R. Bras. Zootec.. 15/Oct/2018;47:e20170093.
Genetic parameters for type score traits and milk production in Brazilian Jersey herds
This study aimed to estimate the heritability coefficients for ten functional type traits and milk production in the Jersey breed in Brazil, besides the genetic and phenotypic correlations between them. The present study utilised data from 1,567 records of linear type traits, including stature (ST), body depth (BD), loin strength (LS), rump width (RW), rump angle (RA), fore udder attachment (FUA), front teat placement (FTP), rear udder height (RUH), central ligament (CL), and final score (FS). Milk yield (MY) adjusted to 305 lactation days was also calculated. Covariance components were estimated by the restricted maximum likelihood approach using the PEST and VCE6 programs on the animal model. Heritability coefficients thus assessed were as follows: 0.22±0.01 (ST), 0.35±0.07 (BD), 0.17±0.01 (RW), 0.55±0.05 (RA), 0.09±0.01 (LS), 0.20±0.02 (FUA), 0.40±0.06 (FTP), 0.40±0.06 (RUH), 0.15±0.02 (CL), 0.21±0.02 (FS), and 0.16±0.02 (MY). Therefore, the higher genetic gain will be obtained for BD, RA, FTP, and RUH, while the other traits would need a medium or long-term period to show improvement. The genetic correlations fell in the range from 0.01 (FTP × FS) to 0.87 (RW × CL), and the only genetic correlation noted between FS and RA was negative (−0.10±0.06). Thus, in the Jersey breed in Brazil, the type traits are genetically associated, and the selection of any one of them may elicit an indirect response in another.