Milk production with or without protein supplement in combination with forage at two protein levels

摘要

With the aim to study the effect of protein supplement, two concentrate diets, one consisting of cereal grain only, and one with protein supplements added, were combined with two grass-clover silages with different contents of crude protein (130 and 170gkg~(-1)1 dry matter) and fed to 37 cows of the Swedish Red breed during 20 weeks. The silages, offered ad libitum, were of first cut, and to achieve the higher protein content additional pure red clover silage was added in a mixer wagon prior to feeding. The low protein silage was 95% dominated by timothy and meadow fescue. Concentrate type did not affect silage intake. Cows fed concentrate without protein supplement had a lower milk yield but a higher milk fat content (P<0.01), resulting in 30.9 kg and 35.3 kg energy corrected milk yield (ECM), respectively. There was no effect of silage type on milk yield or milk composition. The diet without protein supplement gave an increase in nitrogen efficiency by 20% compared with the diet with the protein supplement. The experiment was repeated a second year including only one silage quality. Results confirmed reduction in milk yield by excluding protein supplement, from 40.0 to 37.3 kg ECM (P<0.05).