Abstract

The portable accumulation chamber (PAC) method provides an on-farm methane measurement over a short timeframe that is scalable to measure large numbers of animals. The aim of this study was to assess the safety of use of PAC in pregnant ewes. Methane production was measured in ewes (n=40 per group) using PAC at approximately 70 or 100 days of gestation. Control animals were either exposed to yarding and sorting only (Days 70 and 100) or exposed to yarding, sorting and restriction from feed as outlined in the standard operating procedure for PAC (Day 100 only). Ewe health was not differentially affected by PAC measurement. Confinement in PAC did not affect (P>0.50) lamb survival, with the proportion of lambs weaned relative to number at mid-pregnancy ranging between 0.817 to 0.898. Birth and weaning weights of the lamb were similar (P>0.28) between all groups (birth weight ranged between 4.8 to 5.1 kg, weaning weight ranged between 28.1 to 29.3 kg). Carbon dioxide levels in PAC were not elevated compared to what has previously been observed in non-pregnant ewes. Methane concentrations were calculated for the ewes around day 100 of pregnancy and the average methane production was 23.2 ± 5.8 g per day. In conclusion, PAC appears to be a safe method for measuring methane traits in ewes during the middle to later stages of pregnancy.

Peers-Adams, J., Bilton T.P., Rowe S.J., and Juengel J.L.

New Zealand Journal of Animal Science and Production, Volume 84, Oamaru, 7-10, 2024