Potential of henylpropanolamine and monensin for body weight control and Ad Libitum feeding of broiler breeders from day-old to sexual maturity and effects on subsequent performance

Abstract

Three experiments were performed to evaluate the potential of phenylproanolamine and monensin as appetite suppressants for Indian River broiler breeder birds. In experiment 1, a total of 300 day-old sexed broiler breeder chicks were placed in battery cages and randomly assigned to five dietary treatments, namely 0, 50, 100, 200 and 400 ppm (mg/kg) of phenylpropanolamine hydrochloride added to a corn soybean meal basal diet formulated to contain 2860 kcal ME/kg and 20% crude protein. Phenylpropanolamine levels above 100 ppm significantly reduced feed consumption and body weight gain to four weeks of age. There was evidence of improved feed conversion with the use of phenylpropanolamine in the diet. In experiment 2, a total of 400 day-old sexed broiler breeder chicks were placed in battery cages and randomly assigned to 10 dietary treatments. Birds were fed diets containing 2860 kcal ME/kg and either 20% or 15% crude protein with five different levels of added drugs in the diet, namely 0, 500 and 800 ppm of phenylpropanolamine and 200 and 300 ppm of monensin sodium. Feed consumption and body weight gain to eight weeks of age were significantly reduced from feeding the drugs. Reducing the protein level from 20% to 15% also significantly reduced body weight gain and feed consumption. The drugs were more effective as appetite and growth suppressants with a low protein diet. Birds showed evidence of developing tolerance to phenylpropanolamine, but not to monensin. In experiment 3, a total of 180 male and 360 female day-old broiler breeder birds were randomly allocated to 18 pens. The birds were subjected to six growing systems which were a combination of three levels of monensin (100, 300, 400 ppm) and two levels of starter protein (14% and 18%). Birds on 100 ppm of monensin were feed restricted while birds on 300 and 400 ppm of the drug were fed ad libitum from day-old to sexual maturity. All the birds were fed the same breeder diet during the laying period. Birds grown on high levels of monensin were lighter and less uniform in body size at sexual maturity compared to the restricted controls at both protein levels...