Revista Colombiana de Ciencias Pecuarias
Print version ISSN 0120-0690
ZAMBRANO BURBANO, Gema L; ERASO CABRERA, Yohana M; SOLARTE PORTILLA, Carlos E and ROSERO GALINDO, Carol Y. Kappa casein genotypes and curd yield in Holstein cows. Rev Colom Cienc Pecua [online]. 2010, vol.23, n.4, pp. 422-428. ISSN 0120-0690.
The objective of this study was to relate kappa casein (CSN3) genotypes with curd yield (RC) and total milk protein (PTP) in Holstein cows located in the high tropics in Narino, Colombia. Twenty seven animals were used to establish the mentioned relationships. The genotype of each animal was determined by PCR - SSCP. Variables were analyzed using a linear model which included the fix effects of genotype, lactation stage, and their interaction. Age of the cow and fat percentage in milk were used as covariates. The results for RC indicate no interaction between genotype and lactation stage. Age was not statistically significant (p>0.05), while fat percent and genotype were significant (p<0.05). The Tukey - Kramer test indicated differences between the BB genotype, compared to homozygous AA and heterozygous AB. The BB genotype resulted in the best performance, requiring the least amount of milk to produce one kg of curd. As for protein content, differences were significant (p<0.05) for the effect of genotype and lactation stage: the homozygous BB had the highest percentage of milk protein during the final (third) stage of lactation.
Keywords : lactation stage; milk fat; milk processing; PCR-SSC.