Effect of water temperature on rumen temperature, digestion and rumen fermentation in sheep.

Three studies were conducted to examine effect of water temperature on rumen temperature, digestion and fermentation in sheep. Four, 2-yr-old wethers were used in a Latin square design among four water temperature treatments: 0, 10, 20 and 30 C. Rumen temperature was depressed most by 0 C water followed by 10 C, 20 C and 30 C water. For 0, 10, 20 and 30 C water, respectively, 108, 96, 96 and 72 min were needed to reach initial rumen temperature. Water temperature had no significant effect on N balance or percentage dry matter digestibility, crude protein digestibility and crude fiber digestibility although lowest digestion coefficients were observed for the 0 C treatment. Numerical differences were observed in rumen pH or volatile fatty acid (VFA) and ammonia-N concentrations at the various water temperatures; however, the effects were not significant. Rumen pH was maximally depressed at 2 h postfeeding for 0 C water, 3 h for 10 C water, 4 h for 20 C water, and 3 and 4 h for 30 C water. By 4 h postfeeding, the 0 C water treatment produced the highest concentration of all VFA and ammonia-N; however, by 4 h not all of the VFA or ammonia-N concentrations had reached maxima for 10, 20 or 30 C water treatments. The 0 C water treatment produced the lowest concentrations of ammonia-N and VFA (except acetate) by 5 h postfeeding.