Authors : S.A. Rahmatalla, M. ReiBmann, U. Mueller and G.A. Brockmann
Abstract: The aim of study was to investigate the genetic effects of candidate genes for milk production (Diacylglycerol Acyltransferase 1 (DGAT1), Leptin (LEP), kappa casein (CSN3), Growth Hormone Receptor (GHR), Osteopontin (OPN/SPP1) and ATP Binding Cassette subfamily G member 2 (ABCG2)) in Sudanese dairy cattle breeds. We examined forty Butana and twenty Kenana cows for which milk production data were available from two Sudanese research stations. In the DGAT1 K232A, allele 232 K was most frequent with frequencies of 95.31 and 79.17% in Butana and Kenana breeds, respectively. The DGAT1 K232A genotypes showed significant effects on milk yield (p = 0.0124), fat content (p<0.0001) and protein yield (p = 0.0361). The allele substitution effect of the Alanine variant (232A) was significantly higher milk yield (2.45±0.20 kg, p<0.0001) and protein yield (0.074±0.01 kg, p<0.0001) compared to lysine variant. For the DGAT1 promoter VNTR, three different alleles (3, 4 and 5) were found in Butana cattle and two (3 and 4) in Kenana cattle. Allele 3 was the highest frequent allele of 70.5 and 81.3% in Butana and Kenana breeds, respectively. This allele 3 increased both fat (0.84±0.22%, p = 0.0013) and protein (0.19±0.08%, p = 0.0333) contents. The same trend was observed in Kenana cattle. For the Mbo1-RFLP in the LEP gene, the allele A was almost fixed with frequencies of 97.50 and 97.06% in Butana and Kenana cows, respectively. The AB carriers had higher milk, protein and fat yields when compared with homozygous AA cows in Butana and Kenana cattle. With respect to CSN3, allele A was the major allele with a frequency of 86.25 and 89.29% for Butana and Kenana cows, respectively. The CSN3 polymorphism was not significantly associated with milk yield and composition. No variation was found for the examined SNPs with GHR, OPN and ABCG2 genes. The results of the present study provide evidence that polymorphisms in the DGAT1, Lep and CSN3 genes that segregate in Holstein Friesian dairy cattle also segregate in Butana and Kenana cattle and the direction of effect is the same as in Holstein Friesian cattle. These results provide a potential for genetic selection of animals with a predisposition for high milk yield, fat and protein yield in Sudanese cattle. The improve productivity (milk yield) in Sudanese cattle; selection of the minor allele could be enhanced to increased the milk production for these breeds.
S.A. Rahmatalla, M. ReiBmann, U. Mueller and G.A. Brockmann, 2015. Identification of Genetic Variants Influencing Milk Production Traits in Sudanese Dairy Cattle. Research Journal of Animal Sciences, 9: 12-22.