| The objective of this experiment was to study the effects of the proportion of steam-flaking corn in the diet on rumen fermentation parameters,growth performance,blood biochemical index and microbial system in vitro fermentation and feeding test,aiming to provide a theoretical basis for the application of steam-flaking corn in yak production.The specific research content is the following four aspects:Experiment 1: Effects of yak(Phoephagus grunniens)rumen fermentation parameters by using in vitro gas production method to evaluate corn of different processing methodsThis experiment uses wet chemical analysis and in vitro gas production method to evaluate the nutritional value of corn under different physical processing methods(Steam-flaking corn,Cooked corn and Regular corn).The results showed that :1)Compared with Regular corn(control),there was no significant effect in calcium(Ca)and acid detergent fiber(ADF)between Steam-flaking corn(SFC group)and Cooked corn(CC group)(P>0.05).The contents of Ash,crude fiber(CP)and Phosphorus(P)and the contents of ether extract(EE)in the two treatments were lower than those in the control group.2)The 48 h hand 72 h fermentation speed of SFC group and CC group was higher than that of control group,but the cumulative gas production was not significant(P>0.05).The molar ratio of 48 h hand 72 h SFC group,CC group NH3-N concentration,A/P,ISOB and ISOV was significantly lower than that of control group(P<0.05).In summary,Steam-flaking corn and Cooked corn can improve the digestion and absorption of nutrients in animals.No effect on p H,72 h total gas production,the NH3-N concentration,A/P will be significantly reduced(P<0.05),DMD and PRO significantly increased(P<0.05).Experiment 2: Effects of Steam-flaking corn on Rumen Fermentation Parameters and Methane Emission of yak(Phoephagus grunniens)in VitroThe objective of this experiment was to study the effects of the proportion of steam-flaking corn in the diet on rumen fermentation parameters and methane(CH4)emission of yak by vitro.The ratio of concentrate to forage of the cultivation substrates was 7:3.The trial has adopted one-factor completely random design.Replacing the corn content in concentrate with steam-flaking corn and 0(control),10 %,20 %,30 %,40 %,50 %,60 %,70 %,80 %,90 %,100 %,there were 3 replicates for each 11 groups.The 48 h gas production,CH4 proportion in gas,p H,volatile fatty acid(VFA)and ammonia nitrogen(NH3-N)concentrations were measured for 48 h simulating rumen fermentation cultivation in vitro.The results indicated: 1)24 h and 48 h total volume,gas rate,DMD showed a linearly rised trend with the concentrations of steam-flaking corn increased.Compared with the control group,100 % steam-flaking corn group significantly increased total volume,gas rate,DMD(P<0.05).Significantly increased total VFA concentration and PRO(P<0.05),significantly decreased ACE and A/P and NH3-N concentration(P<0.05),no effect on p H(P>0.05).2)CH4 production showed a linearly decreased trend with the concentrations of steam-flaking corn increased.Compared with the control group,100 % steam-flaking corn group significantly decreased the CH4production(P<0.05).The results indicate that different dietary components have different effects on rumen fermentation parameters and CH4 production in vitro,and which are related to the concentration of steam-flaking corn.Experiment 3: Effects of different gradient of steam-flaking corn on the growth performance,blood biochemical index and economic benefit of yak in the dietIn this study,choose 2-year-old male yaks(weight 137.8 kg ± 37.26 kg)were randomly selected into 3 groups,7 yaks in each group.The experimental treatment was to replace different proportions of grain corn with steam-flaked corn.The control group the middle 50% steam-flaked corn(SFC 50)and the high 100% steam-flaking corn(SFC 100).All feeds were artificially mixed diet(TMR).The prefeeding period is 15 days and the formal period is 127 days.Feed intake was measured daily and body weight was measured monthly.Before the end of the experiment,blood was collected from jugular vein and serum biochemical indexes were measured.The results showed that : 1)DMI of the control group,SFC 50 group and SFC 100 group was 6.15 kg,6.09 kg and 6.08 kg,respectively,with no significant difference between the groups(P=0.911).The daily gain was 775.64 g,781.82 g and 831.92 g,respectively.With the increase of the proportion of steam-flaking corn in the diet,the daily gain also increased,but the difference between groups was not significant(P=0.162).The feed conversion rate(F/G)was 7.98,7.80 and 7.06,respectively,with significant difference(P<0.05).2)With the increase of the proportion of steam-flaking corn in the diet,the content of urea nitrogen in the serum decreased significantly(P<0.05),but there was no significant difference in the content of total protein,albumin,globulin and glucose in the serum(P>0.05).Conclusion: feeding steam-flaking corn has little effect on the dry matter intake of yak feed.Reducing the content of urea nitrogen in serum can increase the daily weight gain of yak,improve the feed conversion rate and improve the economic benefit of yak farm.Experiment 4: Effects of different gradient of steam-flaking corn in diet of micro-biodiversity and function on the growth yak tumorOn the basis of experiment 1,2 and 3 explore the micro-biodiversity and function of replace different proportions of grain corn with steam-flaked corn in the stomach of yak tumor,this experiment were clarified by 16 S r DNA sequencing techniques to detect and analyze the structure of the gastric fluid strain of yak(weight 137.8 kg ± 37.26 kg).The results showed that:1)The species diversity and relative abundance of dominant bacteria at the phylum and genus levels were unaffected by the proportions of grain corn with steam-flaking corn supplementation(P>0.05).2)Had similar rumen microbiota composition at the phylum level and Bacteroidetes 和 Firmicutes were predominant phyla with relative abundances of47.97 %,41.40 %.At the genus level Prevotella were predominant genus with relative abundances of 26.51 %,was no significant effect(P>0.05)in all group.Prevotella production showed a linearly increased trend and Methanobrevibacter showed a linearly decreased trend with the concentrations of steam-flaking corn increased.In summary,under the condition of this test,the species diversity and relative abundance of dominant bacteria at the phylum and genus levels were unaffected by the proportions of grain corn with steam-flaking corn supplementation(P>0.05),can be used as an ideal new energy feeding feed. |
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