Effects Of Plants-based Materials On Growth Performance, Rumen Fermentation And Meat Quality Of Growing Hu Lambs

The components of plant orgin have many active properties, such as antibacterial and antioxidant. Thus, they couled be used in animal feed to replace the antibiotic. This study contained three parts including six experiments and it was conducted to investigate the effect of tea saponins (TS), soybean oil (SO) and chrysanthemun stem-leaf (CSL) on carcass quality, rumen fermentation and fatty acid profiles of muscle in growing lambs and approach to the mechanism involved.Part I:Effect of components of plant origin on carcass quality of growing lambs. (Expt.1 and 2)Experiment 1 was carried out to investigate the effects of TS, SO, and TS-SO on serum parameters and carcass quality of growing lambs. Thirty-two Huzhou lambs weaned at the age of 50 days, with an initial body weight of 14.2±1.38 kg, were assigned to four dietary treatments in a 2×2 factorial arrangement with TS (0 or 3g/d) and SO (0 or 3% of DM). The diet without additives was considered as NTNS (no TS or SO). Feed intake was controlled to be similar among the four groups to minimize the meat differences resultant from growth rate. After the feeding trial, four lambs from each treatment were moved to simple open-circuit respiratory chambers (two animals per chamber) to measure methane production. At the end of methane measurement, blood samples of all animals were taken via jugular vein puncture and serums were separated from the blood samples for analysis. Then animals were slaughtered and carcasses were weighed and dissected. No differences were observed in animal growth performances, carcass qualities among four treatments (P> 0.05). Addition of tea saponins had no effect on the serum parameters. Compared with NTNS, the contents of serum total protein, high density lipoprotein-cholesterol, cholesterol and non-esterified fatty acid were higher but the concentration of glucose was lower in SO and TS-SO groups than in NTNS group (P< 0.05). The content of low density lipoprotein-cholesterol was higher in SO group than in TS group (P< 0.05). These results indicated that addition of TS and SO can suppress the methane emission to improve the efficiency of feedstuff utilization, but have little effect on the carcass qualities of lambs. Experiment 2 was conducted to determine the effect of feeding CSL on growth performance, serum parameters and carcass quality of growing lambs. Thirty-six Huzhou growing lambs were assigned to four groups of nine lambs each, and allotted to three units of three lambs at similar weight. The ratio of roughage to concentrate in all the diets was 70:30. Proportion of rice straw to CSL in roughage was 70:0 (CSLO),45:25 (CSL25),25:45 (CSL45), and 0:70 (CSL70) in diets, respectively. The trial lasted for 72 days with the first 12 days for adaptation. Feed ingested and refused were recorded every week, and body weight gain was measured every two weeks. At the end of the trial, serum biochemical and antioxidant parameters and carcass quality were determined. With increasing levels of CSL, average daily gain and serum urea nitrogen increased, with a significant difference between diets CSLO and CSL70 (P< 0.05). Serum catalase and total antioxidant capacity were significantly higher (P <0.05) in lambs on diets CSL45 and CSL70 than those on diet CSLO. The level of serum glutathione peroxidase was highest in animals on diet CSL45 (P< 0.05). Compared to that in diet CSLO, serum malondialdehyde was decreased in diet CSL70 (P< 0.05). Chrysanthemum stem-leaf had no effect on the carcass quality, but the dressing percent was higher in group CSL70 than in group CSLO (P< 0.05). From the present study, it is inferred that inclusion of CSL in the diets could increase antioxidant ability in growing lambs and improve growth performance.Part II:Effect of components of plant origin on rumen fermentation and microbial populations in the rumen of lambs. (Expt.3 amd 4)In Experiment 3, rumen fluids were sampled from the sheep used in Expt. 1 to determine the effects of addition of TS and SO on rumen fermentation and microbial populations in the rumen of growing lambs. The microbial communities were analyzed by real-time PCR and denaturing gradient gel electrophoresis technique. Populations of rumen methanogens, protozoa, fungi, Ruminococcus flavefaciens, and Fibrobacter succinogenes were expressed as a proportion of total rumen bacterial 16S rDNA. Ruminal pH was decreased (P< 0.05) for lambs fed diets with TS, SO, and TS-SO, vs. the NTNS, and ammonia N concentration was reduced by SO (P< 0.05). Concentrations of total volatile fatty acids were increased in all groups (P< 0.05), with no significant differences in proportions of individual acids among diets. Microbial protein was increased (P< 0.05) with TS, SO, and TS-SO. Addition of TS, SO, and TS-SO had little effect on fungal population (P> 0.05), but protozoa populations relative to total bacterial 16S rDNA were decreased (P< 0.05) for lambs fed diets with TS, SO, and TS-SO, with the lowest value in lambs fed the diet containing SO only. Population of methanogens was inhibited by SO (P< 0.05), but not by TS. Addition of SO and TS-SO had an inhibitory effect on the population of fibrolytic microbes including R. flavefaciens and F. succinogenes. Addition of TS and SO has an effect on the communities of bacterial, protozoa and methanogens. However, the diversities of bacterial, protozoa and methanogens were not affected by TS and SO. From the present study, it is inferred that the rumen microbial communities could be affected by addition of tea saponin and soybean oil.Experiment 4 was conducted to determine the effect of feeding CSL on rumen fermentation and microbial populations in the rumen of growing lambs. The rumen samples both liquid and solid were taken from the animals in experiment 2. Ammonia N concentration was lowest in CSL70 (P< 0.05) and microbial protein was higher in CSL45 and CSL70 than in CSL0 and CSL25 (P < 0.05). In the liquid of rumen fluid, CSL decreased the protozoa populations; the population of B.fibrisolvens was higher in CSL25 than in'CSLO and CSL70 (P < 0.05); the C.proteoclasticum population was greater in diet CSL45 than in diet CSL0 (P< 0.05). In the solid of rumen fluid, the population of protozoa was decreased in diet CSL45 as compared to in the diet CSL0 (P< 0.05); the B.fibrisolvens population was larger in diet CSL0 than in diet CSL70 (P< 0.05); But the population of C.proteoclasticum was uninfluenced by CSL. It is inferred that the rumen fermentation and microbial populations could be affected by the flavone and naphtha components of CSL.Part III:Effect of components of plant origin on fatty acid composition in longissimus dorsi muscle and expression of related enzyme gene. (Expt.5 and 6)In Experiment 5, the longissimus dorsi (LD) muscle and liver tissuses were taken from the animals in Experiment 1 to determine the effects of addition of TS and SO on fatty acid profile in LD muscle, gene expression of lipoprotein lipase (LPL) and stearoyl-CoA desaturase (SCD) both in liver and muscle of growing lambs. Vaccenic acid percentage was enhanced (P< 0.05) in muscle of lambs fed TS and SO. The proportion of cis-9, trans-11 conjugated linoleic acid (CLA) was increased (P< 0.05) by SO, but decreased (P< 0.05) by addition of TS in LD muscle. The percentage of total saturated fatty acids (SFA) in muscle was decreased (P< 0.05) by addition of TS and SO, while addition of SO increased (P< 0.05) the percentage of total polyunsaturated fatty acids (PUFA). The ratio of cis-9, trans-11 CLA to vaccenic acid was decreased (P< 0.05) by TS, but increased (P< 0.05) by SO. Addition of TS and SO had no effect on the LPL gene expression in liver (P> 0.05). Compared with NTNS, the SCD mRNA expression in liver was increased in group TS and SO. The LPL mRNA expression in muscle was higher in group TS and SO than in NTNS. Addition of SO could increase the SCD mRNA expression (P< 0.05). These results indicated that inclusion of TS and SO in the diet of growing lambs affect the fatty acid profiles of LD muscle and that the proportion of cis-9, trans-11 CLA in the muscle influenced by TS and/or SO, may be regulated by SCD gene.Experiment 6:This study was conducted to determine the effect of feeding CSL on fatty acid profile in LD muscle and subcutaneous fat, Acetyl CoA carboxylase (ACC) mRNA expression in liver, subcutaneous fat, and LD muscle. The liver, subcutaneous fat and LD muscle were taken from the animals in Experiment 2. In subcutaneous fat, the content of C 16:1 was increased by CSL; there was a highest proportion of C18:2 in diet CSL70 (P< 0.05); with increasing levels of CSL, the total SFA were decreased but the total undaturated fatty acids (UFA) were increased (P< 0.05). However, CSL did not affect the total SFA and total UFA in LD muscle. Inclusion of CSL had no effect on ACC mRNA expression in liver, subcutaneous fat, and LD muscle (P> 0.05). The ACC gene expression in liver was lower than in subcutaneous fat, and LD muscle. These results indicated that the fatty acid composition of subcutaneous fat and LD muscle could be affected by CSL, which may not be related to the ACC gene expression.In summary, addition of TS and SO could reduce methane production to enhance the efficiency of feedstuff utilization. The intramuscular fat of lambs fed a diet containing TS had lower proportion of CLA. Dietary addition of linoleic acid-rich SO was effective in decreasing SFA proportion and increasing the proportion of PUFA and cis-9 trans-11 CLA in the LD muscle, which may be mediated through the expression of SCD gene. Inclusion of CSL in the diets could increase antioxidant ability in growing lambs and improve growth performance. The CSL could reduce the proportion of total SFA and increase the percentage of total UFA in subcutaneous fat, which may be related to the biohydrogenation associated bacteria in rumen affected by flavone in CSL,...