Table 1.

Heritability (h²) and repeatability estimates (±SE) for gas emission parameters of lambs measured using respiration chambers and portable accumulation chambers (PAC) and ewes using PAC

Trait	Mean	StDev	σp	h 2 (SE)		Repeatability (SE)
				Direct	Maternal	14 day	Season	Year
Respiration chamber, lambs
BW, kg	45.9	8.00	4.80	0.35 (0.05)	0.07 (0.03)	0.89 (0.01)	–1	–1
CH4, g/d	24.0	2.94	2.81	0.23 (0.04)	0.05 (0.02)	0.65 (0.01)	–	–
CO2, g/d	1066	99.5	94.5	0.34 (0.05)	0.03 (0.02)	0.76 (0.01)	–	–
CH4 + CO2, mol/d	25.5	3.71	2.34	0.33 (0.05)	0.03 (0.02)	0.76 (0.01)	–	–
CH4/(CH4 + CO2), mol/mol	0.059	0.006	0.005	0.17 (0.03)	0.03 (0.02)	0.43 (0.02)	–	–
CH4 yield, g/kg DMI	16.0	1.42	1.39	0.13 (0.02)	0.02 (0.02)	0.38 (0.02)	–	–
Portable accumulation chamber, lambs
BW, kg	39.3	7.79	4.45	0.35 (0.07)	0.08 (0.03)	0.90 (0.005)	0.81 (0.01)	–
CH4, g/d	7.5	2.12	2.13	0.19 (0.04)	0.04 (0.02)	0.33 (0.02)	0.36 (0.03)	–
CO2, g/d	623	117.9	117.9	0.16 (0.04)	0.07 (0.02)	0.41 (0.02)	0.37 (0.03)	–
CH4 + CO2, mol/d	14.6	2.73	2.73	0.16 (0.04)	0.07 (0.02)	0.41 (0.02)	0.38 (0.03)	–
CH4/(CH4 + CO2), mol/mol	0.032	0.008	0.008	0.19 (0.04)	0.02 (0.02)	0.27 (0.02)	0.25 (0.03)	–
Portable accumulation chamber, ewes
BW, kg	69.9	8.96	7.60	0.33 (0.07)	–2	0.97 (0.002)	0.88 (0.03)	0.74 (0.08)
CH4, g/d	13.0	3.09	3.08	0.20 (0.05)	–	0.39 (0.03)	0.43 (0.11)	0.14 (0.13)
CO2, g/d	987	232.9	229.7	0.27 (0.05)	–	0.54 (0.02)	0.37 (0.13)	0.15 (0.18)
CH4 + CO2, mol/d	23.3	5.39	5.31	0.27 (0.05)	–	0.54 (0.02)	0.40 (0.12)	0.14 (0.18)
CH4/(CH4 + CO2), mol/mol	0.036	0.009	0.009	0.25 (0.05)	–	0.38 (0.03)	0.21 (0.11)	0.21 (0.11)

¹Not determined.

²Maternal random effect for PAC gas measures in ewes approached zero and is, therefore, excluded from the model.