Identification of Polymorphism within Exon 8 of Bovine HSP90AA1 Gene using PCR-SSCP Technique

Heat shock proteins (HSPs) are a type of molecular chaperones that aid in the recovery of stressed cells and serve as a major system for intracellular self-defense. A study was conducted during the year 2018–19 at College of Veterinary Science Rajendranagar, Hyderabad, Telengana State, India to find polymorphisms in exon 8 of the bovine HSP90AA1 gene in Sahiwal (n=50) and crossbred (n=50) cows. Blood samples were collected from the experimental animals and genomic DNA was isolated. Physiological parameters like body temperature and respiration rate for each animal were taken during the experimental period and the heat tolerance coefficient was calculated. The data on production and reproduction traits were obtained from the history sheets of the animals. To detect the polymorphism, a 539 bp fragment of the HSP90AA1 gene covering exon 8 was subjected to the Polymerase Chain Reaction-Single-Strand Conformation Polymorphism (PCR-SSCP) technique.The PCR-SSCP of exon 8 of HSP90AA1 gene yielded two genotypic patterns AA and AB corresponding to two allelic variants with frequencies of 0.85, 0.15, 0.81 and 0.19 in Sahiwal and crossbred cows, respectively. The PCR-SSCP patterns obtained were correlated with the physiological, productive, and reproductive traits in both Sahiwal and crossbred cows. The association analysis of SSCP patterns of the exon 8 of HSP90AA1 gene revealed non-significant effect in Sahiwal cows, although the AB genotype had a significantly longer service period in crossbred cows.

​Genetic Polymorphism within Exon 3 of HSP90AA1 Gene and its Association Studies in Sahiwal and Crossbred Cows

Background: Heat shock proteins (HSPs) are molecular chaperones that play a critical role in recovering cells from stress and form a primary system for intra cellular self defense. They are highly conserved and play a crucial role in cellular thermo tolerance and heat stress response. Though there are many HSP genes, thermo tolerance is mainly correlated with HSP70 and HSP90 genes in Livestock species. Polymorphisms in these genes have shown an association with heat tolerance, milk production, fertility and disease susceptibility in livestock. They can be used as genetic markers for the selection of animals with better climate resilience, immune response and superior performance. Methods: The present study was carried out in Sahiwal (n=50) and Crossbred cows (n=50) with the objective to identify polymorphisms in HSP90AA1 gene. A 450 bp fragment of bovine HSP90AA1 gene covering exon3 was subjected to Polymerase Chain Reaction-Single-Strand Conformation Polymorphism (PCR-SSCP) technique to identify the polymorphism. PCR-SSCP patterns were correlated with the physiological, productive and reproductive traits in Sahiwal and crossbred cows using the univariate GLM model of SPSS 25. Result: The PCR-SSCP of exon 3 of HSP90AA1 gene yielded two conformational patterns AA and AB corresponding to two allelic variants A and B in both Sahiwal and crossbred cows. The allele frequencies of A and B were 0.78 and 0.22 and 0.84 and 0.16 in Sahiwal and crossbred cows, respectively. The association analysis of SSCP patterns revealed that genotype AA had higher lactation length in Sahiwal cows and higher total lactation milk yield and peak yield in crossbred cows.

Reproductive Performance and Culling Rate of Purebred Holstein Cows and Their Crosses With Fleckvieh and Brown Swiss Cows Under Subtropical Conditions

This study aimed to elucidate the reproductive performance of purebred Holstein (HO) cows with their crosses with Fleckvieh (FV) and Brown Swiss (BS) cows under subtropical conditions. A total of 677 cows [487 HO, 104 HO × FV (HFV); 50% FV and 50% HO and 86 HO × BS (HB); 50% BS and 50% HO] were enrolled in this study. Pure HO cows had significantly greater service per conception (S/C; 3.69), days open (147.9 days), and calving interval (449.6 days), than the HFV (2.89, 116.7, and 407.4 days, respectively) and HB (3.07, 134.3, and 434.2 days, respectively) crossbred cows. At day 28, the conception percentage was significantly greater among HFV crossbred cows vs. pure HO cows [crude odds ratios (COR) = 2.16], but embryonic loss, abortion percentage, calving difficulty, and retained placenta percentage were similar (p > 0.05) among pure HO cows and their crosses. HFV crossbreds had significantly lower incidence of endometritis (COR = 0.70, p = 0.035), mastitis (COR = 0.69, p = 0.015), and ketosis (COR = 0.53, p = 0.004) vs. other cows. HB and pure HO cows had a similar incidence of mastitis, lameness, and ketosis (COR = 0.76, 0.75, and 0.81; p = 0.223, 0.468, and 0.492, respectively). HFV crossbred cows had a lower risk of culling rate than HB crossbred cows. In summary, HFV cows demonstrated the best reproductive performance in terms of S/C, days open, calving interval, conception at 28 days, mastitis percentage, ketosis percentage, and endometritis.

Breed of origin of alleles and genomic predictions for crossbred dairy cows

Background In dairy cattle, genomic selection has been implemented successfully for purebred populations, but, to date, genomic estimated breeding values (GEBV) for crossbred cows are rarely available, although they are valuable for rotational crossbreeding schemes that are promoted as efficient strategies. An attractive approach to provide GEBV for crossbreds is to use estimated marker effects from the genetic evaluation of purebreds. The effects of each marker allele in crossbreds can depend on the breed of origin of the allele (BOA), thus applying marker effects based on BOA could result in more accurate GEBV than applying only proportional contribution of the purebreds. Application of BOA models in rotational crossbreeding requires methods for detecting BOA, but the existing methods have not been developed for rotational crossbreeding. Therefore, the aims of this study were to develop and test methods for detecting BOA in a rotational crossbreeding system, and to investigate methods for calculating GEBV for crossbred cows using estimated marker effects from purebreds. Results For detecting BOA in crossbred cows from rotational crossbreeding for which pedigree is recorded, we developed the AllOr method based on the comparison of haplotypes in overlapping windows. To calculate the GEBV of crossbred cows, two models were compared: a BOA model where marker effects estimated from purebreds are combined based on the detected BOA; and a breed proportion model where marker effects are combined based on estimated breed proportions. The methods were tested on simulated data that mimic the first four generations of rotational crossbreeding between Holstein, Jersey and Red Dairy Cattle. The AllOr method detected BOA correctly for 99.6% of the marker alleles across the four crossbred generations. The reliability of GEBV was higher with the BOA model than with the breed proportion model for the four generations of crossbreeding, with the largest difference observed in the first generation. Conclusions In rotational crossbreeding for which pedigree is recorded, BOA can be accurately detected using the AllOr method. Combining marker effects estimated from purebreds to predict the breeding value of crossbreds based on BOA is a promising approach to provide GEBV for crossbred dairy cows.

Capa-casein gene polymorphism in cows of different breeds of dairy productivity

Genetic polymorphism of milk proteins, in particular kappa-casein, is of considerable research interest due to its possible associations with economically important traits of dairy cattle. The aim of the study was to determine the polymorphism of the kappa-casein gene and its association with signs of milk productivity in cows of different breeds. Polymorphism of the kappa-casein gene was studied in cows of Ukrainian red-spotted dairy (UCHERM), Ukrainian black-spotted dairy (UCHRM), Montbeliard (M) breeds and crossbred cows obtained by crossing cows of Ukrainian red-spotted dairy breed with Mongolians. DNA studies were performed in the Department of Animal Genetics and Biotechnology of the Institute of Animal Breeding and Genetics nd. a. M.V.Zubets NAAS using the PCR-RFLP method. As a result of research, three genotypes of the kappa-casein gene were identified: AA, AB, BB. Genotypes AA and AB were found in all studied groups of cows, genotype BB was found only in cows of Montbeliard breed with a frequency of 0.366. The highest hopes for 305 days of the first lactation among all studied cows were in crossbred cows with genotype AB (7029 kg), the lowest - in crossbred animals with genotype AA (6359 kg). According to the distribution of genotypes and alleles of the kappa-casein gene, domestic breeds of UCHRM and UCHERM are similar in genetic structure and have a low concentration of B-allelic variant, apparently due to the fact that these breeds were created by reproductive crossing with Holstein breed, in populations of which this allele quite low. The presence of such genotypes in the studied groups of first-borns is determined by the peculiarities of selection work in the herd of SE "DG" Niva "of the Institute of Animal Breeding and Genetics named after MV Tooth of NAAS ». Research results genotypes and alleles of the kappa-casein gene is an additional genetic characteristic of animals, which makes it possible to create herds with the desired characteristics of milk productivity

Genotype Environment Interaction on Milk Production Traits of Crossbred Dairy Cows under Tropical Climatic Condition of India

Background: Genotype environment interaction plays vital role in animal productivity. Heat stress is one of the major environmental stressor affecting milk production and measured in terms of temperature humidity index (THI). Indian milk industry largely depends on crossbred cows bearing different degree of exotic inheritance. Thus, the role of genotype (genetic group) of the crossbred cows and environment (THI) interaction plays vital role in Indian climate which is mostly tropical in nature. Therefore, study was undertaken to examine the existence of genetic group × THI in crossbred dairy cows reared at institute herd of ICAR-National Dairy Research Institute, Eastern Regional Station, Kalyani, West Bengal. Methods: A total of 12364 records each of monthly milk yield (MMY) and average daily milk yield in a month (AMY) of crossbred cows spanned over twenty two years (1994-2015) and weather parameters(temperature and relative humidity) for the corresponding years were collected from institute records. The data were classified into 8 genetic groups according to the genetic composition and 3 THI groups (THI less than 72, THI 72-78 and THI above 78). The interaction model was used to study the G×E interaction study using least squares analysis. Result: Effect of non-genetic factors (parity, period of calving and stage of lactation) was found to be highly significant (P less than 0.01) and genetic group × THI was significant (P less than 0.05) of on both MMY and AMY. Genetic group bearing 50% Jersey and 50% Red Sindhi or Tharparkar were the most heat tolerant breeds. Jersey crossbred cows were more heat tolerant than Holstein crossbred cows. Crossbred cows with 50% Jersey inheritance performed better than higher Jersey inheritance during periods of THI above 72.

Association of SSCP Polymorphisms of HSP70 Gene with Physiological, Production and Reproduction Performance in Sahiwal and Crossbred Cows

Background: Cellular tolerance to heat stress is mediated by heat shock proteins (HSPs). The HSPs act as molecular chaperones and are transcribed in response to stress. Among different families of these proteins, HSP70 is considered to be related to the development of temperature tolerance. Unraveling polymorphism in heat shock protein genes could be a step towards the identification of genetic markers for selecting heat-tolerant cattle. Methods: The present study was carried out in Sahiwal (n=50) and Crossbred cows (n=50) with the objective to identify polymorphisms in HSP70 gene. Two fragments (295 and 220 bp) of HSP70 gene were subjected to Polymerase Chain Reaction-Single-Strand Conformation Polymorphism (PCR-SSCP) technique. Statistical analysis was performed to study the association of each SSCP genotype on physiological, production and reproduction traits in Sahiwal and crossbred cows using the univariate GLM model of SPSS 25. Result: The PCR-SSCP of 295 bp fragment of HSP70 gene revealed two genotypes AA and AB in Sahiwal cows and two genotypes AA and AC in crossbred cows. The association analysis revealed that genotype AA had higher peak milk yield in Sahiwal cows while the same genotype had higher total lactation milk yield, lower service period and calving interval in crossbred cows. The 220 bp fragment was found to be monomorphic in both Sahiwal and crossbred cows.