| This study was to investigate how the different NFC/NDF levels influence the production performance,used feeding test,digestion and metabolism test,slaughter test to research the growth performance,serum parameters,rumen fermentation parameters and rumen microflora of weaned male calves in odder to provide theoretical basis for production practice.The specific content is divided into the following three aspects:Exp.1: This study aimed to investigate the effects on different non-fiber carbohydrate(NFC)/ neutral detergent fiber(NDF)diets levels in growth performance,slaughter performance and rumen morphology of male calves.Sixty 2-3 month-old healthy weaned male calves were randomly divided into four groups with fifteen calves each,and were fed four types of total mixed ratio with the same crude protein level and different NFC/NDF ratio: 1.35(A group),1.23(B group),0.94(C group),0.80(D group)respectively.The experiment lasted 105 d,with 15 d of adaptation period and 90 d of formal period.Feed intake of each calf was recorded every day,body weight and body measurements were measured every 15 days.At the end of the experiment,6 calves were randomly selected from each group and were slaughtered to determine slaughter performance and meat quality.After the test for slaughter trial,weighted every stomach and collected rumen tissue,measured the determination of the width and height of nipples,nipple base thickness.The results showed as follows:1)In the whole experiment period,rumen nipple height was significantly increased with the NFC/NDF levels reduced(P<0.05),rumen width was significantly reduced with the NFC/NDF levels reduced(P<0.05),the tunica muscularis was not influenced by diets NFC/NDF levels(P>0.05);2)With the different NFC/NDF levels,average daily gain(ADG)and body length growth rate were significantly different of calves,group A were greater than other groups(P<0.05),body weight of group A is 111.40 kg was significantly higher than group C and group D(P<0.05).To sum up,growth performance of calves were improved,when the ratio of NFC to NDF is 1.35,which could meet the nutrient requirement of of 3 to 6 months old male calves.Exp.2: This study aimed to investigate the effects on diets with different NFC/NDF levels in growth performance,serum indexes and digestive metabolism of male calves.The experiment designs the same as that of experiment one.Blood were sampled at 105,120,135,150,165 and 180 d of age and the concentration of serum glucose(GLU),growth hormone(GH),insulin-like growth factor-1(IGF-1),leptin(LEP),insulin(INS),glucagon(PG),triglyceride(TG),albumin(ALB)and globulin(GLB)were detected.Feces and urine were collected to determine digestion and metabolism experiment in 120 and 180 days age.The results showed as follows: 1)With the NFC/NDF level decreased,the concentrated of LEP reduced significantly(P<0.05),the concentrated of IGF-1 group D significantly high than group B(P<0.05);2)The apparent digestibility of dry matter,neutral detergent fiber and acid detergent fiber decreased significantly with the NFC/NDF level decreased as well as DE/GE,ME/GE and ME/DE(P<0.05),group D CH4 E is significantly higher than other groups(P<0.05),the UE,urine nitrogen,and nitrogen digestible of group A and group D is higher than other groups,and has significantly different(P<0.05).To sum up,the ratio of NFC to NDF is 1.35 can meet the dietary needs of nutrient intake,serum indexes were in normal range when intake this diet and did not affect the health of 3 to 6 months old male calves.Exp.3 : This study aimed to investigate the effects of diets with different NFC/NDF levels on rumen fermentation parameters and microbial flora diversity of male calves.The experiment designs the same as that of experiment one.At the beginning of the experiment,six healthy calves were selected to collect rumen fluid through oral after feeding two hours at the 120,150 and 180 d to determine p H value,volatile fatty acids and NH3-N concentration and rumen microbial diversity.The results showed that: 1)Propionic acid content decreased with the level of NFC/NDF reduced(P<0.05),the concentration of NH3-N concentration and acetate,propionate ratio is also significant increased(P<0.05);2)The concentration of Bacteroidetes group A was significant higher than group D(P<0.05),Christensenellaceae_R-7 and Prevotellaceae_UCG-003 were significant differences(P<0.05);3)Rumen microbial diversity index include chao1 and shannon index,goods_coverage,observed_speciesand PD_whole_tree in group A were significantly lower than that of group D(P<0.05);4)With the increase of day age,rumen microbial richness was significantly increased(P<0.05),but had no significant effect on rumen microbial composition(P>0.05).In summary,the dietary NFC/NDF levels significantly affected the species and abundance in the rumen microorganisms,but have no effects on the level of genus of microorganisms,finally affect the yield of acetic acid and propionic acid. |
