| Popis: |
Thirty-two Holstein cows averaging 132 d postpartum were used in an 8-wk trial to test the effect of feed access time (8, 12, 16, or 20 h/d) on intake and milk production using diets containing either 40 or 60% corn silage. Increasing feed access from 8 to 20 h/d increased total DM intake from 23.5 to 24.7 kg/d but had no effect on DM intake expressed as a percentage of body weight. Milk yield and fat percent were unaffected by feed access time, although protein yield decreased from 920 to 844 g/d by increasing feed access time. There were no interactions between corn silage in diet and feed access time. Feed efficiency (FCM per unit DM intake) was decreased from 1.14 to 1.03 but body weight gains increased from .35 to .66 kg/d by increasing feed access time. Mean eating, rumination, and total chewing times across treatments were 237, 509, and 744 min/d. Feed access time had no effect on chewing activity, but increasing corn silage from 40 to 60% increased total chewing activity from 699 to 789 min/d. We conclude that dairy cows require no more than 8 h/d of feed access if fed amounts required for ad libitum consumption at consistent times during the day using corn silage-based diets. |
