithelium at

first trimester was simple squamous epithelium, the tunica muscularis did not

show any division into inner circular and outer longitudinal, while at second

trimester the tunica mucosa epithelium was of typical stratified squamous

epithelium and the tunica muscularis was composed of inner circular and outer

longitudinal layers. At third trimester, the epithelium was keratinized stratified

squamous epithelium with numerous blood vessels in the tunica sub-mucosa

and tunica muscularis. There was no much secretory or defensive cell in the

sub-mucosa as shown in slide 3.

As shown on the slide 4, the reticulum showed similar disposition with

the rumen i.e. with two district areas. The nature of epithelium, the tunica

mucosa, tunica sub-mucosa, tunica muscularis and tunica serosa had the same

disposition but the fold and projection in the surface of the ventral coarse part

were much prominent than in the rumen.

The abomasum showed an abrupt change in the orientation with a typical

four basic layers. The tunica mucosa epithelium at second trimester showed

stratification with tunica muscularis being composed of inner circular layer and

outer longitudinal layer. At the 3rd trimester, the epithelium in the tunica mucosa

became simple columnar epithelium with a clear distinct tunica muscularis

layer. Numerous lymphatic’s cells, blood vessels and nerves were found in the

tunica sub-mucosa at both 2nd trimester and 3rd trimester fetuses as shown in

slide 5.

The small intestine showed four basic layers too. The surface of the

epithelium showed numerous villi proving more extensive in 2nd and 3rd

45

trimesters in both segments of the small intestine. The duodenum, as shown on

Slide 6, showed numerous projections called the villi with less prominent crypts

in both second and third trimester of age. The villi showed numerous branching

and taller in the jejunum (slide 7) than in the duodenum (slide 6) and ileum

(slide 8).

The tunica muscularis was typical at 2nd and 3rd trimesters having both

inner circular and outer longitudinal layers. At 1st trimester, the tunica

muscularis did not differentiate in to these two parts (slide 6, 7 and 8). All the

four layers were well developed at 3rd trimester fetuses. There were numerous

blood vessels in the tunica sub-mucosa and tunica muscularis of the small

intestine (slide 6, 7, and 8).

The large intestine showed a typical appearance of four (4) basic layers:

the tunica mucosa, tunica sub-mucosa, tunica muscularis and tunica serosa.

There was present of villi in the caecum and colon (slide 9).The epithelium of

the caecum, colon and rectum at 1st trimester showed stratification (pseudo-

stratified epithelium) with tunica muscularis comprising only of single

longitudinal layer (slide 9, 10 and 11). The tunica sub-mucosa of both caecum

and colon had numerous aggregates of lymphatic tissues at both 2nd and 3rd

trimesters. The tunica muscularis showed distinct area of inner circular and out

longitudinal layer in both 2nd and 3rd trimesters, (slide 10 and 11).

A distinct layer of skeletal muscle in the rectum of 2nd and 3rd trimester

fetuses was observed. Numerous aggregate of lymphatic tissues were found in

the sub-mucosa layer of the rectum as shown in slide 11.

46

4.5 HISTOLOGICAL OBSERVATION

A

B C

Slide 1: Transverse section of the oesophagus showing Epithelium (Black arrow),

Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red

arrow), external (longitudinal) layer of tunica muscularis (Green arrow),

serosa (White arrow), G-Oesophageal gland, A- 1ST Trimester, B- 2nd

Trimester, C- 3rd Trimester, 150x

47

G

G

G

A B

C

Slide 2: Transverse section of the coarse rumen showing Epithelium (Black arrow),

Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red

arrow), external (longitudinal) layer of tunica muscularis (Green arrow),

serosa (White arrow), V-Blood vessel, A- 1ST Trimester, B- 2nd Trimester,

C- 3rd Trimester 150 x.

48

V

A

B C

Slide 3: Transverse section of the smooth rumen showing Epithelium (Black arrow),

Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red

arrow), external (longitudinal) layer of tunica muscularis (Green arrow),

serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester, 150

x.

49

A

B C

Slide 4: Transverse section of the reticulum showing Epithelium (Black arrow),

Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red

arrow), external (longitudinal) layer of tunica muscularis (Green arrow),

serosa (White arrow) A- 1ST Trimester, C- 3rd Trimester, 150 x.

50

A B

C

Slide 5: Transverse section of the Abomasum showing Epithelium (Black arrow),

Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red

arrow), external (longitudinal) layer of tunica muscularis (Green arrow),

serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester,

150 x.

51

A

B C

Slide 6: Transverse section of the duodenum showing Epithelium (Black arrow),

Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red

arrow), external (longitudinal) layer of tunica muscularis (Green arrow),

serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester, 150

x.

52

A

B C

Slide 7: Transverse section of the Jejunum showing long villi with branching of microvilli,

Epithelium (Black arrow), Submucosa (Blue arrow), internal (circular) layer of

tunica muscularis (Red arrow), external (longitudinal) layer of tunica muscularis

(Green arrow), serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd

Trimester, 150 x

53

A

B C

Slide 8: Transverse section of the Ileum showing Epithelium (Black arrow),

Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red

arrow), external (longitudinal) layer of tunica muscularis (Green arrow),

serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester,

150 x.

54

A B

C

Slide 9: Transverse section of the Caecum showing Epithelium (Black arrow),

Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red

arrow), external (longitudinal) layer of tunica muscularis (Green arrow),

serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester,

150 x.

55

A

B C

Slide 10: Transverse section of the Colon showing Epithelium (Black arrow),

Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red arrow),

external (longitudinal) layer of tunica muscularis (Green arrow), serosa (White arrow)

A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester, 150 X.

56

A

B C

Slide 11: Transversal section of the Rectum showing Epithelium (Black arrow),

Submucosa (Blue arrow), internal (circular) layer of tunica muscularis (Red

arrow), external (longitudinal) layer of tunica muscularis (Green arrow),

serosa (White arrow) A- 1ST Trimester, B- 2nd Trimester, C- 3rd Trimester, 150

x.

57

CHAPTER FIVE

5.0. DISCUSSION.

5.1 GENERAL OBSERVATIONS

The current study attempted to increase the information about the normal

development of the camel digestive tract. From the results obtained in the

study, it was observed in general that there was increase in body weight, organ

weight and individual segment of the digestive tract in the fetuses with

advancement in gestation period. This is in agreement with the observations of

Warner, 1958, Jamdar and Ema, 1982 and Sonfada, 2008. They observed

obvious body weight increase with advancement of gestation period in different

specie of animals. Danlardi and Riddell, 1991 have also highlighted that

nutritional status and health condition of the dam play a vital role in the

development of the fetus hence increase in weight of the fetus.

5.1 Morphology

From the study, camels’ digestive tract observed comprises of the

oesophagus, the rumen (coarse and smooth parts), the reticulum, abomasum,

duodenum, jejunum, ileum, caecum, colon and rectum. This was inline with the

observations of many scholars (Luciano et al., 1979 and Sukon, 2009) but

contrary to the findings of Lesbre, 1903 ; Mayhew and Ctruz-orive, 1974 who

reported that during the development of the camel fetus, the abomasum had a

constriction or demarcation that showed a primitive omasum but disappear at

post-natal period.

The long and narrow oesophagus with relatively slight variation in the

diameter with regions observed in the study was in line with the findings of

Luciano et. al, 1979 and Sukon, 2009 who divide the regions of the oesophagus

in to five segments due to the size and shape of the oesophagus. The variation in

the diameter of the oesophagus at the developmental stage morphologically,

was in line with the finding of Luciano et al., 1979, who study the digestive

58

tract of Llama at prenatal stage and concluded that there was increase in

thickness in the oesophagus with advancement in gestation.

The division of the camel stomach into 3 major compartments i.e. rumen,

reticulum and abomasum as there was no omasum; in line with the

characteristic of the true ruminants with four chambered stomach is in line with

the finding of Luciano et al., 1979 and Belknap, 1994, who observed that the

abomasum was a long narrow tube-like structure with no constriction and

contrary to the findings of Mayhew and Ctruz-orive, 1974 who reported that

during the development of the camel fetus, the abomasum had a constriction or

demarcation that showed a primitive omasum but disappear at post-natal period.

The absence of demarcation or distinguishing features of small intestine at

first trimester into duodenum, jejunum and ileum grossly, but clearly

distinguishable at second and third trimesters was contrary to that of Llama

which showed clear difference in these segments at the middle of the first

trimester (Belknap, 1994). Nasr, 1959 reported that, most of the monogastric

mammals including rodents with short gestational periods show differentiation

of the small intestine into duodenum, jejunum and ileum, from the middle first

trimester. The gradual transformation in both size and shape of the small

intestine based on age distribution in camel fetus observed was in line with the

finding of Luciano et al., 1979 who reported that, in llama, the duodenum was

short compared to the other segments and the jejunum at first trimester showed

small number of coiling compared to second and third trimesters.

The differentiation of the large intestine into caecum, colon and rectum as

observed from the study from the early first trimester with a gradual increase in

size and shape was observed in most specie (llama, guanaco, buffalo, dog cat

sheep and pig). The diameters of ileum in small intestine and colon in the large

intestine were found to be almost identical at both first and second trimesters;

there was no report on such finding in any specie of animal. The moderately

long rectum observed in the study was in line with that of Llama (Belknap,

59

1994) and Guanaco (Cummings et al., 1972), when compared to the features

given for ruminant and other monogastric animals and this may likely be in line

with the adaptive features of desert animals.

5.2 MORPHOMETRIC STUDY.

The observed increase in weight, length and diameter of various segments

of the digestive tract in the study is in line with the findings of bovine, porcine

and caprine specie by Franco et al., 1993a; Bal and Ghoshal (1972) and

Georgieva and Gerov, (1975) respectively. The digestive tract indices observed

in the study showed significant difference in relation to the age (P≤ 0.05) and

the indices were decreasing with advancement in gestation (body development)

and similar developments were seen in the study of Georgieva and Gerov,

1975 ; and Bal and Ghoshal 1972 in pocine specie.

The progressive increase in length and diameter of the oesophagus based on

gestation period is in line with the observations of Belknap, 1994 and Franco et.

al.,1993c on the oesophagus of Llama and showed to have significant difference

in relation to the age (P≤ 0.05) The observed increase in lengths and widths of

the rumen, reticulum and abomasum in this study showed to have significant

difference in relation to the age (P≤ 0.05) and is in line with the observations of

Franco et. al., 1993a, Franco et al., 1993b and Franco et. al., 1993c; who study

the developmental anatomy of red deer stomach based on gestational period.

A geometrical increase in length and diameter of the various segments of

small intestine and large intestine as observed in this study showed to have

significant difference (P≤ 0.05) with advancement in gestation and was in line

with the findings of porcine (Vivo and Robina, 1991), bovine (Franco et. al.,

1993c and Knospe, 1996), buffalo (Asari et. al., 1985) and Llama (Belknap,

1994).

5.3 HISTOLOGY

In accordance with the finding of Hebel, 1960, Mutoh and Wakuri, 1989,

and Vivo et al., 1990 who studied the comparative Anatomy of the digestive

60

tracts of pig, cattle, sheep, dog and cat; red deer, goat; and cattle respectively,

the oesophagus was found to consist of four layers namely (1) Tunica mucosa,

(2) Tunica sub mucosa, (3) Tunica muscularis and (4) Tunica advantatia /serosa.

Franco et al., 2007 added that the development of this layers based on stages of

development was clearly in quick succession, but from the result, all the four

layers were developed at first trimester of age. The presence of highly

developed oesophageal glands within the sub mucosal layer with a prominent

tunica muscularis at second and third trimester was in line with the findings of

Sukon, 2009 on the Llama and Hebel, 1960 on the sheep and cattle. This may

likely be as a result of the nature of food of the animals.

The appearance of the keratinized stratified squamous epithelium at the

dorsal (smooth) part of the rumen and a columnar epithelium with deep tubular

glands on the ventral (coarse) part, which was referred to as the glandular area,

may likely be the water cell as observed by Sukon, 2009 on the Llama stomach.

The absence of glands /secretory cells in the sub mucosa of the smoother part of

the rumen and reticulum was also in line with that of the guanaco and Llama by

Luciano et. al.,1979 and Sukon, 2009 respectively. The structural appearance of

the rumen and reticulum in both dorsal and ventral portions were found to be

similar. The presence of columnar epithelium at the coarse portion of the rumen

and reticulum indicate a high ability of water absorption in the animal in

keeping with the adaptive features of desert animals. The above finding was in

agreement with the findings of Luciano et. al., 1979 on guanaco and Llama but

is contrary to the finding of Asari et al., 1980 on bovine, Hayward, 1967 on

rabbit and Franco et al., 2007 on porcine.

The small intestine of camel showed clear resemblance to that of a

tubular organ and conformed to organs with four basic layers. One of the most

characteristic features of small intestine is the presence of villi; the nature of

villi in camel showed a conical shape appearance. The villi in duodenum were

almost similar in appearance with these of the ileum, but those of the jejunum

61

were taller and numerous. All the features showed improvement with

advancement in gestation. This finding was in line with those of Luciano et al.,

1979 and Sukon, 2009 on Llama. The development of duodenum, jejunum and

ileum at first, second and third trimesters showed clear improvement in

succession from first, second and third trimesters with the third trimester

resembling that of an adult camel. The above finding was in line with that of

Sukon, 2009 but contrary to the finding of Hayward, 1967 on rabbit.

From the research work, the development of camels’ large intestine

showed differences with the result documented for sheep, goat, dog and horse

by having villi in the caecum and colon. This may be the reason for the

characteristic of dry faeces of camel following more absorption of fluid in the

area.

62

CHAPTER SIX: CONCLUSION AND RECOMMENDATIONS

6.1 Conclusion

The development of the camels’ digestive tract based on embryonic

stage was morphologically in succession.

From the study, the small intestine at first trimester was not divided in

to duodenum, jejunum and ileum morphologically.

The gross anatomy and morphometrical parameters of GIT were

established.

The developmental features of the camels’ digestive tract showed

similarity with that of features reported for Llama.

Several unique features of developing digestive tract prove adaptive

features of the animal to its environment and mode of feeding.

The camels’ stomach had little/few similarities with true ruminant

based on development.

The information obtained in this study will serve as a base-line data for

the specie in this environment.

6.2 Recomendation

Ultrastructural studies of the gastrointestinal tract of the developing

camel are recommended for detailed investigation.

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Appendix I: Materials

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- Polythene bag.

- Hand glove.

- Measuring tape.

- Electrical weighing balance.

- Specimen container.

- Bone cutter.

- Microtome.

- Oven.

- Water bath.

- Refrigerator.

- Glass slides.

- Cover slips.

- Microscope.

- Wooden chocks.

- Specimen bottles.

- Forceps

- Surgical blade & holder

- Seeker

- L-mould and plate

- Chemical balance

- Watch glass

- Measuring cylinder

- Beakers.

- Haematoxylin.

- Eosin.

- Glycerol.

- Distilled water.

- Paraffin wax.

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Appendix II: TISSUE PROCESSING

Tissues are fixed in 10% formal saline for 3-4 days. Tissues were trimmed

to 5-7 mm thick and wash in running tap water for 2 hours. Rinse in distilled

water and dehydrated through ascending grades of ethanol (35%, 50%, 70%,

95% and absolute ethanol). There were pre-cleared in xylene + Ethanol and

cleared in xylene. Tissues were transferred to molten paraffin wax + xylene in

the oven for filtration/impregnation. Tissues were embedded in pure paraffin

wax and allowed to solidify. Embedded block of tissues were mounted on the

wooden chocks and trimmed on microtome. Ribbons of section cut at 5 μm

thickness were placed on warm water in the water bath at 45oC to flatten the

tissues and picked on smeared albumin slides and dried in the oven at 45oC.

HAEMATOXYLIN STAINING

Chemical composition

- Haematoxylin 2g,

- Glycerol 200ml

- Potassium alum 20g

- Absolute alcohol 200ml

- Distilled water 400ml

- Acetic acid 10ml

- Sodium iodide 0.6g

PREPARATION

Haematoxylin is dissolved in absolute alcohol and Dissolve the potassium

alum in distilled water using heat if necessary. Mix the two solutions and add

glycerol then stir. Quickly add the sodium iodide to ripen the solution, allow

stand for 30 minutes and add the acetic acid to sharpen the nuclear stain. Filter

before use.

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PROCEDURE

Dewax and re-hydrate the sections tissue in water. Stain in

haematoxylin for 10 minutes; wash off the excess stain in running tap water.

Rinse in distilled water and differentiate in acid alcohol for 30 seconds. Blue

nuclei in alkaline alcohol for 5 minutes. Counter stain in eosin for 5 minutes.

Dehydrate in absolute alcohol and clear in xylene and mount in synthetic resin.

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