Comparison Of Live Yeast(Saccharomyces Cerevisiae) And Yeast Culture For Growth Performance, Carcass Traits And Meat Quality In Finishing Cattle

Five experiments were conducted to evaluate the effect of ADY and YC, two typical product types of yeast preparations, on in vitro gas production, rumen fermentation characteristics, growth performance, carcass characters, meat quality and blood indexes in finishing cattle fed a high-concentrate diet. This study will lay the foundation for the reasonable application of yeast preparations in practice.Exp.1was conducted to compare the effect of ADY and YC on gas production, dynamics of gas production, methane content and rumen fermentation parameters by in vitro gas production technique. The values of ME, OMD and yield of MP were also predicted according to24h gas production. The results indicated that both ADY and YC had no significant effect(P>0.05)on48h gas production. YC significantly increased the rate of gas production in earlier fermentation (P<0.05), whereas ADY tended to decrease the rate of gas production in earlier fermentation. YC significantly increased the content of methane gas (P<0.05) and significantly decreased content of hydrogen and carbon dioxide (P<0.05). ADY had no significant effect on content of methane gas (P>0.05), but ADY significantly decreased content of hydrogen (P<0.05) and tended to decrease content of carbon dioxide (P>0.05).Both ADY and YC had no significant effect on pH and total VFA of rumen fermentation fluid (P>0.05), but they significantly increased the concentration of NH3-N(P<0.05). ADY had no significant effect on individual VFA, whereas YC tended to increase the ratio of acetic acid (P=0.099) and decrease the ratio of isbutyric acid (P=0.067). Both ADY and YC had no significant effect on OMD, ME and MP (P>0.05). It was concluded that there are certain differences in effect of ADY and YC on gas production, concentrate of gas, the rate of gas production and parameter of rumen fermentation.Exp.2was conducted to study the effect of ADY and YC on growth performance and economic benefit for finishing cattle fed a high-concentrate diet. Forty-five Simmental crossbred finishing cattle (24months old, mean body weight510±29kg) were assigned in a completely randomized design to three treatments which are control group (basic diet), ADY group (basic diet+ADY) and YC group (basic diet+YC). All cattle were harvested after98days of experimental period. The results indicated that feeding ADY to finishing cattle significantly increased final BW, DMI and ADG compared to control group (P<0.05), while YC had no significant effect on above indexes (P>0.05). Both ADY and YC had no significant effect on F:G, but they obtained higher economic benefit compared to control group. It was concluded that ADY significantly improved the growth performance of cattle under our dietary condition, while YC had no effect on performance. Both ADY and YC increased the economic income, in which improvement of growth performance by ADY mainly derived from the increase of feed intake, while the monensin used in our basal die may limit the effect of YC on growth performance. Exp.3was conducted to reveal the action mechanism of ADY and YC on growth performance by determination of blood indexes. The venous blood of all cattle was collected before the end of the feeding experiment, and serum biochemical indexes, immune indexes, anti-oxidation indexes and plasma hormone indexes related to ingestion were measured. The results showed that ADY significantly increased the concentration of TG, FFA, Ghrelin and NPY (P<0.05), and significantly decreased the concentration of NO and CCK (P<0.05). YC significantly increased the concentration of TG as well as Ghrelin,NPY,GHRH, insulin (P＜0.05), and significantly decreased the concentration of SS (P<0.05). In addition, ADY and YC had no significant effect on serum immune and antioxidant indexes of cattle (P>0.05). It was concluded that ADY and YC improved the fat metabolism of cattle. However, there may be a difference between ADY and YC in influence on fat metabolism. The influence of ADY on feed intake may work on regulation of Ghrelin, NPY and CCK.Exp.4was conducted to study the effect of ADY and YC on carcass traits and beef quality in finishing cattle. The results indicated that ADY significantly increased the HCW, NMW CP<0.05) but no significant effect on other carcass indexes; although YC had no significant effect on carcass traits, higher beef marbling score and12th rib fat thickness were observed compared with the other two groups (P>0.05). Neither ADY nor YC showed significant effect on beef quality indexes including value of pH, drip loss, cooking loss and content of moisture, ash, protein, cholesterol, but both ADY and YC significantly (P<0.05) reduced the value of shear force of beef. In addition, both ADY and YC tended to increase intramuscular fat and content of SFA and MUFA, and YC significantly increased content of arachidic acid (C20:0)(P<0.05). It was concluded that ADY significantly improved carcass traits, but YC had no significant effect on carcass traits. However, YC got higher beef marbling score compared with the other two groups. Moreover, both ADY and YC improved the fat metabolism of cattle and increased SFA and MUFA of beef, and thus improved the tenderness of beef.Exp.5was conducted to evaluate the effect of ADY and YC on beef flavor according to MSA of Australia. The results indicated that both ADY and YC got higher tenderness score compared to CON in two cooking ways. In chaffy dish cooking way, beef tenderness score reached the significant level (P<0.05). In addition, both ADY and YC got higher scores in beef flavor and overall acceptability compared to CON, and they both had no significant improvement for juiciness of beef. It was concluded that both ADY and YC improved the tenderness of beef, enhanced the flavor of the beef, and chaffy dish cooking method is more helpful for improvement of beef flavor.