关键词: 葡萄籽原花青素, 羔羊, 高精料, 瘤胃发酵, 抗氧化

Abstract:

【Objective】This study was conducted to investigate the effects of dietary grape seed proanthocyanidins (GSPs) supplementation on growth performance, rumen fermentation, rumen and serum inflammatory factors and antioxidative activity in lambs under the condition of a high-concentrate diet, so as to provide a support for applying GSPs on ruminant. 【Method】A total of forty-eight 1/2 Dorper × 1/2 thin-tailed Han ram lambs with similar body weight (BW = 22.75±1.20 kg, mean ± SD) were randomly divided into four groups, with twelve lambs each group. Lambs were fed a 30:70 forage:concentrate diet with 0 (control), 10 (10GSPs), 20 (20GSPs), and 40 mg·kg^-1 BW (40GSPs) GSPs supplemented, respectively. The feeding experiment lasted for 60 days before sampling, with the first 15 days for diet transition and adaptation. On the first day of the formal experiment period, the BW before morning feeding was weighed as the initial BW. At the end of the trial period, blood samples were collected from the jugular vein, and the serum was separated for the determination of antioxidant and inflammatory indicators and lipopolysaccharide content. At the same time, six lambs in each group were randomly selected to collect rumen fluid by using an oral stomach tube at 1, 3, 4, 6, 8 and 12 hours after feeding, respectively, and the rumen pH were measured immediately. The fluid samples at 3 hours after feeding were used to measured fermentation parameters and lipopolysaccharide content. The other 6 lambs in each group were slaughtered, and the samples of rumen tissue were collected to determine the antioxidation index and inflammatory factors. 【Result】The final weight of lambs in 10GSPs and 20GSPs groups were significant greater than that in control group (P<0.05), with no difference between 40GSPs and 10GSPs or 20GSPs (P>0.05). Lambs in 10GSPs and 20GSPs groups also had higher average daily gain and average daily feed intake than control and 40GSPs (P<0.05), with no significant difference between control and 40GSPs (P>0.05). The dietary GSPs supplementation had a certain regulatory effect on rumen pH. The rumen pH increased linearly with the supplementation of GSPs (P<0.05) at 3, 8 and 12 h after feeding, and tended to increased linearly at 4 h (P=0.057). The concentrations of acetate, butyrate and total volatile fatty acid in rumen fluid tended to decrease after GSPS was added (P<0.1), but there was no significant effect on propionate, isovalerate, valerate, and the ratio of acetic acid to propionic acid (P>0.05). After GSPs was supplemented, the serum lipopolysaccharide concentration was significantly lower than that of the control group (P<0.05), but which did not affect the lipopolysaccharide concentration in the rumen fluid. The activity of GSH-Px in rumen tissue of 20GSPs and 40GSPs groups was significantly higher than that of the control group and 10GSPs group (P<0.05) , however, the content of MDA was significantly lower. The serum SOD activity of 20GSPs and 40GSPs group was significantly higher than that of the control group, and the GSH-Px activity was higher than control and 10GSPs group (P<0.05). There was no significant effect was observed in rumen inflammatory factors when GSPs was supplemented, but there was a trend of decreasing IL-6 and IL-10 (P<0.1). The level of TNF-α in 20GSPs and 40GSPs group were significantly lower than that in the control group and 10 GSPs group (P<0.05). The level of IL-10 in 40GSPs group was significantly lower than control group, with no significant difference between 40GSPs and 10GSPs or 20GSPs (P>0.05). 【Conclusion】Supplementing appropriate amount of GSPs to high-concentrate diet could improve the rumen pH, and the antioxidant capacity of serum and rumen tissue of lambs, suggesting that appropriate amount of GSPs had the potential protective effect on lamb health. The optimal feeding dose was 20 mg·kg^-1 BW under the condition of this experiment.

Key words: grape seed proanthocyanidins, lambs, high-concentrate diet, rumen fermentation, antioxidant capacity