Abstract

This study evaluated the dry matter intake (DMI), rumen fermentation and milk production responses of lactating dairy cows supplemented summer brassicas. Twelve multiparous lactating dairy cows were randomly allocated to three dietary treatments in a replicated 3 x 3 Latin square design. The control diet was composed of 16.2 kg DM of grass silage and 4.5 kg DM of concentrate; 25% of the diet was replaced by rape or turnip. Cows supplemented with summer brassicas showed a lower DMI (P<0.001) compared to the control diet, however milk yield was not affected, resulting in a greater feed conversion efficiency (1.35 for turnip and rape v/s 1.27 for the control diet). Rape supplementation significantly increased microbial protein (P=0.002). VFA concentration and the relative proportion of propionate were increased with turnips, whereas rape increased the acetate:propionate ratio. Mid-lactating dairy cows fed with brassicas are able to maintain production despite the reduced intake, probably due to improved rumen fermentation and therefore nutrient utilisation.

JP, Keim, M Castillo, O Balocchi, R Pulido, D Pacheco, and S Muetzel

New Zealand Journal of Animal Science and Production, Volume 78, Lincoln, 122-124, 2018