Feed intake of sheep when allowed ad libitum access to feed in methane respiration chambers.

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.

Temperament does not affect the overall establishment of mutual preference between the mother and her young in sheep measured in a choice test.

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.