Abstract

This study investigated the impact of weaning age on rumen fermentation profiles in lambs. Mixed-sex lambs (n=32) were ran-domly allocated to one of two weaning groups: early-weaning (4wk) and control (6wk). Milk replacer (24% CP and 25% fat, DM basis) was offered at 20% of initial body weight. Lambs were weaned at either four or six weeks after commencement of the trial using a three-week step-down procedure, initiated at the start of week 2 (early weaned group) or week 4 (control group). Lambs were individually penned indoors and concentrate and chopped meadow hay were offered ad libitum and individual feed intakes recorded until week six. At the end of week six, lambs were moved onto a ryegrass-based pasture and transitioned to an all pasture diet by week ten. Rumen contents were collected at slaughter, half of the lambs from each group at week four and sixteen, to de-termine rumen pH, and short chain fatty acid (SCFA) and ammonia concentrations. Ammonia concentrations were 132% greater (P<0.05) in early weaned than control lambs at week four, but did not differ at week sixteen. Weaning age did not affect ruminal pH and SCFA total concentrations and proportions at week four or sixteen. The results suggest that ruminal fermentation can be established in lambs weaned off milk by four weeks using a step-down weaning method.

O, Cristobal-Carballo, MA Khan, FW Knol, SJ Lewis, D Stevens, and SA McCoard

Proceedings of the New Zealand Society of Animal Production, Volume 77, Rotorua, 49-54, 2017