TABLE 2.

Effect of dietary treatments^a on dry matter intake (DMI)^b, live weight (LW)^c, enteric emissions^d, and fermentation profiles^e in calves during three measurement phases^f.

	P01				P02									P03
	FO	CO	SEM	P-T1	FO	CO	SEM	HQ	LQ	SEM	P-T1	P-T2	P-int	FO	CO	SEM	HQ	LQ	SEM	P-T1	P-T2	P-int
DMI (kg/day)	0.89	2.1	0.039	< 0.01	3.50	3.31	0.202	3.98	2.83	0.202	0.52	< 0.01	0.81	4.11	3.91	0.168	4.20	3.81	0.168	0.4	0.12	0.87
LW (kg)	82.0	75.6	1.751	0.02	123.1	111.3	2.859	121.7	112.8	2.931	< 0.01	0.03	0.78	192.7	182.5	3.974	206.9	168.3	4.073	0.08	< 0.01	0.59
pCH4 (g/day)g	14.59	18.20	1.265	0.06	67.84	62.90	2.321	74.78	56.97	2.321	0.15	< 0.01	0.41	121.6	117.8	4.428	124.6	114.7	4.428	0.55	0.13	0.46
yCH4 (g/kg of DMI)h	16.21	8.66	0.690	< 0.01	20.60	19.42	1.412	18.87	21.16	1.412	0.56	0.27	0.91	29.81	30.41	0.901	29.91	30.32	0.901	0.65	0.75	0.68
pH2 (g/day)i	0.123	0.211	0.063	0.33	0.101	0.062	0.020	0.114	0.049	0.020	0.18	0.03	0.76	0.033	0.036	0.022	0.034	0.035	0.022	0.93	0.97	0.67
yH2 (g/kg)j	0.143	0.101	0.035	0.41	0.027	0.019	0.005	0.029	0.017	0.005	0.26	0.11	0.15	0.008	0.009	0.005	0.007	0.009	0.005	0.91	0.82	0.44
SCFA (mM)k	70.1	101.6	6.150	< 0.01	63.5	64.7	3.831	73.8	54.4	3.831	0.82	< 0.01	0.28	74.5	71.0	5.894	76.2	69.4	5.894	0.68	0.43	0.18
Acetate (%)	62.48	45.05	1.080	< 0.01	70.31	70.6	0.386	68.55	72.36	0.386	0.6	< 0.01	0.8	67.96	67.89	0.548	68.02	67.84	0.548	0.93	0.82	0.26
Propionate (%)	21.83	39.14	1.061	< 0.01	17.51	17.19	0.295	17.98	16.72	0.295	0.45	< 0.01	0.75	16.53	16.63	0.427	16.41	16.75	0.427	0.87	0.58	0.92
Butyrate (%)	12.04	10.99	0.801	0.37	9.19	8.95	0.255	9.41	8.73	0.255	0.52	0.07	0.71	11.71	11.64	0.276	11.77	11.58	0.276	0.87	0.65	0.14
Valerate (%)	1.35	3.53	0.179	< 0.01	0.94	1.00	0.039	1.20	0.74	0.039	0.32	< 0.01	0.32	0.99	1.02	0.038	0.99	1.02	0.038	0.49	0.67	0.43
Caproate (%)	0.45	0.68	0.097	0.11	0.29	0.34	0.027	0.28	0.35	0.027	0.17	0.07	0.13	0.12	0.13	0.008	0.13	0.11	0.008	0.43	0.17	0.72
Isobutyrate (%)	0.92	0.28	0.042	< 0.01	0.89	0.92	0.023	1.22	0.58	0.023	0.45	< 0.01	0.86	1.30	1.27	0.054	1.28	1.29	0.054	0.74	0.84	0.25
Isovalerate (%)	0.94	0.33	0.082	< 0.01	0.87	1.00	0.039	1.35	0.53	0.039	0.03	< 0.01	0.88	1.40	1.42	0.065	1.41	1.41	0.065	0.88	0.96	0.28

Results are the means and standard error of the means (SEM), P-value for treatment effect for FO vs. CO (P01), treatment effect for HQ vs. LQ (P02) and their interactions (P-int).

^aDietary treatments corresponded to phase 1 (P01) concentrate (CO) vs. pasture (FO) diets and phase 2 (P02) high-quality (HQ) vs. low-quality (LQ) pastures, with measurements in P01 (9 weeks), P02 (19 weeks), and phase 3 (P03; 41 weeks) when all calves were offered a common pasture diet.

^bDMI (kg/day) was measured in two consecutive days during gas emission measurements.

^cLW (kg) was analyzed adjusting LW to initial LW.

^dMethane (CH₄) and hydrogen (H₂) production in two consecutive days (g/day) and yield per kilogram of DMI (y; g/kg DMI) measured.

^eTotal concentrations (mM) and individual proportions (%) of short-chain fatty acids (SCFA).

^fDietary treatments in each phase were evaluated as follows: a one-way ANOVA in P01 (9 weeks) to analyze FO vs. CO diets and a 2 × 2 factorial ANOVA in P02 and P03 to evaluate FO vs. CO and HQ vs. LQ dietary treatment effects and their interactions.

^gMethane production per animal (g of CH₄/day).

^hMethane yield (g of CH₄/kg of DMI).

ⁱHydrogen production per animal (g of H₂/day).

^jHydrogen yield (g of H₂/kg of DMI).

^kShort-chain fatty acids.