Effects of different levels of corn silage and alfalfa hay on rumen metabolites and milk production of Holstein cows

In present study investigated the effects of different levels of corn silage and alfalfa hay on rumen metabolites and milk production of Holstein cows. Fifteen Holstein cows (37 ±10 days in milk) were used in a completely randomize design. Treatments included three levels of hay and corn silage included: 1) 10% alfalfa hay -30% silage corn (CS), 2) 20% alfalfa hay -20% silage corn (AH- CS) and 3) 30% alfalfa hay -10% silage corn (AH); And the ratio of forage: concentrate was 60:40. Cows were fed the total mixed rations (TMR) twice daily. Cows were milked 3 times daily at 0200, 1000, and 1800 h. Milk production recorded at each milking time. Milk composition was measured every week and individual dry matter intake (DMI) was measured daily. DMI was higher when cows were fed diets AH-CS (23.20 kg per day) compared with diet CS (22.95 kg per day) and diet AH (18.64 kg per day). Treatments affect on milk production (P= 0.009). Replacing corn silage with alfalfa hay increased milk fat percent, but didn’t affect on milk protein percent (P>0.05). Average concentration of volatile fatty acids (VFA) in rumen were 75.90, 65.58 and 71.40 mM/l, for cows receiving diet 1, 2 and 3 respectively, that did not show significant differences (P>0.05). The results of this experiment indicated that feeding alfalfa hay more than corn silage reduced DMI, therefore decrease milk production, although had a trend to increase milk fat percentage.