engleski

Differences in persistency of heat stress effect in first parity Holsteins due to region of breeding

Aiming determination of the persistency of heat stress effect in first parity Holstein cows regarding the region of breeding test-day records provided by the Croatian Agricultural Agency were analysed. Only cows with detected statistically significant decrease in daily milk yield at set temperature-humidity index (THI) threshold value (65, 70 and 75) were included in the further analyses. The persistency of heat stress effect regarding the daily milk traits was determined as a absolute drop in the subsequent milk recordings (1st and 2nd). The results of this research indicate significant difference in cows’ response to heat stress effect due to region of breeding and animal’s susceptibility to heat stress. The negative effect of heat stress was more pronounced and more persistent in cows bred in Mediterranean and Eastern Croatia. Also, the negative effect of heat stress was more pronounced and more persistent in cows that were more susceptible to heat stress (heat stressed at the lower THI threshold values).

heat stress ; persistency ; first parity Holsteins ; daily milk traits ; region of breeding

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