Influence of Soy Oil Source and Supplementation of the Diet With Vitamin E and Vitamin C on Performance and Egg Quality of Single Comb White Leghorn Laying Hens From Forty Four to Fifty Six Weeks of Age
Two experiments (Exp.) were conducted to determine the AME content of refined soybean oil (SO), recycled soybean oil (RSO), and acidulated soybean oil soapstocks (ASO) and the effects of inclusion of vitamin E and vitamin C in diets containing 3.5% of these soy oils on performance and egg quality of Hy-line hens from 44 to 56 wks of age. In Exp. 1 the AME of the 3 experimental oils were determined in adult cocks using 6 individual replicates per treatment. The apparent total tract digestibility (ATTD) of SO, RSO, and ASO were measured by 1) difference between AME values of the basal diet without any oil added and that of the diet based on 95% basal diet and 5% of the experimental oil, and 2)directly multiplying the ATTD of the ether extract fraction of the diet by the GE of the oil. The determined ATTD were 95.2, 94.5, and 85.9% for SO, RSO, and ASO, respectively. The AME of the oils were 9,138, 8,955, and 7,961 kcal/kg measured by the substitution method, and 8,916, 8,880, and 7,849 kcal/kg calculated directly from the ATTD coefficient of the ether extract, respectively. In Exp. 2 there were 12 treatments arranged factorially with 3 oil sources (SO, RSO, and ASO), 2 levels of vitamin E (0 vs. 250 mg/kg), and 2 levels of vitamin C (0 vs. 250 mg/kg). Each diet was replicated 5 times and the experimental unit was formed by 5 hens caged together. The trial was conducted under moderate temperature conditions (21 ± 3ºC and 50% humidity) and lasted for 12 wks (44 to 56 wks of age). For the entire experimental period, diet did not affect laying hen performance or egg quality traits. It is concluded that recycled oil and acidulated soybean oil soapstocks are good alternatives to refined soybean oil in diets for laying hens. Under the conditions of this research, the supplementation of the diet with extra amounts of vitamin E and C to improve egg production or egg quality is not justified.