Br

ACa

b

ARRAA

KBHILR

1

f

HB

0h

Small Ruminant Research 114 (2013) 272– 279

Contents lists available at ScienceDirect

Small Ruminant Research

jou rna l h om epa ge: www.elsev ier .com/ locate /smal l rumres

lood leptin, insulin and glucose concentrations in hair sheepaised in a tropical climate

.G.V. Catundaa, I.C.S. Limaa, G.C. Bandeiraa, C.R.F. Gadelhaa, E.S. Pereiraa,

.S.B. Salmito-Vanderleyb, A.A. Araújob, G.A. Martinsa, A.C.N. Camposa,∗

Department of Animal Science, Federal University Ceara, Fortaleza, Ceara, BrazilFaculty of Veterinary, State University Ceara, Fortaleza, Ceara, Brazil

a r t i c l e i n f o

rticle history:eceived 1 December 2012eceived in revised form 4 July 2013ccepted 8 July 2013vailable online 13 August 2013

eywords:ody condition scoreair sheep

nsulineptineproduction

a b s t r a c t

The aims of this study were to determine the effects of body condition score (BCS), breedand dietary supplementation on the concentrations of leptin, insulin and glucose found inthe blood obtained from hair sheep during the breeding season. A further aim was to inves-tigate the possible association of fertility and prolificacy with these blood metabolites, BCSand body weight (BW). All ewes were grazed in paddocks with ad libitum access to min-eral salts and water. A total of 96 ewes were divided into two groups according to breedand treatment: Santa Ines (supplemented or unsupplemented) (24 × 24) and Morada Nova(supplemented or unsupplemented) (24 × 24). Blood samples, and BW and BCS informationwere collected during the breeding season. The statistical analyses were performed usingthe program PROC GLM from the SAS software. The leptin concentrations in hair sheepraised in a tropical climate were low. Little effect of breed, treatment or sample collectionwas found for blood insulin concentrations (p < 0.05), although the values were higher in thesupplemented groups from both breeds. Significant differences were observed in glucoseconcentrations between the breeds in the same sample collections, with the higher con-centrations being found in the Santa Ines sheep (p < 0.05). The BCS for ewes that were notpregnant showed the highest correlation with leptin, insulin and glucose concentrations(r = 0.53, 0.52 and 0.43, respectively). In the Morada Nova supplemented sheep (prolificacy:1.45), there were verified correlations between BCS and BW, BCS and insulin concentra-tion, and also between insulin and leptin concentrations. The present study shows that the

Morada Nova breed has a higher reproductive efficiency than the Santa Ines breed. In con-clusion, leptin was present in low concentrations in hair sheep and did not influence thereproductive processes in these animals. The dietary supplementation positively affectedblood leptin, insulin and glucose concentrations in these breeds of hair sheep, but there

t on th

was no major effec

. Introduction

According to data collected by the Brazilian Instituteor Geography and Statistics (IBGE) in 2011, there are

∗ Corresponding author at: Department of Animal Science, Av Misterull, 2977, Campus of Pici – Block 808, Fortaleza, Ceara, CEP: 60356-000,razil. Tel.: +85 3366 9023; fax: +85 3366 9023.

E-mail address: acncampos11@gmail.com (A.C.N. Campos).

921-4488/$ – see front matter © 2013 Elsevier B.V. All rights reserved.ttp://dx.doi.org/10.1016/j.smallrumres.2013.07.008

e reproductive processes.© 2013 Elsevier B.V. All rights reserved.

approximately 9,566,968 sheep in northeastern Brazil.They represent 56.9% of the Brazilian sheep population, andthe predominant genetic group is the hair sheep (60–70%).Of the various breeds of hair sheep, the Morada Nova andSanta Ines breeds are the most widespread in northeasternBrazil because of their adaptation to the climatic conditions

in this region. Sheep husbandry has traditionally been con-sidered to be of low commercial value in Brazil, and it isgenerally practiced by the informal economy (is the incomegenerated by economic agents that operate informally)

minant

A.G.V. Catunda et al. / Small Ru

(Paiva et al., 2005). In the Northeast and Central Westof Brazil, regions characterized by long dry periods, hairsheep represent an important source of protein for the localpopulations. More recently in these regions, market diver-sification has increasingly allowed sheep husbandry to beconsidered as a viable and lucrative occupation.

Despite extensive livestock methods and the semiaridclimate, Morada Nova ewes show good reproductive per-formance and have a better litter size at lambing than othersheep breeds in the Northeast of Brazil (Selaive-Villarroeland Fernandes, 2000). Nevertheless, there have been fewstudies on hormonal metabolism and the influence of nutri-tion in the reproductive processes in hair sheep raised inthe Northeast of Brazil.

Several studies have related the reproductive perfor-mance of flocks to the nutritional status of individuals(Boland and Lonergan, 2003; Kiyma et al., 2004; Kiker et al.,2007), but how this occurs remains unclear. However, it isknown that nutrition might influence ovarian function, asit modulates the secretion of hormones that control thereproductive processes in females (Chilliard et al., 2005).Previous studies have shown that the number of folliclesand the ovulation rate are directly influenced by nutrition.They can be assessed via changes in the concentrations ofcertain metabolites in the bloodstream, such as insulin, lep-tin, glucose and growth hormone (GH) (Davies-Morel andBeck, 2003; Ramin and Majdani, 2005; Scaramuzzi et al.,2006).

Insulin is a small globular protein of about 5.7 kDa thatdiffers between species. It is synthesized and secreted fromthe pancreatic �-cells of the islet of Langerhans in allspecies (González and Silva, 2006). In ruminants, due tomicrobial activity in the rumen, little or no dietary carbo-hydrate is absorbed as hexose sugar in the small intestine(Mcniven, 1984). For this reason, volatile fatty acids (pro-pionate and butyrate) are more potent than glucose forstimulating insulin secretion (Pineda and Dooley, 2003;Brockman, 2005; González and Silva, 2006).

Another hormone, leptin, a 16 kDa protein product ofthe obese (ob) gene is secreted by adipocytes. In normal ani-mals, leptin serves as a metabolic signal to the reproductivesystem, informing it that sufficient fat stores are availableto meet the caloric demands of reproduction (Barash et al.,1996). Thus, leptin expression and secretion are correlatedwith body condition, physiological status (puberty, preg-nancy, lactation), and the age of the animal (Krasnow andSteiner, 2006). Other studies have shown that leptin can beaffected by changes in food intake (Williams et al., 2005).Leptin seems to act by modulating the function of severaltarget glands (Moschos et al., 2002).

Glucose, another metabolite widely discussed inmetabolism studies, plays a key role in animal metabolism.It is an essential source of energy for the maintenance ofmany tissues, such as the nervous system, red blood cells,the placenta, the mammary gland (Sastradipradja, 1998)and the ovaries (Rabiee et al., 1997; Leroy et al., 2004;Krasnow and Steiner, 2006). It also serves as a precursor

for the biosynthesis of essential cell components, and istherefore equally important as a metabolite for all mam-mals. In the ruminant, most glucose must be synthesizedby gluconeogenesis (Sastradipradja, 1998).

Research 114 (2013) 272– 279 273

The aims of this study were to verify the effects of bodycondition score (BCS), breed and dietary supplementationon the blood leptin, insulin and glucose concentrations inhair sheep, and also to study the possible association offertility and prolificacy with these blood metabolites andBCS and body weight (BW) recorded in ewes during thebreeding season.

2. Materials and methods

2.1. Experimental site

The experiment was conducted on the Experimental Farm of the StateUniversity of Vale do Acaraú (Sobral, Ceara, Brazil), which is located in asemi-arid region at 3◦36′ S, 40◦18′ W and is 56 m above sea level. The meanannual temperature in the region is 32 ◦C and average rainfall is 800 mmper year.

2.2. Animals, experimental diets and management

A total of 96 non-pregnant adult ewes of different ages were used inthis study. There were 48 ewes of the Santa Ines breed and 48 ewes of theMorada Nova breed, with average BW and standard deviation of the ini-tial mean of 43.0 ± 5.6 kg and 25.55 ± 3.1 kg, respectively. First the eweswere tagged with an earring for identification. Then they were weighedand were randomly distributed into two groups, unsupplemented andsupplemented, for each breed. During the experimental period, all of theewes were managed under semi-intensive conditions and were grazed ina paddock used for rotational stocking that had been sown with Tifton85 bermudagrass (Cynodon spp.). All of the animals had free access towater and mineral salt. For statistical analysis, the animals were groupedin a randomized block design (homogenous weights) with four treatmentsconsisting of two supplementation levels (unsupplemented and supple-mented) and two breeds (Santa Ines and Morada Nova). The experimentaldiet fed to the ewes in the supplemented groups was formulated accord-ing to the National Research Council (2007) and consisted of ground Tifton85 hay (70%), 94.67% ground corn, 5.04% soybean meal and 0.29% lime-stone. The dietary supplementation was provided two weeks before andthroughout the breeding season, which lasted for 45 days. The Santa Inesewes received 250 g of supplementation daily, whereas the Morada Novaewes received only 150 g because of their smaller size. The supplemen-tation was provided at 9 a.m. each day.

Samples of Tifton 85 forage and concentrates were dried in a forced-air oven at 55 ◦C for 72 h before being ground in a knife mill with a screenwith a 1 mm screen (Wiley mill, Arthur H. Thomas, Philadelphia, PA, USA).The samples were analyzed for their dry matter (DM) content (AOAC,1990; method number 930.15) and crude protein content (CP; AOAC,1990; method number 984.13). To analyze the neutral detergent fiber(NDF), the samples were treated with thermostable alpha-amylase with-out using sodium sulfite. The concentrate consisted of 92% DM, 10% CP,12% NDF, 0.29% calcium and 0.16% phosphorus.

The breeding season for this study was considered to be 45 days long(starting at the end of June and ending in early August 2008). Five maturerams, two of the Santa Ines breed and three of the Morada Nova breed,with normal reproductive status were used during the breeding season.The rams were fed with the same dietary supplementation that had beenformulated for the ewes.

The ewes remained in the paddock during the day and at the end of theday they were taken to the management center. Here they were presentedto a teaser ram that had been painted on its sternum with a vegetable dyemixed in a Vaseline base so that the ewes that had been mounted could beidentified by the pigment that had been transferred to their rump. Afterthis, the ewes were presented to rams of the same breed for controllednatural mating.

The animals were weighed weekly in order to chart weight gain, andthe BCS was measured in all ewes according to Russel et al. (1969). The BCSscale ranges from 1 (thin) to 5 (fat). Blood was sampled from 67 randomly

selected ewes. During the trial, samples were collected from each ani-mal by jugular venipuncture in non-anticoagulation gel separator vacuumtubes (Vacuntainer®) to obtain serum and to determine the leptin, insulinand glucose concentrations. Immediately after collection, the sampleswere centrifuged and the serum was stored at −20 ◦C until it was assayed.

2 minant Research 114 (2013) 272– 279

2

mp‘isc

(ic

eiopooTd

2

fir

2

u(m

Y

w(ecu

cadw

oi2

o

3

tttbsnc(

r(t

Table 1Means ± SD of the blood leptin and glucose concentrations for samplecollections and treatments during the breeding season.

Collection Treatment Leptin (ng/ml) Glucose (mg/dl)

1 Supplemented 1.27 ± 0.068aA 53.88 ± 2.68aBC

Unsupplemented 1.18 ± 0.070aA 45.67 ± 2.76bA

2 Supplemented 1.26 ± 0.064aA 63.51 ± 2.60aA

Unsupplemented 1.07 ± 0.066bAB 47.31 ± 2.59bA

3 Supplemented 1.18 ± 0.064aB 53.92 ± 2.52aAB

Unsupplemented 0.98 ± 0.064aB 49.54 ± 2.51bA

4 Supplemented 1.00 ± 0.066aC 53.14 ± 2.61aBC

Unsupplemented 1.04 ± 0.065aAB 48.79 ± 2.57aA

5 Supplemented 0.99 ± 0.065aC 55.30 ± 2.56aBC

Unsupplemented 0.92 ± 0.073aB 47.69 ± 2.87bA

6 Supplemented 0.97 ± 0.073aC 52.26 ± 2.86aBC

Unsupplemented 1.01 ± 0.071aAB 52.68 ± 2.82aA

7 Supplemented 1.27 ± 0.078aA 49.14 ± 3.06aC

Unsupplemented 1.01 ± 0.067bAB 51.38 ± 2.65aA

Average 1.10 ± 0.246 52.39 ± 9.69

Lowercase letters: comparison between treatments in same sample col-lection.

74 A.G.V. Catunda et al. / Small Ru

.3. Chemical analysis

Plasma leptin was determined using double-antibody radioim-unoassay (RIA) procedures. Serum immunoreactive leptin was inde-

endently determined in 100 �l aliquots of serum samples using amulti-species’ RIA kit (XL-85K; Linco Research, St. Louis, MO, USA) accord-ng to the manufacturer’s recommendations (Delavaud et al., 2000). Theensitivity limit was 1.0 ng/ml (for 100 �l sample size) and the interassayoefficients of variation were 5.3%.

The plasma insulin concentration was determined using a RIA kitPorcine Insulin RIA kit PI-12K; Linco Research, St. Louis, MO, USA) accord-ng to Greenwood et al. (2002) and Szymanski et al., 2011. The interassayoefficient of variation was 8.7%.

Blood glucose concentrations were determined according to Evanst al. (1975), Udum et al. (2008) and Szymanski et al. (2011). The reactions based on the enzymatic oxidation of glucose in the presence of glucosexidase, leading to the formation of hydrogen peroxide. The hydrogeneroxide then reacts with phenol and 4-aminophenazone, in the presencef peroxides, to form a red/violet quinone-imine dye, with the intensityf the color produced being proportional to the glucose concentration.he concentration of glucose in each of the samples was determined inuplicate. The inter-assay coefficient of variation was 9.3%.

.4. Reproductive performance

The reproductive efficiency of the ewes was evaluated according toertility (the number of ewes parity/number of ewes submitted to mat-ng) and prolificacy (number of lambs born/number of ewes parity). Theseesults were expressed in percentage values.

.5. Statistical analyses

A completely randomized design in a 2 × 2 factorial arrangement wassed, with two breeds (Santa Ines and Morada Nova) and two treatmentssupplemented and unsupplemented), according to the mathematical

odel:

ijklm = � + ci + rj + ik + tl + eijklm,

here Yijklm , leptin, insulin and glucose concentrations; �, general meanleptin, insulin and glucose concentrations); ci , body condition class; rj ,ffect of breed (j, Santa Ines and Morada Nova); ik , age, used with theovariate in the model; tl , supplementation effect (l, supplemented ornsupplemented); eijklm , random error.

The data for the parameters of the insulin, leptin and glucose con-entrations were squared in order to fit the analysis of variance (ANOVA)ssumptions. The Pearson correlation coefficient was used to evaluate theegree of association of the variables leptin, insulin, glucose, BCS, and BWith fertility class and ewe prolificacy.

The BCS score classes were created so that all of the informationbtained would be used. The classes were defined as follows in order toncrease the accuracy of these parameters: class 1, ewes with BCS < 2; class, ewes with BCS < 3; and class 3, ewes with BCS > 3.

The statistical analyses were performed using the PROC GLM programf SAS version 9.1 (SAS, 2003).

. Results

Plasma leptin (p < 0.05), insulin and glucose concen-rations were influenced by the dietary supplementationreatment. There was no significant effect of BCS class onhe leptin, insulin and glucose concentrations during thereeding season, and the effect of breed (p < 0.0001) wasignificant only for blood glucose concentration. Also, a sig-ificant correlation between breed, treatment and sampleollection was found only for blood insulin concentrationsp < 0.0001).

Blood leptin concentrations measured in hair sheepaised in a tropical climate ranged from 0.92 to 1.27 ng/mlmean 1.10 ± 0.24 ng/ml). During the mating period,he initial (second sample collection) and final (seventh

Uppercase letters: comparison between sample collections in same treat-ment.

sample collection) blood leptin concentrations of the eweswere significantly different (p < 0.05) between treatments,but not between breeds, with higher concentrations beingobserved for supplemented ewes. A significant decrease inblood leptin was observed from the third to the seventhsample collections in supplemented ewes (Table 1).

The mean blood insulin concentration was7.91 ± 1.54 �U/ml. A significant difference (p < 0.05)was observed between treatments in the insulin concen-trations of Santa Ines ewes in the third sample collectionand Morada Nova ewes in the third, fifth and seventhsample collections. In both breeds, the insulin concen-trations were higher in the supplemented group. At thefinal collection, supplemented Santa Ines ewes had higherinsulin concentrations than Morada Nova ewes. However,when the Santa Ines ewes were unsupplemented, theinsulin concentration was lower than in the Morada Novaewes (Table 2).

The mean blood glucose concentration was52.4 ± 9.7 mg/dl. The glucose concentration was higherin the supplemented group and varied from collection tocollection (Table 1). There was also a significant differencein blood glucose concentration between breeds in onlythe fourth and seventh sample collections, with higherconcentrations being found in the Santa Ines ewes thanin the Morada Nova ewes (Table 3). The supplementedMorada Nova ewes showed more variation in glucoseconcentrations than the supplemented Santa Ines ewes.

There was no significant difference between breedsfor fertility and prolificacy (Table 4). When fertility wasconsidered to be 0% (non-pregnant) (Table 5), signifi-cant associations (p < 0.05) were observed for leptin with

insulin, glucose and BCS, and insulin with glucose, BW andBCS. However, in pregnant ewes, the leptin was correlatedonly with insulin, and insulin correlated only with BW.

A.G.V. Catunda et al. / Small Ruminant Research 114 (2013) 272– 279 275

Table 2Means ± SE of the blood insulin concentrations (�U/ml) for collections,breed and treatments during the breeding season.

Collection Breed Treatment

Supplemented Unsupplemented

1SI 5.27 ± 1.51d 3.11 ± 1.68MN 6.74 ± 1.56B 6.28 ± 1.68

2SI 10.07 ± 1.44bc 5.95 ± 1.62MN 7.15 ± 1.50AB 5.49 ± 1.60

3SI 9.94 ± 1.46c1 3.47 ± 1.702

MN 10.04 ± 1.48AB1 5.58 ± 1.472

4SI 12.86 ± 1.48b1 4.50 ± 1.672

MN 8.69 ± 1.51AB 5.84 ± 1.48

5SI 12.76 ± 1.41ba1 3.85 ± 1.912

MN 9.78 ± 1.52AB1 5.55 ± 1.602

6SI 12.69 ± 1.65ab1 6.06 ± 1.632

MN 11.17 ± 1.61A1 5.67 ± 1.742

7SI 15.96 ± 1.88a1* 3.66 ± 1.592**

MN 9.92 ± 1.71AB** 8.68 ± 1.60*

Average 7.91 ± 1.54

Lowercase letters: comparison between collections in the Santa Ines (SI)ewes.Uppercase letters: comparison between collections in the Morada Nova(MN) ewes.Number: comparison between treatments in the same breed.Asterisk (*): comparison between breeds in the same treatment.

Table 3Means ± SE of the blood glucose concentrations for collections and breedsduring the breeding season.

Collection Breed Glucose (mg/dl)

1SI 46.00 ± 2.823aB

MN 53.55 ± 2.942aA

2SI 56.30 ± 2.744aA

MN 54.53 ± 2.965aB

3SI 50.73 ± 2.755aAB

MN 56.73 ± 2.720aA

4SI 57.24 ± 2.918aA

MN 44.69 ± 2.773bC

5SI 54.19 ± 3.023aA

MN 48.81 ± 2.899aBC

6SI 54.85 ± 2.942aA

MN 50.09 ± 3.126aABC

7SI 57.77 ± 3.234aA

MN 42.75 ± 3.083bC

Average 52.39 ± 9.693

Lowercase letters: comparison between breeds in the same collection.Uppercase letters: comparison between collections in the same breed.

Table 4Fertility and prolificacy in according to breed and treatment in hair sheep.

Breed Fertility (%) Prolificacy

Santa Ines (48) 85.41 (41/48) 1.37 (56/41)Morada Nova (48) 79.16 (38/48) 1.42 (54/38)TreatmentSupplemented (48) 81.25 (39/48) 1.38 (54/39)Unsuplemented (48) 83.33 (40/48) 1.40 (56/40)

Table 5Pearson correlation coefficient between insulin, glucose, body weight and body c

Fertility (%) Insulin

Leptin Not pregnant 0.43762*

Parity 0.29550*

Insulin Not pregnant

Parity

Glucose Not pregnant

Parity

Body weight (BW), body condition score (BCS).* Significant at p < 0.05.

Fertility: the number of ewes parity/number of ewes submitted to matingand prolificacy: number of lambs born/number of ewes parity.

The prolificacy was divided into four categories: 1.35(Santa Ines breed, supplemented); 1.36 (Santa Ines breed,unsupplemented); 1.45 (Morada Nova breed, supple-mented); and 1.46 (Morada Nova breed, unsupplemented)(Table 5). A significant positive correlation was foundbetween BCS and insulin for supplemented Santa Ines(p < 0.05, r = 0.32) and Morada Nova (p < 0.05, r = 0.49) ewes,but not between unsupplemented ewes of either breed. Thecorrelations between BW and leptin (p < 0.05, r = 0.32) insupplemented Santa Ines ewes, and between BCS and lep-tin (p < 0.05, r = 0.57) in supplemented Morada Nova eweswere significant. For supplemented Morada Nova ewes,a significant positive correlation was also found betweenleptin and insulin (p < 0.05, r = 0.41). A significant positivecorrelation between leptin and glucose (p < 0.05, r = 0.39)was only found in unsupplemented Santa Ines ewes.

4. Discussion

There is no information in the literature on the influ-ence of blood leptin concentration and action, or of theeffect of dietary supplementation, on the reproductionof Brazilian hair sheep breeds during the mating period.This is therefore the first study to determine blood leptinconcentrations and confirm that dietary supplementationduring the mating period influences leptin, insulin andglucose concentrations in hair sheep raised in a tropi-cal climatic. The average blood leptin concentration was1.10 ± 0.24 ng/ml (Table 1). Studies carried out on woolsheep from temperate climates have shown higher leptinconcentrations (average minimum of 2.09 ng/dl) (Delavaud

et al., 2000; Marie et al., 2001; Sosa et al., 2009) than thoseobtained for each of the animals (Santa Ines or MoradaNova breeds) in this study. Leptin is secreted mainly byadipocytes (Barash et al., 1996), but it is known that the

ondition score according to fertility.

Glucose BW BCS

0.36945* 0.07959 0.53929*

0.08683 0.12626 0.00369

0.37541* 0.33571* 0.52779*

0.26488* −0.000440

0.45969*

0.07321

2 minant

Sbcsdnra(tp

tift(vnithgdagpnaer(1i

dfmtgcbavwTfsalicd

bosioit

76 A.G.V. Catunda et al. / Small Ru

anta Ines and Morada Nova hair sheep breeds have littleody fat and we believe that this explains the low leptinoncentrations found in this study. These results thereforeuggest that this hormone has less influence on the repro-uction of hair sheep raised in a tropical environment. Inormal animals, leptin serves as a metabolic signal to theeproductive system, informing it that sufficient fat storesre available to meet the caloric demands of reproductionBarash et al., 1996). Energy status is generally consideredo be a major nutritional factor that influences reproductiverocesses.

In the present study, the effect of dietary supplemen-ation on leptin, insulin and glucose concentrations wasnvestigated (Tables 1 and 2). Dietary supplementation wasound to increase blood insulin concentrations in three ofhe sample collections, particularly in the Santa Ines ewesTable 2). This result was in agreement with the obser-ations made by Parra and Beltran (2008) that a properutrient intake in ruminants resulted in increased plasma

nsulin and an increase in body reserves, mainly fat. Inhe female reproductive process, an increase in insulinas been linked to follicular growth modulation, steroido-enesis, oocyte maturation and, consequently, embryonicevelopment by its action on ovarian activity (McCannnd Hansel, 1986; Kawashima et al., 2007). In mono-astric animals, insulin secretion is mediated by thelasma glucose concentration, some amino acids (argi-ine, lysine and leucine), fatty acids, and ketones (Gonzáleznd Silva, 2006). Because ruminants derive metabolizablenergy primarily from volatile fatty acid production in theumen, little glucose is absorbed from their digestive tractsSastradipradja, 1998). Thus, propionate (Johnson et al.,982) and butyrate (Arcus et al., 1976) are insulinogenic

n ruminants.Propionate is a well-known precursor of carbohy-

rate. The amounts of propionate available from rumenermentation can theoretically supply the glucose require-

ents not accounted for by protein sources. Butyrate, thehird major fatty acid of rumen fermentation, influenceslucogenesis but does not contribute carbon directly to glu-ose. Butyrate stimulates glucose production by the livery increasing phosphorylases and gluconeogenesis. Thecetyl-CoA derived from �-oxidation of butyrate also acti-ates pyruvate carboxylase, a key gluconeogenic enzyme,hich further promotes gluconeogenesis (Kaneko, 2008).

he results of the current trial are in agreement with thoseound in the international literature, because the dietaryupplementation promoted an increase in volatile fattycid formation. Tokuda et al. (2002) found a positive corre-ation between leptin, insulin and glucose concentrationsn sheep. They suggested that plasma leptin and insulinoncentrations would be affected by the nutritional con-ition of the animal.

Although moderate, there was a positive correlationetween insulin and glucose concentrations (0.37), butnly in non-pregnant ewes (Table 5). Although an earliertudy had suggested that insulin induced hypoglycemia

n non-pregnant ewes (Downing and Scaramuzzi, 1997),ur experiment showed that dietary supplementationnduced a significant increase in blood glucose concentra-ion in hair sheep. This result indicates that blood glucose

Research 114 (2013) 272– 279

might induce the secretion of insulin in supplementedhair sheep. Downing and Scaramuzzi (1997) also foundthat sheep can maintain their blood glucose concentra-tions by utilizing either endogenous or exogenous sourcesand that glucose is rarely limiting. However, it has beensuggested that the mechanism responsible for regulatinggonadotropin-releasing hormone (GnRH) pulses may berelatively sensitive to severe undernutrition, such as dur-ing late pregnancy or lactation, when there is an extremelyhigh demand for glucose.

Another important aspect is that, in lactating dairy cows,insulin is a positive regulator of plasma leptin (Block et al.,2003). The results of this study suggest that insulin alsoplays an important role in regulating plasma leptin in non-pregnant hair sheep. This assay also showed that insulinconcentration was correlated with leptin. Differences ininsulin concentrations (Table 2) and in glucose concentra-tions (Table 3) were also found between breeds. The reasonfor this difference is not clear; however, similar resultswere found by Herselman and van Loggerenberg (2012),who verified that plasma insulin concentration was consid-erably higher in Namaqua Afrikaner sheep than in all otherbreeds. According to Matsuzaki et al. (1997), the breed dif-ferences observed may be due in part to a distinct breeddifference in glucose turnover that is attributable to the rateof hepatic glucose output (gluconeogenesis) and peripheralglucose utilization. We believe that these differences par-tially explain the higher dependence of the Santa Ines breedon supplementation than the Morada Nova breed.

In this trial, the major correlations were found in non-pregnant ewes (Table 5). In all parameters, the BCS showedthe highest correlations because it is related to the threemetabolites studied. Caldeira et al. (2007) reported that amethodology proposed by Russel et al. (1969) attempted toestimate the quantity of body reserves, which includes fat,the largest source of energy, as well as the major reserveof protein in the body, the skeletal muscle. This informa-tion is important for appraising the adequacy of feedingprograms, particularly in production systems where foodavailability is not constant. So, according to Caldeira et al.(2007), it was established that the quantity of body reserveshas a definite effect on animal reproductive and productionefficiency. Hence, the BCS has gained widespread accep-tance in sheep production, especially as an indicator of thenutritional status of ewes. Moreover, the ability of rumi-nants to cope metabolically with the nutritional demandsof additional production or seasonal changes in pastureyield and quality has made BCS an indispensable tool forewe management. In addition, nutritional condition is animportant parameter because it influences the folliculargrowth rate and maximum diameter, and also affects theability of the follicle to ovulate (Diskin et al., 2003).

In this trial, a correlation was also found between bloodleptin and glucose concentrations. This differs from theresult reported by Kauter et al. (2000), which suggestedthat glucose is not an important short-term regulator ofblood leptin concentration in sheep. These authors also

observed that the hormones that affect blood glucose donot influence leptin concentration. In our trial the ani-mals received dietary supplementation for 59 days (twoweeks before and throughout the breeding season), so

A.G.V. Catunda et al. / Small Ruminant Research 114 (2013) 272– 279 277

Table 6Pearson correlation coefficient between insulin, glucose, body weight and body condition score according to prolificacy.

Prolificacy (unid.) BCS Leptin Insulin Glucose

Bodyweight

1.35 0.29307 0.32637* 0.25934 −0.268511.36 0.24439 −0.04675 −0.25487 0.111191.45 0.57421* −0.11548 0.15013 0.105591.46 −0.3030 0.01082 0.02786 0.08317

BCS

1.35 – −0.00794 0.32376* 0.020951.36 – −0.04001 −0.12613 0.060301.45 – 0.21884 0.49012* 0.071961.46 – 0.22088 0.06408 0.11483

Leptin

1.35 – 0.28430 −0.306371.36 – 0.02449 0.39490*

1.45 – 0.40622* −0.079901.46 – 0.14555 0.02928

Insulin

1.35 – −0.133271.36 – 0.202211.45 – 0.147001.46 – −0.02883

unsup

Prolificacy: 1.35 (Santa Ines breed supplemented), 1.36 (Santa Ines breedNova breed unsupplemented). Body condition score (BCS).

* Significant at p < 0.05.

this difference explains the results observed in this study,because these hormones seem to be interdependent whendietary supplementation is provided long-term.

A correlation was found between insulin and BW andBCS, and between glucose and BCS (Table 5). These correla-tions suggest that knowing a ewe’s BCS is relevant duringthe breeding season because it is a measure of their repro-ductive potential. Tokuda et al. (2002) demonstrated thatthe changes in insulin, leptin and glucose were affected bynutritional status and body fat. Some studies reported thata good BCS in ewes during mating and lambing is impor-tant for achieving favorable reproductive rates (Machadoet al., 1999). Moreover, ewes with a high BCS had a highermean luteinizing hormone (LH) pulse frequency than eweswith a low BCS and higher mean follicle-stimulating hor-mone (FSH) concentrations. It is known that, in ruminants,glucose plays a key role in the metabolic regulation thatfine-tunes pulsatile GnRH release (Ohkura et al., 2004). TheBCS for ewes that were not pregnant showed the highestcorrelation with leptin, insulin and glucose concentrations(Table 5). These results were different from those found byLiefers et al. (2003), which showed that BW affected lep-tin concentrations during pregnancy and lactation in cows.These authors also verified that leptin concentrations werevery low 30 days before parturition, and suggested that therecovery of leptin concentrations after parturition seemedto depend on the quantity of fat deposition. Other studiesfound low leptin concentrations before and after parturi-tion (Block et al., 2001; Barb and Kraeling, 2004), and foundthat the capacity of leptin to act as an indicator of moderatematernal undernutrition may be limited before lambing insheep (Yuen et al., 2002). Our study suggests that leptincan regulate the endocrine pancreas of non-pregnant andpregnant ewes, but that its effect is more efficient in non-

pregnant ewes. Williams et al. (2002) suggested that leptincan modulate both the hypothalamic–pituitary axis and theendocrine pancreas under defined nutritional conditionsin cattle and sheep. Hausman et al. (2012) suggested that

plemented), 1.45 (Morada Nova breed supplemented) and 1.46 (Morada

leptin is a key metabolic signal synthesized and secretedby fat cells that communicates information about bodyenergy reserves, nutritional state, and metabolic shifts tothe reproductive axis.

The correlations were also evaluated according to dif-ferent categories of prolificacy (Table 6). The distributionof correlations was heterogeneous between the categories,but was more numerous in the Morada Nova supple-mented ewes (prolificacy 1.45). The results of the presentstudy were different from those reported by Allden (1956),which suggested that differences in prolificacy were notrelated to the nutritional status of ewes at mating. Thepresent study showed that the Morada Nova ewes werereproductively more efficient than the Santa Ines ewes.These results therefore suggest that the Morada Nova eweswere better adapted to the semi-arid region in a trop-ical climate than the Santa Ines ewes. Previous studieshave reported that in northeastern Brazil, especially insemi-arid regions, some breeds, such as Morada Nova,begin to develop features adapted to the climatic condi-tions that enable them to reproduce in these environments(Costa et al., 2011; Silva et al., 2007). Johnson et al. (2003)reported that energy requirements for maintenance, tradi-tionally defined as those that ensure the maintenance ofBW, may vary between individual animals and betweenbreeds because of the influence of several physiological fac-tors such as sex, BW, age, BCS, physical activity and genetictraits. The reproductive physiology of the hair sheep there-fore requires further study because there have been nospecific studies on the hormonal and metabolic charac-teristics of these breeds. Selaive-Villarroel and Fernandes(2000) observed that the coverage rate and prolificacy ofMorada Nova ewes were affected by BW. For this rea-son, BW may be considered to be more important than

age in reproductive efficiency. We emphasize that theMorada Nova breed has animals with well-established typ-ical traits, but the Santa Ines breed is still undergoingadaptation.

2 minant

5

ap

lbd

A

g

R

A

A

B

B

B

B

B

B

C

C

C

D

D

D

D

E

78 A.G.V. Catunda et al. / Small Ru

. Conclusion

Leptin was present in low concentrations in hair sheepnd it seemed to have no influence on the reproductiverocesses in these animals.

The dietary supplementation positively affected bloodeptin, insulin and glucose concentrations in hair sheep ofoth breeds, but it had no significant effect on the repro-uctive processes.

cknowledgments

The authors thank FUNCAP and Banco do Nordeste forrants to support research and CAPES for scholarships.

eferences

llden, W.G., 1956. Time of mating as a factor influencing prolificacy incross-bred ewes, and its effect upon lamb and woolproduction in the fat lamb flock, 88–99, http://www.asap.asn.au/livestocklibrary/1956/Allden56.PDF (accessed 20.02.12).

rcus, A.C., Ellis, M.J., Kirk, R.D., Beaven, D.W., Donald, R.A., Hart, D.S.,Holland, G.W., Redekopp, C., 1976. Studies with the autotransplantedovine pancreas: glucagon and insulin secretion. Aust. J. Biol. Sci. 29,223–236.

arash, I.A., Cheung, C.C., Weigle, D.S., Ren, H., Kabigting, E.B., Kuijper, J.L.,Clifton, D.K., Steiner, R.A., 1996. Leptin is a metabolic signal to thereproductive system. Endocrinology 137, 3144–3147.

arb, C.R., Kraeling, R.R., 2004. Role of leptin in the regulation ofgonadotropin secretion in farm animals. Anim. Reprod. Sci. 82–83,155–167.

lock, S.S., Butler, W.R., Ehrhardt, R.A., Bell, A.W., Van Amburgh, M.E.,Boisclair, Y.R., 2001. Decreased concentration of plasma leptin inperiparturient dairy cows is caused by negative energy balance. J.Endocrinol. 171, 339–348.

lock, S.S., Rhoads, R.P., Bauman, D.E., Ehrhardt, R.A., McGuire, M.A.,Crooker, B.A., Griinari, J.M., Mackle, T.R., Weber, W.J., Van Amburgh,M.E., Boisclair, Y.R., 2003. Demonstration of a role for insulin in theregulation of leptin in lactating dairy cows. J. Dairy Sci. 86, 3508–3515.

oland, M.P., Lonergan, P., 2003. Effects of nutrition on fertility in dairycows. Adv. Dairy Technol. 15, 21–32.

rockman, R.P., 2005. Glucose and short-chain fatty acid metabolism.In: Dijkstra, J., Forbes, J.M., France, J. (Eds.), Quantitative Aspects ofRuminant Digestion and Metabolism. CABI Publishing, Cambridge, pp.291–310.

aldeira, R.M., Belo, A.T., Santos, C.C., Vazques, M.I., Portugal, A.V., 2007.The effect body condition score on blood metabolites and hormonalprofiles in ewes. Small Rumin. Res. 68, 233–241.

hilliard, Y., Delavaud, C., Bonnet, M., 2005. Leptin expression in rumi-nants: nutritional and physiological regulations in relation withenergy metabolism. Dom. Anim. Endocrinol. 29, 3–22.

osta, R.G., Silva, N.V., Azevedo, P.S., Medeiros, A.N., Carvalho, F.F.R., RitaDe Queiroga, C.R.E., Medeiros, G.R., 2011. Meat quality of lambs fedsilk flower hay (Calotropis procera SW) in the diet. Rev. Bras. Zootec.40, 1266–1271.

avies-Morel, M.C.G., Beck, N.F.G., 2003. A comparison of plasma growthhormone, insulin, free fatty acid and glucose concentration duringoestrus and early pregnancy in Clun Forest ewe lambs and ewes. SmallRumin. Res. 48, 127–134.

elavaud, C., Bocquier, F., Chilliard, Y., Keisler, D.H., Gertler, A., Kann, G.,2000. Plasma leptin determination in ruminants: effect of nutritionalstatus and body fatness on plasma leptin concentration assessed by aspecific RIA in sheep. J. Endocrinol. 165, 519–526.

iskin, M.G., Mackey, D.R., Roche, J.F., Sreenan, J.M., 2003. Effects of nutri-tion and metabolic status on circulating hormones and ovarian follicledevelopment in cattle. Anim. Reprod. Sci. 78, 345–370.

owning, J.A., Scaramuzzi, R.J., 1997. The effect of the infusion of insulinduring the luteal phase of the estrous cycle on the ovulation rate and

on plasma concentrations of lh, fsh and glucose in ewes. Theriogenol-ogy 47, 747–759.

vans, E., Buchanan-Smith, J.G., Macleod, G.K., 1975. Postprandial patternsof plasma glucose, insulin and volatile fatty acids in ruminants fedlow- and high-roughage diets. J. Anim. Sci. 41, 1474–1479.

Research 114 (2013) 272– 279

González, F.H.D., Silva, S.C., 2006. Introduc ão à Bioquímica Clínica Veter-inária, 2nd ed. Editor to UFRGS, Porto Alegre.

Greenwood, P.L., Hunt, A.S., Slepetis, R.M., Finnerty, K.D., Alston, C., Beer-mann, D.H., Bell, A.W., 2002. Effects of birth weight and postnatalnutrition on neonatal sheep: III. Regulation of energy metabolism. J.Anim. Sci. 80, 2850–2861.

Hausman, G.J., Barb, C.R., Lents, C.A., 2012. Leptin and reproductive func-tion. Biochimie 94, 2075–2208.

Herselman, M.J., van Loggerenberg, A.A., 2012. Plasma concen-trations of cortisol, insulin, triiodothironine, thyroxine andinsulin-like growth factor-I in different breeds of small stock,http://gadi.agric.za/articles/Herselman MJ/hor97.php (accessed16.02.12).

Johnson Jr., D.D., Mitchell, G.E., Tucker, R.E., Hemken, R.W., 1982. Plasmaglucose and insulin responses to propionate in preruminating calves.J. Anim. Sci. 55, 1224–1230.

Johnson, D.E., Ferrell, C.L., Jenkins, T.G., 2003. The history of energetic effi-ciency research: where have we been and where are we going. J. Anim.Sci. 81, 27–38.

Kaneko, J.J., 2008. Carbohydrate metabolism and its diseases. In: Kaneko,J.J., Harvey, J.W., Bruss, M. (Eds.), Clinical Biochemistry of DomesticAnimals. Elsevier, London, UK, pp. 45–80.

Kauter, K., Ball, M., Kearney, P., Tellam, R., McFarlane, J.R., 2000. Adrenaline,insulin and glucagon do not have acute effects on plasma leptin levelsin sheep: development and characterization of an ovine leptin Elisa.J. Endocrinol. 166, 127–135.

Kawashima, C., Sakaguchi, M., Suzuki, T., Sasamoto, Y., Takahashi, Y.,Matsui, M., Miyamoto, A., 2007. Metabolic profiles in ovulatory andanovulatory primiparous dairy cows during the first follicular wavepostpartum. J. Reprod. Dev. 53, 113–120.

Kiker, W.A., Salisbury, M.W., May, B.J., Engdahl, G.R., 2007. Effects ofprotein and energy feeding on ovine oocyte production and devel-opmental capacity. Agric. Nat. Resour. 20, 52–62.

Kiyma, Z., Alexander, B.M., Van Kirk, E.A., Murdoch, W.J., Hallford, D.M.,Moss, G.E., 2004. Effects of feed restriction on reproductive andmetabolic hormones in ewes. J. Anim. Sci. 82, 2548–2557.

Krasnow, S.M., Steiner, R.A., 2006. Physiological mechanisms inte-grating metabolism and reproduction. In: Neill, J.D. (Ed.),Physiology of Reproduction. Academic Press, San Diego, pp.2553–2626.

Leroy, J.L.M.R., Vanholder, T., Delanghe, J.R., Opsomer, G., Van Soom,A., Bols, P.E.J., Kruif, A., 2004. Metabolite and ionic compositionof follicular fluid from different-sized follicles and their relation-ship to serum concentrations in dairy cows. Anim. Reprod. Sci. 80,201–211.

Liefers, S.C., Veerkamp, R.F., te Pas, M.F.W., Delavaud, C., Chilliard, Y., vander Lende, T., 2003. Leptin concentrations in relation to energy bal-ance, milk yield, intake, live weight, and estrus in dairy cows. J. DairySci. 86, 799–807.

Machado, J.B.B., Fernandes, A.A.O., Selaive-Villarroel, A.B., Costa, A.L., Lima,R.N., Lopes, E.A., 1999. Parâmetros reprodutivos de ovinos deslanadosMorada Nova e Santa Inês mantidos em pastagem cultivada, no estadodo Ceará. Rev. Cient. Prod. Anim. 1, 205–210.

Marie, M., Findlay, P.A., Thomas, L., Adam, C.L., 2001. Daily patterns ofplasma leptin in sheep: effects of photoperiod and food intake. J.Endocrinol. 170, 277–286.

Matsuzaki, M., Takizawa, S., Ogawa, M., 1997. Plasma insulin, metaboliteconcentrations, and carcass characteristics of Japanese Black, JapaneseBrown, and Holstein steers. J. Anim. Sci. 75, 3287–3293.

McCann, J.P., Hansel, W., 1986. Relationships between insulin and glu-cose metabolism and pituitary–ovarian function in fasted heifers. Biol.Reprod. 34, 630–664.

Mcniven, M.A., 1984. Glucose metabolism in fat and thin adult sheep. Can.J. Anim. Sci. 64, 825–832.

Moschos, S., Jean, L., Mantzoros, S., 2002. Leptin and reproduction: areview. Fertil. Steril. 77, 433–444.

National Research Council – NRC, 2007. Nutrient Requirements of SmallRuminants: Sheep, Goats, Cervids, and New World Camelids. NationalAcademy Press, Washington, DC, USA, pp. 384.

Ohkura, S., Ichimaru, T., Itoh, F., Matsuyama, S., Okamura, H.,2004. Further evidence for the role of glucose as a metabolicregulator of hypothalamic gonadotropin-releasing hor-mone pulse generator activity in goats. Endocrinology 145,3239–3246.

Paiva, S.R., Silvério, V.C., Egito, A.A., McManus, C., Faria, D.A., Mariante,A.S., Castro, S.R., Albuquerque, M.S.M., Dergam, J.A., 2005. Geneticvariability of the Brazilian hair sheep breeds. Pesq. Agropec. Bras. 40,887–893.

minant

A.G.V. Catunda et al. / Small Ru

Parra, B.C., Beltran, M.P., 2008. Integrac ão entre nutric ão e reproduc ão emvacas de corte. Rev. Cient. Eletr. Med. Vet. 6, 1–7.

Pineda, M.H., Dooley, M.P., 2003. McDonald’s Veterinary Endocrinologyand Reproduction, 5th ed. State Press, Iowa.

Rabiee, A.R., Lean, I.J., Gooden, J.M., Miller, B.G., 1997. Short-term studiesof ovarian metabolism in the ewe. Anim. Reprod. Sci. 47, 43–58.

Ramin, A.G., Majdani, R., 2005. Correlations among serum glucose, beta-hydroxybutyrate and urea concentrations in non-pregnant ewes.Small Rumin. Res. 57, 265–269.

Russel, A.J.F., Doney, J.M., Gunn, R.G., 1969. Subjective assessment of fatin live sheep. J. Agr. Sci. 72, 451–454.

Sastradipradja, D., 1998. Glucose in Ruminants. A Review. Ulas Balik 5,59–65.

Scaramuzzi, R.J., Campbell, B.K., Downing, J.A., Kendall, N.R., Khalid, M.,Munoz- Gutiérrez, M., Somchit, A., 2006. A review of the effects ofsupplementary nutrition in the ewe on the concentrations of repro-ductive and metabolic hormones and the mechanisms that regulatefolliculogenesis and ovulation rate. Reprod. Nutr. Dev. 46, 339–354.

Selaive-Villarroel, A.B., Fernandes, A.A.O., 2000. Desempenho reprodutivode ovelhas deslanadas Morada Nova no estado do Ceará. Rev. Cient.Prod. Anim. 2, 65–70.

Silva, N.V., Fraga, A.B., Araújo Filho, J.T., Cavalcanti Neto, C.C., Silva, F.L.,

Costa, P.P.S., Lira Júnior, W.B., 2007. Caracterizac ão morfométrica deovinos deslanados Cabugi e Morada Nova. Rev. Cient. Prod. Anim. 9,65–75.

Sosa, C., Abecia, J.A., Carriquiry, M., Forcada, F., Martin, G.B., Palacín,I., Meikle, A., 2009. Early pregnancy alters the metabolic responses

Research 114 (2013) 272– 279 279

to restricted nutrition in sheep. Dom. Anim. Endocrinol. 36,13–23.

Szymanski, L.A., Schneider, J.E., Satragno, A., Dunshea, F.R., Clarke, I.J.,2011. Mesenteric infusion of a volatile fatty acid prevents bodyweight loss and transiently restores luteinizing hormone pulse fre-quency in ovariectomised, food-restricted ewes. J. Neuroendocrinol.23, 699–710.

Tokuda, T., Delavaud, C., Chilliard, Y., 2002. Effects of dietaryenergy levels on plasma leptin in sheep. Anim. Sci. J. 73,471–478.

Udum, C.D., Cetin, M., Balci, F., Gunes, N., Hecer, C., 2008. Effects of plasmainsulin, glucose and NEFA concentrations of feeding frequency duringlong term in lambs. J. Biol. Environ. Sci. 2, 45–51.

Williams, G.L., Amstalden, M., Garcia, M.R., Stanko, R.L., Nizielski, S.E.,Morrison, C.D., Keisler, D.H., 2002. Leptin and its role in the cen-tral regulation of reproduction in cattle. Dom. Anim. Endocrinol. 23,339–349.

Williams, G.L., Zieba, D.A., Amstalden, M., 2005. Leptina: base fisi-ológica e potencial terapêutico. In: IX Curso Novos Enfoques naProduc ão e Reproduc ão de Bovinos, Uberlândia (Brazil), 17–18 Marc o2005.

Yuen, B.S.J., Owens, P.C., McFarlane, J.R., Symonds, M.E., Edwards, L.J.,

Kauter, K.G., McMillen, I.C., 2002. Circulating leptin concentrations arepositively related to leptin messenger RNA expression in the adiposetissue of fetal sheep in the pregnant ewe fed at or below mainte-nance energy requirements during late gestation. Biol. Reprod. 67,911–916.