Relative metabolizable energy values for fats and oils in young broilers and adult roosters

Abstract

Our goal was to determine if relative bioavailability values (RBV) for fats and oils (lipids) determined in adult roosters are different than RBV determined with young broiler chickens. Lipids that were expected to have widely varying ME content were evaluated using a slope-ratio approach in adult roosters (Exp. 1) via the precision-fed rooster assay (PFRA) and broiler chicks via a growth assay (Exp. 2). The same lipids were tested in both experiments and were refined corn oil (RCO), a 2:1 blend of stearic acid (C18:0) with RCO (SAB1), a 1:1 blend of C18:0 with RCO (SAB2), tallow (TW), poultry fat (PF), and corn oil from a corn ethanol plant (DDGSCO). In Exp. 1, roosters were tube-fed diets containing 0, 5, and 10% of supplemental lipid in ground corn. In Exp. 2, diets consisted of 0, 5, and 10% supplemental lipid in an amino-acid fortified corn-soybean meal diet. Chicks were limit-fed test diets from 10 to 20 d posthatch to maintain energy as the growth-limiting factor. The TMEn of diets or BW gain of chicks were regressed on supplemental lipid level. The RBV were calculated as the regression coefficient of the test lipid divided by that of RCO. For Exp. 1 a non-linear response was observed for SAB2; however, the RBV for SAB1 (22%), TW (72%), PF (96%), and DDGSCO (90%) were as expected. The RBV of SAB1 and TW were lower (P < 0.001) than RCO, while PF and DDGSCO were not different than RCO. For Exp. 2, BW increased linearly in proportion to the energy content of the lipid sources. The RBV of SAB1 (22%), SAB2 (46%), and TW (76%), were lower (P < 0.001) than RCO, while PF (96%) and DDGSCO (97%) were not different than RCO. Excellent agreement was obtained for RBV between the two assays, with rooster and chick values being similar and the ranking of the lipids being the same for the two assays.

The effects of soy oil, poultry fat and tallow with fixed energy : protein ratio on broiler performance

“…In another study that used diets containing corn oil and PF, there was no significant difference in weight gain and FCR between the groups and values improved as oil levels increased (Valencia et al, 1993). No significant differences were found between carcass weights and the yields of the groups that were fed with SO and PF (Andreotti et al, 2001). In a study using SO, PF, T and their combinations, the ALWs of the SO group were higher (Aardsma et al, 2017).…”

“…Some of these advantages provide an intensive energy source to be used for increasing the energy ratios of the poultry diets, improving growth and feed conversion ratio (FCR) and reducing feed consumption due to less heat stress and higher heat resistance (Moura, 2003). However, there are some difficulties with using fat, such as balancing the feed energy, rancidity, additional equipment requirements, and low digestion especially in young chicks (Sell et al, 1986;Wiseman and Lesire, 1987;Aardsma et al, 2017).…”

“…Used alone or mixed with other vegetable oils or animal fats in feeds, SO is one of the most important fat sources used in poultry diets after undergoing various processes such as filtration, hydration, degumming (Beauregard et al, 1996); digestibility of SO is higher than poultry fat (Aardsma et al, 2017) and T (Mahagna et al, 1988;Aardsma et al, 2017).…”

“…Poultry fat is obtained from slaughter by-products and non-edible organs by being processed in a rendering plant via a fat press. The ratio of unsaturated fatty acid in PF is reported to be higher than T (Aardsma et al, 2017). Poultry fat yield varies between 1.3 % and 1.6 % of average live weight (ALW) (Mano et al, 1999).…”

“…Tallow is obtained from sheep and bovines by methods similar to those used to obtain poultry fat. The ratios of saturated fatty acids such as palmitic acid and stearic acid are high in T (Aardsma et al, 2017). Tallow is especially effective when metabolic energy intake decreased and production is limited during heat stress conditions.…”