Effect of climatic conditions on reproductive performance of grazing heifers and lactating cows in the azores, a warm temperate region

The primary aim of this study was to evaluate if climatic conditions affect reproductive performance of heifers and cows in the Azores. Conception data from 234 dairy herds in Azores, involving 12827 artificial inseminations in Holstein-Friesian cowsfrom 1stJanuary to 31stDecember 2008 were recorded. Daily temperature and daily relative humidity data were collected from weather stations placed nearby farms. Maximum temperature and temperature humidity index were observed in August (p<0.05) with averages of 25.5°C and 74, respectively. In the same month, the maximum relative humidity was 93.3%. Reproductive performances of cows tend to be lower in the hot periods. For lactating cows, there was a clear environment effect (p<0.05), as in August the temperature humidity index was the maximum (74), with the lowest conception rate of 45.7%observed. No relationship was found between heifer's fertility and temperature humidity index.In conclusion, HS affects CR in lactating cows but not heifersin this region.