Table 4.

Effect of different levels of biochanin A on the nitrogen metabolism of cows.

Item	Treatment1			SEM	P-value
	Control	Low	High
Nitrogen intake, g/d	733.5	693.6	679.4	10.61	0.114
Feces
Nitrogen excretion, g/d	247.4	221.6	230.4	6.75	0.306
Urine
Urea nitrogen, mg/dL	472.8	513.6	501.6	21.16	0.731
Nitrogen excretion, g/d	243.5	245.5	225.1	9.70	0.392
Milk
Urea nitrogen, mg/dL	13.88a	14.10a	11.18b	0.469	0.017
Nitrogen excretion, g/d	202.9b	199.2b	224.1a	2.89	0.002
Plasma
Urea nitrogen, mg/dL	18.32a	17.64a	12.86b	0.936	0.037
Rumen
Microbial nitrogen, g/d	2069b	2267b	2689a	76.6	0.002
Nitrogen utilization efficiency, %	27.90b	28.81b	33.67a	0.649	0.004

^a,b Means within a row with different superscripts differ significantly (P < 0.05).

¹Control, basic diet without biochanin A; Low, basic diet with biochanin A at 10 g/d per cow; High, basic diet with biochanin A at 40 g/d per cow.