Effect of silage dry matter content and rapeseed meal supplementation on dairy cows. 1. Milk production and feed utilisation

Abstract

Twelve cows (8 multiparous and 4 primiparous) were divided into four treatments to study the effects of direct-cut and wilted silage with or without rapeseed meal supplementation (RSM0 or RSM16) on feed intake and milk production. Experimental design consisted of a 4×4 balanced Latin square with four 3-week periods. Silages were given ad libitum and the concentrate was provided in fixed amounts: 10 kg per day for multiparous cows and 8 kg per day for primiparous cows. Both silages were well preserved. Wilted silage contained more soluble N and ammonium N than direct-cut silage. The dry matter intake (DMI) of wilted silage was on average 16% higher ( p<0.001) than that of direct-cut silage, while milk yield was 2.9% higher ( p<0.05) with direct-cut silage. Silage type had no effect on milk composition. The digestibility of organic matter in the diet was 4.5% lower ( p<0.01) with wilted silage. The cows with wilted silage gained weight, whereas the cows with direct-cut silage lost weight. RSM supplementation increased silage DMI 10.4% ( p<0.05) and milk yield 6.0% ( p<0.001) as well as yields of fat, protein and lactose. There was a tendency towards higher milk yield response to RSM supplementation with wilted silage. In conclusion, wilting increased silage DMI but the lower digestibility and energy content of the wilted silage decreased the energy intake difference between silages. Part of the extra energy with wilted silage was partitioned towards live weight gain. Higher milk yield with RSM supplementation was mainly due to an increase in energy intake.