Association of polymorphism harbored by tumor necrosis factor alpha gene and sex of calf with lactation performance in cattle

Bias of Calf Sex on Milk Yield and Fat Yield in Holstein Crossbreed Cows

Simple Summary

Cattle comprise a species of a domestic animal that is primarily bred for milk production. The birth of a calf is the initiator for the lactation period and the sex of the calf can affect milk yield. Additionally, a calf from a new pregnancy can affect the lactation from the previous calving, since the mother gets pregnant and remains pregnant during most of the lactation, usually at lactation peak. Therefore, the aim of this paper was to further investigate the possibilities of sexually biased milk production of Holstein and Holstein crossbreed cows using data from the Republic of Serbia. We also wanted to test the Trivers–Willard (TW) hypothesis that natural selection favors unequal parental investment between daughters and sons under certain maternal conditions. At the same time, this hypothesis assumes that mothers in good health and condition invest more in sons, while mothers in a poor condition invest more in daughters. The obtained results deviate from the view of the TW hypothesis because it was found that milk and fat yields in the first two lactations were the highest in cows that had a female calf and were then pregnant with a second female calf while the lactation from the previous calving was still in progress. We were the first in the world to investigate the effect of the sex of calves at first and second calving on milk yield and fat yield in the first and second standard lactation, depending on milk production levels on farms.

Abstract

In order to examine the biased milk production depending on the sex of calves, data on calving and milk yield characteristics of 15,181 Holstein type cows in PK Belgrade, Serbia were analyzed. A total of 30,362 lactations that were realized in the period from 1985 to 2017 were analyzed. Data were prepared and analyzed using the SAS software package (SAS Institute Inc. Software License 9.3, 2012). The expression and variability of investigated traits were determined using the PROC MEANS procedure, while the effect of individual factors on milk yield traits was analyzed using the PROC GLM procedure. Obtained results deviate from the views of the Trivers–Willard (TW) hypothesis. The results indicate that mothers invest more in female offspring by producing a higher milk and fat yield in the first and second lactation compared to male offspring. This is especially emphasized under better environmental conditions. The highest milk yield (7788 kg) and fat yield (271 kg) in the second lactation were achieved in the combination with two consecutive female calves in the group of higher-than-average milk production farms, and lowest in the combination of two consecutive male calves (6783 kg for the MY and 243 kg for the FY), respectively.

Promoter variants of OAS1 gene are associated with reproductive performance and incidence of normal calving in cattle

2',5'-oligoadenylate synthetase (OAS) are important components of an interferon-mediated antiviral pathway. But no polymorphisms have yet been identified and associated with reproduction and reproduction traits in the bovine OAS1 gene. The objective of this study was to detect and evaluate the effects of mutations in the promoter region of bovine OAS1 gene with production and reproduction traits in cattle. Two single nuclear polymorphisms were identified, including A to T transversion (rs715937117:A>T) and A to G transition (rs480985443:A>G) and subsequently genotyped in Sahiwal and Frieswal populations. Three haplotypes were constructed including H1 (A-A), H2 (T-A) and H3 (T-G), among them H2 was the most abundant in the Sahiwal (0.677) and Frieswal (0.838) population. The analysis revealed that genotypes of promoter region had significant effect (P ≤ 0.05) on age at first breeding, age at first calving, service period and pregnancy rate. The animals with H1H2 diplotype had higher age at first breeding and age at first calving compared to H2H2 genotyped animals. Further logistic regression analysis also revealed that the probability of normal calving was found more in H2H2 diplotype, as the odds ratios of H1H2 and H2H3 in comparison to H2H2 were 0.516 and 0.486, respectively. H2H2 diplotyped animals also exhibited higher milk production also in terms of total milk yield, 300 day milk yield and peak yield. These results outlined that the bovine OAS1 gene can be used as candidate genes for simultaneous improvement of both production and reproductive performance of cattle.

Association analysis of novel polymorphisms in 2', 5'-oligoadenylate synthetase gene with reproductive traits in indigenous and cross-bred cattle of Indian Origin

2', 5'-Oligoadenylate synthetases (OAS) are important components of an interferon-mediated antiviral pathway. No polymorphisms in exonic regions of bovine OAS1 gene have been identified and associated with reproduction traits. The objective of the study was to detect and evaluate the effects of mutations in exonic region of bovine OAS1 gene with reproduction traits in cattle. DNA samples collected from 250 individual cows of two Indian dairy breeds (Sahiwal and Frieswal) of cattle were used in the study. The genetic variants of the OAS1 gene were identified with polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and sequence analysis using seven set of primer pairs. The PCR-SSCP analysis revealed polymorphism in the fragments comprising of exon 2, exon 5 and first fragment of exon 6 while the fragments of exons 1, 3, 4 and second fragment of exon 6 were monomorphic in Sahiwal and Frieswal cattle. The mutations in the amplified region comprising of exon 2 were found to have significant association with age at first breeding and calving, service period, dry period and pregnancy rate. Significant associations were found between SNPs in the exon 5 and service and dry periods of the animal, whereas the genetic variants in the first fragment of the exon 6 showed significant association with age at first breeding and calving. To our knowledge, this study demonstrated for the first time that the polymorphisms in OAS1 gene were associated with reproductive traits and it can be chosen as a candidate gene for improvement of reproductive performance of cattle.