Sex Of Lamb Research Articles

The Effect of Awassi Ewes Body Condition Scores on Milk Production, Composition and Lambs Growth

This study was performed to evaluate the efficacy of body condition scores (BCS) and Sex of lamb on Awassi ewes milk production, composition and lambs growth. The experiment conducted at one of the Awassi sheep breeders in Baibokht area (8km north of Mosul city ) for three months. Ewes were fed concentrate 500g/ewe/day, 60% barley, 38% wheat bran, 1% salt and 1% limestone, with grazing. ewes were divided in to three groups. First group body condition score (BCS 2), the second group (BCS 3) and the third group (BCS 4). The results revealed BCS3 had a significant effect (P<0.05) on weekly milk yield, total milk yield, fat percentage and lambs weight at different ages and no significant effects of BCS on milk Lactose, Protein, total solid and solid non-fat percentage. Sex of lamb had a significant effect (P<0.05) on weekly milk yield and total milk yield and lambs weight from birth until weaning. And no significant effects on milk composition. In general this means that BCS led to significant improvement in the studied traits for behalf highly BCS compared to low. Male lambs had a significant effect on ewes milk yield and lambs weight.

REMARKABLE CORRELATION OF NON-GENETIC FACTORS WITH GROWTH TRAITS IN TWO BREEDS OF SHEEP

This study was conducted at the college of agriculture – Al-Qasim Green University to investigate the effect of breed and age of dams on several growth traits of two sheep breeds, including 123 Iraqi Awassi and 78 Iranian Karakul breeds. Variables growth traits were examined in the present study, namely body weight (BW), body length (BL), wither height (WH), rump height (RH), and chest circumference (CC), and abdominal circumference (AC). Results indicated the absence of a significant effect between both breeds in all investigated growth traits in birth. Meanwhile, a significant (P&lt;0.05) superiority of Karakul over Awassi was detected in month-3 in three growth traits (BW, WH, and RH), and in month-6, in four growth traits (BW, WH, RH, and BL). The age of dams exhibited a significant (P&lt;0.05) effect on the majority of lambs’ growth traits since lambs born from dams aged over 4 years gave more values than those born from dams aged less than 4 years. Sex of lambs had also contributed to growth traits measurements since higher values were collected from several growth males over females in month-3 (BW, BH, and RH), and month-6 (BW, BL, WH, and RH). Time of birth had also yielded significantly (P&lt;0.05) better values for lambs born in January over those born in other months. However, lambs born in December gave better traits than other lambs. In conclusion, this study demonstrated the obvious superiority of Karakul over Awassi breed in the majority of growth traits measured.

Maternal Supply of Fatty Acids during Late Gestation on Offspring's Growth, Metabolism, and Carcass Characteristics in Sheep.

Simple SummaryGrowth is an important factor that drives animal production, and it can be manipulated through maternal nutrition. In ruminants, previous studies suggested that maternal nutrition during late gestation with polyunsaturated fatty acids altered growth, energy metabolism, muscle development, and body composition of the offspring. This study investigates the effect of supplementing different sources of fatty acids during late gestation on offspring energy metabolism and growth during the finishing period. Maternal fatty acid supplementation during late gestation modified growth, insulin sensitivity, and hot carcass weight in lambs; these changes depended on the unsaturation degree of the fatty acid supplement and lamb sex. Hence, fatty acid supplementation of the gestating ewe can potentially have a lifelong impact on offspring’s growth performance and metabolism, and could be used as a possible management alternative to enhanced offspring productivity.Lambs born from dams supplemented with different sources of fatty acids (FA) during late gestation have a different growth rate and plasma glucose concentration. The main objectives of this experiment were to evaluate the effect of supplementing different sources of FA during late gestation on offspring plasma metabolite concentrations, growth, and on a glucose tolerance test (GTT) during the finishing phase. Fifty-four lambs (18 pens, 3 lambs/pen) were born from ewes supplemented during late gestation with one of three treatments: (1) no FA (NF); (2) a source of monounsaturated FA (PDS, 1.01% of Ca salts); or (3) a source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (EDS, 1.01% of Ca salts containing). At birth (day 0), supplementation ceased, and all ewes and lambs were placed in a common pen. On day 60, lambs were weaned, grouped by sex, blocked by body weight (BW), and placed on a common finishing diet for 54 days (FP). One lamb per pen was used for the GTT after the FP. There was a tendency for FA × Sex × Day interaction (p = 0.08) on lamb growth during the finishing period, with PDS females being heavier than PDS males, while EDS males were heavier than EDS females at day 60. There was a tendency for FA × Sex interaction (p = 0.06) for plasma insulin concentration for the GTT. Plasma insulin concentration of wethers increased as FA unsaturation degree increased during the GTT; the opposite happened with the plasma insulin concentration of female lambs. In conclusion, FA supplementation during late gestation tended to modified growth and insulin response to a GTT; these changes differed with the degree of FA unsaturation of the supplement and lamb sex.

Multivariate quantitative genetic analysis of body weight traits in Corriedale sheep.

In the present study, an attempt was made to elucidate the genetic parameters for body weight traits of lambs from Corriedale sheep population at different ages. Data were collected from 6874 lambs born over a span of 49 years from 1969 to 2017. The traits under study included body weight atbirth (BW), weaning (WW), 6 months of age (6MW), 9 months of age (9MW) and yearling stage (YW). Data were statistically analyzed using restricted maximum likelihood (REML) algorithm in WOMBAT program. A multi-variate animal model was fitted to the data incorporating season andperiod of lambing, sex of lamb and litter size as fixed effects. Variance and covariance components were estimated using the animal model after incorporating direct additive genetic effect of animal as random factor. Genetic and phenotypic correlations with corresponding standard errors were also estimated. The heritability estimates for BW, WW, 6MW, 9MW and YW were 0.130 ± 0.023, 0.300 ± 0.029, 0.292 ± 0.030, 0.191 ± 0.025 and 0.169 ± 0.024, respectively. The genetic correlation between different traits under study was high, except between BW and 9MW for which the estimate was moderate. Phenotypic correlation ranged from low to high for different trait combinations. Among different traits under study, only two traits showed moderate heritability i.e. WW and 6MW while heritability of other traits was low. Both these traits showed high correlation with all subsequent traits. Selection programme for Corriedale sheep should be based on WW which is expressed early in life and shall lead to moderate geneticresponseto selection.

Estimation of (Co)Variance components and genetic parameters of fibre traits in Rambouillet sheep using multi-trait analysis.

The present study aimed to estimate the genetic parameters of different fibre traits, viz., greasy fleece weight, staple length, and fibre diameter in Rambouillet sheep population using a multi-trait animal model. Data, spanning over 10 years (1998-2007) and pertaining to fibre traits at first clip, were collected for a total of 4186 Rambouillet sheep maintained at an organized farm. (Co)Variance structure and genetic parameters were estimated using a multi-trait animal model. The genetic analysis of data was performed based on restricted maximum likelihood (REML) procedure using WOMBAT software. The model incorporated sex of lamb (i = 1, 2), year of birth (j = 1-10), season of birth (k = 1-2), and litter size (l = 1-2) as fixed effects while direct additive genetic and maternal genetic effects were included as random effects. The direct additive genetic heritability estimates were 0.120±0.034, 0.136±0.037, and 0.356±0.070 for greasy fleece weight, staple length, and fibre diameter, respectively. The maternal genetic heritability of all fibre traits under study was very low. Additive genetic correlation was positive and low between greasy fleece weight and staple length; and between staple length and fibre diameter. In conclusion, fibre diameter was moderately heritable which implies that selection may lead to moderate improvement in this trait. The results from the present study will help in formulating optimal breeding plans for improvement of fibre traits in Rambouillet sheep.

Machine learning algorithms for lamb survival

Lamb survival is influenced by the culmination of a sequence of often interrelated events including genetics, physiology, behaviour and nutrition, with the environment providing an overarching complication. Machine learning algorithms offer great flexibility with regard to problems of complex interactions among variables. The objective of this study was to use machine learning algorithms to identify factors affecting the lamb survival in high altitudes and cold climates. Lambing records were obtained from three native breed of sheep (Awassi = 50, Morkaraman = 50, Tuj = 50) managed in semi intensive systems. The data set included 193 spring born lambs out of which 106 lambs were sired by indigenous rams (n = 10), and 87 lambs were sired by Romanov Rams (n = 10).Factors included were dam body weight at lambing, age of dam, litter size at birth, maternal and lamb behaviors, and lamb sex. Individual and cohort data were combined into an original dataset containing 1351 event records from 193 individual lambs and 750 event records from 150 individual ewes. Classification algorithms applied for lamb survival were Bayesian Methods, Artificial Neural Networks, Support Vector Machine and Decision Trees. Variables were categorized for lamb survival, lamb behavior, and mothering ability. RandomForest performed very well in their classification of the mothering ability while SMO was found best in predicting lamb behavior. REPtree tree visualization showed that grooming behavior is the first determinant for mothering ability. Classification Trees performed best in lamb survival. Our results showed that Classification Trees clearly outperform others in all traits included in this study.

The genetics of perinatal behaviour of Merinos in relation to lamb survival and lambs weaned per ewe mated

Data for birth weight (BW), lamb survival (LS) and neonatal behaviour, including records of between 1494 (latency of birth to first suckling or LBS) and 2705 (BW and LS) lambs were used. Additionally to the lamb data, ewe data comprising of between 1003 ewe-year records for the latency of stay on the birth site (SBS) and 2024 ewe-year records for number of lambs weaned per ewe mated (NLW) were analysed. These records were from selection lines that had been divergently selected from the same base population since 1986, either for NLW (termed the High or H line) or against NLW (termed the Low or L line). Overall, H line lambs had an improved LS compared to their L line contemporaries, while H line ewes were superior to L line ewes for NLW. Latency of parturition of H line progeny was shorter than in L line progeny while ewe lambs had shorter births than ram lambs. Lamb sex and selection line had no effect on the latency from birth to suckling, which decreased as dam age increased. The second of multiples took longest to progress to suckling from birth, with singles being the quickest. H line ewes had shorter parturitions and cooperated better with the first suckling attempts of their offspring. Single-trait direct heritability estimates (h²) in lambs were 0.15 for BW, 0.07 for LS, 0.06 for latency of parturition (LP) and 0.14 for LBS. The inclusion of the maternal genetic variance ratio (m²) resulted in an improvement in the log likelihood ratio for BW, LP and LBS, yielding estimates of respectively 0.37, 0.18 and 0.12. The maternal permanent environment variance ratio for LS amounted to 0.07. The genetic correlation of LS with LP was favourable at -0.69. Estimates of h², as ewe traits, were 0.04 for NLW, 0.17 for LP, 0.07 for ewe cooperation score (ECS) and 0.20 for SBS. Genetic correlations indicated that ewes with a high NLW had shorter parturitions while ECS was genetically correlated to SBS. Genetic trends suggested divergence between the lines for breeding values for LP, suggesting that parturitions became shorter in the H line and longer in the L line. Selection for NLW would yield desirable outcomes for ewe and lamb behavioural traits based on genetic trends and correlations. Such selection would putatively benefit animal welfare by reducing birth stress in ewes and lambs and by promoting maternal cooperation with their offspring’s first suckling attempts in ewes.

Genetic parameters for sex ratio in an organised sheep farm

A study was conducted on records of 10413 sheep of two breeds (Avikalin and Malpura) to understand the genetics of sex ratio and how it is governed by several factors in sheep breeding. Data from the ICAR-Central Sheep and Wool research Institute, Avikanagar (Rajasthan), comprising the period 1991-2016 were used for the analysis. The average sex ratio (per cent males at birth) was 50.43±0.28 in Malpura and 51.05±0.32 in Avikalin sheep. Least squares analysis of variance showed that the non-genetic factors did not influence the sex ratio significantly. Descriptive analysis showed that sires had a trend of producing a particular sex of lambs in their lifetime. Genetic analysis showed low additive genetic variance for sex ratio in Avikalin (h 2 = 0.019±0.003) and Malpura sheep (h 2 = 0.04±0.01). Maternal permanent effect was found important for sex ratio in Avikalin sheep. It was concluded that sex ratio is not influenced by management practices in sheep breeding. However, selecting sires with a tendency of producing a specific sex may help in skewing of the sex ratio curve in the farm.

Evaluation of models for estimation of genetic parameters for post-weaning body measurements and their association with yearling weight in Nellore sheep.

The objective of this study was to obtain (co) variance components and genetic parameter estimates for post-weaning body measurements such as body length, height at withers and chest girth recorded at six (SBL, SHW and SHG), nine (NBL, NHW and NHG) and twelve (YBL, YHW and YHG) months of age along with yearling weight (YW) in Nellore sheep maintained at livestock research station, Palamaner, Andhra Pradesh, India and also the association among body measurements with yearling weight was studied. Data on 2,076 Nellore sheep (descended from 75 sires and 522 dams) recorded between 2007 and 2016 (10 years) were utilized in the study. Lambing year, sex of lamb, season of lambing and parity of dam were included in the model as fixed effects and ewe weight was kept as a covariate. Analysis were conducted with six animal models with different combinations of direct and maternal genetic effects using restricted maximum likelihood procedure. Best model for each trait was determined based on Akaike's Information Criterion. Moderate estimates of direct heritability were obtained for the studied traits viz., BL (0.02-0.24), HW (0.31-0.49) and CG (0.08-0.35) and their corresponding maternal heritability estimates were in the range of 0.00-0.07 (BL), 0.13-0.17 (HW) and 0.07-0.13 (CG), respectively. Positive direct genetic and phenotypic correlations among the traits and they ranged from 0.07 (YBL-YW) to 0.99 (SBL-SHG, SHG-YW and NBL-YBL) and 0.01 (SBL-YBL) to 0.99 (NBL-NHG), respectively. Further, the genetic correlations among all the body measurements and yearling weight were positive and ranged from 0.07 (YW and YBL) to 0.99 (YW and SHG). Strong association of chest girth at six months with yearling weight. Further, it is indicated that moderate improvement of post-weaning body measurements in Nellore sheep would be possible through selection.

Analysis of the influence of genetic and non-genetic factors on the birth weight and weaning weight of lambs

The main aim of this paper is to analyze the influence of genetic and non-genetic factors on the birth weight and weaning weight of lambs. The study was carried out on the basis of the Institute of Animal Husbandry of Steppe Regions named by M. F. Ivanov “Askania-Nova” – the National Scientific Agricultural Center in Sheep Breeding of NAAS. Birth and weaning weights data collected during a 5-vear period from 3961 lambs were used. The reproductive traits of the Ascanian fine-fleece (AC) ewes were evaluated in combination with the rams of different genotypes: Ascanian fine-fleece, Australian merino (AM) and half-bred animals (1/2AC+1/2AM). The main effect of the ram genotype and the year of lambing, the age of the ewes, the litter size, the sex of lamb and the sex ratio in twins on the birth weight and weaning weight of lambs was analysed using one-way ANOVA. Differences between years of the 5-year period were highly significantly (P &lt; 0.001) for all lamb traits studied. The effects of the environmental factor (year of lambing) on the birth weight and weaning weight of lambs represented 27.2 and 15.2 per cent of the total variance, respectively. The ram-group effects, which are mainly genetic differences, were highly significant (P &lt; 0.001) in all traits. Age of dam had significant effect on the birth weight of lambs (P = 0.048) and was relatively unimportant as a source of variation. Two-year-old ewes bore lighter lambs than older ewes. There were no significant differences in the weaning weight of lambs from the ewes of different age classes. Survival rate was related to birth weight of lambs. Lamb survival increased up to a birth weight of 4.0 kg and only declined when they weighed more than 5.0 kg at birth. Our results showed that singles were 0.61 kg heavier than twins at birth and were 2.42 kg heavier than twins at weaning. Litter size (type of birth) was responsible for 42.5 and 10.0 % of total variability in birth and weaning weights of lambs, respectively (in both cases: P &lt; 0.001). Average birth and weaning weights of male lambs were higher than the females (in both cases: P &lt; 0.001).

Effect of supplementation of unprotected or protected arginine to prolific ewes on maternal amino acids profile, lamb survival at birth, and pre- and post-weaning lamb growth

This research determined the effects of dietary supplementation with rumen-protected arginine (Pro-Arg) on metabolites and amino acids in maternal plasma and lamb survival rate at birth (LSRAB) in prolific Afec-Assaf ewes. The hypothesis was that Pro-Arg, the precursor for nitric oxide and polyamines, would increase placental development and vascularity, uteroplacental blood flow, and nutrient transport and reduce oxidative stress to increase LSRAB. Ewes were fed either their basal diet, basal diet with Pro-Arg, or basal diet with unprotected arginine (Unp-Arg; 18 g/head/d). The supplemental arginine was about 1% of the dry matter intake from day 40 or 60 of gestation until parturition. Ninety-two of 98 ewes produced live lambs. Ewes fed Pro-Arg had greater (P = 0.002) concentrations of arginine and other amino acids in plasma, whereas Unp-Arg did not affect concentrations of arginine, but decreased (P < 0.05) concentrations of some amino acids. There was no effect of treatments on gestation length (144 ± 2 d), prolificacy (2.65 lambs born per ewe), LSRAB (0.80), body weight (88.8 ± 10.8 kg), and body condition score (2.8 ± 0.6) of ewes, or birth weight and crown-rump length of lambs. The GI (BW/CRL1.5) was affected by sex of lamb (P = 0.008), parity of ewe (P = 0.002), litter size (P = 0.0001), and lamb status (P = 0.003). Of 229 lambs born, 32 were dead and 16 died before 5 mo of age, leaving 181 lambs with records on weights at birth and 5 mo of age. Interestingly, lambs born to ewes fed the Unp-Arg and Pro-Arg weighed 3.6 kg less at postnatal day 150 than lambs from control ewes.

Multi trait genetic evaluation of growth traits in Nellore sheep raised on pasture in semi-arid regions of India using Bayesian approach

Abstract The main aim of this study is to estimate genetic parameters and (co) variance components for body weights at various ages in Nellore sheep born during the period from 1993 to 2016 (23 years). A total of 4822 lambs with pedigree descended from 144 sires and 1299 dams were included in this study. Bayesian analysis using Gibbs sampler multi trait animal model with and without maternal effects was studied. Traits included in this study were birth weight (BW), weaning weight (WW), six months body weight (6MW), nine months body weight (9 MW), Yearling weight (YW). Year-season of birth and sex of lamb (contemporary groups) were considered as fixed effects with ewe weight at lambing as a covariate. Estimates of direct heritability estimates for birth weight, WW, 6MW, 9MW and YW based on best model were 0.17, 0.28, 0.27, 26 and 0.23, respectively and the corresponding maternal heritability estimates were 0.12, 0.14, 0.14, 0.12 and 0.13, respectively. The direct-maternal genetic covariance was negative for all the studied traits. Strong and positive estimates of direct additive genetic correlations were observed in growth traits and they ranged from 0.16 to 0.83, whereas the direct-maternal genetic correlations were negative for all the traits and these estimates ranged from ˗0.89 to ˗0.08. Moderate estimates of heritability for the growth traits obtained in this study suggested the presence of better genetic variability and the possibility for genetic improvement of Nellore sheep through selection. Maternal genetic effects were significant in all the traits. Hence, it is recommended to incorporate these effects in the genetic analysis by including it as a genetic or environmental effect or both. The environmental variance obtained in the study suggested that the growth performance of Nellore sheep may be enhanced by improving the feeding and management aspects. Correlations among traits and effects should be considered while implementing breed improvement program.

Effectiveness of Genetic Parameter Estimation in a Small Flock of Merino Sheep with Shallow Pedigree

In this study, the genetic and non-genetic parameters were estimated for growth traits of Karacabey merino sheep. Growth performance data refer to 1863 lambs born between 2016 and 2018. Analyses were carried out by restricted maximum likelihood fitting animal models and disregarding or including maternal genetic or maternal permanent environmental effect. Six different animal model were fitted for all traits, and the most suitable model for each trait was chosen after Akaike information criterion test (AIC). Year of birth, age of dam, type of birth and lamb sex were significant sources of variation on birth weight (BW), average daily gain (ADG), Kleiber ratio (KR), weaning weight (WW) and six month weight (6MW). Direct heritability (h^2) for BW, ADG and 6MW were 0.12, 0.02 and 0.04, respectively, however, for KR and WW were 0.00 model 6 (which the best). The estimates of maternal heritability (m^2) for ADG, KR and WW were 0.12, 0.04 and 0.04, respectively in model 5, also maternal heritability were low for BW and 6MW. Maternal permanent environmental effects (c^2) have high contribution to the explanation growth traits and were estimated between 0.19 and 0.75 for these traits. These results showed that selecting for improved maternal and/or direct effects for Karacabey merino in the herd would generate very slow genetic improvement in growth traits.

Effect of energy source and level, animal age, and sex on the flavor profile of sheep meat.

The effects of dietary energy source, energy level, sheep age, and sheep sex on flavor and off-flavor intensity were evaluated. Consumer panelists, with previous lamb-eating experience, assessed lamb flavor and off-flavor intensity on a 100-point, end-anchored scale (0 = very mild to 100 = very intense), with off-flavor being defined as anything different than lamb flavor. Lamb longissimus thoracis (LT) and whole, boneless ground shoulder (GS) formed into patties were evaluated. Trial 1 was a randomized complete block design with a 3 × 2 factorial arrangement of treatments. Sheep age (ewe lambs, yearling ewes, and mature ewes; n = 16/age) and ad libitum access to diets [alfalfa pellets (AP) or whole-shelled corn (WSC100)] were treatments. The LT from mature ewes had a greater (P ≤ 0.02) off-flavor intensity when compared with yearling ewes and ewe lambs. Ground shoulder from sheep raised on AP had a greater lamb flavor (P ≤ 0.04) and off-flavor (P ≤ 0.04) intensity than GS from sheep consuming WSC100. Trial 2 was a randomized complete block design with a 3 × 2 × 2 factorial arrangement of treatments. Three dietary treatments [AP, WSC100, and restricted intake of whole-shelled corn to 85% of ad libitum (WSC85)], lamb sex (ewes and wethers; n = 48/sex), and lamb age [short fed, 177 ± 16.6 d of age and 93 ± 20.5 d on feed (DOF); long fed, 294 ± 7.0 d of age and 219 ± 3.8 DOF]. Flavor intensity of the LT was greater (P ≤ 0.05) from lambs offered AP when compared with lambs offered WSC85, whereas lamb flavor of the LT from lambs fed WSC100 was intermediate and not different from the lamb flavor of the LT of lambs fed AP or WSC85. The LT of long-fed lambs had a greater (P ≤ 0.01) lamb flavor and off-flavor intensity when compared with short-fed lambs. Lambs offered AP resulted in a GS with greater lamb flavor intensity (P ≤ 0.01) when compared with lambs offered WSC85 and WSC100, with no diet influence on GS off-flavor intensity. Long-fed lambs produced GS with a greater lamb flavor (P ≤ 0.01) and off-flavor (P ≤ 0.01) intensity when compared with GS from short-fed lambs. Results from the two trials indicate lamb flavor and off-flavor intensity were greater from sheep offered a high-forage (AP) diet when compared with a high-concentrate (WSC) diet. Lamb flavor intensity increased as age of the sheep at harvest increased, suggesting dietary management and associated age-related effects at harvest will influence consumer perception of lamb flavor.

Shearing during late pregnancy increases size at birth but does not alter placental endocrine responses in sheep

Shearing during the latter half of pregnancy is a common practice to improve flock health and productivity. Previous studies have demonstrated that shearing pregnant ewes at mid or late pregnancy is associated with an increase in lamb birth weight. In the present study, we used singleton Polypay × Dorset pregnant sheep, to investigate the potential roles of placental function and changes in maternal metabolism in underlying this increased birth weight response. Two groups were randomly established and blocked at enrollment by animal BW, body condition score and subcutaneous adipose tissue depth. The groups were shorn (SH; n = 18) or not (C; n = 20) at gestational day (GD) 107 ± 1 (mean ± SEM). Weekly maternal plasma samples were collected between shearing and birth, but only six samples were assayed for progesterone, pregnancy-associated glycoproteins (PAG1), glucose and non-esterified fatty acids (NEFAs). At birth, sex, birth weight, and newborn body mass index (BMI) were recorded. Maternal BW during mid- to late-pregnancy was similar between groups. Shearing resulted in increased lamb birth weight and BMI (P < 0.05) regardless of fetal sex but did not affect the maternal concentration of PAG1 or progesterone from GDs 100 to 142. After shearing (GD100) and up to lambing, shorn females had higher circulating glucose concentrations (P < 0.05), but not NEFA, compared to the control group. Maternal circulating PAG1, progesterone, glucose or NEFA concentration across pregnancy did not differ according to lamb sex. Across pregnancy, birth weight was positively associated with PAG1 (P < 0.001), but not with progesterone concentrations. In conclusion, weight and BMI at birth were higher in both sexes upon shearing in singleton pregnancies. Despite PAG1 being associated with birth weight, late-pregnancy shearing did not alter the placental endocrine response. Whether other placental factors are altered upon shearing and may influence the increase in birth weight and BMI remain to be investigated.

The Effect of Some Environmental Factors on the Birth Weight in Anatolian Merino Sheep

In this study, the data of 1510 lambs born in a private sheep farm in Eregli district of Konya in 2018-2019 were evaluated. Birth type, birth times, birth weight and sex of lambs were investigated in this study. 892 of the lambs were born in 2018 and 618 of them were born in 2019. A total of 1510 lambs were born, 699 of them were born in singles, 761 in twins and 50 in triplets. The total number of sheep is 1096. 681 of the lambs were male and 829 were female. Of the environmental factors affecting birth weight, while the effect of the year was statistically insignificant (p &lt;0.05), the effect of season, type of birth and sex was significant (p &lt;0.01). Lambs born in spring have more live weight than those born in other seasons. The live weight of male lambs is higher than that of females, whereas the weight of single born lambs is higher than that of twins and triplets.

The Effect of Some Environmental Factors on the Distribution of Births during a day in Anatolian Merino Sheep

time of birth in sheep were investigated. A day (24 hours) was divided into four timeframes as 22: 01-04: 00, 04: 01-10: 00, 10: 01-16: 00 and 16: 01-22: 00 in order to determine the time period in which births take place. Chi-square (χ2) test was used to determine whether the age, sex, and type of birth were effective on the distribution of births to the time periods during the day. In 2016, 78.09% of births were single and 21.91% were twins. The sex ratio was 48.24% male and 51.76% female. The most frequent birth times are 10: 01-16: 00 (26.95%) and 04: 01-10: 00 (25.57%), the lowest birth times are 16: 01-22: 00 (23.93%) and 22: 01- 04:00 (23.55%). The effect of maternal age and lamb sex on delivery time was significant (P <0.05), but the effect of birth type was not significant.

Refeeding ewe’s ad libitum after energy restriction during mid-pregnancy does not affect lamb feed conversion ratio, animal performance and meat quality

The aim of the study was to evaluate maternal energy restriction in ewes from day 48 to 106 of gestation on pre- and post-weaning lambs`’ performance, carcass and meat quality when their dams were fed ad libitum after the restriction period. Ewes bearing single or twin lambs were assigned to two dietary treatments from day 48 to day 106 of gestation: restricted (R; n = 60) at 60% of their metabolizable energy (ME) requirements, or non-restricted (NR; n = 54) at 100% of their ME requirements. After the restriction period ewes grazed all together ad libitum until weaning. Subsequently, male lambs were placed in a feedlot until slaughter. Ewes body weight was recorded during nutritional treatment application and at weaning. Litter size and lamb sex were recorded, and feed intake and body weight were measured from birth until slaughter. After slaughter, carcass weight and yield, subcutaneous tissue depth (GR site), carcass (CL) and leg length (LL), frenched rack (FR) and leg weights were determined. After 5 days of meat aging, color parameters and Warner-Bratzler shear force were determined on longissimus lumborum muscle. Non-restricted ewes weighed 7.5 kg more than R ewes (P < 0.05) at the end of the restriction period. Lamb birth weight (BW) was no affected (P > 0.05) by dams’ treatment although male and single lambs had a greater (P < 0.05) BW than females and twins, respectively. No significant differences (P > 0.05) were detected on the weaning weight between ewes’ feeding treatments or lamb sex. Estimated average milk intake by lambs was not affected (P > 0.05) by dams’ treatments and litter size. Lambs born to R or NR ewes did not differ (P > 0.05) in feed conversion ratio (FCR) of milk, while twins were more efficient (P < 0.05) than single-born. Male lambs from R and NR ewes did not differ (P > 0.05) in weaning and final weight, feed intake and FCR during the fattening phase. Slaughter and hot carcass weight, carcass yield (CYd), GR, CL and LL were not affected (P > 0.05) by treatment and litter size. Brightness of meat (L* value) was greater (P < 0.05) in lambs from R ewes than NR. Ewes restricted at 60% of their ME requirements in mid-gestation seems to have the capacity to compensate any detrimental effects on lamb growth and development if adequate refeeding conditions are provided in late gestation and throughout lactation.

Environmental effects in the formation of contemporary groups of Santa Inês lambs

The objective of this work was to study the influence of environmental effects, sex of the lamb, type of birth, year of birth, birth season, julian birth date, and lambing weight on the weights and biometric measurements of Santa Inês lambs from birth to weaning (70 days of age), and to define the best-adjusted statistical model. Data on weights, heights, body lengths, and thoracic perimeters obtained at birth and close to 28 and 70 days of age from 270 lambs were used. Three analyses were carried out considering different models; one with isolated environmental factors, one with animals grouped into contemporaries according to lamb sex, type of birth, year of birth, and season of birth (GC1), and one with animals gathered in groups of contemporaries according to lamb sex, type of birth, year of birth, season of birth, and the julian date of birth (GC2). Environmental factors influenced a large proportion of body weights and measurements from birth to weaning; the main factors were type of birth and year of birth. The GC2 evaluations presented higher determination coefficients and lower values for Akaike information criteria. However, many observations were discarded; 114, 111, and 103 compared with those rejected by the GC1 analysis, which included two, three, and four observations at birth, 28 days of age, and at weaning, respectively. This may lead to the exclusion of animals with genetic potential.

Evaluate pure Breeding and Crossbreeding Strategy for Better Carcass and non-carcass Traits of Awassi, Chios, and their Reciprocal Crossbred Lambs

In Jordan, crossing local sheep with the exotic breed has an acceptable sound by farmers but needs scientific proof for planned-ahead crossing and introgression. This work aimed to find the best mating strategy on economic carcass and non-carcass traits of produced lambs under an intensive production system in Jordan. The mating strategy among Awassi and Chios for two years was designed to obtain different pure- and cross-bred lambs. They were pure Awassi, pure Chios, and reciprocal crosses of Awassi-Chios and Chios-Awassi lambs for two years. The studied factors included sex of lamb, breed, lamb birth type, age at slaughtering, and their two-way interactions. The lamb sex significantly affected (P &lt; 0.001) most carcass and non-carcass traits of economic importance. Similarly, the effect of age was notable (P &lt; 0.05) on all carcass and non-carcass traits. The breeds were significantly different (P &lt; 0.05) for the hot carcass, tail, and internal organs weights. Therefore, the use of Awassi sire as a paternal contributor for producing meat over one year in crossbreeding can be implemented for increasing carcass weights. The heterosis effect had only significant for tail weight. Significant differences for the liver with and without a trachea, kidney with and without fat, heart with and without fat, and lung between reciprocal crosses for heterosis percentages always favored the reciprocal cross of Awassi female parent. Interaction effects of age with sex were detected on body weight, carcass length, and kidney, while interaction effect of birth type with sex was significant for body weight and some internal organs. finally, significant interaction effects of the breed with both sex and birth type were significant for the cold carcass, tail, and some organs weights. In the present study, sheep producers might be benefited better if Awassi sire is used as a paternal contributor for producing meat over one year in crossbreeding strategy with Chios for increasing carcass weights.