SUBSTITUTION OF CONCENTRATES BY ENSILED HIGH-MOISTURE MAIZE GRAIN IN DAIRY-CATTLE DIETS

The effect of substitution of concentrates by ensiled ground high-moisture maize grain on voluntary feed intake and milk production by dairy cattle was investigated. In the first trial, 5.3 kg of concentrate (control ration) was substituted by 6 kg high-moisture maize grain (3.65 kg dry matter (DM)), 1 kg soybean meal and 400 g of a mineral-vitamin mixture (experimental ration). In the second trial, the concentrate supply was individually adapted to the requirements. This concentrate was partially or totally substituted by high-moisture maize grain, 1 kg soybean meal and 350 g of the mineral-vitamin mixture. The quantity of maize grain was restricted to 6 kg and averaged 5.25 kg (3.24 kg DM). The two trials were carried out according to a cross-over design with 10 and 12 lactating Holstein cows, respectively. The basal ration consisted of 60% (DM basis) whole-crop maize silage and 40% pre-wilted grass silage. The ensiled maize grain had a DM content of 614 g kg-1, an in vitro organic matter (OM) digestibility of 87.3% and an estimated net energy value of 8.61 MJ kg-1 DM. The maize grain was well preserved. In the two trials, roughage intake was 0.7 and 0.4 kg DM lower for the experimental rations, whereas total DM intake was 0.4 and 0.1 kg lower. For the control and experimental ration, the average milk yield was 26.1 kg and 25.9 kg in Trial 1, and 24.9 kg and 24.5 kg in Trial 2, respectively. Milk fat content was 0.09 and 0.07 percentage units lower for the experimental rations, whereas milk protein content hardly differed. In contrast to the somewhat lower milk fat and milk protein yield, the daily liveweight gain was 90 and 119 g higher for the rations containing maize grain.