Effects of Heat Stress on the Main Reproduction Indices in Romanian Spotted Breed Cows

Abstract

The aim of this paper was to assess the effects of environmental temperature on the main reproduction indices in Romanian Spotted dairy cows. The study was carried out on 144 Romanian Spotted multiparous cows kept in loose housing throughout the whole year at S.C.D.C.B. Arad. The following traits were analyzed: the voluntary waiting period (from calving to first A.I.), the number of artificial inseminations (A.I.) for a new gestation and interval between calving and new pregnancy, according to the season. Thus, in the winter season, characterized by cold temperatures, but relatively easy incurred by dairy cows, the voluntary waiting period was 51.74 days, and 71.35 days to the new gestation, requiring a number of 1.97 AIs per pregnancy. In spring season, characterized by temperatures near the thermal comfort for cattle, the voluntary waiting period was 56.78 days, 96.71 days until the new gestation, with 2.02 AIs per pregnancy. In summer season, characterized by high temperatures, above the thermal comfort, time to first service was 68.34 days, requiring 100.76 days for the installation of new gestation and using 2.85 AIs per pregnancy. Autumn, season with temperatures well supported by dairy cows, favoured shorter periods to first service 56.84 days. Therefore, only 63.16 days were required for installation of a new gestation, and 2.44 AIs per pregnancy.

Keywords

• dairy cows
• heat stress
• reproduction indices