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An assessment of the relationship between tissue growth patterns and selected hormone profiles among sex phenotypes in cattle
Published online by Cambridge University Press: 02 September 2010
Abstract
The four sex phenotypes were used to study the relationship between carcass composition and serum profiles of hormones thought to affect growth. Forty calves (10 bulls, 10 steers, 10 heifers and 10 ovariectomized heifers) from Hereford dams crossed with Simmental-Hereford bulls (¾ Simmental-¼ Hereford) were given a high energy diet from 10 to 16 months of age. Sequential blood samples (20-min intervals) representing 6-h windows were obtained from each animal at the outset of the experiment and at 28-day intervals thereafter. Samples were assayed for growth hormone (GH), insulin, triiodothyronine, cortisol, testosterone, oestradiol-17β, urea and albumin. The 9-10-llth rib was dissected into fat, lean and bone, and chemical analysis was performed on the dissected soft tissue. Bulls accumulated more lean tissue and less fat than any other group. Heifers and ovariectomized heifers accumulated the least lean and most fat while steers were intermediate between bulls and the two heifer groups. Bulls may have accumulated more lean and less fat than the heifers due to higher GH and testosterone concentrations, and lower circulating concentrations of cortisol and insulin. The known function of these four hormones and their relative concentrations between bulls and the two female groups were consistent with their suggested role in the relative carcass compositions. The intermediate composition of the steer carcass may have resulted from an interplay between the proteogenic influence of higher GH concentrations, the proteolytic influence of elevated cortisol, the absence of testosterone and the lipogenic influence of higher insulin.
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- Copyright © British Society of Animal Science 1988
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