The effects of forage type and level of concentrate supplementation on food intake diet digestibility and milk production of crossbred cows bos taurus x bos indicus
Khalili, H.; Varvikko, T.; Crosse, S.
Animal Production 54(2): 183-189
An experiment was carried out to evaluate the effects of forage type and level of concentrate supplementation on forage intake, diet digestibility and milk production. Twenty-four crossbred cows (Bos taurus .times. Bos indicus), in early lactation, were allocated to the following six dietary treatments: native grass hay (H) or oat-vetch hay (OV), offered ad libitum, and supplemented with either 0, 2.5 or 5.0 kg per cow per day of wheat-middling-based concentrate. A four-period, partially balanced, change-over design was used and the treatments were arranged as a 2 .times. 3 factorial The daily dry-matter (DM) intake was 640 g (P < 0.001) higher with cows on (H) diets compared with those on OV diets. However, OV diets were more digestible (0.675 v. 0.566, P < 0.001) resulting in 800 g higher (P < 0.05) daily intake of digestible DM. The daily milk yield was 1.24 kg higher (P < 0.001) for cows on OV diets compared with H diets. Milk fat concentration was higher (P < 0.05), but milk protein concentration was lower (P < 0.001) with H diets. The rates of rumen degradation of DM and nitrogen of OV were higher than of H for all incubation periods; similarly the values of the rate constant of DM and nitrogen were greater for OV than for H. The daily DM intake increased by 3.72 kg/day (P < 0.001), when the amount of concentrate increased from 0 to 5.0 kg/day, indicating a minor substitution of basal forage by concentrate. The apparent DM digestibilities of the diets were higher when the diets were supplemented with concentrates. The milk yield increased linearly (P < 0.001), when the level of concentrate supplement increased from 0 to 5 kg, resulting in 0.52 kg more milk per day per kg additional concentrate given.