Influence of fatty acid composition of soybean oil vs. beef tallow on egg yolk fatty acid profiles of laying hens

Abstract

We investigated the effect of dietary soybean oil (SBO) vs. beef tallow (TAL) on egg yolk fatty acid composition in laying hens. Four laying hens (Hi-Sex brown chickens), 40 weeks of age, were given experimental diet and recorded data between day 7 and 42. The hens were fed cassava starch-soybean meal with 10% SBO or TAL. Fatty acid composition was determined for (a) soybean oil and beef tallow samples, (b) yolk lipids and (c) 5 yolks per hen on day 32 and 35. Feed intake of SBO treatment trended to be depressed (as low as 95.32 g/h/d) compared with the TAL treatment (105.55 g/h/d), albeit the difference was not significant (p>0.05). SFAs accumulation in egg yolks was between 1,141.84-1,509.42 mg/yolk mass, irrespective of SFA intake (i.e., 2,099.56 mg/h/d on the SBO diet or 8,878.16 mg/h/d on the TAL diet). The main residue of SFAs from the intake (stearic acid; 18:0) results in an increase in oleic acid (18:1n-9) or omega-9 fatty acid accumulation in the egg yolk. The linoleic acid (18:2n-6) in the yolk (i.e., 1,337.28 mg/yolk mass in the SBO treatment vs. 312.39 mg/yolk mass in TAL treatment) is directly related to dietary consumption (p<0.05) (i.e., 6,872.47 mg/h/d in the SBO diet and 1,010.40 mg/h/d in the TAL diet). The addition of TAL in diet strongly affects oleic acid (47.03% of 18:1 n:9) accumulation in the yolk, while the addition of SBO to the diet resulted in PUFA (39.08%) accumulation in the yolk (mainly as omega-6 PUFAs).