L.L.L. Prince

Estimates of (co)variance components and genetic parameters for body weights and first greasy fleece weight in Bharat Merino sheep

(Co)variance components and genetic parameters of weight at birth (BWT), weaning (3WT), 6, 9 and 12 months of age (6WT, 9WT and 12WT, respectively) and first greasy fleece weight (GFW) of Bharat Merino sheep, maintained at Central Sheep and Wool Research Institute, Avikanagar, Rajasthan, India, were estimated by restricted maximum likelihood, fitting six animal models with various combinations of direct and maternal effects. Data were collected over a period of 10 years (1998 to 2007). A log-likelihood ratio test was used to select the most appropriate univariate model for each trait, which was subsequently used in bivariate analysis. Heritability estimates for BWT, 3WT, 6WT, 9WT and 12WT and first GFW were 0.05 ± 0.03, 0.04 ± 0.02, 0.00, 0.03 ± 0.03, 0.09 ± 0.05 and 0.05 ± 0.03, respectively. There was no evidence for the maternal genetic effect on the traits under study. Maternal permanent environmental effect contributed 19% for BWT and 6% to 11% from 3WT to 9WT and 11% for first GFW. Maternal permanent environmental effect on the post-3WT was a carryover effect of maternal influences during pre-weaning age. A low rate of genetic progress seems possible in the flock through selection. Direct genetic correlations between body weight traits were positive and ranged from 0.36 between BWT and 6WT to 0.94 between 3WT and 6WT and between 6WT and 12WT. Genetic correlations of 3WT with 6WT, 9WT and 12WT were high and positive (0.94, 0.93 and 0.93, respectively), suggesting that genetic gain in post-3WT will be maintained if selection age is reduced to 3 months. The genetic correlations of GFW with live weights were 0.01, 0.16, 0.18, 0.40 and 0.32 for BWT, 3WT, 6WT, 9WT and 12WT, respectively. Correlations of permanent environmental effects of the dam across different traits were high and positive for all the traits (0.45 to 0.98).

Genetic Adaptability of Livestock to Environmental Stresses

The concept of adaptability revolves around fitness describing relative ability of an individual to survive and reproduce next generation to ensure continued survival of the population and is the result of natural selection over many generations. Current trend in genetic selection has severely eroded the genetic base ignoring the diversity of the production milieu, importance of adaptation, production of multiple products and social value of the livestock. The problem has been compounded with non-capturing of environmental costs though animal genetic resources (AnGR) on extensive and intensive scale are affected by direct impacts of climate change. Unplanned genetic introgression and crossbreeding has contributed to the greatest extent toward the loss of indigenous breeds. The genetic mechanism influencing fitness and adaptation is not well explored and adaptation traits are usually characterized by low heritability. Further, it may be difficult to combine the adaptation traits with high production potential as there seem to be different physiological and metabolic processes involved. Though decision regarding matching genotypes with environment or vice versa will be situation specific, the low and intermediate level of animal production in many parts of the world suggests that increased yields and efficiency will be more environmentally sustainable than extensive goals ensuring genetic diversity, environmental soundness, animal health and welfare, and social viability. Breeding for climate change adaptation or mitigation will not be necessarily different from existing programs. However, the problems associated with measuring the phenotypes relevant to adaptation have to be overcome. Breeding indices should be balanced to include traits associated with heat resilience, fertility, feed conversion efficiency, disease tolerance and longevity in addition to higher productivity, and give more consideration to genotype by environment interactions (GxE) to identify animals most adapted to specific conditions and natural stratification of breeds and species by climatic zones. Favorable correlation suggests that if major importance is placed on performance traits in stressful environments, adaptability traits would not be compromised and thus the most productive and adapted animals for each environment need to be identified for breeding purposes. Recent successes like slick hair gene in cattle, halothane gene in pig asks for extensive efforts for finding significant quantitative trait loci (QTL) for stress and exploitation of heat shock proteins (HSP). Implementation of marker-assisted breeding value estimation (MA-BVE) using dense genome map for highest possible accuracy will be a welcome step. There is a need of extensive study of interaction among the drivers of changes of climate and livestock, studying it in a composite manner. Appropriate organizational structures and adequate funding to support a climate resilient animal agriculture will be vital.

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

ABSTRACT 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.

Scope of Indirect Selection for Wool Traits in Bharat Merino Sheep in Semi Arid Region of Rajasthan

Abstract Gowane, G.R., Chopra, A., Prince, L.L.L. and Arora, A.L. 2010. Scope of indirect selection for wool traits in Bharat Merino sheep in semi arid region of Rajasthan. J. Appl. Anim. Res., 37: 97–100. Estimates of covariance components along with genetic, phenotypic and environmental correlation were obtained for different wool traits, viz. greasy fleece yield (GFY), staple length at six month (SL), medullation percentage (MED) and, fiber diameter (FD) in Bharat Merino Sheep developed and maintained at the Central Sheep & Wool Research Institute, Avikanagar, India. Twenty years data were analyzed by restricted maximum likelihood, (REML) fitting univariate and bivariate animal models. Additive genetic variability for all the traits was low except greasy fleece yield (h2 = 0.16). Permanent environmental variance as a proportion of phenotypic variance (c2) for GFY was 0.26. Genetic correlation between GFY and SL was 0.21, between SL and MED 0.19 and SL and FD 0.20. For further genetic improvement in this breed, MED and FD should be kept restricted at present level (MED: 18.08μ and FD: 1.25%) and emphasis should be given on GFY and SL, which are positively (favorably) associated with each other.

Climate Change Impact on Sheep Production: Growth, Milk, Wool, and Meat

Sheep production is looked upon as the primary meat industry in the future due to production efficiency of mutton and adaptability of the sheep to changing climate. More than 50% small ruminants of the world are located in arid region, indicating their adaptability and future suitability to increasing temperatures. Sheep graze in the ranches, wastelands particularly in Asian and African countries, and also in pasturelands of Australia; this not only reduces emission of the greenhouse gases (GHG) but also increases fertility of land. Increased temperatures will be the first impact of climate change. Cyclones, droughts, heavy rainfall, unpredictable climate, and diseases are other factors which will affect the sheep husbandry; however threats posed by these factors can also be ameliorated with scientific planning and execution. Disease resilience in genomics of sheep can be exploited apart from nutritional interventions for mitigating these challenges. 2050 will see a high demand of food from exisiting resources to feed ~10 billion people, and sheep will play a major role with advanced genomic selection. In sheep, growth traits and meat quality are important criteria. Selection of sheep breeds and candidates that are high producing and also tolerant to the adverse effects can be a mitigating option. Reaction norms in genotype by environment interaction are important, and selection of genotypes for suitability in the future needs considerable research inputs. Revised selection criteria may be a need of the future, where production in the compromised environment seems to be the need of time. The decline in profitability of wool and environmental impacts have forced wool to take backstage; however, wool fiber production consumes significantly less energy than popular man-made fibers. Importance of the sheep husbandry as sustainable livelihood option for landless, marginal, and small farmers needs to be realized along with its global emergence as the desired food animal in the climate change era.

Genetic Variants of β-Lactoglobulin Gene in Garole, Malpura, Patanwadi and Their Crossbred Sheep

Several milk protein polymorphisms have been considered as potential tool for selection of dairy animals. β-lactoglobulin (β-LG) is one of the major whey proteins in ruminant milk. A study was aimed to identify the genetic variants of β-LG gene in Garole (G), Malpura (M), Patanwadi (P) and their crosses i.e. GM, GMM, GMMxP (A), PxGMM (B) by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Two genetic variants and three genotypes were found in all the breeds and crossbreds. Overall frequency of alleles A and B in the breeds and crossbreds were 0.55 and 0.45, respectively. Allele ‘A was more frequent than allele ‘B ’in all the breeds and crossbreds except Patanwadi and GM cross. The GMM crossbred had the highest frequency of ‘A ’allele (0.64) while Patanwadi and GM crossbred had the lowest (0.40). There was predominance of ‘AB ’genotype in these breeds and crossbreds. BB genotype predominated in Patanwadi and GM crossbred with genotypic frequencies of 0.45 and 0.49, respectively. All the genetic groups were in Hardy-Weinberg equilibrium except Malpura, Patanwadi and GM crosses. It can be concluded that variation exist in the Indian sheep breeds/strains at studied locus of β lactogloublin and these variation can be utilized in future to study the effects of different variants on the milk production and quality traits.

Aromatase Gene Polymorphism in Sheep Breeds of India

A study was conducted to find the single nucleotide polymorphism in the aromatase gene in nine Indian sheep breeds. Polymorphism was recorded in the Indian sheep breeds which have both the alleles A/B in the populations. The overall frequencies of alleles A and B in the breeds and crossbreds were 0.48 and 0.52, respectively. AB genotype predominated in all the breeds, whereas AA and BB genotype was absent in Magra, Patanwadi and Dumba breeds.

GROWTH PERFORMANCE APPRAISAL OF MALPURA AND KHERI SHEEP UNDER FIELD CONDITIONS

Malpura is one of the heavy mutton type sheep breeds of semi-arid region of Rajasthan. A field study was conducted to record and analyse the growth performance of Malpura and Kheri and morphometry of Malpura sheep. The least squares means for birth, 3 and 6 month weights in Malpura field flocks were 3.01±0.05, 15.08±0.21 and 24.44±0.50 kg and in Kheri they were 2.97±0.05, 14.76±0.22 and 17.49±0.29 kg respectively. The present results on body weights were on the higher side than previous reports, signifying improvement in the body weights of animals. The study also reports morphometric measurements of Malpura sheep (male, female) in field flocks for various traits such as face length (27.96, 25.73 cm), face width (14.08, 12.04 cm), heart girth (86.18, 78.27 cm), withers height (80.37, 70.28 cm), body length (74.91, 68.21 cm) and tail length (37.22, 29.13 cm). Average scrotum circumference and scrotum length in males were 28.68±0.79 and 17.75±0.72 cm, respectively. The implications of crossing Malpura with Kheri and Kheri x Patanwadi (Desi) genotypes are discussed.

Study of genetic relatedness among meat producing Indian sheep breeds by RAPD-PCR.

Abstract Hatkar, D.N., Prince, L.L.L., Sirothia, A.R. and Paswan, C. 2008. Study of genetic relatedness among meat producing Indian sheep breeds by RAPD-PCR. J. Appl. Anim. Res., 38: 129–133. To estimate the genetic variability and phylogenetic relationship among four breeds (Sonadi, Madgyal, Deccani and Nellore) of sheep adapted in the semi-arid climatic conditions of Rajasthan and part of Deccan plateau RAPD technique was applied. This analysis kept the four breeds in three groups i.e. Deccani and Nellore were kept in same group, Sonadi and Madgyal were kept in entirely different groups but Madgyal has more closenese to Deccani and Nellore. This RAPD marker study revealed that Madgyal, Deccani and Nellore are closer genetically as compared to Sonadi breed.