Resumo

HEREDIA, Fernando; CAMPOS, Rómulo; GIRALDO, Leonidas  e  GARCIA, Katherine. Serum levels of ghrelin, growth hormone, and insulin during growth of cattle under tropical conditions. Ces. Med. Vet. Zootec. [online]. 2015, vol.10, n.1, pp.45-56. ISSN 1900-9607.

From a physiological and animal production standpoint, it is important to know the factors associated with growth and development of the rumen. Calf transition from monogastric into ruminant involves structural and physiological changes of the digestive system. This process involves hormones that affect both the orexigenic (ghrelin) and metabolic phases, and also nutrient utilization (i.e., insulin and growth hormone). The aim of this study was to monitor growth of calves between birth and six months of age and determine serum ghrelin, growth hormone, and insulin, in three breeds. Eight animals were selected from each breed (Harton del Valle, Holstein, and Brahman). Body weight was measured and blood samples collected every 30 days. Protein was analyzed by direct refractometry, insulin and ghrelin by radioimmunoassay (RIA), glucose by enzymatic colorimetry, and growth hormone (HG) by ELISA. A factorial design with two main effects (animal breed and sampling age) was used, blocking by weight groups. Analysis of variance showed differences (p<0.05) for main effects. The observed mean values were: 529 g/ day weight gain, 55.6 g/L protein, 4.99 mmol/L glucose, 297.69 pmol/L insulin, 59.11 pmol/L ghrelin, and 12,87 ug/L HG. Differences were observed for hormone values and indicators by age of calves at the time of sampling.

Palavras-chave : Cattle; gastrointestinal hormones; growth; rumen development.

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