Phenotypic and Genetic Correlation of Reproduction Traits in Simmental Cows

Abstract

Many of cows' production traits are, mostly, interrelated so for those kinds of relationship are said it is a correlative relation of traits. The phenotypic correlation between two quantitative traits depict a value to which individuals upwards of the average value for one trait intend to be above, below or close to the average value for another trait. However, phenotypic correlations initiate the question what is the degree of influence of the genetic basis on observing the association between two traits and what is the influence of exogenous factors. Derived data about tested reproduction traits interrelation, at a Simmental cow farm, are very important for a simultaneous selection of cows in many traits. The average service period length of the total investigated population was 147 days, which was about 1.5 fold longer in regard to the upper value of the optimal level. That had a significant influence on duration of the first inter-birth interval which averaged 436.3 days. The average duration of pregnancy was 283.4 days and the age at the first calving 872 days. The defined genetic correlation coefficients between cows' fertility traits, in the herd, exceed analogous phenotypic correlations in all cases. The genetic interrelation of tested fertility traits ranged from powerless to very strong (from 0.209 to 0.941). Phenotypic correlations among reproductive traits ranged from negative (-0.131) to strong (0.888), which was with high statistical significance (P < 0.01).