Dietary Lysine: Effects on Lysine Homeostasis and Performance of Broiler Chickens
Lysine is an essential amino acid and hence it is indispensable. It is the second most limiting amino acid after methionine. It is considered the most limiting amino acid for growth in poultry. Lysine interactions affect growth performance of growing chicks. This study evaluates the effect of varying dietary lysine on lysine homeostasis and performance of broiler chickens. Birds were fed diets comprising 0.85, 1.14 and 1.42% lysine during the starter period and 0.75, 1.00 and 1.25% lysine during the grower period. These represent 75, 100 and 125%, respectively of National Research Council (NRC) recommendation for broiler chickens. In three replications, 168 birds were reared for 8 weeks. Feed and water were provided for ad libitum consumption. Body weight gain (BWG) and feed consumption (FC) were determined. Mortality was recorded as it occurred. At eight weeks of age, tissues were collected from 10 birds randomly selected from each treatment to assay for the expression of neuropeptide hormones. Ribonucleic Acid (RNA) was extracted and reverse-transcribed to complementary deoxyribonucleic acid (cDNA). Increasing dietary lysine concentrations from 0.75% to 1.42% proportionately increased BWG, FC and decreased feed conversion ratio (FCR, P<0.05) respectively. Low lysine (0.75%) caused high mortality. Ghrelin was up regulated significantly in the hypothalamus and pancreas in birds fed diets containing the 0.75% lysine. Ghrelin was up-regulated in the liver of birds fed diets containing 1.25% lysine. Ghrelin was not expressed in the intestine of birds fed the 0.75% lysine diets. On the other hand, the expression of ghrelin in the intestines of birds fed 1.25% lysine diets was less than the control (1.0% lysine). The highest expression of leptin and adiponectin were observed in the hypothalamus and liver of birds fed the 0.75% lysine diets while at 1.25% lysine diets the expression was significantly lower than that of the control (1.00% lysine). Leptin showed the highest expression in the liver of birds fed the 0.75% lysine diets. While there was no expression of adiponectin in the pancreas and intestines, it was significantly expressed in the liver of birds fed the 0.75% lysine diets. The expression of ghrelin was negatively correlated with the expression of adiponectin and leptin (P<0.05) in the liver, hypothalamus and pancreas. Leptin was positively correlated to adiponectin in the hypothalamus and liver (P<0.05). Therefore, lysine seems to be involved in the regulation of the neuro-endocrine molecules ghrelin, leptin, and adiponectin which also create a sense of satiety when the concentrations of lysine are low.
Molecular biology|Neurosciences|Genetics|Animal sciences
Collins N Khwatenge,
"Dietary Lysine: Effects on Lysine Homeostasis and Performance of Broiler Chickens"
ETD Collection for Tennessee State University.