Molecular markers for metabolic adaptation in dairy cows: SNAI2 gene variations

Healthy transition from non-lactating pregnant state to non-pregnant lactating state is an important in the profitability of dairying. Though feeding and managemental practices play an important role in the adaptation to transition, animals kept on similar feeding and management exhibit differences in adaptation indicating an underlying genetic cause. In the present study, the sequence of gene SNAI2, which is considered to have an effect on metabolic adaptability has been compared among animals with apparently varying adaptability, as indicated by their β-hydroxy butyric acid (BHBA) concentration.

During the period from August 2018 to May 2019, blood was collected and serum was separated from 30 pregnant cross bred (belonging to Sunandini genetic group of cross bred cattle of Kerala) dairy cows at fortnightly intervals from four weeks before the predicted day of parturition until four weeks after parturition. Concentration of BHBA was determined. Based on BHBA concentration the animals were sorted into two groups (High BHBA and low BHBA) using cluster analysis. Blood was collected, DNA extracted and SNAI2 gene amplified using custom synthesised primers. Amplicons from representative animals of each group were sequenced. The sequences obtained were aligned and compared using clustal- ω.

The comparison of the sequence of SNAI2 gene amongst the animals having high BHBA and those with low BHBA revealed two variations between the groups, one at promoter region, 61 bp upstream to the gene and other was at exonic region at 1560 bp. In silico structural analysis revealed difference in protein structure. The changes observed in the gene SNAI2 between the sets of animals grouped based on BHBA has to be studied on a larger population to ascertain the suitability of them being used as markers of genetic selection for metabolic adaptability, which in turn can increase the profitability of dairying.