The Effects of Feed Ingredients and Feed Additives on Energy Metabolism in Chickens

Abstract

Feed is the most expensive cost in rearing poultry. Within the poultry diet, energy is the most expensive component. Maximizing energy utilization can improve poultry growth and production while reducing waste output, ultimately improving both the economic and sustainable poultry production efforts. This thesis examines alternative feed ingredients/feed additives, including soybean soapstock and a natural choline alternative, on their ability to supply energy and alter energy use in chickens. Soybean soapstock was evaluated in chickens to determine the apparent metabolizable energy (AME). Soapstock is a by-product of the soy oil purification industry that can be added back to soybean meal at rates of 0-2%. Soapstock was added to a basal diet at rates of 0, 3, 6 and 9% and the slope of dietary energy vs. soapstock inclusion was used to calculate the AME of both soybean oil (8,159 kcal/kg) and soy soapstock (3,669 kcal/kg). In this experiment, the addition of soybean soapstock to soybean meal can increase the AME of soybean meal by 12 kcal per 1% of soybean soapstock. Soybean soapstock can contribute metabolizable energy when added to soybean meal but also results in a dilution of crude protein. Choline is a required vitamin that is used for fat metabolism among other diverse effects. Typically, the commercial inclusion of choline has been higher than the reported NRC requirement. Some recent publications have suggested that the requirement for choline might be higher than the NRC, but lower than commercial inclusion rates. A 12 wk laying hen experiment evaluated a commercial type corn/soybean meal/animal protein diet that was formulated to be lower but not deficient in choline, a choline chloride control and 2 concentrations of a natural choline alternative. The natural choline alternative at a lower inclusion rate improved FCR (P = 0.10) in comparison to both the NC and NC + CC with the higher inclusion of NCA had an intermediate response. The same lower inclusion of the natural choline alternative increased relative eggshell weight (P = 0.06) and eggshell thickness via other mechanisms. This thesis explores the use of alternative ingredients and feed additives, and their effect on energy digestibility, production and hepatic energy storage in chickens.