Performance of heat stressed dairy cows in response to Saccharomyces cervicae and Mannanoligosaccharids feed additives under Egyptian conditions

摘要

In Egypt, the increase of temperature- humidity index (THI) above the ambient level was associated with heat stress (HS) during at least 4 to 6 months each year. The HS condition influencing not only the physiological functions of dairy cows but alsoit is affecting the efficacy and profitability of dairy enterprises. Many researches investigated different strategies to reduce HS for dairy cattle including dietary modifications in regard to the hot environment. However, the problems concerning with the decrease of dairy cattle performance especially milk yield and fertility are still exist in many hot regions such as Egypt. An experiment was conducted aiming at alleviating the negative effects of HS on productive and reproductive performances of multiparous Holstein dairy cows (transition to early lactation periods) during hot Egyptian summer season using different sources of Direct Fed Microbial (DFM) feed additives .