| In this paper, the experiment consisted of four parts. We mainly studied the nutrient value of stylosanthes in different growth periods, the associative effects of combinations of stylosanthes with king grass or its silage, and the effects on the growth performance, blood indexes, apparent digestibility, slaughter performance, organ development and meat quality of Hainan black goats by feeding different forages combinations of roughage. The aim was to find out the best ratio of different forages, and provide the basis for the effective and reasonable application of stylosanthes in Hainan black goat production.In this experiment, the conventional nutrient components of three varieties of stylosanthes in different growth period were determined at first,and then the in vitro fermentation characteristics of them were determined by in vitro gas production technique,so as to pick out the best period of stylosanthes. In order to select three better ratios of stylosanthes and king grass or its silage, stylosanthes were mixed with king grass and its silage respectively at different ratios (0:100,10:90, 20:80, 40:60, 50:50,100:0) and their associative effects were evaluated using in vitro gas production technique. A total of 28 Hainan black goats with similar weight and age were randomly divided into 7 groups with 4 goats in each goap. The groups were control group (group A: feeding king grass as roughage) and six experimental groups (group B C D: feeding mixtures of stylosanthes and king grass; group E F G: feeding mixtures of stylosanthes and king grass silage), the growth performance,blood indexes and apparent digestibility of Hainan black goats were determined, and the best ratios of two kinds of roughage was selected. Finally,a slaughter test was conducted to verify the above results. 3 goats were respectively and randomly choosed from the control and the two selected experimental groups based on the production performance. The slaughter performance, organ development and meat quality of goats were determined. The main results were as follows:The influence of varieties and growing periods on the feeding value of stylosanthes:The content of CP and EE in S. guianensis Sw. Reyan No.2 (S2) was significantly higher than that of S. guianensis Sw. Reyan No.20 (S20) and S. guianensis Sw. Reyan No.21(S21)(P<0.05),and the content of ADF was significantly lower than S 20. However, the in vitro gas production of the three varieties was similar. The nutrients contents of stylosanthes, such as CP, ADF, NDF and RFV, showedobvious regularity with the growing periods,. The content of CP was increased at first and decreased subsequently, and reached maximum in the initial flowering stage. The content of ADF and NDF was continuous increased, while the RFV was gradually decreased. The in vitro gas production parameters"b" and "a+b" were increased at first and decreased subsequently,and the IVDMD and MCP was gradually decreased.The associative effects of stylosanthes with king grass and its silage: Adding a certain proportion of stylosanthes into king grass or its silage could improve gas production,IVDMD and MCP in vitro fermentation, promoted the vitality of rumial microbes, and produced positive associative effects. The synthetically associative effects of all the combinations showed positive value, and it showed a single peak growth trend with the increment of the stylosanthes proportion.. The results showed that the associative effects was higher while the adding proportion of stylosanthes was 20%?40%, except for combination of S20 and S21 with king grass.Effects of stylosanthes on the growth performance, blood indexes and apparent digestibility of Hainan black goats: The daily weight gain, feed intake and feed conversion rate of goats in the two groups which contain 30% stylosanthes in diets roughage (group C and group F) were higher than other groups. In blood indexes, The TP were significantly higher in group G than group A (P<0.05), and the content of BUN in group C was significantly higher than that in group D and group E (P<0.05), the ALT, AST, TG and TC do not show significantly different (P>0.05). The apparent digestibility of DM in the experimental groups was higher than that in the control. The highest apparent digestibility of CP, EE, NDF and ADF were observed in group C and F.Effects of stylosanthes on the slaughter performance, organ development and meat quality of Hainan black goats: The carcass weight, slaughter rate, meat weight, net meat rate and eye muscle area of the test groups were higher than those of the control group. The neck weight of group A were significantly lower than that group F(P<0.05), the waist abdomen weight of group A were significantly lower than group of C and group F(P<0.05).In organ development, the weight of kidney in group C was significantly higher than that in group F (P<0.05),but there was no significant difference in the kidney index between the three groups (P>0.05). The rumen weight and its percentage of the whole stomach of the three groups were the highest in group C, the second in group F and the lowest in group A, while the weight of wrinkled stomach in group A was significantly higher than that of group C and F (P<0.05). As for the meat quality, the pH24h of group A was significantly lower than that of group F (P<0.05), however, the drip loss of group A was significantly higher than that of group C and F (P<0.05).Conclusion: (1) The contents of CP and EE in S2 were significantly higher than those in S20 and S21, but the in vitro gas production situations of three varieties were not significant difference. (2) The lower content of ADF and NDF and higher RFV value,IVDMD and MCP content were observed in the vegetative stage of stylosanthes., and the results showed that vegetative stage was the proper growing periods to feed animals.(3)According to the results of synthetically associative effects, it is suggested that the suitable amount of stylosanthes into king grass or its silage can be 20%?40%.(4)Under a suitable proportion, the mixed roughage can improve the feed intake, feed conversion rate and nutrient apparent digestibility of goats. In this experiment, the best mix ratio of stylosanthe and king grass, stylosanthe and king grass silage were 30:70.(5)Addition of 30% stylosanthe in the diets of Hainan black goats have improved the slaughter performance, meat production and quality, and promoted the development of digestive tract. |
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