<div>Background:&nbsp;Many genetic variants of beta-casein in different breeds of cattle have been reported. The A1 and A2 are the most common variants. The breeds of Zebu cattle have high frequency of A2 allele or monomorphic for A2 allele. The current study aimed to screen Indian Zebu cattle breeds, Bargur and Umblachery, for A1 and A2 alleles at beta-casein locus. 
 
Methods:&nbsp;A total of 48 Bargur and 42 Umblachery cattle were genotyped for &beta;-casein (CSN2) gene using allele-specific PCR. The gene and genotype frequencies were estimated. The theoretical heterozygosity (Heexp), experimental heterozygosity (Heobs), polymorphism information content (PIC), expected homozygosity (E), effective number of alleles (ENA) and level of possible variability realization (V%) were calculated. 
 
Result:&nbsp;The investigation revealed the presence of both A1 and A2 alleles at beta-casein locus in both Bargur and Umblachery cattle breeds. The A1A1 genotype was not observed in both the breeds. The frequencies of A1A2 and A2A2 genotypes were 0.125 and 0.875 respectively in Bargur and 0.050 and 0.950 respectively in Umblachery breed. The study indicated the predominance of A2 variant in both the breeds. The frequencies of A1 and A2 alleles were 0.063 and 0.937 respectively in Bargur and 0.02 and 0.98 respectively in Umblachery breed. The values of experimental heterozygosity (Heobs), theoretical heterozygosity (Heexp), polymorphism information content (PIC), expected homozygosity (E), effective number of alleles (ENA), level of possible variability realization (V%) were 0.125, 0.1163, 0.1095,0.8837, 1.131 and 11.88 respectively in Bargur breed. These values were 0.048, 0.0468, 0.0458, 0.9532, 1.049 and 4.79 respectively in Umblachery population. The observed heterozygosity and PIC values revealed the existence of very low genetic variability in the tested populations. The present work will be a contribution to the study on beta-casein locus in Indian zebu cattle.</div>

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Detection of A1 and A2 Alleles at Beta-casein Locus in Bargur and Umblachery (Indian Zebu) Cattle Breeds by Allele-specific PCR

Background: The choice of superior herd sires is essential for genetic improvement in dairy cattle, with sperm quality serving as a key factor. Bull semen&rsquo;s superior qualities are essential for accelerating genetic improvement through AI. These characteristics are affected by several factors, including the environment, management techniques, physiological condition and hereditary factors. This study involved in evaluating genetic and non-genetic factors influencing seminal attributes. 
 
Methods:&nbsp;Data on 1,85,413 ejaculates from nine genetic groups viz. Jersey, Holstein Friesian, crossbred Jersey, crossbred Holstein Friesian, Bargur, Kangayam, Pulikulam, Umblachery and Red Sindhi were collected from four frozen semen stations of Tamil Nadu State. Semen production data viz. ejaculate volume (mL), spermatozoa concentration (million per mL), initial motility (percentage), post-thaw motility (percentage), total initial motile spermatozoa and total post-thaw motile spermatozoa were also examined for various genetic and non-genetic factors affecting them using linear mixed model with repeated measures. 
 
Result:&nbsp;The overall estimated marginal means for Volume of ejaculate, Concentration of spermatozoa, Initial motility, Total initial motile spermatozoa per ejaculate, Total doses per ejaculate, Post-thaw motility and Total post-thaw motile spermatozoa per ejaculate were 3.11 &plusmn; 0.11 (mL), 963 &plusmn; 30.60 (106/mL), 79.50 &plusmn; 1.29 (per cent), 1847 &plusmn; 118 (106), 151.00 &plusmn; 7.20, 51.00 &plusmn; 0.42 (per cent) and 1535 &plusmn; 80.20 (106) respectively.The effect of all genetic and non-genetic factors (farms, ejaculates, period, seasons, age) were observed to be significantly influencing the seminal traits considered in the study. However, the estimated marginal means of each trait displayed varied ranges of mean against non-genetic factors.

Detection of A1 and A2 Alleles at Beta-casein Locus in Bargur and Umblachery (Indian Zebu) Cattle Breeds by Allele-specific PCR

Genetic and Non-genetic Factors Influencing Semen Production Traits in Dairy Bulls