Seasonal Variation of Anestrus Conditions in Buffaloes (Bubalus bubalis) in Southern Nepal

A synonymous single nucleotide polymorphism (g.36417726C > A) in the Lama2 gene influencing fat deposition is associated with post-partum anestrus interval in Murrah buffalo

Postpartum absence of estrus exhibition known as postpartum anestrus interval (PPAI) for more than 90 days after calving is a concerning issue for dairy buffalo farmers' economy. The PPAI duration is influenced by both management practices and animal genetics. Investigating genetic markers associated with PPAI is crucial for incorporating them into marker-assisted selection programs. Towards this goal, our study focused on exploring potential genetic markers from early postpartum adipose tissue gene networks. We successfully identified 24 Single Nucleotide Polymorphisms (SNPs) within 9 candidate genes. In our initial analysis involving 100 buffaloes, we detected a significant association (P = 0.02267) between a specific synonymous SNP within the Lama2 gene (g.36417726C > A) and PPAI. This finding was subsequently validated (P = 0.02937) in a larger cohort of 415 buffaloes, where the SNP explained 1.36 % of the genetic variance. Intriguingly, buffaloes with the CC genotype of this SNP exhibited a PPAI that was 12.71 ± 3.21 days longer compared to buffaloes with AA and CA genotypes. To gain insight into the functional relevance of this SNP, a computational analysis was performed which indicated that the C allele of the SNP (g.36417726C > A) increased the stability of LAMA2 mRNA compared to the A allele. This computational prediction was corroborated by observing a significant increase (P = 0.01798) in Lama2 gene expression (greater than 8-fold) and higher fat percentage (P < 0.05) in adipose tissue of CC genotypes (48.78 ± 1.87 %) compared to AA genotypes (33.59 ± 4.5 %). Furthermore, we noted a significant (P < 0.05) upregulation of C/ebpβ, Pparγ, Fasn, C/ebpα, and Pnpla2 genes, along with the downregulation of Bmp2 and Ptch1 in CC genotypes as opposed to AA genotypes. This observation suggests the involvement of the Pparγ-mediated pathway in both adipogenesis and lipolysis within CC genotypes. In summary, our comprehensive analysis involving association and functional validation underscores the potential of the SNP (g.36417726C > A) within the Lama2 gene as a promising genetic marker against extended PPAI in Murrah buffalo.

Reproduction and Fertility of Buffaloes in Nepal

Water buffalo (Bubalus bubalis) in Nepal contributes 57% of the total milk and 36% of the total meat production in the country. The productive efficiency of Nepalese buffaloes is quite low, due mainly to subfertility and infertility. Delayed puberty and prolonged inter-calving intervals, attributed mainly by anestrus due to silent cyclicity and ovarian acyclicity, are the major forms of infertility in Nepalese buffaloes. Moreover, buffaloes in Nepal show a distinct seasonal breeding pattern, with July to December as the active breeding season, and with April to June and January to March as the low and transitional breeding seasons, respectively. Endoparasitic infection and poor nutritional status, which are more severe during the low season, are found to be the major factors causing anestrus and compromising its treatment response in buffaloes. Various hormonal protocols for timed artificial insemination (TAI) have been attempted, with a varying pregnancy outcome. Recently, an integrated technique including anthelmintic treatment, nutritional supplementation and hormone-based fertility management programs for TAI has been developed and implemented successfully. A wider adoption of this technique as a package of practices could be key to improving the reproductive efficiency of buffaloes in Nepal.

A single nucleotide polymorphism of the thyrotropin releasing hormone degrading ectoenzyme (TRHDE) gene is associated with post-partum anestrus in Murrah buffalo

Thyrotropin releasing hormone degrading enzyme (TRHDE) gene is implicated in Thyrotropin releasing hormone (TRH) mediated prolactin secretion. It has been shown that the prolactin secretion alters the Gonadotropin-releasinghormone(GnRH) mediated estrous cycle. Therefore, TRHDE may also regulate postpartum anestrus. Earlier studies reported the role of non-synonymous single nucleotide polymorphism (SNPs) in various pathophysiological conditions by altering the structure and function of the proteins. Hence, in the present study, we identified SNPs in the putative promoter, first exon, middle exon and 3'-UTR containing the last exon of TRHDE gene and determined their association with postpartum anestrus (PPA) in Murrah buffaloes. We found one non synonymous SNP (G > C at 118095875 bp on chromosome 4) in the first exon of TRHDE and performed its association analysis in a population sample of 50 extreme PPA (residual PPAI: 123.06 ± 12.98 days) and 50 normal (residual PPAI: -80.46 ± 3.19 days) buffaloes. The residual PPAI value was the observed PPAI adjusted for the effect of 38 non-genetic factors. The analysis showed a significant (P < 0.004167) association of this SNP with PPA in buffaloes. Molecular dynamics simulations (MDS) also supported that the C allele altering Glutamine to Histidine at the amino acid 148 of TRHDE could enhance the stability and rigidity of TRHDE protein, which may lower its activity, increase TRH and prolactin, and reduce GnRH in PPA buffaloes. The MDS analysis further strengthens the association of the SNP (G > C) in the TRHDE gene with PPA condition in Murrah buffaloes. However, further investigation is needed to prove the MDS observations.

Effects of treatment for anestrus in water buffaloes with PGF2α and GnRH in comparison with vitamin-mineral supplement, and some factors influencing treatment effects

The effect of treatment for anestrus in buffaloes with a PGF2α or GnRH injection and vitamin-mineral (Vit-M) supplementation for 1 to 2 months and some factors influencing the treatment effect were studied. In anestrus buffaloes with CL, an injection of PGF2α tended to show higher estrus detection and pregnancy rates within 17 days after treatment than Vit-M supplementation (P<0.10). In those with inactive ovaries, effect of GnRH and Vit-M did not differ. Body condition score of the animals before treatment affected pregnancy rate within 17 days after treatment (P<0.05). Pregnancy rate within 4 months after treatment was adversely influenced by low serum concentrations of calcium (P<0.01) and gastrointestinal parasitic infection before treatment (P<0.05).