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Oxygen consumption (VO2), carbon dioxide production (VCO2), heart rate and the arterial plasma concentrations of glucose, non-esterified fatty acids, thyroxine (T4), 3,5,3'-tri-iodothyronine (T3), TSH, insulin, cortisol and GH were measured before and after feeding a formula milk diet to lambs aged 9, 21, 33 and 46 days. In all age groups, VO2, VCO2 and heart rate increased significantly following feeding and this effect was greatest at 9 days of age. Both VO2 and VCO2 before and after feeding decreased with age. Plasma concentrations of T3 before feeding did not change with age, but plasma T3 levels after feeding were significantly higher in lambs aged 9 days compared with 33 and 46 days. There was no effect of feeding on TSH or age on plasma TSH and T4 concentrations. In all age groups, glucose concentration increased after feeding and was paralleled by a rise in insulin concentration. At 9 and 21 days of age plasma glucose and insulin concentrations reached a plateau after the initial postprandial increase and together with a rise in respiratory quotient was indicative of a stimulation of carbohydrate oxidation. Plasma concentrations of GH increased after feeding at 21 days and older, when the mean growth rate was also stimulated by 75%. Basal metabolic rate and dietary-induced thermogenesis both decreased with age and, as a result, metabolism associated with an increase in GH levels after feeding became more efficient in terms of growth rate after 21 days. It is therefore concluded that there are major endocrine and cardiorespiratory changes in response to feeding of the young lamb which are important in stimulating and/or facilitating its growth and development.

Original publication

DOI

10.1677/joe.0.1230295

Type

Journal article

Journal

The Journal of endocrinology

Publication Date

11/1989

Volume

123

Pages

295 - 302

Addresses

Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Headington.

Keywords

Thyroid Gland, Animals, Sheep, Carbon Dioxide, Hormones, Energy Metabolism, Oxygen Consumption, Body Temperature Regulation, Heart Rate, Eating, Animal Nutritional Physiological Phenomena