Effect of macroclimatic factors on milk production and reproductive efficiency of Holstein Friesian × Deoni crossbred cows

This study was undertaken to evaluate the effects of different macro climatic variables on milk production and reproduction efficiency of Holstein Friesian × Deoni crossbred cows. Data of 256 HF × Deoni crossbred cows with 1485 total records of lactation and the meteorological data over a 30-year period (1981 to 2010) were obtained from Marathwada Agricultural University Cattle Cross Breeding Project and the University Meteorological Observatory Weather Station, respectively. The parameters used as indicators of milk production and reproduction performance in this study were lactation milk yield, lactation length, dry period and inter calving period. They were plotted against the monthly climatic variable for regression analysis. It was observed that maximum temperature, maximum humidity, bright sunshine hours and maximum temperature humidity index exhibited negative and significant regression result with lactation milk yield and lactation length. All the considered climatic variables accounted for 28 and 21% direct variation on lactation milk yield and lactation length as verified by the value of coefficients of determination (R2). In contrast, maximum temperature, maximum humidity, wind speed and maximum temperature humidity index showed positive and significant regression on dry period and inter calving period. All the considered climatic variables accounted for 25 and 23% direct variation on dry period and inter calving period, respectively. The summary of the meteorological data confirmed that there were high values of temperature humidity index for considerable months yearly, which suggested that most crossbred cows were exposed to the negative effects of heat stress. Hence, other productive and reproductive strategies like improving environmental, productive and reproductive management of cows are needed to reduce the adverse effect of heat stress.   Key words: Productive and reproductive traits, milk loss, climatic variables, heat stress.