| Yak, as a rare breed of Tibetan Plateau, is in a natural grazing mode with low production efficiency for a long time, and the research of feed nutrition on yak lags with other animal species. In recent years, in order to break through the research status of nutrition for yak, the mode of housing-feeding attracts wide attention of scholars. However, the first topic faced by researchers is how to take full advantage of the local feed resources, and improve their utilization rate. There is a large of yield for distiller's grains in China, and the fresh distiller's grains commonly used in feeding cattle or cow, but the efficiency is lower. Therefore, it is a hotspot to study and development the fermented distiller's grains by utilizing fermentation process.However, there were no studies reported to applicate the fermented distiller's grains for the diets of yaks and evaluate its application value. In addition, little study on the carbohydrates structure and energy of housing-feeding yaks were reported. In view of this, two experiments were designed in winter and summer to evaluate the application value of fermented distiller's grains supplemented in diets of housing-feeding fishing yaks, and discuss the effects of carbohydrates structure and energy levels on the performance, apparent digestibility of nutrients, ruminal fermentation and carcass quality of housing-feeding fishing yaks and aims to provide the reference for rational utilization of fermented distiller's grains and scientific feeding for yaks. In view of this, two feedlot experiments were designed in the winter and summer based on angle of the type of diet, carbohydrate composition and energy level, and to explore the optimized dietary type, neutral detergent fiber(NDF) and energy level on the condition of housing-feeding. Our experiments were conducted to provide reference for scientific feeding of housing-feeding of yaks.Experiment1: Effects of fermented distiller's grains and neutral detergent fiber on performance, apparent nutrient digestibility, ruminal fermentation and blood metabolites of housing-feeding yaks.A 2×2 factors experimental design was arranged in this experiment, and the 2fators were dietary type and NDF level respectively, and dietary types were with vs.without supplementation of fermented distillers' grains respectively, and almost 40%and 48% NDF levels(DM basis) were set up in the diets, respectively. 32 adult Maiwa male yaks(4 years of age, 206.30±8.59 kg) were selected, and they were divided into 4 treatments(A, B, C and D) according to the randomized block design based on the body weight with 8 replicates of each group, and 1 yak in each replicate. Pre-feeding period was 7 d, and the positive test period was 60 d.The results showed that(1) fermented distillers' grains diet improved the ADG,DMI and increased the apparent digestibilities of GE, ADF and NDF and then increased the ruminal TVFA concentration, cellulase and xylanase activities and GLO,HDL content in serum of yaks compared with the corn soybean meal diet(P<0.05),and there was a trend to improve the slaughter rate and net meat rate(P<0.10);(2)lower NDF level in diets significantly increased ADG, net meat rate and apparent digestibilities of CP, GE, ADF and NDF and then increased the TVFA concentration of yaks and(P<0.05), and there was a trend of increasing DMI and slaughter rate, but decreased ruminal p H, acetate / propionate, cellulase and xylanase activities(P<0.05);(3)interaction of the two fators had no significant effects on the performance,slaughter performance, ruminal fermentation parameters and serum biochemical indexes(P>0.10). Therefore, the diet with fermented distillers' grains supplementation was better than without fermented distillers' grains supplementation; and 40% NDF of diet was better than 48% NDF of diet on the same condition of diets.Experiment 2: The effects of energy level on performance, ruminal fermentation,and carcass quality in housing-feeding yaksSingle factor experiment design was arranged in this experiment, and 60 adult Maiwa male yaks(4 years of age) were selected, and they were divided into 3treatments(LE, ME and HE). The diets contained net energy for gain(NEg) were4.17, 4.48 and 4.79 MJ/kg(DM diet) in the 3 treatments respectively. And there were 20 replicates of each group and 1 yak in each replicate. Pre-feeding period was 7 d,and the positive test period was 90 d.The results showed that(1) the ADG of yaks were 1099.89 and 1019.02 g/d in ME(1099.89 g/d)and HE(1019.02 g/d)groups respectively, and increased 27.26 and17.90% compared with LE(864.31 g/d) group, respectively(P=0.002), and there were the trends of decreasing the F/G value(P=0.073) and increasing the slaughter rate of yaks(P=0.092);(2) ruminal p H of yaks in ME group was higher than the other groups, but that was a trend(P=0.064), and opposite trend appeared in acetate/propionate(P=0.063), in addition, TVFA and acetate concentrations in ME group were significantly higher than those in the others(P<0.05);(3) moreover,increasing dietary energy level had a trend to decrease the relative content of R. albus(P=0.068), but no significant effects on the relative content of R. flavefaciens and F. succinogenes were found( P>0.10);(4) no significant differences were found with p H value, cooking loss, drip loss and nutritional composition of yak muscle among the treatments(P>0.10);(5) the contents of total amino acids and other kinds of amino acids were not significant(P>0.10); the relative contents of UFA, MUFA, and PUFA of yak muscle in ME group were higher than other groups(P<0.05), and the relative contents of 12-methyl-Tetradecanoic acid(C15:1n-3),14-methyl-Pentadecanoic acid(C16:1n-2), and 10-Octadecenoic acid(C18:1n-8) of yaks in ME group were higher than others; but the relative content of Heptadecanoic acid(C17:0) of yaks in HE group was higher than others(P=0.056),even though that was a trend. Therefore, under the condition of this experiment, the best NEg content of diet was 4.48 MJ/kg(DM diet).On the whole, under the condition of this study, the optimized dietary type,neutral detergent fiber(NDF) level of yaks were fermented distillers' grains diet and40% respectively; the optimized NEg level of diet in housing-feeding yaks was 4.48MJ/kg. |
PDF Full Text Request