effects of elevated moisture content of total mixed ration on nutrient digestibility, rumen fermentation, microbial enzyme activity and growth performance in fattening lambs

The objective of the current study was to determine the effects of increased water content in the total mixed ration (tmr) on feed intake, apparent nutrient digestibility, rumen fermentation parameters, microbial enzyme activity, blood metabolites, performance and feeding behavior in fattening lambs. twenty-eight fat-tailed lori-bakhtiari male lambs [120±6.5 d of age; 33.4±2.24 kg body weight (bw)] were randomly assigned to four experimental diets containing 10% [control], 20%, 30% and 40% moisture content. increased moisture content of tmr up to 30%, increased the intake of dry matter (dm), organic matter (om), crude protein (cp), neutral detergent fiber (ndf) and non-fiber carbohydrates, total weight gain and average daily gain [linearly (l), p<0.05] while acid detergent fiber (adf) intake, final bw and feed conversion ratio remained consistent across the experimental diets (p>0.05). increasing the moisture content of tmr up to 30% linearly increased the digestibility of dm, om and cp and increased ruminal nh­­3-n, total volatile fatty acid content, molar proportion of propionate and activities of cmcase and ɑ-amylase (l, p<0.05) while ndf and adf digestibility, individual vfa contents and selected blood metabolites were unchanged (p>0.05). feeding-related behaviors were unaffected, but rumination and chewing times increased linearly (l, p<0.05). overall, increasing the water content of the tmr diet by adding water increased the feed intake and digestibility and improved the ruminal condition and growth performance in finishing lambs.