Effects of different proportion of buckwheat straw and corn straw on performance, rumen fermentation and rumen microbiota composition of fattening lambs

摘要

This experiment was conducted to investigate growth performance, nutrient digestibility, rumen fermentation, and microbiota composition when different proportions of buckwheat straw (BS) and corn straw (CS) were included in the diet of male lambs. A total of sixty 1/2 Dorper x 1/2 Small Thin-Tailed male lambs (150 d of age; 25 +/- 1 kg of BW; mean +/- SD) were selected and divided into five groups, and were allocated to 1 of 5 treatment diets randomly. Diets were formulated containing different levels of BS: 1) 0% of BS (control diet, C); 2) 13.7% BS (14BS); 3) 27.5% BS (28BS); 4) 41.2% BS (41BS); and 5) 55.0% BS (55BS). Diets were iso-nitrogenous, with a forage-to-concentrate ratio of 55:45 (air-dry basis). For dry matter intake and average daily gain, quadratic (P < 0.01) effects were observed among treatments. Therefore, response to inclusion level of BS was quadratic (P < 0.01) for the feed efficiency with the greatest value at intermediate BS levels. The concentrations of rumen total volatile fatty acids, ammoniacal nitrogen, and microbial protein responded quadratically (P < 0.05) across BS levels, with the greatest total VFA, ammoniacal nitrogen, and microbial protein production for 28BS. For the carbohydrate hydrolytic enzyme activities, BS displayed quadratic response, with the highest values at 28BS diet. Moreover, feeding BS at increasing inclusion levels resulted in a linear decrease in bacterial diversity. The relative abundance of Prevotella, Butyrivibrio, Coprococcus, Ruminococcus were linearly (P < 0.05) decreased, and some pernicious bacteria like Sutterella, Helicobacter, Akkermansia were increased linearly (P < 0.05). Thus, it appears that BS can be used as a forage resource for sheep and the optimal proportion in diet was 28% under the test condition.