Use of combinations of re-esterified oils, differing in their degree of saturation, in broiler chicken diets

Abstract

Re-esterified oils contain higher proportions of mono- and diacylglycerols, and also higher proportions of saturated fatty acids (SFA) at the sn-2 position of acylglycerol molecules than does a native oil with the same degree of saturation, which enhances the apparent absorption of SFA. Moreover, as happens with native oils, their nutritive value could be further improved by blending re-esterified oils of extreme degrees of saturation. Therefore, the aim of the current study was to assess the effect of increasing the dietary unsaturated-to-saturated fatty acid ratio (UFA:SFA) by adding re-esterified soybean oil in replacement of re-esterified palm oil, on fatty acid (FA) apparent absorption and its consequences on growth performance, carcass fat depots, and FA composition of abdominal adipose tissue. For this purpose, one hundred twenty 1-day-old female broiler chickens were randomly distributed in 30 cages. The 2 pure re-esterified oils, together with 3 re-esterified oil blends, were included in the basal diet at 6%. The increasing dietary UFA:SFA ratio resulted in an improved total FA apparent absorption (linear effect for the starter period, P = 0.001; quadratic effect for the growerfinisher period, P = 0.006) and, therefore, an improved feed conversion ratio (FCR) for the overall period (linear effect, P = 0.003). In the starter period, the improved fat absorption was due to the growing presence of linoleic acid and the enhanced absorption of SFA, mono- and polyunsaturated FA (associative effects among FA; P < 0.05). In the growing-finishing period, however, the absorption of mono- and polyunsaturated FA was not affected (P > 0.05). The UFA:SFA ratio of the abdominal adipose tissue varied in the same direction, but to a lesser extent than that of the diet. Whilst the deposited-to-absorbed ratio of polyunsaturated FA remained relatively constant as the dietary UFA:SFA ratio increased, the deposited-to-absorbed ratio of SFA increased, and that of monounsaturated FA decreased. Taken together, the addition of re-esterified soybean oil in replacement of re-esterified palm oil improved fat absorption, but no synergism was observed between re-esterified oils.