TECHNICAL BULLETIN 40 SSN 0070-2315

REQUIREMENTS OF THE CHIOS SHEEP

1. REQUIREMENTS FOR MAINTENANCE AND LATE PREGNANCY

S. Economides , .

. .

,. , . ~

AGRICULTURAL RESEARCH INSTITUTE MINISTRY OF AGRICULTURE AND NATURAL RESQURCES

NICOSIA

O C T O B E R 1 9 8 1

CYPRUS

THE ENERGY REQUIREMENTS OF THE CHlOS SHEEP

I. REQUIREMENTS FOR MAINTENANCE AND LATE PREGNANCY

Two feeding trials with 60 dry non'pregnant Chios ewes, and one dlgestibiiiw trial were carried out to estimate the energy requirements for maintenance. The pooled simple linear regression of the weight changes (kglday) on the metabolizable energy (ME) intake (KJlkg W.73) Was Y = -0.1994+0.0005X. The daily requirements for maintenance were esti- mated at 401 KJ of ME or 25.8 g of digestible organic matter per kg W0.73.

Another 38 pregnant Chios ewes were used to study the effects of two levels of feeding (medium and high) on the birth weight of iambs end the weight changes of ewes during the last six weeks of pregnancy. The metabOlizabie energy intake of pregnant ewes was 15.1 and 12.4 MJlday on the high and medium level of feeding, respectively. Birth weight of single or twin lambs was not affected by plane of nutrition. The weight of placenta was similar tor both levels of feeding. Ewe liveweight Qain from the commencement of the trial to one day pre-partum was similar for both levels of feeding. Net we~ght chanoe of ewes was not affected by plane of nutrition. It was estimated that the energy requirements for rnalnte- nance of a 60 kg ewe were about 9.0 MJ of ME daily and that these require- ments increased to 15.7 MJ of ME daily during the last six weeks of pregnancy.

INTRODUCTION

The maintenance requirements of sheep comprise a large pro- portion of their annual energy requirements. Studies on the energy requirements of sheep have been mainly carried out with mutton breeds, which were either stall fed (Coop 1962; Langlands et al., 1963a) or allowed to graze (Coop and Hill, 1962; Langlands et al., 1963b). The requirements of grazing sheep were higher than those of sheep kept indoors, particularly under poor grazing conditions (Lambourne, 1961; Coop and Hill, 1962; Langlands et aL, 1963b).

Most of the studies with pregnant sheep were concerned with late pregnancy and the effects of particular feeding levels on lamb birth weight and weight changes of ewes (McClelland and Forbes,

1973; Shevah et al., 1975; h u c a et al., 1974). The use of certain bio- chemical parameters such as the levels of blood glucose, free fatty acids and ketone bodies have been suggested as indices of the nutri- tional status of the pregnant ewe (Robinson et al., 1971; Davies et al., 1971; Russel et al., 1967). Moreover, attempts have been made to estimate from such studies the additional requirements for energy in late pregnancy (Robinson et al., 1971; Russel et al., 1967).

With increasing emphasis on the intensification of sheep pro- duction, the estimation of the energy requirements at different stages of the re roductive cycle is of considerable importance for maintaining normal I! ealth of the ewe and viability of the lambs, and decreasing feeding costs.

The objectives of this work were to estimate the energy require- ments of dry non-pregnant Chios ewes and to examine the effects of two levels of feeding on the birth weight of lambs and the weight changes of Chios ewes during the last six weeks of pregnancy.

MA'I%RIALS AND METHODS

Trials with dry non-pregnant sheep

Two trials were carried out in two consecutive years using 36 ewes in the first trial and 24 in the second. During the lactating and the dry period preceding the commencement of the trials the animals were kept in the same flock under similar feeding and management conditions. Two weeks before the commencement of the trials the ewes were placed in individual concrete-floor pens equipped with faci- lities for individual feeding and watering. A preliminary period of one week was used for both trials. The ewes were offered 0.5 kg of lucerne hay and 0.4 kg of concentrates in the first trial and 0.3 kg of barley straw and 0.6 kg of concentrates in the second trial per head daily. All ewes were weighed at the end of the first week. In the first trial they were divided in four groups on the basis of liveweight and were randomly allocated to one of four energy levels, i.e. 351(1), 401(2), 451(3) and 501(4) KJ of ME/kg W0.73. In the second trial only energy levels, 1, 2 and 3 were tested. After an adjustment period of one week on the new diets the animals were reweighed. The ewes were weighed once weekly at 0800h and on the last day of the trials. .Feed was offered once daily at 0900h and feed residues were collected daily prior to feeding. Each trial lasted six weeks.

The concentrate mixtures were formulated to differ in protein content by varying the barley and soyabean meal, so that with differing intake of concentrate, the daily intake of protein per ewe was similar in each trial (Table 1). Protein intake was 158 and 79g in trials 1 and 2, respectively.

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The digestibility of the diets in the second trial was measured after the completion of the trial. Twelve Chios wether sheep, four for each diet, were placed in metabolic crates designed for the separate collection of urine and faeces and were offered the mean daily consumption of straw and concentrates of the corresponding treat- ments. Faeces were collected daily for 7 days, following a 7 - day adjustment period. Representative bulk samples of feeds and faeces were dried at 105°C to constant weight for dry matter determination. The ash content of the same samples was determined by ignition at 600°C in a muffle furnace.

Trials with pregnant sheep

A flock of 100 Chios ewes, mated within five weeks, were fed as a group in early pregnancy on concentrates and green sudex. Approximately three months after mating, 40 ewes expected to lamb within two weeks were divided into two groups on the basis of live weight and expected date of lambing. They were gradually accustomed to the experimental rations and transferred to individual pens when 107 days pregnant. The ewes received either 1.7 kg of feed, High Plane of nutrition (HP), or 1.2kg of feed, Medium Plane of nutrition (MP). The feed was offered in pelleted form and consisted of 29.4% lucerne meal, 9.8% cottonseed cake, 58.8% barley grain, 1.5% dical- cium phosphate and 0.5% sodium chloride. Vitamins A and Da were included at the rate of 4,000 and 400 I.U./kg feed, respectively. The crude protein content of the diet was 16.6% and its energy value 10.54 MJ ME/kg feed on air dry basis.

Feed intake and residues were measured daily. Live weight of the ewes was recorded on the first day of the experiment (107th day of pregnancy), at 14- day intervals thereafter, daily during the last seven days of the expected lambing and at lambing after the expulsion of the placenta. The weight of the placenta, and individual lamb birth weights were also recorded. The weight of fluids was estimated from the difference between the live weight one day prior to lambing and the live weight at lambing plus the weight of placenta and the total weight of lambs per ewe at birth. Net weight changes of the ewe were calculated as the difference between the liveweight at the 107th day of pregnancy and the weight at lambing.

Metabolizable energy (ME) intake was calculated from the dry matter content and published values of the ME content of feedstuffs (N.R.C. 1975; Economides and Hadjidemetriou, 1976).

RESULTS

Dry non-pregnant ewes One ewe in treatment 3 of trial 1 showed inappetance and was

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removed from the trial. Mean daily weight changes ranged from -32 to +47g in trial 1 (Table 2) and -21 to +21g in trial 2 (Table 3). Energy intake on treatment 2 in both trials (Tables 2 and 3) caused a very small deviation of live weight from zero gain, suggesting that maintenance requirements for energy should lie between 393 and 449 KJ hE/kg W0.73.

The regression of weight changes (kg/day) on the ME intake (KJ/kg W0.73/day) was Y=-0.2016+0.0005X and Y=-0.1915+0.0005X for trials 1 and 2, respectively. For zero gain (Y=O) X was equal to 400.2 (trial 1) and 401.9 (trial 2) KJ MEBg Wo.73/day.

Since no differences were found between the two regression lines, the pooled regression Line was Y= -0.1994+0.0005X. Setting Y equal to zero, X was 400.8 KJ ME/kg W0.73/day. Hence, 400.8 KJ ME/kg W0.73/day was sufficient to maintain constant weight.

The organic matter digestibitily of the diets in the second trial was 72.7, 71.0 and 69.8% in treatments 1, 2 and 3, respectively. The mean digestible organic matter intake (DOMI) was 23.6. 25.7 and 28.4 g/kg w~~~ in treaiments 1, 2 and 3 respect<vely. ~he'regression of weight changes (kg/day) on DOMI (g/kg Wo.73/day) was Y = -270.7+ 10.47X. At Y=O. X was eaual to 25.8 PAP W.73/dav: thus. 25.8 n of - DOMI per kg U"o.73/day wis sufficient to maintain gonitant weiguht.

Pregnant ewes

Two non-pregnant ewes from treatment HP and the last two ewes to lamb from treatment MP were removed from the experiment. Average gestation length was 152 days for both groups, hence the results of this study refer to the last 45 days of pregnancy. Feed intake among animals of the same treatment ranged from 1.04 to 1.70kg (70 to 114% of the mean intake) in treatment HP and 0.86 to 1.20kg (74 to 102% of the mean intake) in treatment MP. Feed intake decreased in both treatments during the last few days of pregnancy to about 1.1 kg daily (Fig. 1).

The birth weight of either single or twin lambs was not affected by plane of nutrition (Table 4), but singles were heavier than twins (P<0.01). Ewes in both treatments made similar gains from 30 days after mating to the commencement of the trial at 107 days of pre- gnancy and from the 107th day to one day prepartum (Table 4). Net weight change of ewes was not affected by plane of nutrition, but ewes that gave birth to single lambs gained more weight than those giving birth to twin lambs (P<0.05). Ewes on the high plane of nutrition lost more weight at parturition than those on the medium plane (P<0.05). Also ewes with twin lambs lost more weight than those with singles (P<0.01).

The weight of placenta was not affected by plane of nutrition, but ewes with twin lambs had higher placental weights than ewes

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with single lambs (P<0.01). There was a highly significant relationship between the weight of placenta and the total lamb birth weight per ewe. The linear regression of the weight (kg) of placenta on the total lamb birth weight (kg) per ewe was Y=0.141 + 0.1X (r=0.64). The weight of maternal fluids was higher (P<0.05) in ewes on the high plane of nutrition.

DISCUSSION

In both trials with the dry non-pregnant sheep the diets were isonitrogenous to avoid interactions between energy and protein intake. However, even though the nitrogen intake of ewes in the second trial was about half that of the first trial the results were similar for both trials.

The energy requirements for maintenance estimated from the second trial, either from published energy values of the feeding stuffs used or by estimation from the digestible organic matter intake, were in very close agreement. Considering that the calorific value of l g of digestible organic matter is 15.68 KJ ME (Blaxter and Wainman, 1964) the corresponding ME intake was 405 KJ/kg W0.73 compared to 402 KJ/kg W0.73 found from the regression of daily weight change on the ME intake from published energy values of feeding stuffs

The pooled estimate of 401 KJ ME/kg WRT3 is equivalent to 25.5 g DOMI/kd.". This value is verv close to the value of 25.75~ DOMI/kc ~~- - ~ - - - W0.73 reported by coop (19821, higher -than the value of 22.02 DOMI/kg WD.73 reported by Langlands et a]., (1963), and lies between the recommended allowance of 368 and 443 KJ ME/kg W0.73 suggested by A.R.C. (1965) and N.R.C. (1975), respectively. It is also very close to the values of 414 -431 KJ ME/kg W0.73 reported by Oyenuga and Akinsoyinu (1971) for tropical breeds of sheep.

The pregnant ewes were in good body condition at mating and both groups made similar liveweight gain between 30 days after mating and 107 days of pregnancy. The weight of placenta was also similar between ewes carrying single or twin lambs. It is reasonable to assume that maternal nutrition from mating to the commencement of the trial had no residual effect on the nutrition of the ewes during the last six weeks of pregnancy.

Feed intake by individual animals on the same treatment differed considerably and there was a decline in feed intake in the last week prior to parturition particularly in ewes on the high level of feeding. Similar decline in the feed intake of pregnant ewes was reported by others (Forbes, 1968, 1969; Shevah et al., 1975).

The birth weight of single or twin lambs was not affected by the level of nutrition imposed in late pregnancy. Similar results were reported by others (Treacher, 1971; Robinson et al., 1970; McClelland

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TABLE 1. The cornpodtion, crude proteh and energy content of the concentrate mixhrrra* in the two feeding Mals.

Trio1 1 Trial 2 - - - Trmrrnznrs 1 2 3 4 1 2 3 - - - -

KJ MEikg wo73 351 401 451 501 351 401 451 - - -

Ingredienrs Barley grain 69 81 89.5 94.5 80 88 94 Soyabean meal 29 17 8.5 3.5 18 10 4 Limestone 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Sodium chloride 0.5 0.5 0.5 0.5 0.5 0.5 0.5

- - - - ----- Crude Protein (%) 20.2 16.0 13.0 11.2 16.8 14.2 12.3 KJ ME/kgfinishedfeed 11.1 11.2 11.3 11.3 11.2 11.3 11.3

'Vitamins A and D, were included at the rate of 4,000 and 400 I.U. per kg feed, respecti- vely.

TABLE 2. Intake of feed, energy and protein, end weight chsnges of ewes im Trial 1.

Trealments - 1 2 3 4 SD -

No. of animals 9 9 8 9 - Intake

Concentrates (glday) 230 329 390 499 47.8 Lucerne hay Wdav) 475 475 475 475 -

KJ MEIKg Wo7Jiday 341 393 445 497 1.3 Crude Protein (gjday) 154 160 158 163 7.4

Initial weight (kg) 53.0 54.3 51.8 53.8 5.38 Weight change &/day) -32 -3 +26 +47 33.2

TABLE 3. Intake of feed, energy and protein, snd weight charges of ewes in Trial 2.

No. of animals Intake

Concentrates (glday) Straw (glday) ME (KJ/day) KJ MEIkg WO "/day Crude Protein (glday)

Initial weight (kg) Weight change @/day)

SE*

* Standard error of difference between treatment means

TABLE 4. Energy intake and weight changes of single or twin bearing ewes, and birth weight of lambs.

High Plane HP -

Single Twin Siogle Twin births bivrhs births births SE*

No. of ewes 10 8 6 12 - Energy intake (MJ ME/day/ewe) 14.9 15.4 12.32 12.45 1.63 Weight 30 days after mating (kg) 58.7 62.3 59.0 58.8 6.2 Initial weight (kg) 62.7 65.6 59.7 63.0 5.4 Weight 1 day prepartum (kg) 74.6 79.6 70.3 74.8 6.0 Weight immediately after

lambing (kg) 66.1 66.1 62.3 63.2 5.7 Net weight gain (kg) 3.4 0.5 2.6 0.2 3.15 Weight of placenta (kg) 0.62 1.02 0.62 0.98 0.2 Weight of fluids (kg) 2.75 3.90 2.03 2.70 1.26 Birth weight of lambs (kg) 5.13 4.29 5.35 3.96 0.65

'Standard error of difference between two treatment means.

I 0 I 2 3 4 5 . A , . Partur#t~m

W e e k s

Fig. 1. Daily feed intake 01 ewes during the last 45 day. of pregnancy. ( High plane, 0 Medium plane)

Days pre-partum

Fig. 2 Uve welght changes of ewes from mating to iamblng ( High plane, 0 Medium plane, - Single births, -----. Twin births)

and Forbes, 1973; Shevah et al., 1975). However, in other studies the birth weight of twin lambs was affected by lower levels of nutrition (Treacher, 1970; Davies et al., 1971; Louca et al., 1974).

Liveweight of ewes increased sharply from day 40 pre-partum to lambing (Figure 2), particularly in twin bearing ewes, indicating maximum f e t a l development (Wallace, 1948) and, consequently, higher energy requirements at this stage of pregnancy. Ewes on both levels of nutrition gained live weight. However, ewes producing single lambs gained on average 3.0 kg (5.0% increase over the initial weight) compared to 0.35 kg for those giving birth to twins (0.5% increase over the initial weight). Other workers reported that ewes producing twins lost more net weight compared to ewes giving birth to singles (Davies et aL, 1971; McClelland and Forbes, 1973).

These results showed that the ewes on the medium plane of nutrition consumed 12.45 MJ of ME daily and produced twin lambs of 8.0 kg total lamb weight, while maintaining their maternal weight (0.2 kg net gain). The energy requirements of the ewes at mating were estimated at 7.8 MJ ME from the results with dry non-pregnant sheep (401 KJ ME/kg W0.73). Thus the energy requirements of the two lambs during the last six weeks pre-partum were about 4.65 MJ ME per day or 581 KJ ME/kg lamb weight at birth.

The results of the present studies were obtained with ewes in individual pens, with minimum movement and no wastage of feed. Chios sheep are usually kept under intensive conditions of manage- ment and feeding, and maximum walking of two miles daily. The cost of energy in walking and waste of feed at feeding will amount to no more than 10-1570 of the estimated maintenance requirements (401 KJ ME/kg W0.73). Thus the daily energy allowance for a 60kg dry non-pregnant ewe should range between 8.7 and 9.1 MJ ME. The pregnant Chios ewe has additional requirements of energy for possible multiple births, activity and wastage of feed. Therefore, a daily energy allowance of 15.7 MJ ME for a ewe weighing 60 kg a t mating is recommended during the last six weeks of pregnancy.

ACKNOWLEDGEMENTS

The author wishes to thank C. Photiou, Y. Loizou, L. Hadjipara- skevas, C. Heracleous and Maria Theodoridou for technical assistance.