| Betaine,i.e.,N,N,N-trimethylglycine,is a methyl derivative of glycine and a coproduct of extracting molasses from sugar beet.The objective of the study is to compare the impacts of betaine and glycine on growth performance,carcass trait,meat quality and lipid metabolism of finishing Huan Jiang mini-pigs.A total of 144 Huan Jiang mini-pigs with an average initial body weight of 10.55 ± 0.15 kg(mean ± SEM)were assigned to three treatment groups(basal diet,0.16% glycine and 0.25% betaine)in a completely randomized design,with eight replications of six pigs per replicate(pen).The experimental period lasted for 60 d following a 3-d preliminary feeding period with the same basic diet.At the end of the trial,samples were collected.Subsequently,we analyzed growth performance and carcass trait,and measured related indicators such as meat quality,serum biochemical parameters and hormone levels,free amino acids in serum and longissimus dorsi(LD)muscle,chain fatty acids in LD muscle,the m RNA expression levels of MyHC and the genes related to lipid metabolism.The main results were as follows:(1)Growth performance: Compared with the control group,dietary betaine increased the pig’s final weight and average daily weight gain(P < 0.05),but there was no significant difference in the glycine group(P > 0.10).(2)Carcass trait: Compared with the control group,dietary glycine and betaine significantly reduced backfat thickness and fat percentage(P < 0.05)and increased lean percentage(P <0.01),but had no significant effect on organ index(P > 0.10).(3)Meat quality: Compared with the control group,dietary betaine and glycine markedly increased a* value(P < 0.05).Moreover,the shear force showed a notable decrease in the betaine group compared to the other two groups(P < 0.05).(4)Serum biochemical parameters: Compared with the control group,dietary betaine markedly increased the levels of IGF-I,INS,GH and GHRH in serum(P < 0.05).Diet supplemented with betaine and glycine did not affect the concentrations of ALT,AST,TP,ALB,BUN,CREA,and NH3 L in serum of the pigs(P > 0.10).(5)Free amino acids: Compared to the other two groups,an obvious increase was observed in glycine concentration in the glycine group(P < 0.05).Compared with the control group,dietary glycine and betaine markedly reduced the cysteine concentration and increased the methionine and threonine concentration in serum and LD muscle(P < 0.01).(6)Fatty acids: Betaine and glycine decreased the concentration of saturated fatty acid(SFA,P < 0.05),whereas the concentration of polyunsaturated fatty acid(PUFA,P < 0.05)and PUFA: SFA markedly increased relative to the control group(P < 0.01).(7)The relative m RNA expression levels of myosin heavy chain(MyHC)and the genes related to lipid metabolism: Compared with the control group,dietary betaine markedly up-regulated the gene expression level of MyHC I in LD muscle(P < 0.05).Compared with the control group,betaine and glycine both down-regulated the m RNA expression levels of ACC,FAS,and PPAR γ(P < 0.05),and the m RNA expression levels of HSL and CPT1 B were up-regulated(P < 0.05).In summary,diet supplemented with 0.25% betaine could improve growth performance,carcass trait,pork quality and lipid metabolism of Huan Jiang finishing mini-pigs,and equimolar amounts of glycine could also improve meat quality and lipid metabolism of the finishing pigs to some extent,but was inferior to betaine. |
