The effect of ewe nutrition and body condition during late-pregnancy on the behaviour of twin-bearing ewes and their lambs

Abstract

This study describes the effect of maternal nutrition and body condition score (BCS) during pregnancy on the behaviour of twin-bearing ewes and their lambs as assessed 3h to 18h after birth. Ewes (n=274) of BCS 2.0, 2.5 or 3.0 were offered either pregnancy maintenance requirements (fed to allow for foetal but not maternal weight gain; ‘medium’) or ad libitum feeding from day 112 until day 136 of pregnancy for experiment 1 and from day 128 until day 141 of pregnancy for experiment 2. Lamb vigour behaviours (time to stand, suck, make contact with and follow their dam) and bleating behaviour of ewes and lambs were recorded for 5min, following handling at 3–18h. A subgroup of lambs in experiment 1 was tested in a maternal-recognition test. A lesser percentage of ewes in the ad libitum treatment than in the medium treatment high-pitched bleated (86.9% [95% CI 77.4–92.8%] versus 80.0% [69.2–87.7%], and 95.4% [86.5–98.5%] versus 86.9% [70.0–90.5%], in experiments 1 and 2 respectively, P<0.05). Number of low pitched bleats per ewe was generally greater for ewes in the ad libitum than the medium treatment, although this effect was mediated by mid-pregnancy body condition in a different way for each experiment. Effects of maternal body condition and nutrition treatment on bleating behaviour of lambs were not repeatable across experiments, and the ewe nutrition treatments did not affect lamb vigour behaviours (P>0.05) in the 5-min observation period immediately following handling at 3–18h after birth. Behaviour of twin-bearing ewes of BCS2-3 in mid pregnancy, and their twin-born lambs, showed very few changes 3–18h after birth in response to ad libitum versus pregnancy-maintenance feeding during mid to late pregnancy.