Predict of productional and physiological performance of Friesian cows by calculating Heat Tolerance Coefficient

Abstract

This research was conducted in Ishaqi Cattle Station north of Baghdad, and use of 36 Friesian cows in the beginning of the lactation for the period, 2010. the aim of this research to study the predicted production and physiology performance of Friesian cows for the heat tolerance coefficient (HTC). Negative and highly significant regression of daily and total (monthly) milk production on HTC, while the speed of access to the peak lactation on HTC was positive and significant, the regression coefficient of this relationship was 21.56 day, while the regression coefficient of the length of peak had negative and highly significantly (-44.99 day). This investigated should be significant negative regression of protein , fat and lactose of milk on HTC were -0.85, - 1.11 and – 0.42 % respectively. Positive and significant (P<0.01) regression coefficient of days open and services per conception on HTC. Negative & highly significant of packed cell volume (PCV) , red blood cell (RBC) and Hemoglobin on HTC . Highly significant and negative regression coefficient of glucose , total protein and albumin on HTC, while the regression coefficient of AST , ALT and cholesterol had positive and highly significant. Negative and significant (P<0.01) regression coefficient of T3 and T4 hormones on HTC were – 1.40 and 2.95 n.mol/L respectively .