Effects of Different Water Amount in Total Mixed Ration on Performance, Rumen Hydrolytic Enzymes Activity and Rumen and Blood Metabolites of Fattening Lambs

Over the last half century, the shortage of animal feed in many parts of the world, including Iran, has increased the feed costs of animal husbandry and it also has affected revenues from the production of livestock products. Therefore, any improvement in nutritional management and increasing the feed use efficiency in this sector will increase productivity and production. Adding water to ruminant diets is inexpensive physical processing method that has had a positive effect on efficiency of ruminant production. Traditionally, adding water to total mixed diets has been a useful management practice to reduce feed selection behavior by livestock. It has been shown that adding water to the feed of adult cows (decreasing dietary dry matter (DM) from 81% to 64%) reduced the choice of fine components over long particles and also to reduce the preferential consumption of concentrate components (Leonardi et al., 2005). Recent studies have shown that adding water to the starter diet of suckling calves up to 25% during the winter has improved their growth performance (Beiranvand et al., 2018). These positive responses are probably due to the increased adhesion of feed particles, which has led to a reduction of diet dust, condensation of fine particles and increased palatability and consumption. This experiment was conducted in animal house and laboratories of Lorestan University. Twenty-eight Lori male-fattening lambs with120 ± 6 days old and 33.4 ± 3.4 kg of live weight were used in completely randomized design experiment with 4 treatments and 7 lambs per treatment. Dietary treatments in which water was used at levels 10 (control), 20, 30 and 40 % were fed to the lambs for 56 days. Blood and ruminal samples were taken from all of lambs at day 45 and 50 respectively 3 h after morning feeding. A completely randomised design was used to determine the effect of different levels of water on the measured traits. All data were analyzed using the GLM procedure in SAS. Linear (L) and quadratic (Q) contrast statements were included in the model to test the effect of increasing amounts of water. Differences among means were tested using Duncan method. Results showed that increasing the level of dietary moisture up to 30% linearly increased (P<0.05) ruminal ammonia-N, propionate and total VFA concentration, while pH and concentration of other individual VFAs were unchanged among dietary treatments (P>0.05). Increasing the level of dietary moisture up to 30% linearly increased (P<0.05) activity of carboxymethyl cellulase and ɑ-amylase, while activity of microcrystalline cellulase and filter paper degrading activity and blood metabolites (including glucose, total protein and blood urea nitrogen) were similar among treatments (P>0.05). Intake of dry matter (DM) and average daily gain increased linealrly (P<0.05) with elevating dietary water level up to 30%, while NDF and ADF intake and final body weight and feed conversion ratio was unchanged by the level of dietary moisture (P>0.05). Results of present study showed that adding water to the total mixed ration of fattening lambs up to 30% improved ruminal parameters, feed intake and growth performance.