The breeding structure for the small ruminant resources in India.

Intense selection for a few desired traits has resulted in reduction of the effective population size (Ne) in most of the plant and livestock populations across the world. The objective of the research was to assess the impact of Ne on the genetic architecture of the population in a simulated data with variable Ne for general population under selection. Along with this, the estimate of Ne and its ratio to adult breeding population (NB) in the census data of small ruminants of India were also investigated. Results indicated that the average inbreeding ([Formula: see text]) decreases with increase in Ne; similarly, increase in [Formula: see text] per generation was highest in population with lowest Ne. Correlation of estimated breeding value (EBV) with true breeding value (TBV) was not much affected with effective population size. An effective number of chromosome segments (Me) in the populations under selection were significantly affected by magnitude of Ne, with linear positive relation between Ne and Me. Results on livestock census data revealed that all the sheep and goat breeds have sufficiently large Ne based on derived and actual census data. The median for ratio of effective population size to adult census size in sheep breeds was 0.120 and for goat breeds was 0.131. Karnah and Poonchi sheep shares the status of endangered breeds due to a smaller number of breeding female population and hence need attention for conservation. The Ne was large in sheep and goat due to less selection pressure as a result of low coverage of breed improvement programs, availability of large number of breeding males, and absence of artificial insemination (AI) in the field flocks. The estimates of Ne and its ratio to the adult census size (NB) excluded several factors such as fluctuating population size and overlapping generations. Study revealed introspection from most of the industrial breeding programs on the issue of Ne for populations under selection. Similarly, in small ruminants, large Ne indicates huge genetic diversity and scope of improvement in the productivity in near future.

Genetic diversity of Cahi DRB and DQB genes of caprine MHC class II in Sirohi goat.

The objective of this study was to assess the genetic diversity of the Sirohi goat for DQB and DQB1 loci, and to study their association with antibody response induced by the Peste des petits ruminants (PPR) vaccine. A total of 360 Sirohi kids were studied using single stranded confirmation polymorphism (SSCP) followed by polymerase chain reaction sequence-based typing (PCR-SBT) for DQB and DQB1 diversities. The competitive enzyme-linked immuno-sorbent assay (C-ELISA) was used to evaluate immune response post-PPR vaccination. Study revealed rich diversity of major histocompatibility complex (MHC) region in goat. A total of 18 DQB and 15 DQB1 alleles were obtained which were new. Alleles DRB*0104 and DQB1*0101 were the most common. The approach of SSCP combined with PCR-SBT reflects cost-effective and most powerful approach to decipher the genetic diversity in complex MHC region. Study revealed variation in DQB and DQB1 genes in Sirohi flock along with high Wu-Kabat index. A total of 16 of the 89 amino acid residue sites in DQB and 19 of 86 residue sites in DQB1 had more than three amino acid substitutions. Positive evolutionary selection was evident in Sirohi for MHC region. Nonsignificant association of DQB and DQB1 genotypes with PPR virus (PPRV) vaccine response revealed complexity of the phenotype and importance of other factors for vaccine response. Rich diversity of DQB and DQB1 genes reflects the fitness of the population and importance of this locus for future selection programmes.

Ovar-MHC Polymorphism in Malpura and Avikalin Sheep Vaccinated for Peste des Petits Ruminants (PPR) Virus.

India harbors a vast diversity of sheep (40 breeds). The study was carried out to assess the genetic diversity of DRB1 and DQA2 locus of the ovar-MHC and their possible association with Peste des petits ruminants (PPR) virus vaccine response in Malpura and Avikalin sheep breeds maintained at an organized institute flock in the semi-arid region of India. Genetic analysis revealed the rich diversity of DRB1 locus with 23 alleles in Malpura and 21 alleles in Avikalin sheep that included 9 new alleles. DQA2 locus also had rich diversity with 19 alleles in Malpura and 20 alleles in Avikalin sheep that included 7 new alleles. At the protein level, high variability alike at the nucleotide level was observed. A marker for footrot susceptibility, DQA2*1101 was absent in both breeds. Genotypic association of DRB1 and DQA2 with PPR vaccine response was statistically non-significant. Vaccine response being a multifactorial (polygenic and influenced by environment) variable, could not show statistically significant association with MHC genotypes in the present study. However, rich genetic diversity of DRB1 and DQA2 gene reflects the importance of this locus for future selection programs.

Genetic appraisal of serological response post vaccination against enterotoxaemia (ET) in Malpura and Avikalin sheep.

Enterotoxaemia (ET) is a fatal enteric disease of small ruminants attributable to a toxigenic type of Clostridium perfringens. The key strategy for prevention of ET is the management and vaccination. Present study aimed at identifying the sources of variation for ET vaccine response especially against epsilon toxin in 173 sheep that included 83 Avikalin and 90 Malpura lambs raised at the institute flock in the semi-arid region of India. The mean age at vaccination was 90 days. Sera were tested by blocking ELISA. Study showed significant variability for response to ET vaccine. 5.2% animals had + positivity, 20.8% animals had ++ positivity, 51.4% animals had +++ positivity and 22.5% animals had ++++ positivity. Amongst environmental determinants, breed, season, sex and age at vaccination proved to be non-significant sources of variation (P > 0.05). MHC genotypes with DRB1 gene and DQA2 genes also revealed non-significant association with ET vaccine response; however, a trend of decreasing PI values with increasing ranks was observed. Study revealed strong response of epsilon toxin along with complexity of the ET vaccine response as phenotype to be explained by genetic and non-genetic factors. The importance of better management practices and vaccination is suggested for preventive measures.