Carotenoid supplementation in poultry

Dietary incorporation of carotenoids into the skin and fat of broilers is relatively fast. Broiler meat birds can be supplemented for 4 weeks out of the 8-week growing period with satisfactory results (Marusich and Bauernfiend, 1981). Carotenoids are generally supplemented at higher levels in grower and finisher feeds than in starter rations. Marusich and Bauernfiend (1981) reported that a range of 2.2-11 mg carotenoid/ 

The yellow coloration of egg yolks is important for consumer acceptance of this product. Moderately colored egg yolks are appropriate for table use, while highly colored yolks are desired as ingredients in processed foods (Klaui and Bauernfiend, 1981). The pigmentation of yolk is directly correlated to the amount and type of carotenoid supplementation (Marus-ich et al, 1960). The addition of antioxidants to carotenoid-supplemented diets resulted in increased pigmentation of egg yolks over those without added antioxidant (Madiedo and Sunde, 1964). It is likely that the antioxidant provided a protective effect for the carotenoid during feed storage and/or in the digestive tract of the bird. Williams etal. (1963) reported that 8-10 days are required to reach a steady-state carotenoid concentration in egg yolks of hens provided a carotenoid-rich diet. 

In the egg yolk, zeaxanthin and lutein appear to be the primary carotenoids responsible for yellow color (Smith and Perdue, 1966 Schiedt et al, 1985 Schaeffer et al, 1988). Schaeffer et al. (1988) utilized HPLC analysis to reveal over 20 carotenoid species in the yolks of hens fed typical layer diets. Hamilton et al (1990) recently reported that the oleoresin of red pepper could be supplemented to laying hens to yield egg yolks with increased redness and yellowness. The three major pigments isolated were trans-lutein, trans-zeaxanthin and trans-capsanthin. The authors noted that the incorporation of small amounts of reddish capsanthin is advantageous for intensifying the yellow color of yolks. 

Vitamin C, or ascorbic acid, is an effective antioxidant in foods (Deng et al., 1978 Cort, 1982 Shivas et al., 1984 Mitsumoto et al., 1991a). Numerous studies have been performed to determine the effects of ascorbic acid supplementation on food-producing animals, especially poultry. Pardue and Thaxton (1986) have published an excellent review on ascorbic acid supplementation in poultry. The potential benefits of supplemental ascorbic acid extend beyond the current focus of improved animal-based food products. 

The greatest benefit of dietary vitamin C supplementation appears related to broiler carcass yield. Quarles and Adrian (1988) recently reported that 976 ppm of ascorbic acid in drinking water of broilers for 24 hours prior to slaughter improved dressing yield (%) and breast yield 

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