Table 2. Luteinizing hormone (LH) profiles in the jugular vein during the whole 12 h and the 6-h pre- and post-feeding sampling periods in lactating (L; n=4) and non-lactating (N; n=4) cows.

LH characteristic	Group	Whole 12 h	6 h Pre-feeding	6 h Post-feeding
Mean concentration (ng/ml)	L	0.34 ± 0.07	0.32 ± 0.10	0.36 ± 0.10
	N	0.41 ± 0.05	0.40 ± 0.09	0.42 ± 0.06
Basal level (ng/ml)	L	0.28 ± 0.07	0.26 ± 0.08	0.31 ± 0.12
	N	0.33 ± 0.05	0.32 ± 0.07	0.33 ± 0.07
Pulse frequency (pulses/12 h or 6 h)	L	7.0 ± 0.7 a	3.8 ± 0.3	3.3 ± 0.5
	N	4.3 ± 0.9 b	1.8 ± 0.6	2.5 ± 1.0
Pulse amplitude (ng/ml)	L	0.24 ± 0.03	0.27 ± 0.06	0.21 ± 0.03
	N	0.37 ± 0.10	0.34 ± 0.15	0.40 ± 0.14

Values are means and SE. ^{a, b} Different superscripts within a column indicate significant differences (P<0.05) between the L and N groups.