Table 4.

Effects of dietary energy levels on the ammonia nitrogen and volatile fatty acids (VFA) of rumen samples in heifers aged 7 to 10 months

Items	Treatments			SEM	P
	L	M	H		Treatment	Age	Treatment × Age
NH3-N (mg/dl)	15.15	15.17	15.60	1.339	0.9650	0.0204	0.0440
Total VFA (mM)	102.80	105.62	110.02	12.010	0.9131	0.0035	0.0304
Acetate (%)	67.61	67.37	67.89	0.0066	0.8586	0.1948	0.5483
Propionate (%)	20.12	19.80	20.03	0.0105	0.9766	0.4745	0.7426
Butyrate (%)	8.92	9.48	9.06	0.0033	0.4900	0.0630	0.9302
Valerate (%)	2.39	2.44	2.30	0.0012	0.7164	0.0607	0.2125
Isovalerate (%)	0.79	0.90	0.71	0.0009	0.4099	0.0588	0.5280