Effects of different ratios of concentrate to roughage of wheat straw-based diet on rumen environment and blood parameters

To evaluate the effects of different ratios of concentrate to roughage of wheat straw-based diet on rumen pH value,volatile fatty acids(acetic acid,propionic acid,butyric acid) concentrations,and serum mineral and biochemical indicators,three healthy nonpregnant Holstein cows with body weight(450± 5) kg were selected and the experiment was designed with 3×3 Latin square method.The cows were fed with diet in different ratios of concentrate to roughage(40∶60,60∶40,80∶20) respectively.The results showed that the rumen pH was higher when concentrate-to-roughage ratio was 60∶40,but decreased significantly when concentrate-to-roughage ratio was 80∶20.With the increase of the ratio of concentrate to roughage,the ratio of acetic acid to propionic acid in rumen decreased,and the contents of propionic acid and butyric acid increased significantly.With the increase of the ratio of concentrate to roughage,serum K+ content increased(P0.05),but no significant changes of other mineral contents were observed(P0.05);the serum glucose content increased significantly(P0.05),but the contents of serum total protein,serum albumin and serum urea nitrogen didn't change significantly(P0.05).It was concluded that concentrate-to-roughage ratio could significantly change the rumen pH value,volatile fatty acid proportion,serum K+ content and serum glucose content.