The effect of ovariectomy on liver metabolism and maintenance energy requirement of hens.

Six pullets from each of an egg-producing and meat-producing strain were ovariectomised at 12 weeks of age. Ovarian regrowth occurred in two of the egg-producing and four of the meat-producing strain. 2. Measurements of heat production and energy balance were made after peak lay with ovariectomised and sham-operated laying pullets of both strains. Measurements on the ovariectomised pullets were made before and after implantation with oestrogen pellets. 3. Within each strain the ME requirements for maintenance (per kg W0.75), determined by linear regression analysis, were similar whether or not the starvation heat production data were included. 4. The ME requirements for maintenance decreased substantially after ovariectomy but subsequent implantation with oestrogen pellets did not increase these requirements. 5. Studies of hepatic enzyme activities indicated that the major influence of the mature ovary was on hepatic lipid metabolism. This was exerted through a specific stimulation of lipogenesis rather than a general increase in metabolism.