Ewe Litter Size Research Articles

Integration of multi-omics reveals the important role of the BBS10 gene in reproduction.

Blood samples are easily obtained from sheep. Therefore, blood analysis can be a convenient method for evaluating reproductive traits in sheep by detecting genetic and metabolic changes in the ovary. By combining 167 RNA sequencing (RNA-seq) data and 60 untargeted metabolomics data, this study analyzed the relationship between genes and metabolites in the ovary and blood. The conjoint KEGG enrichment analysis enriched glutathione metabolic pathways both in the ovary and blood. This finding provides an explanation for possible glutathione metabolic processes in the ovary with metabolite exchange in the blood. The metabolite-gene-disease interaction network revealed a correlation between the expression of certain Bardet-Biedl syndrome (BBS) family genes in the ovary and blood. This indicates that BBS family genes, such as BBS10 in sheep blood, could be a potential biomarker for BBS. We investigated the relationship between BBS10 gene expression in the ovary and lambing numbers using whole-genome sequencing data from 450 ewes. Our findings suggest that g.112314188C > G may lead to decreased litter size in ewes carrying the FecB gene. These SNPs could be potential molecular markers for breeding sheep.

Genetic Diversity, Selection Signatures, and Genome-Wide Association Study Identify Candidate Genes Related to Litter Size in Hu Sheep.

Hu sheep is a renowned prolific local sheep breed in China, widely distributed across the country due to its excellent reproductive performance. Deciphering the molecular mechanisms underlying the high fecundity of Hu sheep is crucial for improving the litter size of ewes. In this study, we genotyped 830 female Hu sheep using the Illumina OvineSNP50 BeadChip and performed genetic diversity analysis, selection signature detection, and a genome-wide association study (GWAS) for litter size. Our results revealed that the Hu sheep population exhibits relatively high genetic diversity. A total of 4927 runs of homozygosity (ROH) segments were detected, with the majority (74.73%) being short in length. Different genomic inbreeding coefficients (FROH, FHOM, FGRM, and FUNI) ranged from -0.0060 to 0.0126, showing low levels of inbreeding in this population. Additionally, we identified 91 candidate genomic regions through three complementary selection signature methods, including ROH, composite likelihood ratio (CLR), and integrated haplotype score (iHS), and annotated 189 protein-coding genes. Moreover, we observed two significant SNPs related to the litter size of Hu sheep using GWAS analysis based on a repeatability model. Integrating the selection signatures and the GWAS results, we identified 15 candidate genes associated with litter size, among which BMPR1B and UNC5C were particularly noteworthy. These findings provide valuable insights for improving the reproductive performance and breeding of high-fecundity lines of Hu sheep.

FecB Was Associated with Litter Size and Follows Mendel's Laws of Inheritance When It Transited to Next Generation in Suhu Meat Sheep Breeding Population.

In order to investigate the effect of FecB on litter size and growth and development traits of Suhu meat sheep and the inheritance patterns of FecB between parents and offspring in the population. In this experiment, 2241 sheep from the Suhu meat sheep population were tested for FecB using capillary electrophoresis. We combined the lambing records of 473 ewes, the growth trait records of 881 sheep at both the birth and weaning (2-month-old) stages, and the complete genealogical records of 643 lambs to analysis the distribution of FecB in the Suhu meat sheep breeding population, its effect on litter size of ewes, growth and development of lambs, and the inheritance patterns of FecB. The results showed that there were three genotypes of FecB in the Suhu meat sheep population, namely the AA genotype, AG genotype, and GG genotype. FecB in this population has a moderate polymorphism (0.25 < PIC < 0.5), and deviates from Hardy-Weinberg disequilibrium (p < 0.05). The litter size of GG genotype ewes was significantly higher than that with the AG and AA genotypes (p < 0.01). A Chi-square test showed that the inheritance patterns of FecB follows Mendel's Laws of Inheritance (p > 0.05). An association analysis of different genotypes of FecB with body weight and body size of Suhu meat sheep at birth and weaning revealed that FecB adversely affects the early growth and development of Suhu meat sheep. In summary, FecB can improve the litter size of ewes but it has negative effects on the early growth and survival rate of lambs in sheep. Therefore, FecB test results and feeding management measures should be comprehensively applied to improve the reproductive performance of ewes, the survival rate and production performance of lambs in sheep production, and thus improve the economic benefits of sheep farms.

Detection of polymorphisms in six genes and their association analysis with litter size in sheep

Litter size in sheep is a complex trait controlled by micro-effective polygenes. APAF1, CLSTN2, CTH, PLCB1, PLCB4, and CHST11 are all involved in mammalian reproduction. However, the effects of these genes on litter size in sheep are still unclear. Therefore, in this study, we used Sequenom MassARRAY® SNP assay technology to type the single nucleotide polymorphisms (SNPs) loci of six genes in five sheep breeds. The results showed that most sheep breeds contain three genotypes at each locus. Then, we conducted population genetic analysis on the SNPs of six genes and found that the polymorphic information content in all sheep breeds ranged from 0 to 0.37, and most sheep breeds were in Hardy-Weinberg equilibrium (p > 0.05). In addition, association analysis in Small Tail Han sheep indicated that the rs399534524 locus in CLSTN2 was highly associated with first parity litter size, and litter size in ewes with CT genotype was higher than that in ewes with CC genotype or TT genotype. Furthermore, the rs407142552 locus in CTH was highly associated with second parity litter size in Small Tail Han sheep, and litter size in ewes with CT genotype was higher than that in ewes with TT genotype. Finally, we predicted the CTH and CLSTN2 protein interaction network and found that HTR1E, NOM1, CCDC174 and ALPK3 interact with CLSTN2 and have been reported as candidate genes related to litter size in sheep. These results suggest that they may be useful genetic markers for increasing litter size in sheep.

The relationship between G1 (c.260 G>A) and G4 (c.721 G>A) polymorphisms in the GDF9 gene and the litter size of sheep: A meta-analysis study.

The results of G1 and G4 polymorphisms as litter-size (LS) markers of ewes remain contradictory. The aim was to evaluate the impact of G1 (c.260 G>A) and G4 (c.721 G>A) polymorphisms on the LS of sheep by synthesizing data from multiple previous studies. Data were extracted from 14 eligible articles. The genotypes of G1 and G4 polymorphisms were homozygous wild-type (WW), heterozygous (WM), and homozygous mutant-type (MM). The standardized mean difference (SMD) method using random effect models was employed to determine the effect size of G1 and G4 polymorphisms on LS under dominant, recessive, additive, and co-dominant genetic models. Heterogeneity was analyzed with the I2 statistic index. Publication bias was depicted with funnel plots and tested by Egger's and Begg's tests. The study showed that the correlation between G1 polymorphism and LS in sheep was not significant (p > 0.05) under all genetic models. The influence of G4 polymorphism on the LS of sheep was found significantly (p < 0.05) under dominant [SMD = 0.28, I2 = 0% (no heterogeneity)] and co-dominant [SMD = -0.14, I2 = 36% (moderate heterogeneity)] genetic models. The WM genotype of G4 polymorphism increased LS, while the MM genotype reduced LS in sheep. Publication bias among G1 and G4 polymorphism studies was absent in all genetic models. Thus, the study revealed that G4 polymorphism could be a potential genetic marker for LS in ewes. On the contrary, G1 polymorphism has no association with the LS of ewes.

Association between the prion protein genotype and animal performance traits in a large multibreed sheep population

Genetic susceptibility to scrapie, a fatal disease of sheep and goats, is modulated by polymorphisms in the prion protein (PrP). Neither the frequency of the PrP genotypes nor their association with animal performance has been investigated in a large multibreed Irish sheep population. Scrapie genotypes were available on 16 416 animals; the breeds represented included purebred Belclare (733), Charollais (333), Suffolk (739), Texel (1 857), Vendeen (191), and crossbreds (12 563). Performance data on lambing, lamb and ewe performance as well as health traits were available. The association between alternative approaches of describing the PrP genotype (i.e. 15 individually called PrP genotypes, five genotype classes representing susceptibility to scrapie, or number of ARR haplotypes) and animal performance were quantified using animal linear mixed models. All 15 of the possible scrapie genotypes were detected, although the frequency differed by breed. The frequency of the five PrP haplotypes in the entire population were 0.70 (ARR), 0.15 (ARQ), 0.11 (ARH), 0.02 (AHQ) and 0.01 (VRQ); the most susceptible haplotype (VRQ) was only detected in purebred Texels and crossbreds. No association was detected between the PrP genotype of either the animal or dam and any of the lambing traits (i.e. lambing difficulty score, perinatal mortality and birth weight). With the exception of ultrasound muscle depth, no association between the PrP genotype and any of the lamb performance traits (i.e. lamb BW and carcass) was observed. Lambs carrying the category four PrP genotype (i.e. ARR/VRQ) had 1.20 (SE = 0.45) mm, 1.38 (SE = 0.12) mm, 1.47 (S = 0.25) mm shallower ultrasound muscle depth relative to lambs of the less susceptible scrapie categories of 1, 2, 3, respectively (P < 0.05). Nonetheless, no association between PrP genotype and lamb carcass conformation, the ultimate end goal of producers, was detected. Ewe litter size, body condition score or lameness did not differ by PrP genotype of the ewe (P > 0.05). For ewe mature BW, ARH/VRQ ewes differed from most other ewe PrP genotypes and were, on average, 3.79 (SE = 1.66) kg heavier than ARR/ARR genotype ewes. Lamb dag score differed by dam PrP genotype (P < 0.05), although the differences were small. Results from this study show that scrapie is segregating within the Irish sheep population, but the PrP genotype was not associated with most traits investigated and, where associations were detected, the biological significance was minimal. This suggests minimal impact of selection on PrP genotype on performance, at least for the traits investigated in the present study.

The Identification of Mutation in BMP15 Gene Associated with Litter Size in Xinjiang Cele Black Sheep.

Simple SummaryThe gene for Bone Morphogenetic Protein 15 has multiple single-nucleotide polymorphism sites related to fertility in sheep. To increase fertility, a better understanding of the regulation of Bone Morphogenetic Protein 15 in sheep is essential. This work describes the phenotype and molecular characteristics of a mutation identified in the Bone Morphogenetic Protein 15 gene of Cele black sheep in Xinjiang, China. This mutation may affect the fertility of sheep, which is very useful for breeding purposes.The Bone Morphogenetic Protein 15 (BMP15) gene is known to have multiple single-nucleotide polymorphism sites associated with sheep fecundity. This study used gene sequence analysis and mutation detection assays for BMP15 by using 205 blood samples of ewes with known lambing records. Sequence analysis showed that mutation B1 missed the CTT base in exon 1 at positions 28–30, leading to a leucine deletion in the BMP15 protein. Litter size of ewes differed significantly between BB and B+ genotypes of B1 (p < 0.05); however, the differences between wild genotype (++) and homozygous (BB) or wild genotype (++) and heterozygous (B+) were not significant (p > 0.05). Another mutation, T755C, is a T-to-C base change at position 755 of exon 2, resulting in leucine replacement by proline at this position of the BMP15 protein (p.L252P). Two genotypes were identified in the flock: heterozygous (E+) and wild-type genotype (++). Ewes with heterozygous (E+) p.L252P had significantly larger litter sizes than those with the wild-type genotype (p < 0.05). Comprehensive analysis suggests that p.L252P is a mutation that affects fecundity in Cele black sheep.

REPRODUCTIVE PERFORMANCE OF WEST AFRICAN DWARF SHEEP AND GOATS AT VILLAGE LEVEL IN OGUN STATE, NIGERIA

Reproductive performance of 20 pregnant ewes and 20 pregnant does of West African Dwarf breeds at village level in Ogun State, Nigeria were compare in a study which lasted for 8 months. Litter size in ewes was 1.50 while that of does was 1.85. the number of males produced by the two species out-numbered that of females. However, multiple birth were higher in goat that in sheep. Results of birth weights and body weight of lambs and kids at 3 month of age were significantly different (P &lt; 0.05). Lambs were heavier at birth with overall mean birth weight of 2.00kg compared with 1.48kg recorded for kids. At the age of 3 monthes the overall body weight of lamb was 10.38kg while that of kid was 7.61kg. mortality in lamb was 23.33% as against 10.81% in kids. Effective management system of West African Dwarf sheep and goats at village level before and after birth will improve the reproductive efficiency of the species

Eukaryotic expression, Co-IP and MS identify BMPR-1B protein\u2013protein interaction network

BackgroundBMPR-1B is part of the transforming growth factor β super family and plays a pivotal role in ewe litter size. Functional loss of exon-8 mutations in the BMPR-1B gene (namely the FecB gene) can increase both the ewe ovulation rate and litter size.ResultsThis study constructed a eukaryotic expression system, prepared a monoclonal antibody, and characterized BMPR-1B/FecB protein–protein interactions (PPIs). Using Co-immunoprecipitation coupled to mass spectrometry (Co-IP/MS), 23 proteins were identified that specifically interact with FecB in ovary extracts of ewes. Bioinformatics analysis of selected PPIs demonstrated that FecB associated with several other BMPs, primarily via signal transduction in the ovary. FecB and its associated interaction proteins enriched the reproduction process via BMP2 and BMP4 pathways. Signal transduction was identified via Smads proteins and TGF-beta signaling pathway by analyzing the biological processes and pathways. Moreover, other target proteins (GDF5, GDF9, RhoD, and HSP 10) that interact with FecB and that are related to ovulation and litter size in ewes were identified.ConclusionsIn summary, this research identified a novel pathway and insight to explore the PPi network of BMPR-1B.

Polymorphisms of the melatonin receptor 1A gene that affects the reproductive seasonality and litter size in Small Tail Han sheep.

Previous researches have shown that MTNR1A plays an essential role in sheep reproduction. However, most researches focused more on the reproductive seasonality of sheep, and few scientists had studied the association of polymorphisms of the MTNR1A gene with ovine litter size and reproductive seasonality. Therefore, we chose MTNR1A gene to detect its novel sequence polymorphisms and population genetics and analyse their association with seasonal reproduction and litter size in ewes. The mRNA expression level in hypothalamus, pituitary and ovary was also detected. In this study, five polymorphisms (g.15118664G > T, g.15118683C > T, g.15118756C > T, g.15118774C > T and g.15118951G > A) were identified in exon 2. Most importantly, the g.15118683C > T and g.15118951G > A were significant difference between year‐round oestrous sheep and seasonal oestrous sheep (p < .01), and g.15118756C > T had a great effect on litter size of Small Tail Han sheep (p < .05). In addition, the mRNA expression level of MTNR1A in the hypothalamus of polytocous Small Tail Han sheep was significantly higher than that in monotocous Small Tail Han sheep (p < .01) and the expression of MTNR1A in the hypothalamus of year‐round oestrous sheep was significantly higher than that in seasonal oestrous sheep (p < .01). Polymorphisms in exon 2 may regulate the reproductive seasonality and litter size of ewes by influencing gene expression to regulate the reproductive seasonality and litter size of ewes. Our studies provided useful guidance in marker‐assisted selection of the litter size in Small Tail Han sheep.

Productive and reproductive performances of Sheep at field level of Rajshahi and Mymensingh District of Bangladesh

This study was undertaken to assess the reproductive performances of sheep at field level of Rajshahi and Mymensingh district of Bangladesh during January to December, 2016. A total of 52 farms (26 each in Rajshahi and Mymensingh) were selected for determining the reproductive parameters of ewes. Ewe lambs in Mymensingh reached puberty at significantly (P&lt;0.03) younger age (186.9±18.4 days) than in Rajshihi (199.9±24.9 days). The average age at first pregnancy was 201.4±20.0 days in two regions. Similarly, the ewes in Mymensingh was lambing at significantly (P&lt;0.002) early age than ewes in Rajshahi (356.0±6.8 days vs. 372.7±27.8 days). The observed duration of oestrus at Rajshahi and Mymensingh was 36.0±6.7 hrs and 36.0±7.3 hrs, respectively. The gestation length varied from 145 to 150 days. The average gestation length was 147.9±3.4 days in two regions. The gestation length was not significant (P˃0.05) in the ewes between Rajshahi and Mymensingh (148.7±3.4 and 147.1±3.2 days; respectively). The pooled over litter size was 1.6±0.2 in two regions. However, there was no significant (P&gt;0.05) difference in litter size of ewes in Rajshahi and Mymensingh region (1.7±0.2 vs. 1.6±0.2). The pooled lambing interval was 193.9±21.7 days in two regions. Mean birth weights of lambs, weaning weight and mature weight were 1.7±0.6 vs. 1.3±0.1 kg; 8.9±2.7 vs. 6.9±1.0 kg and 24.9±7.3 vs. 19.4±2.7 kg in Rajshahi and Mymensingh, respectively. These reproductive parameters were significantly higher (P&lt;0.001) in Rajshahi compared with in Mymensingh. The reproductive parameters are almost similar between confined and the traditional management system if the farms are well managed.Asian J. Med. Biol. Res. March 2018, 4(1): 63-68

The novel T755C mutation in &amp;lt;i&amp;gt;BMP15&amp;lt;/i&amp;gt; is associated with the litter size of Iranian Afshari, Ghezel, and Shal breeds

Abstract. The present study was conducted to determine the molecular genetic variation in bone morphogenetic protein 15 (BMP15) of some selected Iranian sheep breeds and aims to provide relevant genetic information for twin-birth lambing. Therefore, a total of 44 rams and 213 ewes with single-, twin-, and triplet-birth lambing were used from Shal, Ghezel, Afshari and Lori-Bakhtiari sheep breeds. Three primer pairs were used for amplification of exons 1 and 2 of the BMP15 gene. The sequencing result of distinctive single-strand conformation polymorphism (SSCP) patterns showed segregation of the T755C mutation and the ensuing non-conservative substitution of L252P in the BMP15 propeptide. All three ewes with triplet-birth lambing and two sterile ewes were heterozygotic for this mutation. Association analysis revealed that this mutation was significantly related to the ewe's litter size, so that ewes with the CT genotype had 0.24 and 0.30 more lambs than those with the CC (p &lt; 0.05) and TT (p &lt; 0.01) genotypes, respectively. The mutation effect on the litter size was incomplete dominance in Afshari breed and over-dominance in Shal and Ghezel breeds. In conclusion, the findings in this experiment suggested synergistic effects of the T755C mutation and other unknown mutations in other effective genes which cause infertility and higher litter size in two different ways.

Effect of double GnRH injections on reproductive parameters in Awassi ewes receiving long-term progesterone

ABSTRACTThe aim of this study was to investigate the effect of single or double Gonadotropin releasing hormone (GnRH) injections at the time of mating and following on day 9 on pregnancy rates and litter size in ewes. Oestrus was synchronized in 130 adult ewes using intravaginal sponges containing 20 mg of fluorogestone acetate for 14 days. All ewes received 10 IU/kg of pregnant mare serum gonadotropin (PMSG) at the sponge withdrawal. Then animals were divided into three groups. Ewes in group 1 (G1; Control, n = 68) received 1 ml placebo injection. In group 2 (G2; n = 30), ewes in oestrus were treated with 1 ml GnRH (4 μg/ml) at the time of mating. In group 3 (G3; n = 32), ewes were injected 1 ml GnRH not only at the time of mating but also on day 9 post-mating. There was significantly higher in duration of oestrus G1 compared with the G2 and G3. Pregnancy rate was found to be higher in G3 (96.0%) than in G1 (72.7%) and G2 (83.3%). The litter size was significantly higher for G3 (1.26 ± 0.14) in comparison with the G1 (1.18 ± 0.07) and G2 (1.22 ± 0.10). In conclusion, Post-mating GnRH injection enhanced the pregnancy rate and litter size, because of its beneficial effects on embriyo viability by increasing luteal formations.

Booroola Gene (Fec B) Polymorphism and its Liaison with Litter Size in Indigenous Sheep Breeds of Telangana, India

The present study was aimed to find out the presence of Fec B gene in Deccani and Nellore with its association to litter size. From forty ewes of each Nellore and Deccani breed, having variation in litter size, blood was collected and genomic DNA extraction was done. Animals were screened by PCR-RFLP method for the presence of Fec B gene. Digestion of the Fec B gene 190 base pair with Ava II restriction enzyme resulted in separation of non-carrier (++) 190 bp band (wild type) and heterozygous carrier (B+) 160+190bp indigenous sheep. Frequency of Fec B gene polymorphism distributions was different among these breeds. Among the forty Nellore sheep blood samples, there was only one ewe with (BB) homozygous (160bp) genotype, five ewes with (B/+) heterozygous (160+190bp) genotype and thirty four ewes with (+/+) homozygous (190bp) genotype in Fec B loci. There was only five ewes with (B/+) heterozygous (160+190bp) genotype and thirty five ewes with (+/+) homozygous (190bp) genotype in Fec B loci and none of the individuals carried homozygous genotype for the Fec B gene in Deccani sheep. The average litter size of ewes with the homozygous Fec B (BB) gene was 2.0, heterozygous Fec B (Bb) gene was 1.4 and 1.2, respectively in Nellore and Deccani breeds and others were 1.0 in respective genotypes of both breeds. The study revealed the presence of Fec B gene in indigenous sheep breeds of Telangana, India having good association with litter size in both the breeds.

Inbreeding and its impact on the prolific Polish Olkuska sheep population

The aim of this study was to assess the level of genetic variability in the Olkuska sheep population and evaluate inbreeding effects on birth weight, weaning weight (at 56 days of age), lamb survival up to 56 days and the litter size of ewes. Pedigree information over a 36 year period of Olkuska population (from 1976 to 2012) was used in this study. A small number of important ancestors, with only four individuals explaining over 50% of the total genetic variation of the population resulted in high levels of inbreeding, with mean values exceeding 10% for lambs born from 2007 till 2012. Animal model was used to test the effects of inbreeding depression on lamb weight and survival. Significant inbreeding depression was found for birth weight (P<0.01), and for body weight at the age of 8 weeks, −0.0071kg and −0.0325kg per 1% increase in inbreeding respectively. The effect of inbreeding on lamb survival was statistically significant, but very small. No significant impact of inbreeding on litter size was observed, due to the segregation of the major gene affecting fecundity. The main factors determining lamb weight and survival were its gender and type of birth.

Time trends and epidemiological patterns of perinatal lamb mortality in Norway

BackgroundPerinatal mortality is a major cause of loss in the sheep industry. Our aim was to explore time trends in crude population stillbirth and neonatal mortality rates in Norway. We used data on 6,435,715 lambs from flocks enrolled in the Norwegian Sheep Recording System (NSRS) from 2000 through 2010 for descriptive analysis of trends. Longitudinal patterns of mortality rates were compared for lambs within different levels of variables suspected to be associated with perinatal loss.ResultsThere was an approximately linear increase in the annual proportion of stillborn lambs during the study period, from 3.3 % in 2000 to 4.7 % in 2010. In the same time period, average litter size of ewes in NSRS flocks increased from 2.00 to 2.19. However, a steady rise in stillbirth rate was observed within each litter size group, suggesting a gradually increasing impact on stillbirth risk of other, yet unidentified, factors. Average flock size increased during the study period. The highest stillbirth rates were found in the largest and smallest flocks. Early neonatal mortality rates (0–5 days of life) varied from year to year (minimum 2.2 %, maximum 3.2 %) and were invariably higher among triplets and quadruplets than among singletons and twins. Annual fluctuations were parallel within the various litter sizes. A significant overall decreasing trend was present within all litter sizes with the exception of singletons. Weather data for the prime lambing months (April and May) 2000–2010 indicated a relationship between low temperatures and high neonatal mortality rates. At the flock level, there was a significant positive correlation between stillbirths and early neonatal mortality rates (r = 0.13), between stillbirth rates in two consecutive years (r = 0.43) and between early neonatal mortality rates in two consecutive years (r = 0.40).ConclusionsThe substantial increase in ovine stillbirth rate in recent years in Norway was to some extent related to a corresponding increase in the proportion of lambs in triplet or larger litters; however, other factors apparently have contributed. Early neonatal mortality rate exhibited year-to-year variations, partly following temperature fluctuations, which is somewhat unexpected, considering that lambing mainly occurs indoors in Norway.

Pregnancy scanning can be used as a source of data for genetic evaluation of reproductive traits of ewes

Reproductive traits generated from mothering up lambs to ewes (n = 59 603 records) were compared with data resulting from pregnancy scanning (n = 46 663 records), to examine the consistency between the two data sources for deriving specific reproductive traits and to estimate genetic parameters. The reproductive traits considered were fertility (FERT: 0/1) of ewes joined, total litter size (LSIZE: lambs born), the number of lambs surviving at weaning (LSIZEW: lambs weaned) and the percentage of lambs surviving (LSURV = LSIZEW/LSIZE) for ewes that lambed, along with the composite traits number of lambs born (NLB) and number weaned (NLW) for ewes joined. Corresponding trait values were derived from pregnancy scan data (FERT_S, LSIZE_S and NLB_S) for comparison, and were classified as inconsistent if the trait values did not match from scanning and lambing records. Data were obtained from four flocks, representing different time frames, locations, management and breeds or bloodlines. Each flock recorded scan data separately from lambing outcomes. Genetic parameters were estimated separately within each flock. Average levels of inconsistency between scan- and lambing-data values varied between 4.6% and 14.8% across flocks, tending to be highest (9.1–18.5%) for litter size of ewes scanned with multiple fetuses, and lowest (0.29–7.3%) for assignment of fertility. Inconsistencies did not have a significant impact on estimates of trait heritabilities, suggesting recording errors were independent of genetic merit. In three flocks, the genetic correlations (ra) between comparable traits derived from the different data sources were not different from unity (ra ≥ 0.99) even when phenotypic correlations (rp) were lower (rp ≥ 0.84). In the flock with the highest inconsistency rate between data sources, the range in ra varied between 0.60 (fertility) and 1.0 (litter size). Therefore, pregnancy scan data can be directly substituted for reproductive traits traditionally based on lambing data, but attention should be paid to ensuring accuracy of the data sources used. Scan data also provide no information on lamb-survival outcomes after birth, so does not constitute complete data on reproductive outcomes. Genetic evaluation systems might also benefit from fine tuning for scale-induced effects (due to litter size) on parameters to improve the accuracy of across flock prediction of breeding values for reproductive traits.

Effects of behavioral reactivity on production and reproduction traits in Dorper sheep breed

Abstract The aim of the current research was to evaluate the effects of behavioral reactivity on production and reproduction performance in Dorper sheep, a meat breed. Temperament of animals was subjectively evaluated using a 5-point scoring system at weighing, during which sheep spent 30 seconds on the scale. The heritability of temperament was low (0.10 ± 0.03). Estimated phenotypic ( r p ) and genetic ( r g ) correlations between temperament and litter size in ewes were negative and negligible ( P > 0.05) at −0.06 ± 0.18 and −0.08 ± 0.09, respectively. Significant genetic correlations were found between lamb temperament and preweaning growth rate ( r g = −0.44 ± 0.07, P ≤ 0.05) and postweaning growth till the age of 120 days ( r g = −0.52 ± 0.08, P ≤ 0.05). Significant genetic correlations were found between lamb temperament and growth rates during their first 3 months of age. As a result, selection for calm temperaments should translate to increased growth rates of lambs. Negative correlations between temperament and production traits, both in ewes and lambs, suggested that selection against animals that are highly reactive to improve welfare and ease of handling would not have detrimental impacts on productivity.

Phenotypic and genetic associations between lamb growth traits and adult ewe body weights in western range sheep

Data from the Montana State University Targhee flock were used to estimate genetic and environmental relationships between lamb BW and adult ewe BW, condition score, and prolificacy. The flock was managed under commercial western range conditions typical of the area. Data included records from 12,154 lambs born to 2,930 dams and 200 rams between 1960 and 2005. Lamb traits included BW at birth and approximately 45 d, 120 d (weaning), 12 mo, and 18 mo of age and fleece characteristics at 12 mo of age. Adult traits included ewe litter size; BW and BCS at weaning, in late gestation, and in early lactation; and adult fleece measurements. Multiplicative factors were used to adjust (pre)weaning lamb BW for effects of age of dam, type of birth and rearing, and lamb sex and to adjust adult litter sizes for effects of ewe age. An animal model was used to estimate genetic relationships. Models for lamb traits included fixed effects of year of birth and, for postweaning data, lamb sex and random additive genetic effects and, for (pre)weaning BW, additive genetic maternal and permanent environmental maternal effects. Models for adult traits included fixed effects of year of birth, year of record, and, when appropriate, numbers of lambs born or born and reared and random additive genetic and animal permanent environmental effects. Heritability estimates for lamb birth weight, 45-d BW, weaning weight, yearling weight, 18-mo BW, fleece weight, staple length, and spinning count were 0.19, 0.07, 0.12, 0.32, 0.38, 0.32, 0.31, and 0.25, respectively. Maternal heritabilities for lamb birth, 45-d, and weaning weights were 0.15, 0.09, and 0.08, respectively. Heritability estimates for adult traits were 0.12 for litter size, averaged 0.43 for BW and 0.13 for body condition, and were 0.44, 0.37, and 0.25 for adult fleece weight, staple length, and spinning count, respectively. Correlations between genetic effects on adult BW and direct and maternal genetic effects on lamb BW ranged from 0.21 to 0.96 (P < 0.05) and 0.29 to 0.53 (P < 0.05), respectively, with residual correlations ranging from 0.05 to 0.95. Correlations of lamb traits with adult body condition and number of lambs born were generally not different from zero; genetic and residual correlations ranged from -0.52 to 0.69 and -0.39 to 0.31, respectively.

Reproductive Performance and Lamb Growth Characteristics of Ramlıç Sheep

This study was carried out to investigate some reproductive and lamb growth performance of Ramlic sheep in 2005, 2006, 2007 and 2008 years. The effect of year was found significant on fecundity and litter size of the ewes. The average fecundity, litter size and lamb survival rate of Ramlic ewes were 0.79, 1.13 and, 94.9%, respectively. The birth weight (BW), weaning weight (WW) and six month live weight (SMLW) for male and female lambs were 4.63 kg and 4.20 kg, 30.92 and 26.94 kg, 37.40 and 33.21 kg, respectively. The effect of age of dam, year, birth type and sex were significant on BW, WW and ADWG of lambs. The average daily weight gain of lambs at weaning was 286.88 g and male and female lambs were 303.62 g and 270.13 g, respectively.