Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 8, 1998
Publication Date: N/A
Interpretive Summary: Growth efficiency is fundamental to the productivity of meat animals such as the pig. It is widely accepted that nutritional status has a strong influence on the production and secretion of a variety of hormones which mediate growth and performance in domestic meat animals. While many studies have demonstrated the importance of identifying and understanding the hormones associated with growth, less is known with regard to the potential impact of management practices associated with nutritional changes which can alter the production and secretion of these growth- related hormones. Therefore, the purpose of this study was to evaluate the effects of weaning and changing post-weaning diets on developmental profiles of a variety of these growth-related hormones in the neonatal pig. This study provided some unique data which demonstrated that standard dietary changes can influence the developmental progression of growth- related hormones and their function in the neonatal pig. Additionally, this study identifies important interactions between dietary changes and animal age on growth-related hormones which will aid future efforts in the design and interpretation of developmental studies which focus on growth- related hormones. The results from this study will be of interest to agricultural scientists in academia and industry who are interested in the interactions between age and nutritional changes as they relate to overall growth and performance.
Technical Abstract: The effects of weaning and changing post-weaning diet composition on growth patterns and growth-related hormonal profiles were evaluated in neonatal pigs. Forty-eight crossbred piglets were assigned to two groups (n=24/group) based on weaning at 2 or 3 wk of age. At weaning, piglets were removed from the sow and placed on a commercial starter ration for the efirst 11 d post-weaning (Phase I diet). At d 12 post-weaning, pigs were placed on a growing ration for the remainder of the study (Phase II diet). Body weights and blood samples were collected twice weekly from birth until 42 d of age. Serum IGF-1, IGF-2, and ADG were reduced (P < 0.05) in both groups as a result of weaning, whereas serum GH was elevated (P < 0.05). Mild decreases in ADG occurred following the phase I to II dietary change (P < 0.05). Serum IGF-1 decreased following the phase I to II dietary change in the 2 wk weaning group (P < 0.05). Growth hormone secretion tended to increase following the change in post-weaning diets. A developmental decline in serum T3 occurred from birth to d 18 in both experimental groups (P < 0.05). Serum T3 levels were unaltered by weaning but declined in both groups following the change in starter diets (P < 0.05). Changes in T4 and cortisol secretion patterns were not associated with weaning or the change in post-weaning diets. Results from this study demonstrate that growth-related endocrine function is affected by management practices associated with dietary changes in the neonatal pig.