Impact of heat stress on rumen functions

Abstract

The livestock sector is evolving in response to rapidly increasing demand for livestock products. Ruminant population is the main driver of the growth of the livestock sector besides pig and poultry. The rise in environment temperature due to climate change alters the basic physiology of rumen which negatively affects production. Dry matter intake begins to decline in an adaptive response to heat stress. Increased environmental temperature reduces the gut motility, rumination, ruminal contractions and depresses appetite in ruminants. Heat stress reduces the total production of volatile fatty acid (VFA) with individual variation and also results in changes in ruminal pH. Passage rate and retention time of digesta is also influenced by rise in ambient temperature and thus affects digestibility. The change in microbiota due to heat stress may change the fermentation pattern in the rumen resulting in variation in digestibility, VFA production and also methane emission.