. 2019 Dec 11;9(12):1123. doi: 10.3390/ani9121123

Table 3.

Effects of dietary energy and slaughter age on rumen fermentation parameters of Holstein-Friesians bulls.

Item ¹	LE			ME			HE			SEM	p-Value
Item ¹	20	23	26	20	23	26	20	23	26		Diet	Age	Diet × Age
pH	6.73	6.74	6.89	6.67	6.71	6.83	6.85	6.70	6.69	0.08	0.687	0.378	0.231
NH₃-N (mg/dL)	4.50	4.47	4.41	4.64	5.28	4.72	5.53	4.93	5.38	0.71	0.381	0.994	0.927
VFA ² (mmol/L)
Acetate	60.2	60.7	61.1	57.7	56.8	58.4	54.0	54.2	51.3	1.19	<0.001	0.929	0.340
Propionate	13.6	13.7	13.0	16.3	16.1	15.5	18.2	18.0	17.2	0.67	<0.001	0.294	0.999
Isobutyrate	0.61	0.59	0.59	0.58	0.60	0.57	0.65	0.61	0.60	0.04	0.475	0.698	0.966
Butyrate	7.15	6.91	7.37	6.82	7.22	7.47	8.32	7.19	7.91	0.49	0.194	0.485	0.635
Isovalerate	1.62	1.39	1.56	1.45	1.76	1.53	1.55	1.64	1.77	0.15	0.579	0.793	0.412
Valerate	0.63	0.67	0.84	0.68	0.71	0.81	0.80	0.87	0.86	0.06	0.019	0.031	0.637
Total VFA	83.8	83.9	84.5	83.5	83.2	84.3	83.5	82.6	79.7	1.33	0.133	0.767	0.373
A/P	4.42	4.44	4.73	3.56	3.57	3.79	2.98	3.02	3.00	0.18	<0.001	0.398	0.899

¹ LE: low energy; ME: medium energy; HE: high energy. 20, 23 and 26 represent bulls slaughtered at 20, 23 and 26 months of age, respectively. ² VFA: volatile fatty acid; A/P: the ratio of acetate to propionate.