饲粮中添加不同比例的压片玉米对奶牛瘤胃酸度的影响

Effect of feeding steam-flaked corn in varying proportions on ruminal acidity

研究改变饲粮中淀粉与可消化淀粉间的比例,对观察瘤胃内酸性环境的影响及其机理的讨论。选用4头体重在500 kg体况良好、体重相近、胎次相同、装有永久性瘤胃瘘管的中国荷斯坦奶牛,采用4×4拉丁方的试验设计,研究饲粮中添加4个水平的压片玉米(0%、30%、60%、100%)对奶牛进行饲喂。试验期为26 d,其中前14 d为预饲期,后12 d为试验期。结果表明,随着压片玉米添加比例增高,瘤胃内pH值幅度变化大,4组间差异显著(P<0.01);总挥发性脂肪酸产量(TVFA)、丙酸产量随压片玉米添加比例增高而显著增加(P<0.01),而乙酸丙酸比呈显著降低(P<0.01);单位时间内,瘤胃内氨态氮产量随日粮中压片玉米比例升高而显著上升(P<0.01)。由此可得,饲喂添加不同比例压片玉米的日粮,不同时间点对瘤胃内pH值及氨态氮变化影响显著,瘤胃内丙酸、TVFA产量受添加压片玉米比例变化影响显著,其改变了瘤胃的发酵类型。干奶期奶牛日粮中添加压片玉米对促进奶牛机体对日粮的吸收利用有积极的作用。

This experiment was conducted to investigate the effects of feeding steam-flaked corn invarying proportions on ruminal acidity. This experiment was designed as a 4＊4 Latin square using fourHolstein cows in dry period with rumen- cannulated. Diets were chemically similar but varied insteam-flaked corn added（0%, 30%, 60%, 100%）. They were divided into 4 groups（4 trial time） andfirst 14 d to adjust the diet and last 12 d for experiments. The results showed that reducing steam-flaked corn ritio of diets, declined ruminal pH significantly（P〈0.01）; As increasing steam-flaked cornritio of diets, the propionate acid content and TVFA（total volatile fatty acids） content is significantlyhigher than three other groups（P〈0.01）, and acetate/propionate ratio of high steam-flaked corn addedsignificantly lower than three other groups（P〈0.01）,it had changed the ruminal fermentation type.Therefore, the effects of feeding steam-flaked corn in varying proportions on ruminal pH in varyingtime had difference significantly, and so were the propionate acid, it had changed the ruminal fermenta-tion type. This study indicates that adding steam-flaked corn in dairy diets play an active role.