Ghrelin is an endogenous ligand of the growth hormone secretagogue receptor and a potent orexigenic agent in human and rodent studies, but there is limited information about its effect in dairy cows. Twelve low genetic merit and 9 high genetic merit Holstein-Friesian dairy cows in peak lactation that were offered unrestricted access to fresh pasture were used to determine whether genetic selection for milk production resulted in an associated increase in plasma ghrelin concentration in grazing dairy cows. Blood samples were taken prior to the a.m. milking (i.e., baseline) and following 2 h of grazing after the a.m. milking on 2 consecutive wk during peak lactation. Milk production and dry matter intake were greater in high genetic merit cows compared with low genetic merit cows. Plasma ghrelin and growth hormone concentrations were elevated in high genetic merit cows pre- and post-grazing, and there was no significant interaction between genetic merit and time of sampling. Genetic merit did not affect the plasma nonesterified fatty acid or glucose concentration, but the plasma concentrations of metabolites and hormones measured were diminished 2 h after feeding. Data indicate an increase in plasma ghrelin associated with genetic selection for milk production, and an associated increase in dry matter intake. © American Dairy Science Association, 2006.

Item Type:	Refereed Article
Research Division:	Agricultural, Veterinary and Food Sciences
Research Group:	Animal production
Research Field:	Animal nutrition
Objective Division:	Animal Production and Animal Primary Products
Objective Group:	Livestock raising
Objective Field:	Dairy cattle
UTAS Author:	Roche, JR (Dr John Roche)
ID Code:	41277
Year Published:	2006
Web of Science® Times Cited:	21
Deposited By:	Agricultural Science
Deposited On:	2006-12-20
Last Modified:	2006-12-20
Downloads:	0