Abstract

An outdoor winter-feeding study conducted over 14 days using 40 Friesian-Jersey cross dairy cows measured dry matter (DM) intake and nitrogen (N) excretion of cows fed kale with either barley straw (S), whole crop barley silage (WCBS) and Lotus pedunculatus silage (LS) fed with (LS+PEG) or without polyethylene glycol (LS-PEG). Treatment groups did not differ in DM utilisation of kale (80%) or apparent intake of kale (11.6 kg DM/cow/d). Total daily intake of N was lowest for S, intermediate for WCBS and highest for LS+PEG and LS-PEG (280, 323, 350 and 352 g N/cow/d, respectively). Urinary N excretion was lower (P < 0.05) on kale diets supplemented with either S or WCBS (202 and 186 g N/cow/d respectively) compared with LS+PEG and LS-PEG (227 and 239 g N/cow/d respectively). Supplement treatment did not affect total faecal N excretion but faecal N% was higher (P < 0.05) in LS treatment groups (3.05% in LS+PEG and 3.28% in LS-PEG), compared with WCBS (2.74%) and S (2.43%). This study indicates that the current commonly used feeding system of kale, supplemented with straw, is a feeding system that has a low urinary N excretion compared with alternatives.

ME, Miller, RH Bryant, and GR Edwards

Proceedings of the New Zealand Society of Animal Production, Volume 72, Christchurch, 8-13, 2012