| As a functional feed additives, yeast culture is a kind of complex microecologics, which can improve the growth and immune performance of animal. But its effective promotion is affected by many factors including strains of yeast, fermentation process, the nutrition ingredient of diet and so on. Therefore, this experiment was conducted to evaluate the optimum dose of yeast culture(YC) as a additive in feed, which was fermented by using molasses medium of self-preparation, and the effect of it in feed with different CP levels on production performance and immune system of AI pull acres broilers by two tests.Experiment I: the test using single factor randomized block design, 192(96♂+96♀) 1-d-old healthy Arbor acres broiler chickens with a similar body weight were randomly allocated to 4 treatments with 6 replicates in each treatment and 8 birds per replicate. Birds in the control group were fed a basal diet, and the rest of birds in treatments included 3 groups which were fed the basal diet supplemented with 0.024%,0.192% and 0.384%YC respectively. The trial lasted for 42 days, two bird were randomly selected from each repeated and slaughter for sampling to measure indicators.Experiment II: the test using a full factorial randomized block design(2×3 factorial test). Factor 1 was the crude protein levels in diet, which contain the normal level and the low-protien level; Factor 2 was the dose of yeast culture added in feed, which was set to 0.024%, 0.192% and 0.384% of three levels. 288(144♂+144♀) 1-d-old healthy Arbor acres broiler chickens with a similar body weight were randomly allocated to 6 treatments with 6 replicates in each treatment and 8 birds per replicate.Normal CP groups were fed the basal diet with three horizontal proportion of yeast culture. Low protein groups were fed low protein diet with three horizontal proportion of yeast culture as same. The trial lasted for 42 days, two bird were randomly selected from each repeated and slaughter for sampling to measure indicators.Experiment I results show that: 1) Throughout the whole experimental period, ADG in 0.384% group was increased significantly(P < 0.05), FCR in 0.192% group was significantly decreased(P < 0.05). In 22 ~ 42 days of age, compared with the control group, ADG were significantly increased in 0.192% and 0.384% groups(P < 0.05) and FCR in 0.192% group was decreased significantly.2) Compared with control group, apparent nitrogen deposition rate in 0.192% group was increased significantly in the later of the test(P<0.05). Newcastle disease antibody titer in serum were significantly higher in 0.192% and 0.384% groups than the control(P < 0.05).3) Compared with control group, GLO in 0.384% groups were significantly increased(P <0.05); ALK in 0.192% groups were significantly increased(P< 0.05); GLO in 0.384% group were significantly increased(P < 0.05).4) Compared with control group, villus height of the duodenum was improved significantly in 0.192% and 0.384% groups(P<0.05); the crypt depth was decreased and VCR of the duodenum was increased significantly in 0.384% group; villus height of the jejunum would be significantly improved in 0.384% groups(P < 0.05), and VCR in 0.192% and 0.384% were higher.5) Compared with control group, liver organ index was significantly reduced(P < 0.05) in 0.384% group, and the thymus index was significantly increased in 0.024% and 0.196% groups(P < 0.05).Experiment II results show that: 1) Throughout the whole experimental period, ADG was effected significantly by protein level in diet as the main effect, and ADG in groups of normal diet was significantly higher than low-protein diet groups(P < 0.1). Meanwhile, ADG was also effected significantly by interaction, ADG in 0.384% groups which fed low-protein diet was significantly lower than in 0.192% and 0.384% groups which fed normal diet(P<0.1). In 1~21 days of age, ADG was effected significantly by protein level in diet as the main effect, and ADG in groups of normal diet was significantly higher than low-protein diet groups(P < 0.1). In 22~42 days of age, ADG was effected significantly by interaction, ADG in 0.384% groups was significantly lower than 0.024% groups which fed low-protein diet(P<0.1). ADFI was affected significantly by the dose of dietary supplement of YC as the main effect in 1~21 and 1~42d of age(P<0.1), and ADFI increased along with the dose of dietary supplement of YC. In the period of whole Experiment, FCR was effected significantly by two factors and interaction produced by them(P<0.1). FCR in groups which fed low-protein diet was higher than groups which fed normal deit, and 0.384% groups were lower significantly than the other which1 fed diet added other dose, 0.384% groups which fed low-protein diet was significantly higher than other groups by the interaction. During 1~21days of age, FCR was affected significantly by protein level in diet as the main effect(P<0.1), FCR in groups of normal diet was significantly lower than low-protein diet groups(P<0.1); and during 22~42d of age, FCR was effected significantly by the dose of dietary supplement of YC and interaction(P < 0.1).2) In the 39~41d of age, apparent nitrogen deposition rate was effected significantly by the dose of dietary supplement of YC in the groups which were in same CP level(P < 0.1), and 0.192% group was significantly higher than that of 0.384% group(P < 0.1). Apparent nitrogen deposition rate was also effected significantly by the interaction.3) GLO, BUN and AST in serum were significantly effected by the dose of dietary supplement of YC(P < 0.1), the concentration of GLO and BUN in 0.384% group were higher significantly than 0.024% group(P < 0.1); and concentration of AST was decreased by adding YC, 0.384% group was significantly lower than 0.192% and 0.024% group(P < 0.1). The concentration of BUN, UA, AST and ALT in serum was significantly effected by protein level in diet(P < 0.1), the concentration of BUN, UA and ALT with the decline of dose of dietary supplement of YC in fall, and AST was opposite. ALP, BUN, AST and ALT in serum were effected significantly by interaction(P < 0.1).4) Newcastle disease antibody titer in serum were significantly effected by the dose of dietary supplement of YC as the main effect(P < 0.1), and it increased with adding dose rise.5) Villus height of the duodenum, crypt depth and VCR of the jejunum were significantly effected by the protein level in diet as the main effect(P < 0.1), villus height of the duodenum and VCR of the jejunum were in fall with the decline of the protein level in diet, and crypt depth of the jejunum were opposite. Villus height of the duodenum, crypt depth and VCR of three segment of small intestine were significantly effected by interaction(P < 0.1).6) Bursa of fabricius index was significantly effected by the dose of dietary supplement of YC as the main effect(P < 0.1), 0.192% group was higher significantly than 0.384% group; liver and bursa of fabricius index were significantly effected by the protein level in diet(P < 0.1), liver index was increased with the decline of the protein level in diet, and bursa of fabricius index was opposite. |
PDF Full Text Request