Total Lamb Research Articles

Genetic parameters for ewe lifetime productivity traits in Central Anatolian Merino sheep

Rapidly increasing population size, recent breaks in production and supply chains, due to pandemics, and those further expected because of climate change emphasize the compelling importance of animal productivity. Traits associated with the productivity of ewes have a direct impact on the overall productivity, profitability and efficiency of sheep farms. Therefore, the objective of the current study was to estimate the variance components, heritabilities as well as genetic and phenotypic correlations, for traits associated with the lifetime productivity of Central Anatolian Merino ewes. Birth and weaning records of lambs for each ewe as well as environmental factors such as sex and birth type were utilized for deriving ewe lifetime productivity traits. Genetic parameter estimations involved observations from 3101 Central Anatolian Merino ewes, encompassing mean and total lamb birth weight per ewe (MBW and TBW), mean and total lamb weaning weight per ewe (MWW and TWW), and the mean and total number of lambs weaned (MNLW and TNLW). This analysis utilized a pedigree comprising 13229 animals. Average Information Restricted Maximum Likelihood (AIREML) based Animal Linear Mixed Model estimations for the decomposition of (co)variance components were implemented based on pedigree-derived numerator relationship matrix by also accounting for the number of parities as a fixed factor. Low to moderate heritability estimates, ranging between 0.29 and 0.42, were observed for the lifetime productivity traits of the breed. A wide range of genetic and phenotypic correlations (between −0.56 and 0.99) was observed among the traits of interest. The outcomes of the study are anticipated to significantly enhance the global sheep production systems by uncovering the essential parameters for incorporating ewe’s lifetime reproductive performance and productivity into the selection indices. This will also benefit Central Anatolian Merino farmers, who form a large proportion of sheep producers in Turkey.

114 The efficacy of a natural fungus (Duddingtonia flagrans) in reducing gastrointestinal nematode indicators in lambs

Abstract Sustainable and profitable small ruminant production in the US is affected by infections with gastrointestinal nematodes (GIN), especially the blood sucking GIN, Haemonchus contortus. The overuse and misuse of available drug classes has led to multi-drug resistant GIN that pose significant challenges to parasite control on many farms. The objective of this study was to evaluate the effectiveness of a natural fungus (Duddingtonia flagrans; Bioworma, International Animal Health) in reducing GIN larval counts and other GIN indicators in hair sheep wethers. Eighteen St. Croix (n = 9) and Barbados Blackbelly (n = 9) wethers (227 ± 1.4 days of age and 29.7 ± 0.6 kg BW) were dewormed (d 0) with a combination of levamisol (Prohibit; 8 mg/kg BW) moxidectin (Cydectin; 0.2 mg/kg BW) and albendazole (Valbazen; 7.5 mg/kg BW) prior to the start of feeding according to the manufacturer’s recommendations for feeding BioWorma. At this time, lambs were separated into two treatment groups (n = 9/group), split into 3 replications per treatment group and placed on six pasture paddocks (0.06 ha; n = 3 per paddock) after accounting for breed, initial fecal egg count (FEC) and BW. Lambs were then fed daily either a grain supplement ration (corn and soybean meal) with Livamol with Bioworma (LIV) or without (CON) at 2% of their BW for 98 d. LIV was added to the ration based on total lamb BW/paddock. To evaluate the effect of LIV treatment, BW and body condition scores (BCS) were recorded every 2 wk for 98 d. Blood and fecal samples were also collected for determination of packed cell volume (PCV) and FEC. Pooled treatment group feces (d 0 – 98) were collected and cultured to determine GIN genera. A subset of animals/treatment (n = 3) will be harvested to determine abomasal worm counts. Data were analyzed using repeated measures in a mixed model, and FEC were log transformed before analysis. Following deworming (d 0), FEC were reduced by 100% by d 14. There was a mixed population of GIN at the start of the study (averaging 54%, 42%, 1.2% and 1.8% for H. contortus, Tricostrongylus spp., Oesphagostomum spp. and Nematodirus spp., respectively). LIV with Bioworma supplementation had no impact on BW, BCS, PCV or FEC in this study averaging 34.2 ± 0.3 kg, 2.5 ± 0.04, 34.7 ± 0.5% and 150.9 eggs per gram, respectively. Under the conditions of this study, Bioworma® supplementation had no influence on GIN indicators measured up to 100 d of grazing. This research will be continued during subsequent grazing seasons to determine the effect of continued supplementation on lamb parasite load and performance as well as pasture infestation levels.

PSV-22 Productivity at Weaning of F1 Dorper X Pelibuey Ewes Carrying the Fecge Allele of the Ovine GDF9 Gene

Abstract The FecGE allele of the ovine GDF9 gene has been reported segregating in the Pelibuey hair type breed in México. Homozygous E/E ewes reproduce normally, in contrast to the sterility of homozygous ewes reported for other GDF9 variants. Thus, potential exists to cross homozygous and carrier Pelibuey ewes with meat type rams of low-prolificacy but well-adapted breeds to obtain F1 commercial flock ewes. The aim was to evaluate ewe productivity, as total lamb weight weaned (TWW), of FecGE carrier vs non-carrier F1 Dorper x Pelibuey ewes. Sixty one first lambing ewes (34 carrier and 27 non-carrier) equally served with two Texel rams were used. Management was under feedlot conditions. Genotyping was done by real time PCR (StepOnePlus) using the FAMACTTCAAACAGTTTCTTTTTMGBNFQ and VICTCAAACAGTGTCTTTTTMGBNFQ probes (Applied Biosystems). Type of birth (TB; twins vs single) and weaning (TW) were analyzed with PROC CATMOD of SAS. Fixed effects of ewe genotype (carrier vs non-carrier), contemporary group and ram of service were included in a logistic generalized linear model. Lamb weaning weights were adjusted to a common age of 75 d and by sex. Equivalent to male average birth lamb weight (ABW), average weaning lamb weight (AWW) and TWW per ewe were analyzed with PROC GLM of SAS. Carrier ewes had more twins (P < 0.01) for TB (75 vs 19.4 %) and TW (58.8 vs 21.7 %) than non-carrier ewes. Equivalent to male ABW on carrier ewes was less (P < 0.05; 3.17 ± 0.21 vs 3.97 ± 0.20 kg) than for non-carrier ewes but not difference (P > 0.05) was observed for AWW (21.96 ± 0.85 vs 22.93 ± 0.90 kg). Ewe productivity, as indicated by TWW, was greater (P < 0.05; 33.16 ± 1.78 vs 27.23 ± 1.88 kg) for FecGE carrier ewes than for the non-carrier ones. More research on this topic deserves further attention, especially under range conditions, with multiple parity ewes, different years and reproductive activity seasons, using a larger simple.

Identification of copy number variation in Tibetan sheep using whole genome resequencing reveals evidence of genomic selection

BackgroundCopy number variation (CNV) is an important source of structural variation in the mammalian genome. CNV assays present a new method to explore the genomic diversity of environmental adaptations in animals and plants and genes associated with complex traits. In this study, the genome-wide CNV distribution characteristics of 20 Tibetan sheep from two breeds (10 Oula sheep and 10 Panou sheep) were analysed using whole-genome resequencing to investigate the variation in the genomic structure of Tibetan sheep during breeding.ResultsCNVs were detected using CNVnator, and the overlapping regions of CNVs between individual sheep were combined. Among them, a total of 60,429 CNV events were detected between the indigenous sheep breed (Oula) and the synthetic sheep breed (Panou). After merging the overlapping CNVs, 4927 CNV regions (CNVRs) were finally obtained. Of these, 4559 CNVRs were shared by two breeds, and there were 368 differential CNVRs. Deletion events have a higher percentage of occurrences than duplication events. Functional enrichment analysis showed that the shared CNVRs were significantly enriched in 163 GO terms and 62 KEGG pathways, which were mainly associated with organ development, neural regulation, immune regulation, digestion and metabolism. In addition, 140 QTLs overlapped with some of the CNVRs at more than 1 kb, such as average daily gain QTL, body weight QTL, and total lambs born QTL. Many of the CNV-overlapping genes such as PPP3CA, SSTR1 and FASN, overlap with the average daily weight gain and carcass weight QTL regions. Moreover, VST analysis showed that XIRP2, ABCB1, CA1, ASPA and EEF2 differed significantly between the synthetic breed and local sheep breed. The duplication of the ABCB1 gene may be closely related to adaptation to the plateau environment in Panou sheep, which deserves further study. Additionally, cluster analysis, based on all individuals, showed that the CNV clustering could be divided into two origins, indicating that some Tibetan sheep CNVs are likely to arise independently in different populations and contribute to population differences.ConclusionsCollectively, we demonstrated the genome-wide distribution characteristics of CNVs in Panou sheep by whole genome resequencing. The results provides a valuable genetic variation resource and help to understand the genetic characteristics of Tibetan sheep. This study also provides useful information for the improvement and breeding of Tibetan sheep in the future.

Extremely large Lamb shift in a deep-strongly coupled circuit QED system with a multimode resonator

We report experimental and theoretical results on the extremely large Lamb shift in a multimode circuit quantum electrodynamics (QED) system in the deep-strong coupling (DSC) regime, where the qubit-resonator coupling strength is comparable to or larger than the qubit and resonator frequencies. The system comprises a superconducting flux qubit (FQ) and a quarter-wavelength coplanar waveguide resonator (lambda /4 CPWR) that are coupled inductively through a shared edge that contains a Josephson junction to achieve the DSC regime. Spectroscopy is performed around the frequency of the fundamental mode of the CPWR, and the spectrum is fitted by the single-mode quantum Rabi Hamiltonian to obtain the system parameters. Since the qubit is also coupled to a large number of higher modes in the resonator, the single-mode fitting does not provide the bare qubit energy but a value that incorporates the renormalization from all the other modes. We derive theoretical formulas for the Lamb shift in the multimode resonator system. As shown in previous studies, there is a cut-off frequency omega _{textrm{cutoff}} for the coupling between the FQ and the modes in the CPWR, where the coupling grows as sqrt{omega _n} for omega _n/omega _{textrm{cutoff}}ll 1 and decreases as 1/sqrt{omega _n} for omega _n/omega _{textrm{cutoff}}gg 1. Here omega _n is the frequency of the nth mode. The cut-off effect occurs because the qubit acts as an obstacle for the current in the resonator, which suppresses the current of the modes above omega _{textrm{cutoff}} at the location of the qubit and results in a reduced coupling strength. Using our observed spectrum and theoretical formulas, we estimate that the Lamb shift from the fundamental mode is 82.3% and the total Lamb shift from all the modes is 96.5%. This result illustrates that the coupling to the large number of modes in a CPWR yields an extremely large Lamb shift but does not suppress the qubit energy to zero, which would happen in the absence of a high-frequency cut-off.

Comparison between the CIDR or sponge with hormone injection to induce estrus synchronization for twining and sex preselection in Naimi sheep

Abstract The management of sheep reproduction requires the induction and synchronization of the estrus cycle and ovulation for the ewe out-of-season and/or synchronized lambing. These managements are based on the insertion of an intravaginal device of controlled internal drug release (CIDR or sponge) and then the administration of a hormonal injection, such as PMSG, eCG, hCG, or GnRH. This study aimed to compare the impact of CIDR or sponges, with PMSG and GnRH injection, respectively, for inducing estrus synchronization, lambing rate, twining, and sex preselection rate in Naimi sheep. A total of 86 Naimi sheep ewes and six male rams with proven fertility were used in this study. The results showed that the first ewes or CIDR group had the highest ewe fertility rate of 26/28 (92.59%) with a 35/92 (38.04%) lamb production ratio. The offspring sex ratio was 22/35 males (62.85%) and 13/35 female lambs (37.14%). Their twin ratios were 9/22 (34.4%), producing 14 males (77.77%) and 13 females (37.14%). The second or sponge ewe group’s fertility ratio was 16/26 (61.53%). They sired the lowest offspring ratio of 20/92 total lambs (21.73%) and had sex ratios of 11/20 males (55.0%) and 9/20 (45.0%) female lambs. The twin production ratios were 4/22 (25% with two males and two males with female twins). Their twin sex ratio was six males (77.77%) and two females (22.34%). The third or control ewe group’s fertility rate was 29/33 (87.87%). They produced 37/92 (40.27%) lambs, and the total sex ratios were 22/37 male lambs (59.45%) and 15/35 (40.45%) female lambs. They produced eight twins (27.58%), and their twins’ sex was equal to six male and six female (50%) lambs. Regarding the progesterone and testosterone hormone levels, no differences during pre- or post-intravaginal insertion were observed, but the estrogen level showed some differences during pre-insertion. In conclusion, the use of CIDR with hormone injection is better for reproduction management, male lambing, and sex preselection rate. The control group produced approximately the same fertility rate with equal male and female lambing sex preselection rates.

Genetic and phenotypic relationships between ewe reproductive performance and wool and growth traits in Uruguayan Ultrafine Merino sheep.

This study reports genetic parameters for yearling and adult wool and growth traits, and ewe reproductive performance. Data were sourced from an Uruguayan Merino flock involved in a long-term selection program focused on reduced fiber diameter (FD), and increased clean fleece weight (CFW) and live weight (LW). Pedigree and performance data from approximately 5,700 mixed-sex yearling lambs and 2,000 mixed-age ewes born between 1999 and 2019 were analyzed. The number of records ranged from 1,267 to 5,738 for yearling traits, and from 1,931 to 7,079 for ewe productive and reproductive performance. Data on yearling and adult wool traits, LW and body condition score (BCS), yearling eye muscle area (Y_EMA), and fat thickness (Y_FAT), and several reproduction traits were analyzed. The genetic relationships between FD and reproduction traits were not different from zero. Moderate unfavorable genetic correlations were found between adult CFW and ewe lifetime reproduction traits (-0.34 ± 0.08 and -0.33 ± 0.09 for the total number of lambs weaned and total lamb LW at weaning, respectively). There were moderate to strong positive genetic correlations between yearling LW and all reproduction traits other than ewe-rearing ability (-0.08 ± 0.11) and pregnancy rate (0.18 ± 0.08). The genetic correlations between Y_EMA and reproduction traits were positive and ranged from 0.15 to 0.49. Moderate unfavorable genetic correlations were observed between yearling FD and Y_FAT and between adult FD and BCS at mating (0.31 ± 0.12 and 0.23 ± 0.07, respectively). The genetic correlations between adult fleece weight and ewe BCS at different stages of the cycle were negative, but generally not different from zero. This study shows that selection for reduced FD is unlikely to have any effect on reproduction traits. Selection for increased yearling LW and Y_EMA will improve ewe reproductive performance. On the other hand, selection for increased adult CFW will reduce ewe reproductive performance, whereas selection for reduced FD will negatively impact body fat levels. Although unfavorable genetic relationships between wool traits and both FAT and ewe reproductive performance existed, simultaneous improvements in the traits would occur using appropriately designed indexes.

Ewes with higher embryo survival rear lambs that grow faster.

A key economic driver of a meat producing sheep flock is the total kilograms of lamb liveweight at weaning per ewe exposed to the ram. Optimization of key reproductive steps is required to achieve peak performance of a sheep flock. The goal of this paper was to use more than 56,000 records from a commercial flock to investigate the key reproductive steps affecting flock reproductive performance. We also applied a maximum-likelihood based technique to predict the embryo survival and ovulation rate for daughters of individual sires based on measurements of the number of fetuses at midpregnancy (detected by ultrasound-scanning). The model was used to determine how changes in premating liveweight, age, predicted ovulation rate, embryo survival, number of fetuses at midpregnancy, lamb survival, and lamb growth rate affect the total lamb liveweight at weaning per ewe exposed to the ram in the flock. The data from the commercial flock was also used to investigate the role of ewe age and premating liveweight on each reproductive step. Sensitivity analyses were performed to identify the key reproductive steps affecting flock reproductive performance. The elasticity for embryo survival was 80% of that for lamb survival. There was also significant between sire variance in the estimates of ovulation rate and embryo survival. The reproductive performance of daughters of sires with high (top 50%) and low (bottom 50%) embryo survival was investigated. Embryo survival was 0.88 in the high group and 0.82 in the low group (a 6% reduction in embryo survival). The expected total weight of lambs weaned per ewe exposed to the ram was 42 kg in the high embryo survival group and 37 kg in the low embryo survival group (a 12% reduction in the total weight of lambs weaned per ewe exposed to the ram). The proportion of twin litters was 70% in the high group and 60% in the low group, highlighting the potential importance of embryo survival for the rate of twinning in flocks with ovulation rates greater than two ova. Although lamb survival was similar between the high and low embryo survival groups, lamb growth was reduced by 10% in the low embryo survival group for the same litter size (P < 0.001). This novel positive phenotypic association between embryo survival and lamb growth rate can potentially be exploited to improve flock performance.

Effects of inbreeding on reproduction and fitness traits in a closed flock of Nilagiri sheep, an endangered Indian breed

The objective of this study was to investigate the effect of inbreeding on reproductive and fitness traits in Nilagiri sheep. Information on pedigree of 6430 animals collected during the year of 1965–2015 by Sheep Breeding Research Station (SBRS) in Sandynallah were used for analysis. Inbreeding coefficient (F) was calculated from pedigree information using Wright’s method. The average inbreeding per cent was 1.82% in the whole population studies (6430 animals). The average inbreeding per cent was 3.9% for 3007 no. of inbred animals. The effect of inbreeding on most of the reproduction and fitness traits were significant and depression due to inbreeding was evident.The significant effect of inbreeding on reproduction traits viz., age at first service (AFS), weight at first service (WFS), age at first lambing (AFL) and fitness traits viz., tupping percent (TP), number of lambs weaned per ewe mated (NLWEM), number of lambs weaned per ewe lambing (NLWEL) and total lambs weaned per ewe over lifetime (TLWE) was studied using a general linear model, with individual inbreeding coefficient as covariate. The partial regression coefficient for AFC, WFS, AFL, TP, NLWEM, NLWEL and TLWE were 1.28 days, −0.25 kg, 8.13 days, −0.02%, −0.028, −0.017 and −0.182 per 1 per cent increase in inbreeding for Nilagiri sheep. Survival and litter size were not affected by inbreeding. In general, inbreeding had a depressive effect on most of the reproduction and fitness traits. Inbreeding in the population has to be restricted through methods such as introduction of unrelated animals or following co-ancestry based mating system.

Impact of Coxiella burnetii vaccination on humoral immune response, vaginal shedding, and lamb mortality in naturally pre-infected sheep.

Sheep are considered to be one of the main reservoirs for Coxiella burnetii, a gram-negative bacterium with high zoonotic potential. Infected sheep shed tremendous amounts of the pathogen through birth products which caused human Q fever epidemics in several countries. Information about the impact of an inactivated C. burnetii Phase I vaccine on humoral immune response, vaginal shedding, and lamb mortality in naturally pre-infected sheep is scarce. Two identically managed and naturally C. burnetii-infected sheep flocks were examined for two lambing seasons (2019 and 2020). One flock (VAC) received a primary vaccination against Q fever before mating and the second flock served as control (CTR). In each flock, one cohort of 100 ewes was included in follow-up investigations. Serum samples at eight different sampling dates were analyzed by C. burnetii phase-specific ELISAs to differentiate between the IgG Phase I and II responses. Vaginal swabs were collected within three days after parturition and examined by a C. burnetii real-time PCR (IS1111). Lamb losses were recorded to calculate lamb mortality parameters. After primary vaccination, almost all animals from cohort VAC showed a high IgG Phase I response up until the end of the study period. In cohort CTR, the seropositivity rate varied from 35.1% to 66.3%, and the Phase I and Phase II pattern showed an undulating trend with higher IgG Phase II activity during both lambing seasons. The number of vaginal shedders was significantly reduced in cohort VAC compared to cohort CTR during the lambing season in 2019 (p < 0.0167). There was no significant difference of vaginal shedders in 2020. The total lamb losses were low in both cohorts during the two investigated lambing seasons (VAC 2019: 6.8%, 2020: 3.2%; CTR 2019: 1.4%, 2020: 2.7%). Neither the C. burnetii vaccine nor the C. burnetii infection seem to have an impact on lamb mortality. Taken together, the inactivated C. burnetii Phase I vaccine induced a strong IgG Phase I antibody response in naturally pre-infected sheep. It might also reduce vaginal shedding in the short term but seems to have little beneficial impact on lamb mortality.

Legumes are the key to increasing productivity at “Inverary”, a summer moist hill / high country farm in mid-Canterbury

About half the 4250 ha of Inverary is undevelopedmountain land above 750 m a.s.l. There are 300 haof river flats, where lucerne and winter feed cropsare grown, and 300 ha conventional grass/cloverpastures. Limited areas of clover/plantain and winterfeed crops have been established at ~700 m a.s.l. oneasy rolling country. The 1600 ha of steep country,dominated by browntop, gives low spring and highsummer production that is difficult to manage. In2009, there were no lucerne or legume rich pastures.The legume emphasis increased animal productivitythrough improved lambing and lamb weight sold perewe. Total lamb meat production lifted from 230,113kg in 2009 to 245,039 kg in 2020, despite 1000 fewerewes. The current sheep to cattle ratio is 60:40 with13,000 stock units being wintered. Pre-development,a major shortage of nutritious forage in early springwas compounded by difficulty controlling reproductivegrass in summer and autumn. In 2016, total productionof legume dominant pastures was 40% more than sowngrass/clover pastures with limited nitrogen fertiliser(15 vs. 11 t DM/ha/year). In early spring, legumeshad higher growth rates of conventional grass/cloverpastures (90 vs. 44 kg DM/ha/day), whereas browntopdominant hill pastures grew 10 kg DM/ha/d and 5 tDM/ha/yr.

Effect of Breeding Heavier Romney Ewe Lambs at Seven Months of Age on Lamb Production and Efficiency over Their First Three Breeding Seasons.

Simple SummaryThis experiment examined the impact of breeding heavier ewe lambs on lamb production and the ability of a ewe to produce a high number and heavier lambs (i.e., efficiency) over the first three breeding seasons. Two groups of ewe lambs were bred at seven months of age at an average live weight of either 47.9 ± 0.36 kg (n = 135) or 44.9 ± 0.49 kg (n = 135). Ewe live weight, number of lambs born and weaned, and lamb live weights were recorded, and ewe efficiency was calculated for each ewe. The weight and number of lambs at weaning over the three-year period did not differ between treatments, however, when data were pooled, heavier ewe lambs at breeding had a greater number and lamb weaning weight over the three-year period. Breeding heavier ewe lambs had no effect on ewe efficiency. There was a positive relationship between ewe lamb breeding live weight and their mature weight. These results suggest that breeding heavier ewe lambs increased the total lamb production over the three-year period, however, it had no effect on ewe efficiency. Before final recommendations can be made, ewe lifetime performance and longevity of heavier ewe lambs at breeding are required.This experiment examined the effect of breeding heavier ewe lambs on lamb production and their efficiency over their first three breeding seasons. Two groups of ewe lambs were bred at seven months of age at an average pre-breeding live weight of either 47.9 ± 0.36 kg (heavy; n = 135) or 44.9 ± 0.49 kg (control; n = 135). Ewe live weight, number of lambs born and weaned, and lamb live weight were recorded until 39 months of age, and efficiency was calculated for each ewe. Although the number and lamb weaning weight did not differ between treatments over three years, when data were pooled, heavier ewe lambs at breeding weaned a greater number of lambs over the three-year period. The total lamb weaning weight over the three-year period increased by 2% for each additional kilogram at ewe lamb breeding. Breeding heavier ewe lambs had no effect on efficiency. These results suggest that although breeding heavier ewe lambs had a positive effect on lamb production over the three-year period, it had no effect on efficiency. Before final recommendations can be made, lifetime performance and longevity to five years of age of heavier ewe lambs at breeding are required.

Identification of genes associated with litter size combining genomic approaches in Luzhong mutton sheep.

Litter size is one of the most important reproductive traits of sheep, which has pronounced effects on the profit of husbandry enterprises and enthusiasm of breeders. Despite the importance of litter size, the underlying genetic mechanisms have not been entirely elucidated. Therefore, based on a high-density SNP chip, genome-wide comparative analysis was performed between two groups with different fecundity to reveal candidate genes linked to litter size via detection of homozygosity and selection signatures in Luzhong mutton sheep. Consequently, nine promising genes were identified from six runs of homozygosity islands, and functionally linked to reproduction (ACTL7A, ACTL7B, and ELP1), embryonic development (KLF5 and PIBF1), and cell cycle (DACH1, BORA, DIS3, and MZT1). A total of 128 genes were observed under selection, of which HECW1 and HTR1E were related to total lambs born, GABRG3, LRP1B, and MACROD2 to teat number, and AGBL1 to reproductive seasonality. Additionally, the presence of inbreeding depression implies the urgency of reasonable mating system to increase litter size in the present herd. These findings provide a comprehensive insight to the genetic makeup of litter size, and also contribute to implementation of marker-assisted selection in sheep.

Effect of Inbreeding Coefficient on Growth and Fitness Traits in a Closed Flock of Corriedale Sheep

Background: The corriedale sheep breed was imported into J and K during sixties for use in improvement of local sheep and are maintained at Mountain Research Station of Sheep and Goat, SKUAST- K. The animals over the years were allowed to mate within the selected animals of the flock as there was hardy any fresh importation of exotic animals from last 49 years due to which closed flock population was established within the farm. This has led to apprehensions over the loss of genetic diversity through years.Methods: The present study was to undertaken to evaluate the performance of Corriedale sheep under temperate climate and to estimate the inbreeding coefficient and its effect on growth and fitness traits of Corriedale sheep maintained at Mountain Research Centre for Sheep and Goat (MRCSG), F.V.Sc and A.H, SKUAST-K Shuhama, Kashmir. The information on performance and pedigree spanning over a period of 49 years (1969-2017) was collected and utilized for the study. The traits studied were birth weight (BW), weaning weight (WW), 6 months weight (6MW), 9 months weight (9MW) and 12 months weight (12MW) age at first lambing (AFL), litter size (LS), total lambs born per ewe (TLB) and survival rate (SR). Result: The averages estimates for BW, WW, 6MW, 9MW, 12MW, AFL, LS, TLB and SR were 3.72±0.01 kg, 13.31±0.07 kg, 18.65±0.05kg, 22.15±0.04 kg, 25.84±0.06 kg 807.20±4.34 days, 1.08±0.00, 4.83±0.03 and 80.76±1.98, respectively. The overall inbreeding coefficient (F) and proportion of population inbred (per cent) for Corriedale sheep were 18.3 and 43.3, respectively. The increased inbreeding coefficient had negative impact and highly significant (p less than 0.01) on all the traits under study except LS. The increased inbreeding coefficient (F) also had a negative impact on all the traits under study. With increase in the level of inbreeding there was a decrease in total body weight traits, lambs born per ewe and survival rate where as age at first lambing was increasing with the increase. he results indicated as decrease of 0.25 kg, 1.45 kg, 5.04 kg, 5.53 kg and 5.48 kg in body weight of the animals at birth, weaning weight, six months, nine months and twelve months from 1969-2017. To overcome the negative impact of inbreeding coefficient in the flock introduction of genetic variability through importation of Corriedale germplasm into the farm is highly recommended.

The role of reproductive loss on flock performance: a comparison of nine industry flocks.

The reproductive performance of a sheep flock is dependent on a multitude of complex interacting factors. Attaining optimal flock performance requires information about how the reproductive steps are linked and relate to readily available measurements of the state of the flock. The goal was to use data from nine commercial flocks (greater than 300,000 records) to investigate and model the key reproductive steps affecting flock reproductive performance. We also developed a maximum-likelihood based methodology to predict flock ovulation rate based on measurements of the number of fetuses at mid-pregnancy (detected by ultrasound-scanning). The model was used to determine how changes in premating liveweight, age, predicted ovulation rate, number of fetuses at mid-pregnancy, lamb survival and lamb growth rate affect the total lamb liveweight at weaning per ewe exposed to the ram in each flock. The data from the commercial flocks were also used to investigate the role of ewe age and premating liveweight on each reproductive step. Sensitivity analyses were conducted to identify the key reproductive steps affecting flock reproductive performance, with a focus on understanding how these steps vary between flocks. The elasticity for embryo survival was 60% of that for lamb survival for these flocks and the elasticities for ovulation rate were highly variable between flocks (0.16 to 0.50 for mature ewes). This indicates that ovulation rate was near-optimal for some flocks, whereas there was potential to significantly improve flock performance in suboptimal flocks. The elasticity for ewe premating liveweight was highly variable between flocks (−0.03 to 0.84 for mature ewes and −0.18 to 1.39 for ewe lambs), indicating that premating liveweight ranged from optimal to suboptimal between flocks. For these suboptimal farms, the opportunity exists to increase flock performance through improved management of ewe premating liveweight. Reproductive loss was significantly greater in ewe lambs than mature ewes, although the difference is dependent on the stage of reproduction and flock. Predicted ovulation rate was 25% lower for ewe lambs and there was a 30% relative decrease in the predicted embryo survival probability from ovulation to scanning for ewe lambs. There was a 10% relative decrease in lamb survival probability from birth to weaning for ewe lambs and lamb growth rate was 25% lower for ewe lambs.

Effect of milk replacer supplementation on growth and disposal of neonatal lambs of indian sheep

A study was conducted to assess the effect of milk replacer (MR) supplementation on growth and mortality of neonatal lambs. The lambs in treatment group were supplemented MR (Memnaprash©) from 4 to 28 days of age in addition to ewe suckling as compared to only ewe suckling in the control. Observations were recorded for daily milk intake, body weight at birth, 7th, 15th, 22nd and 30th days of age and mortality / culling, if any. In single-born lambs, MR intake varied significantly (P<0.001) from 103.8±5.2, 91.9±11.7 and 124.3±15.2 ml (on 4th day of age) to 373.4±27.0, 392.1±26.2 and 433.2±21.7 ml (on 26th -28th days of age) and in multiple- born lambs, from 79.4±6.6, 75.8±11.2 and 130.6±7.0 ml (4th day of age) to 358.6±27.3, 440.8±35.4 and 431.7±11.0 ml (on 27th -28th ) day of age in Malpura, Avikalin and Avishaan sheep, respectively. In comparison to the control the total lamb weight per ewe at one month of age was higher (5.67% in Malpura, 15.5% in Avikalin and 11.4% in Avishaan) in MR supplemented group. The overall disposal was almost two times higher in control (27.32%) as compared to treatment group (14.05%). After supplementation of MR for 25 days, the net return increased by Rs 218.00 per ewe (18.53%) over the control. The study suggested that supplementation of MR in lambs is a remurerative approach for improving growth and reducing disposal of lambs in Indian sheep.

PSX-26 The identification of novel SNPs significant for reproductive abilities in sheep using GWAS

Abstract Reproductive ability of ewes is one of the most important traits in sheep breeding. Hence the mechanisms underlying this complex trait are poorly understood till now. To study the genetic architecture of litter size and search for SNPs associated with Total lambs born (TLB) we conducted genome-wide association study of Volgograd sheep. A total of 48 sheep after the second lambing were collected: 24 of them had 1 lamb, and 24 others had two lambs. All the samples were genotyped using the OvineSNP50 Genotyping BeadChip according to the manufacturer’s protocol. Then they were filtered using the parameters –hwe = 10–3, --maf = 0.05, --geno = 0.1, --indep-pairwise 50 5 0.5. After the quality control 46249 SNPs of 54241 were retained in the working dataset for the GWAS. A total of 14 significant SNPs located on chromosomes 1, 2, 4, 7, 15, 18, and 19 reached the genome-wide significance level. More than 50% of SNPs are located in the introns of genes, the rest are located in regulatory regions of genes and intergenic regions. We searched for candidate genes located near the significant SNPs using the Ensembl database. A total of 14 genes were selected. Gene annotation was completed using Panther. The detailed information about those significant SNPs and the possible genes associated with TLB are presented in Table. These genes take part in cellular processes, biological regulation and regulation of metabolic processes, some of them are involved in the formation of the immune system and biological adhesion. The data obtained allowed us to determine a number of SNPs that are significant for the formation of such complex reproductive trait as Total lamb born (TLB) in sheep and could be potentially applied in sheep breeding programs.

Factors associated with ewe and lamb survival, and subsequent reproductive performance of sheep undergoing emergency caesarean section.

Clinical records of all 212 ewes undergoing emergency caesarean surgery at a veterinary teaching hospital between January 2008 and December 2019 were evaluated retrospectively. Their age ranged from 1 to 10years (median=4years), with German merino the predominant breed (48.1% of cases). The most frequently diagnosed indications were insufficient cervical dilatation (n=94, 44.3%), uterine torsion (n=50, 23.6%), foetopelvic disproportion (n=31, 14.6%) and vaginal prolapse intra partum (n=11, 5.2%). Fifty-four (25.5%) of the 212 ewes additionally suffered from one or more concurrent, pre-existing conditions. Overall ewe mortality until hospital discharge was 10.8% (23/212), and 3.8% (n=6) for the 158 ewes without a history of concurrent disorders. Mortality during hospitalization increased to 31.5% (17/54) for those with pre-existing conditions. Total lamb mortality was 49.1% (173/352) until hospital discharge. Pre-existing conditions (p=.001) and the presence of post-surgical complications (p=.025) were identified as significant factors influencing dam mortality, while delayed presentation for veterinary attention with an observed duration of labour of >12hr was identified as the most influential factor on total lamb mortality (p=.010). The presence of dead or emphysematous foetuses was not significant for ewe mortality. Follow-up information on further outcomes was available for 156 (82.5%) of the 189 discharged ewes. Eighty-nine animals (57.1%) were re-bred in the following season and achieved a 93.3% (83/89) pregnancy rate, while the remainder had either been slaughtered (n=56, 35.9%), sold (n=5, 3.2%) or had died of unknown causes (n=3, 1.9%). The subsequent incidence of dystocia was 15.6% (n=12) in the 77 ewes with available information on lambing ease. Adequate management of underlying conditions and timely intervention are important factors for best possible short-term outcomes. In the long term, the subsequent pregnancy rate was good and the incidence of subsequent dystocia was within the normal range.

Animal performance changes over 11 years after implementing a lucerne grazing system on Bog Roy Station

In 2008, Bog Roy was run as a typical high-country station with merino ewes and lambs set stocked for long periods of the year, with 60 ha of lucerne grown for hay. Over the next 7 years, the lucerne and ryecorn areas increased by 30 ha per year. Total lamb meat weaned increased from 91 to 130 t in the first three years direct feeding of lucerne commenced, which improved ewe and two-tooth performance at lambing (% and survival). In the second phase, ewe numbers and pre-weaning lamb growth rates increased. Lambs were weaned earlier and ewes returned to higher pasture covers on hills, which improved their condition score and weights at mating and lambing. In 2016, a change from flood to pivot irrigation resulted in a further production increase to 160 t weaned lamb. By 2018, the mixed age ewes had 141% lambing (to tailing), and pre-weaning lamb growth rates of over 270 g/hd/d which allowed weaning after 80 days. The lamb weaned per ewe mated has increased from 25 to 37 kg over the decade despite increased feed demand from 900 more ewes. These animal performance indicators quantify the transformational change achieved through a focus on grazing and increasing the area of lucerne. This was followed by lucerne and red clover based pastures being established under pivots. The ability to record and quantify changes in stock performance has given the farmer confidence to trust and embrace the transformational change.

Lamb performance in hardwood silvopastures, I: animal gains and forage measures in summer.

The integration of trees into pasture systems can have variable effects on forage and animal growth. Some reports of these systems have indicated that animal gains are similar or better even when tree presence lowers forage yield. Forage production and animal performance were compared in black walnut (Juglans nigra L.)-based and honeylocust (Gleditisia triacanthose L.)-based silvopasture systems and open pastures in a randomized complete block design with three blocks over three summers. Cool season-based, mixed grass pastures were rotationally stocked with four to seven lambs depending on available forage. A rising plate meter was used to estimate pre- and post-graze forage mass. Forage samples of the mixed sward were collected and analyzed for nitrogen (N) and neutral detergent fiber (NDF) concentrations. Species percent cover was estimated using a modified Daubenmire approach at the same 12 points within each experimental unit every 4 wk during the study. Pre-graze herbage mass was similar (P = 0.0717) in honeylocust silvopastures (5020 ± 30 kg·ha−1) and open pastures (4930 ± 30 kg·ha−1) and lowest (P < 0.0001) in the black walnut silvopastures (3560 ± 30 kg·ha−1). Forages in the black walnut and honeylocust silvopastures had similar (P = 0.4867) N concentrations (23.3 ± 0.4 and 23.9 ± 0.4 g·kg−1, respectively), which was greater (P ≤ 0.0003) than that of the forages in the open pastures (21.0 ± 0.4 g·kg−1). Forages in the honeylocust silvopasture had lower (P ≤ 0.0042) NDF concentrations (507 ± 3 g·kg−1) than forages in the black walnut silvopasture and open pastures (mean = 525 ± 3 g·kg−1). Forage species present in the black walnut silvopastures differed from those present in the open and honeylocust systems, which had similar composition. Despite differences in stocking rates, total lamb weight gains per system did not differ (P ≥ 0.7592) among black walnut, honeylocust, and open pasture systems (10 ± 2, 12 ± 2, and 10 ± 2 kg·d−1, respectively). Silvopasture practices can improve land productivity when incorporated into cool season forage pastures.