| In recent years,with the improvement of Chinese residents' consumption level,the consumption of goat milk products is increasing year by year,which promotes the upgrading of China's dairy goat breeding,goat milk processing,feed production and other industries.At the same time,the raising of dairy goats is faced with problems such as extensive feeding management,low feed conversion rate and low production efficiency,which seriously limit the healthy development of dairy goat industry in China.Lack of dietary energy severely limits dairy goat productivity.Starch can effectively increase the dietary energy concentration and is the main energy source of dairy goats.For ruminants,the small intestine has a much higher utilization efficiency of starch energy than the rumen.When the content of starch in ruminant feed was increased,the digestibility of starch in rumen was not significantly changed,but the digestibility of starch in small intestine was significantly decreased.Therefore,improving the ability of small intestine starch elimination is an important way to improve the production efficiency of dairy goats.Studies have shown that the addition of RP-Leu to the diet can effectively promote the synthesis and secretion of pancreatic adenylase in ruminants,and promote the elimination ability of intestinal starch,thus improving the production efficiency of ruminants.In this study,young Guanzhong milk goats were added RP-Leu to compare the difference between RP-Leu and RP-Lys in the utilization of small intestine starch of guanzhong milk goats through growth performance,rumen fermentation parameters,blood metabolism and other indicators,so as to provide a theoretical basis for the application of RP-Leu in ruminant nutrition.Eighteen healthy Guanzhong dairy goats with similar age,weight and feed intake were randomly divided into three groups: the control group(basal diet),the RP-Lys group(basal diet supplemented with rumen-protected lysine,28.94 g/d/goat)and the RP-Leu group(basal diet supplemented with rumen-protected leucine,17.45 g/d/goat).During the experimental period,feed and water offered ad libitum.This trial lasted 55 d including 10 d adaption time..Growth performance and body size were measured at the beginning and end of the experiment.Rumen fluid and blood samples were collected on d 45 to detect rumen fermentation parameters and blood indicators.The results showed that administration of RP-Leu significantly reduced the feed intake and feed conversion ratio,but increased bodyweight gain(P < 0.05).Feeding RP-Lys reduced feed intake and feed conversion ratio although body weight gain was not influenced(P < 0.05).Compared with goats in RP-Lys treatment,the body weight gain of goats from RP-Leu treatment was higher(P < 0.05),whereas no difference in the other tested parameters was not observed.The total cholesterol in RP-Lys treatment was higher than control treatment(P < 0.05).The dietary treatment did not affect body size,rumen fermentation,and measured blood parameters with the exception of total cholesterol(P > 0.05).In conclusion,these results suggested that RP-Leu could improved growth performance of in young Guanzhong dairy goats.Compared with RP-Lys,The effect of RP-Leu on the growth indexes of young Guanzhong dairy goats was specific,but not on the rumen fermentation parameters and blood metabolism indexes. |
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