Lysine mediation of neuroendocrine food regulation in guinea fowl

In poultry, obesity is partly influenced by food intake, and is increasingly becoming a nationwide problem. Hypothalamic food intake mechanisms are involved metabolically and neurologically via two peptide hormones, leptin and ghrelin, and the amino acid glutamate, which is enzymatically derived from lysine metabolism. We hypothesize that lysine homeostasis mediates regulation of feed intake and performance characteristics via the brain–liver axis through glutamate sensing. The objective was to examine the effects of lysine homeostasis in avian food regulation and performance through neuroendocrine signaling. One-day-old male French Guinea fowl (GF) keets (n = 270) were weighed and randomly assigned to 5 dietary treatments (0.80%, 0.86%, 0.92%, 1.10% control, and 1.22% lysine) in 3 replicates. At 4 and 8 wk of age 20% of experimental birds were randomly selected, weighed and euthanatized. The liver, pancreas, and hypothalamus were excised, snap frozen in liquid nitrogen and stored at –80°C until use. Tissue mRNA was extracted and cDNA synthesized for qPCR assays. Lysine at 0.80 and 0.86% hindered growth, development of digestive organs, expression of brain and liver glutamate and leptin receptors, and caused high mortality in GF. The fold change for metabotropic glutamate receptor I was lower (P \u3c 0.05) in liver and higher in brain at 0.86 and 0.92% than the control (1.10%) and 1.22% lysine. The 1.22% lysine exhibited highest expression of ionotropic glutamate receptor, while brain ghrelin receptor expression was highest at 0.86 and 0.92% lysine. Therefore, dietary lysine concentration may influence signaling pathways regulating food intake in brain-liver axis via glutamate synthesis

Evaluation of Lysine Requirement of the French Guinea Fowl Broiler

The commercialization of the guinea fowl has become a trend in many countries including the United States (Nahashon et al., 2006). Guinea Fowl were first introduced in the United States from Africa before the Civil War. There are three principle varieties of helmeted guinea fowl reared in the United States at this time. These include the Pearl, White and Lavender. The French variety is mostly reared for meat and served in restaurants all over the world. French guinea fowl are often raised for meat as the birds grow twice as fast and are about two pounds heavier than the common guinea fowl. Today, guinea fowl are also farmed all around the world for their meat, eggs and feathers. Over the years there has been an increase in the demand for guinea as specialty meat. This is due to its nutritional value. Guinea meat is very tender, lean and also is rich in protein and essential fatty acids. The commercialization of the guinea fowl has become a trend in many countries including the U.S. (Nahashon et al., 2006). Also, other guinea fowl products such as table eggs have shown to be profitable in other countries including the US. In order to have a profitable guinea fowl enterprise, we must first understand their growth characteristics. We also know that feed amounts to a major percentage of total cost of poultry production. Therefore, it is important to design and formulate feeds that can be utilized more efficiently by complementing the genetic potential of the bird. Doing so will profit the guinea fowl industry. Guinea fowl are fed turkey rations, which are very expensive, and contain 1.6% and 1.5% digestible lysine at 0-4 weeks of age (WOA) and 1.5 % at 4-8 (WOA) respectively (NRC 1994). The focus on the availability of amino acid has been a concern when formulating poultry diet. Lysine is the second most limiting amino acid, after methionine, in standard diets of poultry, such as the guinea fowl. It is considered an essential amino acid because the body cannot synthesize it, therefore it must be provided in the diet. Lysine is important because it influences growth and carcass characteristics as well as overall growth and feed conversion in poultry. Lysine also builds muscle tissue, produces antibodies and also enzymes that are important in overall growth. Therefore, when evaluating lysine levels there are many factors that can play a significant role in the outcome. These include sex, strain, protein levels, environment, and stress can affect the bird\u27s response to the levels of lysine. Many studies on broilers and other types of poultry have been carried out to explore the different factors that affect lysine levels. Since the lysine requirements for the French guinea fowl is unknown, this research was conducted to evaluate lysine requirements for optimum growth and performance of the French guinea fowl. We therefore hypothesize that controlling for environmental factors; optimum dietary level of lysine will be determined to be lower than those in the turkey rations that are routinely fed to the French guinea fowl broiler