PSII-21 - Effects of barley starch proportion in diets on nutrient digestion, rumen fermentation parameters and rumen microorganisms of fattening Hu sheep

The purpose of this experiment was to study the effects of fattening Hu sheep diet with barley starch instead of corn starch in different proportions on the production performance, nutrient digestion, rumen fermentation parameters and rumen microbial of fattening Hu sheep. In this experiment, 72 Hu lambs (average BW:29.70 ± 1.70 kg) were selected and randomly divided into 4 treatments according to single factor block experiment. Each treatment included 18 replicates(n=18) and each sheep was raised in individual pen. Barely starch (BS) and corn starch (CS) were the starch source of the diets. Four treatments are BS-0 group(0%BS+100%CS), BS-33 group(33%BS+66%CS), BS-66 group(66%BS+33%CS), BS-100 group(100%BS+0%CS). The experiment lasted for 79 days with 7 days pre-feeding period and 63 days formal period(n=18), the last 6 days and 3 days were assigned to the digestibility(n=6) and sampled(n=10) after slaughter respectively. All date were analyzed using the one-way ANOVE of SPSS 25.0. The results showed that the DM, OM, NDF and ADF digestibility of BS-0 group were higher than BS-100 group (P<0.05). the DM, OM and NDF digestibility of BS-66 group were higher than BS-100 group. Total VFA concentration of BS-66 and BS-100 is significantly higher than BS-33 and BS-0 (P<0.05). the propionate concentration of BS-33 is lower than BS-66 (P<0.05). The ruminal pH and NH3-N concentration of BS-33 are higher than BS-66 (P<0.05).BS-0 group has a higher ACE Chao1 and Shannon index than BS-100. At the phylum level, the abundance of Firmicutes increased and the abundance of Proteobacteria decreased in BS-100(P<0.05). At the genus level, the abundance of Ruminobacter in BS-100 is higher than other groups (P<0.05). These results indicated that the feeding efficiency of corn starch has positive affect than barley starch. 66% barley starch substitutes corn starch can improve nutrient digestibility and be good for rumen health.