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Effect of added crystalized dietary fat on the energy digestibility and growth performance of fattening pigs
In view of the easy handling during feed preparation, crystalline fat powder (CF) are often utilized in pig diets. Their energetic value is declared to be equal to its original source. To assess the correctness of this assumption, a digestibility and growth performance study with 48 pigs (4 littermates of the same sex from 12 litters) was carried out. The pigs were offered from 25 to 105 kg BW either a diet without added fat (F-) or a diet with either 6% added palm oil (P6) or 3 or 6% added CF (CF3 and CF6). The CF was produced from the same palm oil batch used in P6. As a result of the crystallization process the CF contained greater amounts of SFA (99.4 vs. 49.8%) and less MUFA (4.3 vs. 40.4%) and PUFA (0.1 vs. 9.8%). For the experiment, pigs were penned in grouping pens equipped with an automatic feeder system which allowed restricted feed allowance. Because diets were not isoenergetic (DE = 14:5, 15.9, 15.1 15.7 MJ/kg; dLys:DE = 0.61; 0.52; 0.56; 0.52 g/MJ, respectively), daily amount of feed offered was based on the DE intake for an ADG of 750 g. Energy and fat digestibility was determined at 30, 50, 70 and 90 kg BW using celite as indigestible marker. Although, DE intake was similar (26.9 MJ/kg; P > 0.05) for all treatments, CF6 pigs grew slower (P < 0.001) than F-, P6 and CF3 pigs (714 vs. 780, 754, 760 g/d). This difference was mainly accumulated from 25 to 60 kg BW (616 vs. 710, 667, 666 g/d). At 30, 50, 70 and 90 kg BW, the energy digestibility coefficients amounted to 0.71, 0.72, 0.76 and 0.74 for palm oil and 0.50, 0.67, 0.65 and 0.66 for CF. These differences were caused by on average 5% lower fat digestibility, the difference being larger in the grower than the finisher period. Based on these digestibility coefficients, the DE content of palm oil was 28.5 and 29.8 MJ/kg at 30 and > 50 kg BW, respectively. The corresponding values for CF were with 20.2 and 26.4 MJ/kg markedly lower. In conclusion, these results show that the greater degree of saturation of the fat due to the crystallization process markedly reduced the DE contents compared to its original source. In addition, it appears that compared to older pigs younger pigs can cope less well with highly saturated dietary fat.
Keywords: Saturated fat, energy digestibility, pig