| Candida utilis is one of the 28 microbial additives approved by the Ministry of agriculture to be used in livestock and poultry breeding,but there are few reports on its feeding efficacy in beef cattle fattening.In this study,through in vitro fermentation experiments,the effects of Candida utilis and active dry yeast on in vitro fermentation parameters of different substrates were verified,and then Candida utilis and two TMR substrates were applied to production practice to explore the effects of Candida utilis on the production performance of fattening Xinjiang Brown Cattle at different ages,in order to replace the active dry yeast with higher cost and reduce the breeding cost.Experiment 1: Through in vitro gas production method,13-month-old diet and 15-month-old diet were designed.The effects of five kinds of active dry yeast on gas production dynamic parameters and rumen fermentation parameters were compared with that of Candida utilis prepared in our laboratory,so as to provide a theoretical basis for the application of Candida utilis in production practice.The results showed that:(1)Candida utilis significantly increased the gas production and MCP concentration(+11.98%,+ 0.81%)after 48 hours of in vitro fermentation of 15-month old diet;(2)Candida utilis could prolong the rumen fermentation time for 48 hours(+ 10.08%,+ 8.37%);(3)Candida utilis could increase propionic acid,butyric acid,valeric acid,total volatile acid and fermentation efficiency(+ 37.90%,+41.74%,+ 36.71%,+ 21.69%,+ 2.04%),and reduce the ratio of acetic acid to propionic acid and NGR(-17.64%,-9.84%);Increase the acetic acid,propionic acid,butyric acid,isovaleric acid,valeric acid and total volatile acid produced by in vitro fermentation of 15-month-old diet(+ 8.68%,+ 35.26%,+ 31.01%,+ 53.59%,+ 32.31%,+ 21.25%),and reduce the ratio of acetic acid to propionic acid and NGR(-16.41%,-12.02%).Experiment 2: In order to explore the practical application effect of Candida utilis in animal production,30 Xinjiang Brown Cattle aged 13-months(312.93 ± 18.73kg)and 30 Xinjiang Brown Cattle aged 15-months(376.53 ± 29.8kg)were randomly divided into control group(CT group,n = 15)and Candida utilis addition group(CU group,n = 15).The 13-month group was fed with 13-month diet and the 15-month group was fed with a 15-month diet,In the CU group,Candida utilis was added to the basic diet according to 10 g / 100 kg Bw,and the feeding period was 150 day and 120 day respectively.The results showed that:(1)under heat stress,Candida utilis could significantly increase the feeding proportion of the first layer(+ 28.75%,+ 23.53%),the second layer(+ 8.35%,+ 8.56%)and the fourth layer(+ 6.57%,+ 5.17%)of Pennsylvania sieve,and significantly reduce the feeding proportion of the third layer(-29.08%,-25.23%);(2)Candida utilis could significantly reduce the feed weight ratio(-4.18%)of 13-month old beef cattle,and significantly reduce the dry matter intake and feed weight ratio(-9.90%,-17.97%)of 15-month-old beef cattle;(3)Candida utilis had no significant effect on the chemical composition of muscle;(4)Candida utilis significantly increased the contents of total fatty acids(SUM),saturated fatty acids(SFA)and monounsaturated fatty acids(MUFA)(+ 9.34%,+ 4.37%,+ 15.94%)in13-month-old beef cattle,significantly reduced the contents of polyunsaturated fatty acids / saturated fatty acids(PUFA)(-3.13%),significantly increased the contents of SUM,SFA and MUFA(+ 12.55%,+10.20%,+ 15.52%)and significantly increased the contents of n-3 fatty acids(+ 22.16%);(5)Candida utilis can improve the digestibility of beef cattle to long roughage;(6)Candida utilis can significantly improve the digestibility of OM,ADF,NDF and GE(+ 12.37%,+ 35.94%,33.12%,+ 12.34%)of 15-month-old beef cattle,but it has no significant effect on the whole-term digestibility of 13-month-old beef cattle.In conclusion,Candida utilis can replace active dry yeast in production,which can improve the resistance,growth performance and nutrient digestibility of beef cattle to heat stress,so as to reduce the breeding cost. |
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