Metabolic and endocrine profiles and hepatic gene expression of Holstein cows fed total mixed ration or pasture with different grazing strategies during early lactation

Table 3 Hepatic expression of genes related to the GH-IGF axis during the peripartum and early lactation periods (from −40 to 55 days relative to parturition) of dairy cows assigned to three different feeding strategies during the first 60 days of lactation

Gene³	Days	All⁴	Treatments¹			SE	P value²
Gene³	Days	All⁴	G0	G1	G2	SE	PER	Days (PER)	TREAT (PER)
GHR							0.39	0.27	0.09
	−40	1.00	–	–	–	–
	−20	0.88	–	–	–	–
	10	0.75	0.78^ab	0.91^ab	0.56^b	0.57
	55	1.01	0.88^ab	1.47^a	0.69^b	0.56
GHR1A							<0.01	0.10	0.97
	−40	1.00^a	–	–	–	–
	−20	0.91^a	–	–	–	–
	10	0.56^b	0.58	0.58	0.51	0.19
	55	0.41^c	0.42	0.40	0.41	0.18
IGF1							0.08	0.70	0.20
	−40	1.02^xy	–	–	–	–
	−20	1.12^x	–	–	–	–
	10	0.84^y	0.58	0.79	1.17	0.32
	55	0.92^xy	0.74	1.11	0.91	0.31
IGF2							<0.01	0.05	0.91
	−40	1.00^b	–	–	–	–
	−20	1.20^b	–	–	–	–
	10	1.29^b	1.20	1.27	1.39	0.43
	55	1.76^a	1.80	1.98	1.51	0.48
IGFBP1							<0.01	0.42	0.25
	−40	1.00^b	–	–	–	–
	−20	1.15^b	–	–	–	–
	10	1.96^a	2.09	1.56	2.25	0.93
	55	2.44^a	3.25	1.85	2.20	0.97
IGFBP2							<0.01	0.10	0.94
	−40	1.00^b	–	–	–	–
	−20	1.24^b	–	–	–	–
	10	3.35^a	3.46	3.20	3.38	0.79
	55	2.43^a	2.25	2.78	2.26	0.81
IGFBP3							0.09	0.10	0.54
	−40	1.00^ab	–	–	–	–
	−20	1.25^a	–	–	–	–
	10	0.91^b	1.10	0.74	0.90	0.24
	55	1.05^ab	1.00	1.04	1.10	0.24
IGFBP4							0.04	0.54	0.73
	−40	1.00^ab	–	–	–	–
	−20	0.97^b	–	–	–	–
	10	1.14^ab	1.05	1.04	1.32	0.41
	55	1.35^a	1.25	1.34	1.45	0.40
IGFBP5							<0.01	0.62	0.74
	−40	1.00^b	–	–	–	–
	−20	1.10^b	–	–	–	–
	10	2.03^a	2.09	1.60	2.41	0.84
	55	1.75^a	1.36	2.03	1.85	0.94
IGFBP6							0.08	0.71	0.06
	−40	1.00^y	–	–	–	–
	−20	0.97^y	–	–	–	–
	10	1.13^xy	0.93^b	1.01^ab	1.46^ab	0.34
	55	1.29^x	0.86^b	1.33^ab	1.68^a	0.34

¹Feeding strategies from calving (day 0) to 60 days postpartum: G0 DM offered as 100 % total mixed ration (TMR; n = 9), G1 DM offered as 50 % pasture in one (am) grazing session (6 h) plus 50 % TMR (n = 9), G2 DM offered as 50 % pasture in two (am/pm) grazing sessions (9 h) + 50 % TMR (n = 7)
² PER period (pre vs. postpartum), TREAT treatment. The interaction TREAT (PER) × Days was not significant (P > 0.25) for any of the genes
³ GHR = growth hormone receptor, GHR1A = growth hormone receptor 1A, IGF1 = insulin-like growth factor-I, IGF2 = insulin-like growth factor-2, IGFBP = IGF-binding protein 1 to 6. Relative units, data are expressed as fold difference relative to first sample (−40 days)
⁴Lsmeans for Days(PER) effect, including all treatments
^a,b,cLetters denote least squares means differ (P ≤ 0.05)
^xyIndicate a tendency 0.05 < P > 0.10, according to Tukey–Kramer test for the interaction between PER, Days and TREAT

ISSN: 1751-0147