Nutritional Evaluation Of Mixed Silage With Corncob And Citrus Pulp And Its Effects On Rumen Degradation And Growth Performance Of Beef Cattle

In this study, three tests were conducted. The first test was conducted to study the nutrient content of mixed silage with corncob and citrus pulp, and filter optimum combination.Nylon bag was used to investigate the degradation characteristics of mixed silage during the second test. The last test was carried out to study the effect of mixed silage on the growth performance and blood parameters of beef cattle.In experiment 1, Four treatments included control group:40% corncob+60% citrus pulp,no fermentation;A group:100% mixture with corncob and citrus pulp+0.0015% lactic acid bacteria;B group:92.43% mixture with corncob and citrus pulp+0.3% urea+7.27% corn;C group:92.43% mixture with corncob and citrus pulp+0.3% urea+7.27% corn+0.0015% lactic acid bacteria.A,B,C group were fermented 30 days by 25℃. The results showed that pH values of A,B,C group were below 4.0,water 66%-70%,no significant differences in color, these three groups were excellent. The crude protein of B,C group were significantly higher than that in control group (P<0.01); the NDF of C group was significantly lower than that in control group,A group,B group(P<0.01); the ADF of C group were significantly lower than that in control group (P<0.01); the lactic acid of C group was significantly higher than that in A,B group (P<0.01); the ammonia nitrogen/total nitrogen of C group was significantly lower than that in A, B group (P<0.01); the Ash of B,C group were significantly lower than that in control group (P<0.01); the WSC of B,C group were significantly lower than that in A group (P<0.01); the acetic acid of C group were significantly higher than that in A group (P<0.01);comprehensive evaluation of sensory evaluation and chemical composition, A, B group were good, C group was excellent. In experiment 2, nylon bag was used to investigate the degradation of dry matter, crude protein, neutral detergent fiber, acid detergent fiber of mixed silage and control group. Two treatments include treatment group:40% corncob+60% citrus pulp+0.3% urea+7.27% corn+ 0.0015% lactic acid bacteria, was fermented;control group:40% corncob+60% citrus pulp+0.3% urea+7.27% corn+0.0015% lactic acid bacteria, was not fermented. The results showed that as time increases, the degradation rate of dry matter, crude protein, neutral detergent fiber and acid detergent fiber of control group and tests group increase, there was no significant difference(P>0.05), the average degradation of test group was higher than that in control group, fermentation can improve the nutritional value of the mixture.In experiment 3,this experiment was conducted to determine the effects of mixed silage with corncob and citrus pulp on growth performance, nutrient digestibility and blood profiles of beef cattle. A total of 24 healthy Simmental cross cattle with initial body weight of (173.13±5.10)kg were randomly allocated into 4 treatments with 6 replicates per treatment and 1 cattle per replicate. The feeding trial lasted for 50 days. Four treatments included 1) control group (CON),40% basal diet+60% hemathria sibirica; 2) test group 1 (S20),40% basal diet+40% hemathria sibirica+20% mixed silage; 3) test group 2 (S30),40% basal diet+30% hemathria sibirica+30% mixed silage; 4) test group 3 (S40),40% basal diet+20% hemathria sibirica+40% mixed silage. The results showed that the average daily gain of S20 group was increased by 17.14% compared with CON group (P<0.01). The dry matter intake of S30 group was improved by 14.51% compared with CON group (P<0.05). The S20 group had a lower feed to gain ratio than the other three groups (P>0.05). No effects were observed in apparent digestibility of dried matter, crude protein, neutral detergent fiber and acid detergent fiber (P>0.05). The digestibility of organic matter in S20 group was significantly higher than that in CON group (P<0.05). No effects were observed in total protein and glucose (P>0.05). The blood urea nitrogen was significantly decreased in S20, S30 and S40 groups than that in CON group by 23.08%(P<0.01),26.09%(P<0.01) and 30.32%(P<0.01), respectively. In conclusion, the mixed silage with corncob and citrus pulp substituted of some hemathria sibirica can increase the dry matter intake, average daily gain and nutrient digestibility, and improve the production performance of beef cattle. Therefore, the study suggests that it is feasible when mixed silage with corncob and citrus pulp accounts for 20% in beef cattle diet.