ANIMAL SCIENCE·VETERINARY SCIENCE
WEN YuanYuan, LI Yan, LI JianGuo, WANG MeiMei, YU ChangHui, SHEN YiZhao, GAO YanXia, LI QiuFeng, CAO YuFeng
【Objective】The purpose of this experiment was to explore the effects of different proportions of mixed silage of raw potato chips processing by product with rice straw (hereinafter referred to as “mixed storage”) instead of whole plant corn silage (hereinafter referred to as “silage”) on fattening performance, nutrient apparent digestibility, rumen fermentation parameters, blood biochemical indexes and economic benefits of Holstein bulls, so as to provide a theoretical basis for the use of potato processing by-products in cattle production.【Method】Sixty healthy Holstein bulls with similar body weight ((461.33 ± 33.47) kg) were randomly divided into four groups with 15 replicates in each group and one bull per replicate, including T20 group (concentrate + 20% mixed silage + 80% silage), T40 group (concentrate + 40% mixed silage + 60% silage), T60 group (concentrate + 60% mixed silage + 40% silage), and T80 group (concentrate + 80% mixed silage + 20% silage). The ratio of concentrate to roughage and the composition of concentrate were the same in the experimental group. Adaptation and experimental periods lasted for 10 and 150 d, respectively.【Result】(1) there was no significant difference in average daily gain (ADG) of Holstein bulls with different proportions of mixed silage instead of whole plant maize silage (P>0.05). The dry matter intake (DMI) of T20 group was 4.30% higher than that of T40 group (P<0.01), 5.24% higher than that of T60 group (P<0.01), and 6.01% higher than that of T80 group (P<0.01). The feed gain ratio (F/G) of T40 group was the lowest, which was 4.08% (P<0.01), 3.14% (P<0.05), and 5.60% (P<0.01) lower than that of T20, T60, and T80 groups, respectively. (2) Compared with T80 group, the apparent digestibility of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF) and ether extract (EE) of the first three groups were significantly increased (P<0.05). The apparent digestibility of crude protein (CP) of T20 group was significantly higher than that of T60 and T80 groups (P<0.05), but there was no significant difference between T20 group and T40 group (P>0.05). (3) The rumen pH, propionic acid and butyric acid contents were not affected by increasing the proportion of mixed storage (P>0.05). However, the concentrations of ammonia nitrogen (NH3-N) and total volatile fatty acids (TVFA) of T60 and T80 groups were significantly lower than those of T20 group (P<0.05), and the content of acetic acid was significantly higher than that of T20 group (P<0.01). The ratio of acetic acid to propionic acid of T80 group was significantly higher than that of T20 and T40 groups (P<0.05). (4) Albumin (ALB) content of T20 group was significantly higher than that of T60 and T80 groups (P<0.05). Urea nitrogen (UN) concentration of T80 group was significantly increased (P<0.01), 29.05%, 20.96% and 11.31% higher than that of T20, T40 and T60 groups, respectively. Glucose (Glu) concentration of T20 group was significantly higher than that of T60 and T80 groups (P<0.01), and there was no significant difference between T20 group and T40 group (P>0.05). (5) The economic benefit of T40 group was the highest (17.96 yuan·head-1·d-1), followed by T20 (16.91 yuan·head-1·d-1), T60 (16.79 yuan·head-1·d-1) and T80 (15.91 yuan·head-1·d-1).【Conclusion】In conclusion, with the increase of the proportion of mixed silage instead of silage, the digestibility of nutrients, rumen fermentation and blood biochemical indexes would be affected to some extent. When replacing 40% whole plant maize silage, the production performance was the best and the economic benefit was the highest.