Amino acid nutrition and ghrelin O-acyltransferase mRNA characterization in the broiler
Dimova, Mira Prodanova
MetadataShow full item record
Determining digestible amino acid requirements for broilers is essential for further improving feed efficiency and optimizing muscle accretion as broiler strains continue to be selected for better performance. Several trials were conducted with Cobb 500 FF and Cobb 500 FF x Hubbard M99 broilers to determine the digestible lysine (dLys) and threonine (dThr) requirements at varying ages and grow-out conditions. In the U.S., the number of birds raised to 49 days has increased to meet the demands of the breast products produced by these sized birds. The dLys requirement calculated in two genetic crosses of broilers from 35 to 49 days of age in this research will allow poultry nutritionists to formulate diets that better meet the requirement for this essential nutrient, which is critical for optimal breast meat yield. There had been a trend by poultry nutritionists to increase dietary dThr levels based on several reports, which indicated that the increased levels of dLys used to maximize breast yield increased the dThr requirement. The current research indicated that increasing the dThr levels in diets fed from 14 to 28 days of age is not warranted. Although great strides have been made in optimizing broiler performance, continued improvement will result from a better understanding of the regulatory mechanisms involved in feed intake and energy metabolism. One hormone implicated in the regulation of energy homeostasis and feeding behavior is ghrelin, which is activated through n-octaoylation carried out by the enzyme ghrelin O-acyltransferase (GOAT). Through real time RT-PCR, GOAT mRNA expression was detected in a few broiler tissues, but primarily expression was observed in the proventriculus. Furthermore, fasting caused up-regulation of GOAT mRNA expression in the proventriculus. By determining digestible amino acid requirements and better understanding the role of the ghrelin-GOAT axis in broilers, production efficiency can be optimized. Thus, fewer resources will be utilized for rearing the birds and less waste will be generated, thereby improving the environmental stewardship of the poultry industry while optimizing economic gains.