| Based on determining MG values of three diets by in vivo technique, this paper mainly studied on the proper level of Metablizable Glucose (MG) in growing goats of Inner Mongolian cashmere breed . 1 Determination of MG value of three diets1.1 Determination of ME values of the three dietsThe ME values of the three diets were determined by in vitro technique. The result showed they had similar ME value.1.2 Determination of the propionate yield and absorption rate in the rumen of the goats fed the diets by in vivo techniqueNine growing goats of Inner Mongolian Cashmere breed (21-27Kg) fitted with permanent cannulas were used to determine the propionate yields and absorption rates in the rumen of the animals fed the diets by continuously infusing propionate solution technique. The results showed that the propionate yields of three diets were 172.25mmol/d, 193.12mmol/d and 301.39mmol/d, respectively; the corresponding absorption rates of propionate in the rumen were 49.81%,54.86% and 69.03%. The glucose supply originated from propionate were 7.70g/d, 9.54g/d and 18.72g/d. With increasing MG levels of the diets, the yields and the absorption rates of the propionate in the rumen were enhanced.1.3 Determination of the quantities and the digestibility of bypass starch in the small intestine of the growing goats fed the diets.9 growing goats of Inner Mongolian Cashmere breed (21-27Kg) fitted with permanent cannulas in the rumen ,at the proximal duodenum and terminal ileum were used to investigate the quantities and digestibility of bypass starch of the diets in the small intestine. The results indicated that the quantities of bypass starch of the diets were 56.65g/d, 71.93g/d and 91.42g/d, respectively; the digestibility of bypass starch in the small intestine were 51.73%, 61.18% and 63.10%, respectively. The absorbed glucose amounts from the small intestine were respectively 26.38g/d,39.74g/d and 51.92g/d. The quantities and digestibility of bypass starch were improved when the dietary MG level increased.1.4 Determination of MG value of the dietsAccording to the results of Exp.2 and Exp.3, the dietary MG levels were 45.95g/Kg, 67.97g/Kg and 84.30g/Kg and the metabolizable glucose intakes for three groups of experimental goats were respectively 34.08g, 49.28g and 70.64g. The results suggested it is possible to compound a diet using single feedstuff's MG value. However, it must be considered the associative effects in mixed feeds. 2 Evaluation of proper level of MG for growing Goats2.1 Effect of different dietary MG level on digestibility and metabolism in growing goats of Inner Mongolian cashmere breed9 growing goats of Inner Mongolian Cashmere breed were used to investigate the effect of different dietary MG levels on digestibility and metabolism in the animals. The results showed when dietary MG levels increased, total tract digestibilities of DM, OM improved but total digestibilities of NDF, ADF decreased (P > 0.05) . The dietary MG levels had no effects on digestibility N but improved utilization of digestable N and increased nitrogen retention (P > 0.05) .Although gross energy digestibilities were decreased , the ME intakes had no significantly difference among the three groups. The concentrations of serum non- esterifled fatty acids (NEFA) and plasma urea nitrogen (PUN) were reduced (P > 0.05) but the plasma glucose concentration were increased ( P > 0.05) with dietary MG levels increased.2.2 Effects of different dietary MG levels on weight gains in growing goats of Inner Mongolian cashmere breed18 growing goats of Inner Mongolian C ashmere breed, which had similar age and body weights were divided into 3 groups (6 goats in each group) randomly and were given the 3 diets with different MG levels. These goats had 71days feeding time. The results showed daily weight gains significantly enhanced (P < 0.05) and feed conversion rate improved with dietary MG level increased (P > 0.05) .2.3.Effect of different dietary MG levels on body compositions and energy rete... |
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