牛至油和过瘤胃蛋氨酸不同组合对奶牛产奶性能和氮排泄的影响

Effects of oregano oil and rumen-protected methionine on lactation performance and nitrogen excretion of dairy cows

本试验旨在研究牛至油(Oo)和过瘤胃蛋氨酸(RPMet)的不同添加量组合对奶牛产奶性能与氮排泄的影响。选取年龄、体重、胎次、产奶量、乳成分及泌乳期(90±15)d相近的荷斯坦奶牛40头随机分为10个组,每组4头。对照(C)组饲喂基础日粮,试验组饲喂不同添加水平的Oo和RPMet,Oo添加水平分别为11.5(L)、13.0(M)、14.5(H)g·(d·头)^-1;RPMet添加水平分别为22.5(L)、25.0(M)、27.5(H)g·(d·头)^-1,共组成9个不同的添加量组合,分别为LL、ML、HL、LM、MM、HM、LH、MH、HH(第1个字母为Oo添加水平,第2个字母为RPMet添加水平)。预试期15 d,正试期60 d。结果表明:产奶量方面,LL、HL、HM、MH、HH组产奶量极显著高于对照组(P<0.01),以MH组最高。乳成分方面,MH、HM组乳脂率极显著提高(P<0.01);HM、HH组乳蛋白率极显著提高(P<0.01),各试验组在乳体细胞数均极显著低于对照组(P<0.01)。在氮排泄方面,LL、ML、LM、MM、HM、LH、MH、HH组氮排泄极显著低于对照组(P<0.01),以MH组最低。综合考虑上述指标,在本试验条件下,以MH组[Oo 13.0 g·(d·头)^-1、RPMet 27.5 g·(d·头)^-1]组合效果最好。

This experiment was conducted to determine the effects of different combinations of oregano oil(Oo)and rumen-protected methionine(RPMet)on lactation performance and nitrogen excretion of dairy cows.Forty lactating holstein dairy cows of similar age,body weight,parity,milk yield,milk composition and lactation status[(90±15)days post-calving]were divided into 10 groups with 4 cows per group.A Control group was fed a basal diet,and experimental groups were supplemented with different levels of Oo[11.5(L),13(M)or 14.5(H)g·(d·head)^-1]and RPMet[22.5(L),25(M)or 27.5(H)g·(d·head)^-1]to make nine treatment combinations,which were designated LL,ML,HL,LM,MM,HM,LH,MH and HH(i.e.the first letter indicates Oo supplementation rate,and the second letter indicates RPMet supplementation rate).Following a pre-experiment adjustment period of 15 days,the experiment lasted for 60 days.It was found that:The milk yield of LL,HL,HM,MH and HH groups was significantly higher than in the Control group(P<0.01),with MH being the highest.In terms of milk components,the milk fat percentages of MH and HM groups were significantly higher than the Control group(P<0.01),and the milk protein percentages of HM and HH groups were significantly higher than the Control group(P<0.01).Milk somatic cell of the experimental groups were significantly lower than the Control group(P<0.01).Nitrogen excretion rate of LL,ML,LM,MM,HM,LH,MH and HH groups was significantly lower than the Control group(P<0.01),with the MH group being the lowest.Under the conditions of the experiment,the MH group[Oo 13 g·(d·head)^-1,RPMet 27.5 g·(d·head)^-1]was the best treatment combination.