Evaluation of candidate genotype of leptin gene associated with fertility and production traits in Hardhenu (Bos taurus × Bos indicus) cattle

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.

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.

Study of milk production genes and their association with production traits in Rathi cattle

The study aimed to identify polymorphism of LEP, and STAT5A milk-producing genes and their association with production traits in Rathi cattle. An overall 160 animals were selected from a population of Rathi cattle from Livestock Research Station, Rajasthan University of Veterinary and Animals Sciences, Bikaner (Rajasthan). The phenotypic information on total milk yield, peak yield and lactation length were recorded from the years 2012- 2018. Each animal’s milk sample (100 ml) was analysed for milk composition parameters. Genomic DNA was extracted from the whole blood sample through the spin column method and association analysis was done. The polymorphism have been observed in exon-3 (454 bp) of LEP gene, intron 9-10 (224 bp) and intron-15-exon-16 (379 bp) of STAT5A genes by PCR-SSCP and revealed two types of genotypic pattern. The STAT5A exon-7 (215 bp) also showed polymorphism with three genotypic patterns. The AB pattern of LEP exon-3 and AA pattern of intron 9-10 and intron-15-exon-16 of STAT5A genes showed a significant effect on total milk yield. The BB genotypic pattern of the STAT5A exon-7 gene showed a significant impact on peak yield. The AB pattern of LEP and STAT5A genes were associated with more milk fat % in the studied population of Rathi cattle. All these genes showed a significant effect on total solids. The association analysis of LEP and STAT5A genes with different milk production and milk composition traits illustrated the worth of these genes for marker-assisted selection of dairy cattle. Thus, the present study was designed to unmask the relevant genetic factors responsible for variation in milk performance traits.

Evaluation of candidate genotype of GH gene associated with growth, production and reproduction traits in Dairy Cows

Growth hormone (GH) is a major regulator of postnatal growth and metabolism in mammals and plays a critical role in growth, production and fertility in cattle. The present study was conducted in dairy cattle to find the association of g.48769565 C>T mutation with growth, production and reproduction traits in Sahiwal and Hardhenu cattle. PCR-RFLP was performed to genotype g.48769565 C>T mutation using the MspI restriction enzyme in our resource cattle population. In Hardhenu cattle, the frequencies of C and T alleles were 0.59 and 0.41 respectively while genotypic frequencies were 0.06, 0.36 and 0.58 for CC,CT and TT respectively. The frequencies of the C and T allele were 0.24 and 0.76 respectively in Sahiwal cattle and it was observed that highest frequency was forTT genotype (0.58) and lowest for CC genotype (0.06). Chi-square analysis showed that g.48769565C>T SNP loci did not meet with the Hardy-Weinberg equilibrium (p< 0.01) in Sahiwal cattle. From the least-squares analysis, it was observed that CC genotype was significantly associated with total Milk Yield (TMY), 300 days milk yield (300D MY), lactation length (LL), Dry period (DP) and Artificial insemination (AI)/conception (p<0.05). We also observed a significant association (p<0.05) of genotype CT with 3-month calves body weight. Cows with TT genotype revealed comparatively revealed favourable service period (SP) and calving interval (CI) in both Hardhenu and Sahiwal. These observed differences in their allelic and genotypic frequencies in association with the traitsunderlying production and fertility can be utilized for genetic improvement in dairy cattle.

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.