Persistence in CH 4 yield ranking across four seasons in sheep on - PowerPoint PPT Presentation

Persistence in CH 4 yield ranking across four seasons in sheep on pasture AJ Jonker *, S Hickey, S MacLean, C Woju, M Calzada, W Yu, JC McEwan, S Rowe

Variation in CH 4 from sheep • Large variation in CH 4 yield found among sheep (e.g. Blaxter and Clapperton, 1965) • CH 4 yield found to be repeatable trait in sheep (e.g. Pinares-Patiño et al., 2003, 2011)

Creation CH 4 yield selection lines Lucerne pellets (2×MEm) 9%

Breeding values of low and high CH 4 yield sheep

How about on pasture in different seasons • Objective: Determine CH 4 emissions from CH 4 yield selection line sheep in respiration chambers when fed cut pasture in four seasons.

Methods • 72 CH 4 yield selection line rams (born spring 2016) • 4 seasons of cut pasture ( ad libitum ) • CH 4 in respiration chambers for 48 h

Results: Pasture species Other 100% 6.0 Dead matter 11.8 12.7 1.5 Clover 21.0 36.9 80% 21.4 Grass Proportion of DM (%) 9.0 60% 8.5 45.2 84.9 40% 57.7 54.3 20% 27.8 0% March June September December P1 P2 P3 P4 (autumn) (winter) (spring) (summer)

Results: Pasture composition CP NDF NFC fat Ash Summer 8.4 53.1 28.0 8.5 Spring 19.2 44.8 20.3 11.7 Winter 19.5 43.0 23.0 12.1 Autumn 20.2 40.4 26.1 10.9 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% (% of dry matter)

Results: Methane yield 7% 28 8% 8% 7% CH 4 Low line CH4Low 24 CH4High CH 4 High line 20 CH 4 (g/kg DMI) 16 12 23.5 21.8 21.1 20.9 19.6 19.3 19.2 P-values 18.3 8 CH 4 line = P<0.001 Season = P<0.001 4 CH 4 line × season = P=0.737 0 Autumn Winter Spring Summer Autumn Spring Winter Summer (March) (September) (June) (December) (2017)

Results: Repeatability Pasture (current study) (n=72) CH 4 (g/d) 0.46±0.05 CH 4 (g/kg DMI) 0.32±0.05

PAC CH 4 /(CH 4 +CO 2 ) r g of 0.54 with respiration chamber CH 4 yield Discussion SF 6 method: 18% lower CH 4 yield (Jonker et al., 2018; JAS, 96:3031) Respiration chamber (Jonker et al., 2017; JAS, 95:3905) (Jonker et al., 2017; Proc BSAS)

Conclusion • The CH 4 yield trait of selection lines sheep was repeatedly expressed on fresh pasture across four seasons • Therefore, CH 4 breeding values generated in sheep are applicable to pastoral farming systems in New Zealand

Acknowledgements Research was provided through the PGgRc-NZAGRC science programme .