| This research investigated suitable roughage and MG level for fattening 4 to 6 months lambs by combined different kinds of roughages with different metabolizable glucose content.Trial 1, the value of POEG, BSEG and MG of corn gluten meal, extruded soybean, soybean straw, bagasse and peanut straw were evaluated by in vitro rumen fermentation, in vitro small intestine and nylon bag technique. The results:1) The POEG values of 5 feedstuffs:corn gluten meal was 139.96 g/kg, extruded soybean was 93.28 g/kg, bagasse was 27 g/kg, soybean straw was 37.76 g/kg, and peanut straw was 47 g/kg.2) Rumen dry matter degradation of corn gluten meal was 37% and starch rumen degradation rate was 13%; Rumen dry matter degradation of extruded soybean was 58% and starch rumen degradation rate was 30%.3) BSEG values of corn gluten meal and extruded soybean were 10.04 g/kg and 6.72 g/kg, respectively.4) Metabolizable glucose value of five feeds:corn gluten meal was 150.00 g/kg, extruded soybean was 100.00 g/kg, bagasse was 27.00 g/kg, soybean straw was 37.76 g/kg and peanut straw was 47 g/kg.Trail 2, the experiment was aimed to investigate the sheep rumen fermentation parameters (pH, ammonia nitrogen, microbial protein and volatile fatty acids) and gas production parameters、 digestion kinetic parameters under the different levels of MG through rumen fermentation in vitro. The results:1) after 8 h cultured, pH decreased significantly with the MG content increasing; Bacterial proteins at 6 h, total microbial proteins and protozoa proteins at 8 h, enhanced significantly with the increasing of MG content. With the improvement of MG content, the production of propionic acid, butyric acid and total volatile fatty acids increased significantly; while the acetate/propionate decreased significantly.2) With the improvement of MG content, the anticipated maximum gas production and the time of reach half of the maximum gas production reduced significantly; In (?)rskov digestion kinetics model, the potential gas production has no significant difference. The 24 hours gas production with the enhancing of MG content were decreased significantly. And the rate of gas production was the opposite. The results showed that,the yields of propionic acid and total volatile fatty acids were significantly improved with the increasing of MG content. Improving the MG content could provide more sugar precursors for the sheep.Trail 3, the experiment was aimed to investigate the effect of different MG and roughages on the rumen fermentation, digestion, serum biochemical indexes and growth performance of lambs.48 experimental lambs,21.02 kg average body weight, were randomly divided into 6 groups,8 lambs for each group, and each ear mark was recorded. Diet composition and the nutrient levels were decided on the basis of the NRC (2007) in which the ME was 10.45 MJ/kg and CP content was 99 g/kg. Feeding was restricted as 90% of ad libitum intake (3.6% of body weight). Experiment was combined with two kinds of MG and three roughages. The results:The results were listed as follows:1) Average daily gain and feed conversion ratio were significant effected by both different roughages and MG. And there was significant interaction between roughages and MG. Average daily gain were highest at the 164.05 g/kg MG, at the same time, feed conversion ratio was lowest of 6.36.2) Digestibility of dry matter of soybean straw was significantly higher than the other two groups. Digestibility of NDF of bagasse was the lowest. There was no significant difference in digestibility of CP, ADF, and starch among 6 groups. The extraction of urea nitrogen was higher in the group of lower MG, and there was significant interaction between roughages and MG.3) The principal component analysis found that the first four VIP were GOT> GGT> GPT and UA. Correlation analysis found that there were greater correlations between daily gain and LDH, GGT, GOT and UA.4) There were positive correlations among the quantity of Ruminobacter amylophilus, total volatility fatty acids, propionic acid, acetic acid, butyric acid, lactic acid, P/(A+2B) and a-amylase activity, but exist negative correlations with NH3-N, xylanase activity and pH.5) There were positive correlations among the quantity of Butyrivibrio fibrisolvens and lactic acid and P/(A+2B), but there were existed negative correlations butyric acid, cellulase activity and lipase activity. Different roughages would significant affect the quantity of Ruminobacter amylophilus and Butyrivibrio fibrisolvens, while Anaerovibrio lipolytica was significantly effected by MG (P=0.012).6) Different roughages had significant effect on the activity of amylase, xylanase, lipase and cellulose. Both different roughages and the time after feeding had significantly effect on pH, NH3-N and every organic acid. The highest propionic acid was appeared in group 153.34 g/kg (9 hours after feeding) and group 164.05 g/kg (24 hours after feeding), the lowest Propionic acid was appeared in group 109.92 g/kg.Combined the results of animal experiment and fitting model, we could conclude that combined a suitable roughage with metabolizable glucose would enhance the average daily gain and the utilization of protein in Hu sheep, and the average daily gain would be the highest when the MG/NDF=0.50. |
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