Studies On Manipulation Of Rumen Fermentation, Growth And Meat Quality In Fattening Lambs By Adding Glutathione

Four experiments were conducted to evaluate the effects of glutathione on rumen fermentation, growth performance, carcass characteristics, meat quality, apparent nutrient digestibility and antioxidant defense system of sheep and its regulatory functions on growth performance were further discussed in this paper by determining the concentration of serum GH and IGF-â… in fattening lambs.In Exp.1, three wethers fitted with permanent fistula were used as donor of rumen fluid for experiment in vitro to select optimal dose of glutathione according to MFAEI.In Exp.2, twelve wethers fitted with permanent fistula were divided randomly into four groups and were fed a diet with 0mg/kg (control group), 500mg/kg, 800mg/kg and 1000mg/kg of glutathione respectively to investigate the effects of glutathione on rumen fermentation in sheep.In Exp.3, an experiment was conducted to determine the effects of glutathione on growth performance, carcass characteristics, meat quality and antioxidant defense system in fattening lambs fed a diets supplemented with 0mg/kg (control group), 500mg/kg and 800mg/kg of glutathione and its regulatory functions on growth performance was investigated by determining the concentration of serum GH and IGF-â… in fattening lambs.In Exp.4, an experiment was conducted to determine the effects of glutathione on apparent nutrient availability in fattening lambs fed a diet supplemented with 0mg/kg (control group), 500mg/kg and 800mg/kg of glutathione.The results showed that:1. According to MFAEI conducted in this trial, rumen fermentative function was highly performed when animals supplemented with 500mg/kg, 800mg/kg and 1000mg/kg of glutathione in vitro.2. Rumen pH of the animals was not affected by glutathione supplementation (P>0.05). NH3-N concentration in fattening lambs fed a diet with 1000mg/kg were increased significantly at 8h after feeding (P<0.05). BCP concentration in animals supplemented with 1000mg/kg of glutathione was significantly higher than did the fattening lambs in control group at all time points (P<0.05), however, this parameter in animals fed a diet with 800mg/kg of glutathione was significantly higher than the control group at 0h or 4h after feeding (P<0.05). Butyric acid concentration in rumen fluid was also significantly increased when sheep were fed a diet supplemented with 1000mg/kg of glutathione (P<0.05).3. Fattening lambs fed a diet with 500mg/kg and 800mg/kg of glutathione increased ADG by 14.6% and 11.4% (P<0.05) and decreased feed to gain ratio by 11.0% and 8.1%(P<0.05) and a tendency was observed that supplementation of glutathione increased feed intake of animals(P>0.05).4. Live body weight of fattening lambs was increased significantly when animals supplemented with 800mg/kg of glutathione(P<0.05), whereas net meat rate and GR value were increased significantly in animals fed with 500mg /kg of glutathione (P<0.05).5. Shearing force decreased significantly in animals fed a diet supplemented with 500mg /kg of glutathione (P<0.05) and pH of mutton at 24h after slaughter(P<0.01). Glutathione supplementation decreased water loss of mutton (P<0.05), but increased cooking rate of mutton (P<0.05). 6. Apparent availability of iron and calcium tended to be increased when fattening lambs fed a diet supplemented with glutathione(P>0.05), apparent availability of manganese, however, was increased significantly(P<0.05). Concentration of zinc in excreta was decreased significantly when animals fed a diet supplemented with 800mg/kg of glutathione(P<0.05), while apparent availability of magnesium was increased significantly in animals fed with 500mg /kg of glutathione (P<0.05).7. Level of serum GH and IGF-â… in fattening lambs fed a diet supplemented with GSH were higher than did the animals in control group (P<0.05). Correlation coefficient between serum GH and IGF-â… was 0.568(P=0.054). A tendency that glutathione affected growth performance of fattening lambs was observed by it's regulatory function on level of serum GH and IGF-â… in animals.8. Serum MDA of fattening lambs was decreased significantly in the latter phase when animals supplemented with glutathione, whereas serum GSH-Px and CAT activity were also increased (P<0.05) in the latter phase when qanimals supplemented proper dose of GSH (P<0.05). Serum T-AOC was increased significantly in animals fed with glutathione in the experiment.In conclusion, supplementation of GSH can improve the growth and feed conversion rate of fattening lambs. GSH also improved mutton quality to some extent. The possible mechanisms are:â‘ GSH increased thelevel of serum GH and IGF-â… .â‘¡GSH improved rumen fementation of fattening lambs.â‘¢GSH improved the availability of magnesium and manganese.â‘£GSH improved antioxidation activity, thereby protected animals from oxidation damage.