Effects of Different Dietary NFC/NDF Ratios on Ruminal pH,VFA and Lactate Content in Dairy Goats

To explore the effects of different dietary NFC/NDF ratios on ruminal fermentation parameters,6 Guanzhong dairy goats with permanent rumen cannula were divided into 4 groups (4 trial periods) and each period lasted for 10 d according to self-contrast experiment design.The goats were fed diets with different NFC/NDF ratios,which were 1.02 (periodⅠ),1.24 (periodⅡ),1.63 (periodⅢ) and 2.58 (periodⅣ),respectively.The results showed that with the increase of dietary NFC/NDF ratios,ruminal pH decreased,at the same time, the rate and degree of pH decline and duration time for pH lower than 5.2, 5.5,5.8 and 6.0 were increased.Ruminal propionate,butyrate and TVFA content tended to increase,while ruminal acetate content and A/P ratio tended to decrease.Plasma acetate, propionate,butyrate and TVFA content tended to increase.When NFC/NDF ratio was 2.58,duration time of ruminal pH between 5.2 and 5.5 could last for more than 7 h per day.In this case,ruminal lactate content remained at a low level,blood and ruminal TVFA content increased significantly (P0.05).The results indicated rumen fermentation pattern was changed with the increase of dietary NFC/NDF ratios which caused acid environment in rumen;the accumulation of TVFA was the main reason for pH decrease but not lactate itself;when NFC/NDF ratio was 2.58,SARA occurred in dairy goats.