The patterns of feed intake when animals are allowed ad libitum access to feed in a respiration chamber is not known, nor are the potential effects of the artificial environment of chambers on voluntary feed intake. The objectives of the study were to describe the pattern of hourly feed intake of sheep when fed for ad libitum intake in respiration chambers and determine the repeatability of this pattern and the correlation between feed intake and methane production calculated at hourly intervals. Daily and hourly measurements of methane production and feed intake of 47 Merino wethers were measured in respiration chambers twice, 4 wk apart. We found that hourly feed intake of sheep with ad libitum access to feed in respiration chambers showed a repeatable pattern over the 2 measurement periods (r = 0.89, P < 0.001). During both measurements, sheep ate continuously throughout the 23 h period, but most of the eating occurred during the first 8 h in the respiration chambers. There was a significant linear correlation (r = 0.22) between hourly feed intake and hourly methane production (P < 0.001). An unexpected result from this study was that despite using an accepted and published acclimatization procedure to habituate the animals to the respiration chambers, sheep had 15 to 25% lower feed intake in the respiration chambers compared with their feed intake during the previous week in the animal house pens. In addition, daily feed intake in the respiration chamber was not correlated with feed intake in any of the 7 d before entering the chamber (P > 0.05). Future methane research may consider using feed intake and changes in intake levels as a quantitative indicator of habituation to the methane measurement procedure and environment, which, given the tight association between feed intake and methane production, will be crucial in providing accurate values for methane production.

Maternal and lamb behaviours play a major role in lamb survival and there is evidence that selection for calm temperament may help improve lamb survival by improving maternal behaviour. However, the apparent better maternal behaviour of calm ewes might be due partly to their lower reactivity to the presence of the human observer rather than to better maternal behaviour per se. The extent to which the selection for temperament influenced the behaviour of the ewe and lamb after parturition with minimal human disturbance was investigated in the present work. Single-bearing multiparous and primiparous ewes were observed to determine any interactions of temperament with maternal experience on ewe and lamb behaviours. Postpartum ewe-lamb interactions under outdoor lambing conditions were captured by continuous video recordings by a remote controlled recording device for up to 2 h postpartum. Calm ewes licked their lambs more and tended to stay longer on the birth site. Nervous lambs stood up earlier and were quicker to start performing exploratory behaviour. However, duration of suckling during the observation period did not differ between the calm and nervous lambs. There were no effects of maternal experience on the behaviour of the lamb and there were no interactions between temperament and maternal experience on the behaviour of the ewe or lamb. Our study indicates that temperament does influence the early postpartum behaviour of ewes and lambs under extensive field conditions.

Temperament influences maternal behavior and lamb survival in Merino sheep selected for calm or nervous temperament. The impact of this selection on mother-young recognition and early expression of temperament in lambs is unknown. We tested the ability of multiparous ewes selected for calm (n = 16) or nervous (n = 18) temperament to recognize their own lambs 6 hr after parturition, the ability of the lambs to display a preference for their own mother at 18 hr, and the temperament of the lambs at 1 and 16 weeks of age. Ewes and lambs from both genotypes showed a similar preference for their familiar kin. In contrast, differences in temperament were detectable at 1 and 16 weeks of age. Nervous lambs showed higher vocal and locomotor activity than calm lambs. Thus, temperament did not affect the early process of ewe-lamb bonding but might affect the quality of the mother-young relationship under more challenging situations.