Poultry, Fisheries & Wildlife Sciences
Open Access

Abstract

Retinoic acid and Broiler Carcass Lipid Feeding Retinoic Acid Reduces Total Carcass Fat in Growing Broiler Chickens

TD Brandebourg and CY Hu

All-trans retinoic acid (RA), the carboxylic form of vitamin A, inhibits fat cell differentiation in vitro in multiple mammalian species. However, the ability of RA to limit adipose tissue accretion in monogastric meat-producing animals in vivo has not been investigated. The objective of this study was to determine the effect of feeding RA on total carcass lipid and tissue concentrations of RA in growing broilers. In the first experiment, 48 one-day-old birds were fed either a commercial starter-grower diet or the commercial diet supplemented with 14 mg/kg RA for six weeks. Feeding RA decreased carcass weight (12%; P<0.0001), feed intake (9%; P<0.0001), and average daily gain (12%; P<0.0001) while tending to increase feed efficiency (4%, P<0.07). Retinoic acid significantly decreased total carcass lipid was by 14% (P<0.008) though abdominal fat mass only tended to be decreased in RA-treated birds (12%; P<0.07). In the second experiment, 36 one-day-old chicks were randomly assigned to either the control or RA-supplemented diet (14 mg/kg) and liver and adipose tissue RA concentrations were determined using HPLC. Liver RA concentrations were three-fold higher in birds consuming the RA-supplemented diet (P<0.02) diet did not significantly affect RA concentration in adipose tissue (P<0.21). However, RA concentrations were numerically lower in birds fed the RA-supplemented diet on each day measured. Expression of retinoic acid receptors, retinoic acid receptor alpha (RARα) and retinoid X receptor alpha (RXRα) was verified in adipose tissue by semi-quantitative PCR. These results suggest that feeding RA can reduce carcass adiposity. However, this approach may be limited by physiological mechanisms that constrain retinoic acid accumulation in adipose tissue. Better characterization of these mechanisms may reveal targets that could be useful for reducing carcass fat in growing broilers either through selection programs or the administration of exogenous effectors.