NUTRITIONAL ASPECTS OF HYDROGENATED AND REGULAR SOYBEAN OIL ADDED TO DIETS OF BROILER-CHICKENS

The objective of the present study was to evaluate the effect of degre e of saturation of fat incorporated into broiler diets on performance and body fatty acid (FA) profile. The various degrees of saturation we re achieved by using regular soybean oil (SO) and hydrogenated soybean oil (HSO), mixed at different proportions. The work was carried out o n commercial broilers (Experiment 1) and on lines of chickens divergen tly selected for high (HF) or low (LF) abdominal fat (Experiment 2). D aily BW gain and gain:feed ratio increased and the amount of feed inta ke decreased as the dietary fat saturation decreased. Digestibility of total fat and of each of the FA was lowest in the HSO group and reach ed maximal values when 23% or more of the added oil was SO. The AME(n) , values of the diets were almost parallel to fat digestibility. The p erformance of the HF and LF chickens was affected by the degree of sat uration similarly to that observed for the commercial stock. The degre e of dietary fat saturation had very little effect on saturated FA (C- 16:0 and C-18:0) in body Lipids, reduced the level of monoenoic FA (C- 16:1 and C-18:1), and raised that of polyunsaturated FA (PUFA) (C-18:2 , C-18:3, and C-20:4). Monoenoic FA were higher, whereas PUFA were low er in the HF than in the LF line. The improved AME, in diets containin g unsaturated fat is probably due to higher fat digestibility, direct deposition of PUFA in body lipids, and lower lipogenesis, associated w ith lower heat production.