Semen sexing and its impact on fertility and genetic gain in cattle.

Semen sexing is among one of the most remarkable inventions of the past few decades in the field of reproductive biotechnology. The urge to produce offspring of a desired sex has remained since traditional times. Researchers have tried many methods for accurate semen sexing, but only the flow cytometry method has proved to be effective for commercial utilization. However, there were always concerns about the effects of sexed semen, especially on fertility and the rate of genetic gain. Some concerns were genuine because of factors such as low semen dosage in sexed semen straws and damage to sperm during the sorting process. Various researchers have conducted numerous studies to find out the effect of sexed semen on fertility and, in this article, we reflect on their findings. Initially, there were comparatively much lower conception rates (∼70% of conventional semen) but, with refinement in technology, this gap is bridging and the use of sexed semen will increase over time. Concerning genetic gain with use of sexed semen, a positive effect on rate of genetic progress with the use of sexed semen has been observed based on various simulation studies, although there has been a mild increase in inbreeding.

Estimation of maternal and additive effect on reproduction and productive traits in Hardhenu cattle.

The study aimed to assess performance traits in Hardhenu cattle by analysing data from 445 animals born to 59 sires and 227 dams. The investigation focused on estimating (co)variance components and genetic parameters for reproduction and production traits in dairy cattle. Results from least-squares analysis indicated a significant effect (p < .01) of the period of calving (POC) on key production traits, including first lactation milk yield (FLMY), 300-day milk yield (FLMY300), first peak yield (FPY) and total lactation milk yield (TLMY) in studied population. The least squares means for these traits were reported as follows: FLMY (2665.68 ± 45.66 kg), FLMY300 (2425.52 ± 34.41 kg), FLL (312.95 ± 3.83 days), FPY (11.52 ± 0.15 kg) and TLMY (9282.44 ± 167.03 kg) in Hardhenu cattle. In the studied population, only additive genetic variability was found to be present and there was absence of any significant maternal effect with respect to targeted traits in the resource population. Direct heritability estimates (h2) for FLMY, FLMY300, FLL, FPY, TLMY and other traits ranged from 0.03 to 0.41 in Hardhenu cattle. These findings offer valuable insights into the genetic factors influencing performance traits, contributing to the enhancement of breeding and management practices in Hardhenu cattle.

Exploring MicroRNA biogenesis, applications and bioinformatics analysis in livestock: A comprehensive review.

Small non-coding RNAs called microRNAs (miRNAs) control the expression of genes post-transcriptionally. Their correlation with commercial economic traits including milk, meat and egg production, as well as their effective role in animal productivity, fertility, embryo survival and disease resistance, make them significant in livestock research. The miRNAs exhibit distinct spatial and temporal expression patterns, offering insights into their functional roles within cells and tissues. Aberrant miRNA production can disrupt vital cellular processes and genetic networks, contributing to conditions like metabolic disorders and viral diseases. These short RNA molecules are present in extracellular fluids, displaying remarkable stability against RNA degradation enzymes and extreme environmental conditions. miRNAs preservation is facilitated through packaging in lipid vesicles or complex formation with RNA-binding proteins. Numerous studies have illuminated the roles of miRNAs in diverse physiological processes, including embryonic stem cell differentiation, haematopoietic stem cell proliferation and differentiation and the coordinated development of organ systems. The integration of miRNA profiling, next-generation sequencing and bioinformatics analysis paves the way for transformative advancements in livestock research and industry. The present review underscores the applications of miRNAs in livestock, showcasing their potential to improve breeding strategies, diagnose diseases and enhance our understanding of fundamental biological processes.

Polymorphism of growth hormone (GH) gene and its association with performance and body conformation of Harnali sheep.

The present study was carried out to study the polymorphism in the GH gene and its association with various performance and body conformation traits, viz., birth weight (B-WT), weaning weight (W-WT), six-month body weight (6 M-WT), one-year body weight (Y-WT), annual greasy fleece weight (AGFW), body length (BL), body height (BH), heart girth (HG) and paunch girth (PG) in 138 Harnali sheep. PCR-RFLP was performed to identify polymorphism in the targeted region of the GH gene. The PCR product of 422 bp size of the GH gene was amplified encompassing partial exon 2 and inton 3 in Harnali sheep. The PCR product was digested with HaeIII restriction enzyme for the detection of Single nucleotide polymorphism (SNP). The digested products revealed the presence of two genotypes, i.e. AA and AB in the studied population. A > G mutation (A781G) was observed in our resource population. The AA genotype was found to be the predominant genotype (0.62). Chi square value revealed that resource population was not under Hardy-Weinberg equilibrium with respect to target locus. Period of birth was found to have significant effect on W-WT, Y-WT, BL, BH and PG. Sex of animal was found to have significant (P < 0.05) effect on W-WT and highly significant (P < 0.01) effect on 6 M-WT, Y-WT and AGFW in Harnali sheep. The effect of genotype was found to be significant (P < 0.05) on annual greasy fleece weight. AB genotype was found to be associated with higher annual greasy fleece weight and can be used as a potential candidate marker in selection criteria for improving greasy fleece weight in Harnali sheep.

Expression profiling of immune genes associated with black pepper (Piper nigrum) powder supplementation in the diets of broiler chickens.

The present study was conducted on three hundred commercial broiler chicks with the aim to evaluate the effect of black pepper supplementation on expression of TLR gene where the negative control (T1) group was given basal diet without antibiotic and in the control group (T2) basal diet with antibiotic was fed, third (T3), fourth (T4), fifth (T5) and sixth (T6) groups were supplemented with black pepper powder (BPP) at levels 0.25, 0.5, 0.75 and 1%, respectively in diet. After 42 days, a significant reduction (p < 0.05) in ileal E. coli count and a higher value of Lactobacilli was recorded in the various black pepper powder supplemented groups, and they differed significantly (p < 0.05) from negative control. The mRNA expression levels of Toll-like receptors (TLR 2 and TLR 4) had shown significant (p < 0.05) changes in experimental groups. The TLR 2 and TLR 4 genes revealed differential expression in all black pepper supplemented groups in comparison to negative control and control group, while TLR 7 did not show any significant change. Thus, supplementation of black pepper powder can be exploited as an immunomodulator to enhance adaptive immune response of broiler chicks after validation on large number of samples.

Investigating the impact of linseed supplementation, rich in omega-3 fatty acids, on the expression of immune genes in Beetal Goats.

The present study investigated the effect of linseed supplementation on serum profiling and differential expression levels of IL-2 and TLR 2 genes involved in the immune system of lactating goats. The study was conducted on 15 lactating Beetal goats for 3 months, which were divided into three groups. Treatment group T1 was kept as a control group with no linseed supplementation, whereas treatment group T2 received ground linseed at the rate 10% of concentrate per day per animal, and treatment group T3 received 20% ground linseed. The concentration of triglycerides, cholesterol and LDL concentration were found to be significantly lower (P < 0.05) in both 10% and 20% linseed supplemented group than the control group. Whereas, HDL concentration in T2 and T3 group were found to be significantly higher than the control group. The differential expression of targeted genes comparatively revealed highest relative expression in the group that received 20% linseed supplementation. Although the study did not show a significant effect of linseed supplementation on the expression of TLR-2 and IL-2 genes in goats, it highlights the potential benefits of omega-3 PUFA supplementation on immune system modulation in animals.

Candidate K232A mutation of DGAT1 gene associated with production and reproduction traits in Indian Dairy cattle.

The present study was conducted on Hardhenu and Sahiwal cows to evaluate the genetic diversity and the effect of candidate K232A mutation of diacylglycerol O-acyltransferase (DGAT1) gene on performance traits. PCR product of 413 bp size targeting K232A mutation of DGAT 1 gene was genotyped by Eae1 restriction enzyme and further confirmed by sequencing. The PCR-RFLP analysis for K232A showed that the frequencies of alleles K and A were 0.80 and 0.20 in Hardhenu and 0.98 and 0.02 in Sahiwal cattle, respectively. The frequencies of genotypes for KK and KA genotype were estimated as 0.60 and 0.40 in Hardhenu and 0.96 and 0.04 in Sahiwal cattle, respectively. Chi-square test showed that K232A SNP did not meet with the Hardy-Weinberg equilibrium (p < .01) in Hardhenu cattle. Association analysis revealed that KA genotype was significantly associated with total milk yield (p < .01) and 305 days milk yield (p < .01)in Hardhenu cattle. Hardhenu cows having KA genotype comparatively revealed favorable mean values for AFS (880.31 ± 26.65), AFC (1166.36 ± 19.94), SP (157.46 ± 22.80), CI (441.41 ± 44.28) and AI/Conception (1.80 ± 0.17), indicating that KA genotype can be used as a candidate marker for simultaneous improvement of both production and reproduction traits.

Effect of BsaA I genotyped intronic SNP of leptin gene on production and reproduction traits in Indian dairy cattle.

In the present study, candidate single nucleotide polymorphism (SNP) g.92450765 G > A of leptin gene was explored for Bos indicus cattle with an aim to explore its possible effect on production and reproduction traits. The genotypic and allelic frequencies of BsaA 1 genotyped SNP g.92450765 G > A indicated the predominance of AG (0.65) genotyped Sahiwal cows in our studied population. The least-squares analysis showed a significant association (p < 0.05) of identified genetic variants with total milk yield (TMY) and 305 days milk yield (MY) (p < 0.05). The GG genotyped cows were found to be associated with higher milk yields. However, for reproduction traits under study AA genotype was found to be more favorable with respect to service period and calving interval (p < 0.05). Computational analysis was also performed to predict changes if any in the transcription factor binding sites (TFBS) caused due to the identified SNP in the intronic region of the leptin gene. TFBS analysis predicted that the targeted SNP at g.92450765G > A may lead to the disappearance of TFBS such as Hypermethylated in cancer 2 protein (HIC2), Max-binding protein MNT (MNT), Cyclic AMP-dependent transcription factor -3 (ATF3), Myc-associated factor X (MAX) and Microphthalmia-associated transcription factor (MITF). It may lead to changes in transcriptional regulation.

Cross-population genetic analysis revealed genetic variation and selection in the Ovar-DRB1 gene of Indian sheep breeds.

In sheep, MHC variability is studied widely to explore disease association. The aim of the current study was to explore the genetic diversity of Ovar-DRB diversity across sheep breeds of India. Here, Ovar-DRB1 locus was studied across 20 sheep breeds. DRB1 was amplified (301 bp) and sequenced using a PCR-sequence-based typing approach. Results revealed a high degree of heterozygosity across breeds (mean: 73.99%). Overall mean distance for DRB1 was highest in Sangamneri (0.18) and lowest in Madgyal sheep (0.10). There was a higher rate of transition, across breeds. Further, 39 alleles were isolated in different breeds, out of which 10 were new. To allow easy access and use of the immune-polymorphic database, an online database management system was launched (http://www.mhcdbms.in/). Nucleotide content across breeds for the DRB1 region revealed the richness of GC content (59.26%). Wu-Kabat index revealed vast genetic variation across peptide binding sites (PBS) of DRB1. Residues 6, 66, 69, 52, and 81, were polymorphic showing utility for antigen presentation. All breeds were under positive selection for DRB1 locus (dN > dS). Study revealed the importance of DRB locus diversity for beta chain specifically at PBS across sheep breeds of the Indian subcontinent and presented evidence of positive selection for DRB owing to its evolutionary significance.

Population-wide genetic analysis of Ovar-DQA1 and DQA2 loci across sheep breeds in India revealed their evolutionary importance and fitness of sheep in a tropical climate.

Genetic variability at the major histocompatibility complex (MHC) is important in any species due to significant role played by MHC for antigen presentation. DQA locus has not been studied for its genetic variability across sheep population in India. In the present study, MHC of sheep at DQA1 and DQA2 loci were evaluated across 17 Indian sheep breeds. Results revealed high degree of heterozygosity (10.34% to 100% for DQA1 and 37.39 to 100% for DQA2). 18 DQA1 alleles and 22 DQA2 alleles were isolated in different breeds. Nucleotide content for DQA region revealed richness of AT content (54.85% for DQA1 and 53.89% for DQA2). DQA1 and DQA2 sequences clustered independently. We could see evidence of divergence of DQA as DQA1 and DQA2 across sheep breeds. Wu-Kabat variability index revealed vast genetic variation across DQA1 and DQA2, specifically at peptide binding sites (PBS) that consisted 21 residues for DQA1 and 17 residues for DQA2. Evolutionary analysis revealed the presence of positive and balancing selection for DQA1 locus, however DQA2 was under purifying selection across sheep breeds. Higher heterozygosity and large diversity at both loci especially at PBS indicated the fitness of the sheep population for evading pathogens and adapt to the harsh tropical climate.

Influence of single nucleotide polymorphism in the IGF-1 gene on performance and conformation traits in Munjal sheep.

Genetic polymorphism research in livestock species aims to assess genetic differences within and among breeds, primarily for conservation and development objectives. The aim of the present study was to determine the point mutation in the IGF-1 gene (g.855G>C and g.857G>A) and its association with performance traits in Munjal sheep. In total, 50 Munjal sheep were selected and the genomic DNA was isolated using the Automated Maxell RSC DNA/RNA purification system and the Maxwell RSC whole blood DNA kit. A reported set of primers was used to amplify the 294-bp fragment encompassing the targeted region, i.e. the 5' flanking region of the IGF-1 gene. The polymerase chain reaction product of 294-bp size harbouring the g.857G>A mutation in the 5' flanking region of the IGF-1 gene was digested with HaeII enzyme. Three possible genotypes were defined by distinct banding patterns, i.e. GG (194, 100 bp), GA (294, 194, 100 bp) and AA (294 bp) in the studied population of Munjal sheep. The genotypic and allelic frequencies of g.857G>A single nucleotide polymorphism of the IGF-1 gene indicated that the frequency of the A allele was higher in the studied population, i.e. 0.59 and the GA genotype was found to be the predominant genotype (0.66). Allele A of the IGF-1 gene was found to be associated with higher body weights and can be used in selection criteria for improving the performance of Munjal sheep. The positive effect of the IGF-1 gene on several conformational traits as observed in this study suggests that this area of the ovine IGF-I gene is particularly important and warrants further investigation on a larger population size.

Evaluation of physiological and morphological parameters for early prediction of prenatal litter size in goats.

The aim of the present study was to evaluate the physiological and morphological parameters of pregnant does for early prediction of prenatal litter size. In total, 33 does were screened using ultrasonography and further categorized into three groups based on does bearing twins (n = 12), a single fetus (n = 12), or non-pregnant does (n = 9). The rectal temperature °F (RT) and respiration rate (RR) as physiological parameters, while abdominal girth in cm (AG) and udder circumference in cm (UC) as morphological parameters were recorded at different gestation times, i.e. 118, 125, 132 and 140 days. In addition to this, age (years) and weight at service (kg) were also used. The statistical analyses included analysis of variance (ANOVA) and linear discriminant analysis (LDA). The results indicated that groups had significant (P < 0.05) differences among morphological parameters at each gestation time, with higher AG and UC in does bearing twins followed by a single fetus and non-pregnant does. However, both physiological parameters were non-significantly (P > 0.05) associated with litter size groups. It was also revealed that the studied parameters showed increasing trends over gestation time in single and twin fetus categories, but they were on par among non-pregnant does. The results of the LDA revealed that estimated function based on age, weight at service, RR, RT, AG and UC had greater (ranging from 75.00 to 91.70%) accuracy, sensitivity and specificity at different gestation times. It was concluded that using an estimated function, future pregnant does may be identified in advance for single or twin litter size, with greater accuracy.

Impact of temporal variations and risk factors associated with udder inflammation in Hardhenu cattle (Bos taurus × Bos indicus).

This study aimed to explore the occurrence and risk factors associated with clinical mastitis within the Hardhenu cattle herd over a span of 14 years (2008-2021). A comprehensive analysis of 1515 lactation records was conducted to ascertain the incidence of clinical mastitis. The investigation determined an overall incidence rate of 26.80% in the studied population. A significant relationship between the year and clinical mastitis incidence was established through Chi-square analysis (p < .05). Temporal variations in clinical mastitis odds were apparent, with the highest odds (ranging from 0.91 to 1.00) observed during the initial years of 2008-2009 and 2009-2010. Logistic regression revealed that odds values for clinical mastitis incidence were highest in 2008-2009 (1.00), succeeded by 2009-2010 (0.91), 2012-2013 (0.88), 2018-2019 (0.67) and reaching the lowest in 2021-2022 (0.35). Subsequent rankings included 2010-2011 (0.39), 2014-2015 (0.43) and 2019-2020 (0.45). Parity was found to be significantly associated with clinical mastitis occurrence. When compared to Parity 3, both Parity 1 (odds ratio: 1.516, 95% confidence interval: 0.881-2.612) and Parity 2 (odds ratio: 2.626, 95% confidence interval: 1.568-4.398) exhibited higher odds values for clinical mastitis incidence. While the period of calving did not exert a significant influence on clinical mastitis incidence, a heightened occurrence was observed during the rainy season within the targeted population. These findings offer valuable insights into the patterns of incidence, temporal fluctuations, and non-genetic determinants impacting clinical mastitis within the Hardhenu cattle. The implications of this study can facilitate the development of targeted strategies and management protocols aimed at enhancing udder health and overall productivity in dairy cattle.

Temporal variation and risk factors associated with reproductive disorders in Hardhenu (Bos taurus × Bos indicus) dairy cattle.

This study aimed to investigate the incidence and effect of non-genetic factors on reproductive disorders in the Hardhenu cattle population over a period of 11 years (2010-2021). The study included a total of 1340 cattle for calculating the incidence of reproductive disorders and analysed the occurrence of different reproductive disorders. In the present study, retention of placenta had highest frequency, accounting for approximately 18.36% of the incidence, followed by repeater cows (11.19%), metritis (6.27%), dystocia (0.60%), anestrus (0.45%) and prolapse (0.37%). Chi-square analysis revealed a significant relationship between the year and the incidence of reproductive disorders (p < .05). Logistic regression analysis of temporal variability of reproductive disorders was also analysed, with an increase in the odds from 2014 to 2020, peaking in 2017-2018 and 2018-2019. Logistic regression analysis showed that season and parity did not significantly influence the incidence of reproductive disorders. However, period of calving had a significant impact. Cows calving between 2008 and 2014 had a significantly lower odds ratio (0.13, 95% CI: 0.06-0.30), indicating a decreased risk, while those calving between 2014 and 2017 had a higher odds ratio (0.59, 95% CI: 0.38-0.90), suggesting an increased risk of reproductive disorders. Compared to parity 3, parity 1 (1.344, 95% CI: 0.869-2.08) and parity 2 (1.193, 95% CI: 0.768-1.851) showed highest odds ratio. Similarly, the odds ratio for winter (1.64, 95% CI: 0.93-2.89), summer (1.71, 95% CI: 0.89-3.26) and rainy season (1.64, 95% CI: 0.92-2.91) was higher as compared to autumn. The present results provided valuable insights into the incidence of various reproductive disorders and associated risk factors in Hardhenu cattle. These results can be utilized for targeted interventions to enhance reproductive health and overall productivity in dairy cattle.

Association of CXCR1 gene polymorphism with clinical mastitis, reproductive disorders and performance traits in Hardhenu (Bos taurus × Bos indicus) cattle.

The present study investigated the presence of CXCR1 gene polymorphisms and their association with clinical mastitis, reproductive disorders and performance traits in Hardhenu cattle. Genotyping of the targeted SNP rs211042414 (C>T) at the g.106216468 loci of the CXCR1 gene was performed through PCR amplification and Bsa1 restriction enzyme digestion. The genotypic frequencies revealed three genotypes: CC, CT and TT, with the C allele being the most prevalent. Significant associations were found between the targeted SNP and clinical mastitis occurrence using chi-square and logistic regression analyses. The CC genotype showed higher susceptibility to clinical mastitis with a higher odds ratio of 3.47 compared to TT (1.00) and CT (2.90) genotypes (p < .05). Furthermore, least squares analysis revealed significant associations between genotypes and performance traits such as total milk yield, 305-day milk yield and peak yield (p < .05). The CC genotype exhibited higher milk yields than CT and TT genotypes, indicating a positive association between the C allele and increased milk production. These findings have practical implications for the genetic improvement of Hardhenu cattle. Incorporating the identified CXCR1 gene polymorphisms into existing selection criteria can help enhance disease resistance and milk production traits. However, further validation with a larger sample size is necessary to strengthen the observed associations and ensure their practical applicability.

Modelling the growth curve and estimation of associated genetic parameters in Munjal sheep.

The study of growth curves in sheep is an effective approach to monitor the animal development for predicting the growth rate and improving overall flock performance. The purpose of the present work was to study the growth curve traits of Munjal sheep using different non-linear models and to estimate the genetic parameters of those traits for the possibility of inclusion of them under selection strategy. Total 2285 weight records at birth, 3, 6 and 12 months of age of 706 lambs born to 48 sires and 149 dams were collected from the registers maintained from 2004 to 2019. Various non-linear growth models viz., Brody, Gompertz, logistic, Bertalanffy and negative exponential were fitted to targeted growth curve traits and then evaluated using goodness of fit criteria such as adjusted R2, root means square error (RMSE), Akaike's information criterion (AIC) and Bayesian information criterion (BIC). The genetic parameters of growth curve traits were estimated using animal model. The results suggested that Brody model was best fitted to the data than other models. The growth curve estimates for mature weight (A), inflexion point (B) and rate of maturation (k) under Brody model were 25.82 ± 1.72, 0.84 ± 0.04, and 0.21 ± 0.04, respectively for female lambs, and 29.55 ± 2.04, 0.86 ± 0.03 and 0.19 ± 0.04, respectively for male lambs. The males showed superiority for mature weights whereas female lambs had higher maturation rates. The estimates of direct heritability for A, B and k were 0.33, 0.41 and 0.10, respectively. The moderate estimate of direct heritability of A and its negative genetic correlation with k indicated the scope of genetic improvement through selection based on mature weights. Therefore, it was concluded from the present findings that Brody model was the one that best describes the growth curve in the Munjal sheep and the selection based on mature weights can be employed for genetic improvement of Munjal flock.

Meta-Analysis of Gene Polymorphism of Beta-Lactoglobulin Gene in Indian Dairy Cows.

The aim of the present paper was to summarize the gene polymorphisms of beta-lactoglobulin (BLG) gene and its effects on milk yield in 1840 genotyped Indian dairy cows reported in 17 published studies. The meta-analysis was undertaken using gene frequencies of individual studies under random effects model, whereas for association analysis of genotypes with milk yield, standardized mean differences (SMDs) along with 95% confidence interval (CI) were obtained under four genetic models such as additive (AA vs. BB), dominant (AA+AB vs. BB), completely over dominant (AA+BB vs. AB) and recessive (AA vs. AB+BB). The heterogeneity index (I2) was used to determine heterogeneity between studies. The results of meta-analysis suggested that the pooled allelic frequency of allele A was subsidiary as 0.29 (95% CI 0.24, 0.33, I2 = 88.54%) in targeted population, and also, it was non-significantly (P > 0.05) different between Bos indicus (0.28) and Bos taurus/cross cows (0.30). Egger's test indicated no risk of publication bias (P > 0.05). The results also revealed that BLG gene variants have non-significant (P > 0.05) association with milk yield under all genetic models. Although positive effects of SMDs under some models were observed, however, they failed to meet statistical significance (P > 0.05) due to high heterogeneity between studies which lead to conclusion of only uncertain influences of SNP genotypes with milk yield. It was concluded that BLG markers may not be beneficial for improving milk yield in Indian dairy cows. However, it is suggested that the revalidation of the present results should be done by using more number of studies.

Impact of mother genetic and resource environment on her offspring's growth features in Munjal sheep.

The present study evaluated maternal and additive influences that contribute to phenotypic variation in various growth traits in Munjal sheep. The targeted traits that pertained to 2278 records of 706 lambs were birth weight (BWT), weaning weight (WT3), 6-month body weight (WT6), 12-month body weight (WT12), average daily gain (ADG1: 0-3 months; ADG2: 3-6 months, ADG3: 6-12 months of age) and their corresponding Kleiber ratios designated as KR1, KR2 and KR3. The direct heritability estimates for BWT, WT3, WT6, WT12, ADG1, ADG2, ADG3, KR1, KR2 and KR3 under animal models were 0.20 ± 0.08, 0.28 ± 0.08, 0.17 ± 0.07, 0.47 ± 0.09, 0.33 ± 0.08, 0.09 ± 0.06, 0.36 ± 0.10, 0.33 ± 0.08, 0.09 ± 0.06 and 0.32 ± 0.10, respectively. The estimates of maternal genetic effects contributed significantly and were 8% and 7% for BWT and WT3 traits, respectively, which highlighted the considerable role of maternal effects on early growth traits. Genetic and phenotypic correlations ranged from moderate to high between weaning and post-weaning traits. It was concluded that early selection that considered additive as well as maternal effects at weaning age may be delivered to the desired genetic progress in Munjal sheep.

Genetic and non-genetic effects associated with ewe productivity in Harnali sheep.

The objective of the current study was to estimate the genetic parameters for ewe productivity traits of Harnali sheep by examining non-genetic effects. The data records of 440 animals born to 85 sires and 259 dams were collected with respect to various traits such as litter size at birth (LSB), litter weight at birth (LWB), litter size at weaning (LSW), litter weight at weaning (LWW) and age at first lambing (AFL) for the period of 2001 to 2020. Genetic parameters were estimated by fitting a series of animal models using an average information restricted maximum likelihood (REML) algorithm in WOMBAT software. Least-squares analysis revealed significant (P < 0.05) influences of period of lambing, age and weight of ewe at lambing on the studied traits. These results indicated that heavier ewes had significantly higher (P < 0.05) values of litter weight traits than their counterparts. On the basis of likelihood ratio test, the estimates of direct heritability under best model for AFL, LSB, LWB, LSW and LWW were 0.06, 0.18, 0.09, 0.07 and 0.16, respectively. Maternal permanent environment effect made a significant contribution to the LSB trait (0.20). The genetic correlation between litter size and LWW was negative, while the remaining correlations were positive. The present results suggest that selection based on ewe productivity traits will result in low genetic progress and therefore the management role is more important for better gains.

Survival analysis for estimating lamb survival up to weaning in Harnali sheep.

The present study was carried out to estimate lamb survival (in days) from birth to weaning under survival analysis using data records from 2057 Harnali lambs born to 134 sires and 623 dams between the period from 2001 to 2020. The weaning age in resourced population was 90 days from birth. The hazard ratio in terms of risk of death up to weaning was determined using Cox proportional hazards model by subjecting some fixed factors such as year of birth, sex of lamb, birth weight (kg), dam's weight at lambing (kg) and dam's age at lambing (years). The overall survivability up to weaning among lambs was 91.59% and Kaplan-Meier estimates of mean survival time up to weaning was 85.77 days. Cox proportional hazard modelling revealed that the hazards of death up to weaning was higher in male lambs [1.66, 95% confidence interval (CI): 1.22-2.26] compared with female lambs [hazard ratio (HR) = 1.00]. It was also observed that the hazards of death (HR = 0.91, 95% CI: 0.88-0.94) had decreasing trends over years. For birth weight (kg), hazard rate was 0.34 (95% CI: 0.25-0.46), which indicated that the risk of pre-weaning mortality was lower as birth weight increases. The weight and age of dams at lambing did not influence the survival time of studied population. The present findings indicated that survival time increased in studied lambs over the years and it could be increased more by giving more emphasis on better litter weight and general health aspects at farm level.