Vyhodnocení produkce mléčného tuku a bílkovin inbredních a outbredních holštýnských krav

Abstract

The aim of this study was to explore the depression effects of level of inbreeding on kg of fat and protein presented in the form of breeding values. The data included cows calved in the years 1990–2006 at farms in the Czech Republic. Inbred cows were grouped according to Fxcoefficients (Fx= 1.25%, Fx= 2.0–3.125%, Fx= 4.0–12.5% and Fx= total). The breeding values for inbred cows were compared with their outbred equals (2689 equals in sum) – half–sisters, sharing the same sire, dam reaching the same breeding value (± 5%) and their first calving occurring at the same farm, at the same time (±2 month). The PROC GLM of SAS®with fixed effects (age at first calving, year of calving, number of lactations, first calving interval and relative breeding value of sire and dam were applied to all data).In the groups with Fxcoefficients (Fx= 1.25 %, Fx= 2.0–3.125 %, Fx= 4.0–12.5 % and Fx= total) we found a decrease in the breeding values of kg fat in inbred cows of −1.48; 0.17; −8.26 and −0.51 kg. In the case of protein content the depressed production in inbred cows was: −0.58; −0.48; −3.21 and −0.94 kg. These differences were significant (p ≤ 0.01) in the group with the highest Fxvalue (Fx= 4.0–12.5%). The inbred animals showed higher variability within the range of observed corrected breeding values (Yijklmno) for kg of fat and protein.The results also show that increasing the level of parents (as RBV) caused a very significant increase in production both in inbred and outbred daughters but greater increase in fat and protein was evident in the non–inbred cows.