| The purpose of this experiment was to evaluate the outflow rate of ruminal digesta and the effective degradation in five total mixed rations with different levels of grape seed residue after distillation(GSRD).To investigate the effects of GSRD levels on whole tract digestibility,nitrogen(N)metabolism,and production performance of sheep.Experiment 1: using Folin Ciocalteu reagent colorimetric means to analyze the GSRD of common nutrients and condensed tannins content.Three rumen cannulated Kazakh wethers weighed in average(35.0±3.7 kg)body weight were selected as experimental animals.The test consists of five period,rumen perfusion test were conducted with TMR of different GSRD levels [ 0(TMR 1),4.17 %(TMR 2),8.33 %(TMR 3),12.50 %(TMR 4)and 16.67 %(TMR 5)],respectively.The test was carried out from low to high according to the feeding GSRD levels.Each period of 15 d,consisting of 7 days for adaptation,8 to 12 days for continuous perfusion period,13 to 15 days for sampling period.At the same time,the nylon bag test was carried out on the 13 to 15 days of each period.Ytterbium-acetate(Yb-ac)was used as the marker for digesta.The concentration of Yb element in the chyme was measured and its decay curve was fitted by using NLIN regression to calculate the outflow rate(Kp).The results explained that the GSRD of dry matter,crude protein,crude fat,the neutral detergent fiber,the acid washing lignin fibers,condensed tannins were92.43%?11.91%?6.39%?69.41%?53.39% and1.42%.The Kp value increased with the increase of NDF level in the diets with different level of GSRD,and there was a significant positive correlation between them(r=0.607 0,P<0.05).the Kp value was significantly increased when the added amount exceeded 12.5% of the diet.Experiment 2: Three rumen cannulated Kazakh wethers weighed in average(35.0±3.7 kg)body weight were selected as experimental animals for a nylon bag test to evaluate the effective degradation of dry matter,organic matter and crude protein in five total mixed rations with different levels of GSRD.The results showed that the effective degradation rate of DM,OM and CP decreased significantly with the increase of the level of GSRD(P<0.05),the effective degradation rate of DM in TMR4 and TMR5 group were significantly lower than that of other three groups(P<0.05).The five total mixed rations with different levels of GSRD were the rumen energy and nitrogen negative balance feed type,and the rumen energy nitrogen balance decreased linearly with the increase of the GSRD(P=0.0055).Experiment 3:The trial was designed useing a 5×5 Latin square experiment to investigate the effect of supplementation of five levels of grape seed residue after distillation(GSRD)in rations on rwhole tract digestibility and nitrogen(N)metabolism of sheep.The results showed that dietary intake of N,duodenal flow of total N and also endogenous N at duodenum were not affected by experimental treatments,nitrogen fractions in digesta did altered.Ruminal microbial N decreased(P = 0.0005)linearly,in contrast,ruminal undegradable protein increased linearly(P = 0.0003)in response to the increased addition of GRSD.Although there was no significant difference in fecal N among treatments,nitrogen retention was increased(P =0.0139)linearly owing to remarkable reduction(P =0.0156)of urinary N excretion with increasing level of GSRD.The results indicated that the GSRD has some potential benefits of increasing supply of bypass protein and of improving the utilization efficiency of nitrogen for sheep.Therefore,supplementation of GSRD in fattening sheep feeding is recommended that feeding at a level not exceeding 12.5 % of the diet. |
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