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A study was undertaken during 2015–2017 to assess the milk yield potential and to estimate the effect of dam's milk yield on ewe productivity efficiency of newly developed prolific Avishaan and GMM (25% Garole-75% Malpura) sheep at ICAR-Central Sheep and Wool Research Institute, Avikanagar, Rajasthan. A total of 369 test day milk records from 34 Avishaan ewes and 199 test day milk yield records from 19 GMM ewes were collected. Average milk recording period in GMM and Avishaan ewes was 66 and 74 days, respectively. Birth and weaning weight data of lambs born to these ewes were also collected. The data were analyzed using the general linear model procedure with different fixed effects and covariates in the model. The least squares means of daily milk yield was 672.73±15.60 g in Avishaan and 531.85±19.77g in GMM ewes. Daily milk yield was significantly affected by stage of lactation, dam's parity and type of birth in both the genotypes. The least squares means of 90-day lactation yield were 63.49±2.46 and 48.40±2.86 kg in Avishaan and GMM ewes, respectively. First parity ewes recorded the lowest lactation yield in both the genotypes. The least squares means of litter weight per ewe at weaning were 21.40±0.72 and 18.47±1.10 kg in Avishaan and GMM ewes, respectively. Positive correlations between ewe's milk yield with litter weight at weaning and average daily gain in litter weight was observed for both the genotypes. It can be concluded that prolific Avishaan sheep has higher milk yield potential compared to GMM sheep and higher milk yield in dam resulted in higher litter weight and average daily gain at weaning.

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.

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.