1,721,035 research outputs found
Thyroid hormones in small ruminants: effects of endogenous environmental and nutritional factors
No full textAppropriate thyroid gland function and thyroid hormone activity are considered crucial to sustain the productive performance in domestic animals (growth, milk or hair fibre production). Changes of blood thyroid hormone concentrations are an indirect measure of the changes in thyroid gland activity and circulating thyroid hormones can be considered as indicators of the metabolic and nutritional status of the animals. Thyroid hormones play a pivotal role in the mechanisms permitting the animals to live and breed in the surrounding environment. Variations in hormone bioactivity allow the animals to adapt their metabolic balance to different environmental conditions, changes in nutrient requirements and availability, and to homeorhetic changes during different physiological stages. This is particularly important in the free-ranging and grazing animals, such as traditionally reared small ruminants, whose main physiological functions (feed intake, reproduction, hair growth) are markedly seasonal. Many investigations dealt with the involvement of thyroid hormones in the expression of endogenous seasonal rhythms, such as reproduction and hair growth cycles in fibre-producing (wool, mohair, cashmere) sheep and goats. Important knowledge about the pattern of thyroid hormone metabolism and their role in ontogenetic development has been obtained from studies in the ovine foetus and in the newborn. Many endogenous (breed, age, gender, physiological state) and environmental factors (climate, season, with a primary role of nutrition) are able to affect thyroid activity and hormone concentrations in blood, acting at the level of hypothalamus, pituitary and/or thyroid gland, as well as on peripheral monodeiodination. Knowledge on such topics mirror physiological changes and possibly allows the monitoring and manipulation of thyroid physiology, in order to improve animal health, welfare and production.
Keywords: goats, nutrition, seasons, sheep, thyroid hormone
A leptin sandwich ELISA kit unusable for domestic animals
No full textAn instance of hormone assay method flaw is reported. In this journal Chronobiology International,
two papers appeared in which an ELISA method for human serum or plasma was utilized for blood
serum of horse and sheep, respectively. From our testing, it is resulted that such method does not
work at all for equine, sheep and other animal species. The use of commercial hormone assay kits
for heterologous species always needs a careful validation procedure. First, the same hormone
molecule by different species could not share enough homology to be regognized by and react
with antibodies utilized in the method. Furthermore, even with a full overlap of the molecules,
possible interferences by other components of the sample (matrix effect) have to be considered
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