Recent years have witnessed the discovery that amino acids (AA) are not only cell signaling molecules but are also regulators of gene expression and the protein phosphorylation cascade. Additionally, AA are key precursors for syntheses of hormones and low-molecular weight nitrogenous substances with each having enormous biological importance. Physiological concentrations of AA and their metabolites (e.g., nitric oxide, polyamines, glutathione, taurine, thyroid hormones, and serotonin) are required for the functions. However, elevated levels of AA and their products (e.g., ammonia, homocysteine, and asymmetric dimethylarginine) are pathogenic factors for neurological disorders, oxidative stress, and cardiovascular disease. Thus, an optimal balance among AA in the diet and circulation is crucial for whole body homeostasis. There is growing recognition that besides their role as building blocks of proteins and polypeptides, some AA regulate key metabolic pathways that are necessary for maintenance, growth, reproduction, and immunity. They are called functional AA, which include arginine, cysteine, glutamine, leucine, proline, and tryptophan. Dietary supplementation with one or a mixture of these AA may be beneficial for (1) ameliorating health problems at various stages of the life cycle (e.g., fetal growth restriction, neonatal morbidity and mortality, weaning-associated intestinal dysfunction and wasting syndrome, obesity, diabetes, cardiovascular disease, the metabolic syndrome, and infertility); (2) optimizing efficiency of metabolic transformations to enhance muscle growth, milk production, egg and meat quality and athletic performance, while preventing excess fat deposition and reducing adiposity. Thus, AA have important functions in both nutrition and health.

Amino acids: metabolism, functions, and nutrition

Economic losses from heat stress by us livestock industries

SYNOPSIS. Superimposed upon seasonal changes in morphology, physiology and behavior, are facultative responses to unpredictable events known as labile ( i.e. , short-lived) perturbation factors (LPFs). These responses include behavioral and physiological changes that enhance survival and collectively make up the “emergency” life history stage. There is considerable evidence that glucocorticosteroids, and other hormones in the hypothalamo—pituitary—adrenal (HPA) cascade, initiate and orchestrate the emergency life history stage within minutes to hours. This stage has a number of sub—stages that promote survival and avoid potential deleterious effects of stress that may result from chronically elevated levels of circulating glucocorticosteroids over days and weeks. These sub—stages may include: redirection of behavior from a normal life history stage to increased foraging, irruptivetype migration during the day, enhanced restfulness at night, and elevated gluconeogenesis. Once the perturbation passes, glucocorticosteroids may also promote recovery. Additional evidence from birds indicates that glucocorticosteroid responses to a standardized capture, handling and restraint protocol are modulated both on seasonal and individual levels. Field work reveals that these changes in responsiveness to LPFs have ecological bases, such as reproductive state, body condition etc., that in turn indicate different hormonal control mechanisms in the HPA cascade.

/pdf/ecological-bases-of-hormone-behavior-interactions-the-51sxihwmf0.pdf

Ecological bases of hormone-behavior interactions : the emergency life history stage

Undesirable side effects of selection for high production efficiency in farm animals: a review

Feeding behaviour feedback signals ruminant gastrointestinal tract metabolites and hormones central nervous control integrative theories of food intake control growth and fattening reproduction and lactation diet digestability and concentration of available energy specific nutrients affecting intake learning about food - preferences diet selection appetites for specific nutrients environmental factors affecting intake the intake of fresh and conserved grass prediction of voluntary intake. Appendices: particular features of poultry and ruminant animals outline programme to identify and store meals from the identities of animals and weights of food containers.

Voluntary food intake and diet selection in farm animals.

Utilization of phytate phosphorus and calcium as influenced by microbial phytase, cholecalciferol, and the calcium: total phosphorus ratio in broiler diets

D. M. Denbow

Papers

Utilization of phytate phosphorus and calcium as influenced by microbial phytase, cholecalciferol, and the calcium: total phosphorus ratio in broiler diets

Effect of Heat Stress Early in Life on Mortality of Broilers Exposed to High Environmental Temperatures Just Prior to Marketing

Leptin-induced decrease in food intake in chickens.

Effect of Microbial Phytase on Nitrogen and Amino Acid Digestibility and Nitrogen Retention of Turkey Poults Fed Corn-Soybean Meal Diets

Supplemental Microbial Phytase Improves Zinc Utilization in Broilers