Effect of chemical structure of fats upon their apparent digestible energy value when given to growing/finishing pigs

Abstract

Four metabolism trials were conducted. Trials 1 and 2 (Tl, T2) investigated degree of saturation of fats (ratio of unsaturated to saturated fatty acids, U/S) on digestible energy (DE) content. Fats evaluated were rape oil (RO) and tallow (T) for Tl (U/S 15-67 and 0-97 respectively) and RO and palm oil (PO) for T2 (U/S 15-33 and 0-85 respectively). Three fats of intermediary U/S for each trial were produced by blending the two fats in proportions to give U/S of 3-18,2-08 and 1-49 in both trials. Trials 3 and 4 (T3, T4) investigated the effect of free fatty acid (FFA) content of fats on DE value. Fats were soya-bean oil (SO) and soya-bean acid oil (SAO) for T3 (FFA 6-2 and 626-0 g/kg respectively) and T and tallow acid oil (TAO) for T4 (FFA 44-3 and 818-2 g/kg fat respectively). Three fats of intermediary FFA for each trial were formed by blending the two fats in the ratios of 72 :25, 50:50 and 25 : 75 in both trials. The FFA content of the blends were 161-2, 316-1 and 471-1 g/kg fat for T3 and 237-8, 431-3 and 624-7 g/kg fat for T4. All trials evaluated five fats by substitution, at 40, 80 and 120 g/kg into a basal diet, in a cross-over design, with 16 gilts of 25 kg initial live weight evaluating 16 diets over four time periods. Diets were offered for 10 days followed by a 5-day collection period using the marker to marker technique. Fat content of food and faeces, with methodology based on acid hydrolysis, allowed calculation of apparent digestible fat (AFD) of experimental diets. Analysis of variance gave effects of fats (P < 0-001 for Tl, T3 and T4 and P = 0-014 for T2), rates of inclusion (P < 0-001 for all trials), and fats X rates (P > 0-05, P > 0-05, P < 0-001, P < 0-01 for Tl, T2, T3 and T4 respectively). Extrapolation of the function obtained by regressing AFD of diets (y) on rate of inclusion of fat (x) to x = 1000 generated values for the fats. The product of the coefficient of apparent fat digestibility of fats and their respective gross energies gave DE values for fats which were MJ/kg: Tl . Data for fat blends intermediary between the two fats showed that DE improved exponentially as a function of U/S and that DE declined linearly with increasing FFA content.

Use of re-esterified palm oils, differing in their acylglycerol structure, in weaning-piglet diets

“…In this sense, SN, due to its high unsaturated FA content, showed the greatest total FA apparent absorption and, therefore, the greatest digestible energy. The more unsaturated the fat, the greatest the digestible energy, as has been observed by several authors with young pigs (Cera et al, 1988;Powles et al, 1994) and also with growing/ finishing pigs (Wiseman et al, 1990;Powles et al, 1993). However, SN treatment also showed the lowest SFA apparent absorption, in particular, of stearic acid.…”

Use of re-esterified palm oils, differing in their acylglycerol structure, in fattening pig diets

“…The difference of FFA was mainly relevant in the case of UFA (the proportion of UFA located at the sn-2 position of acylglycerol molecules was 52.8% and 11.3% for PN and PA oils, respectively). However, the effect of FFA on UFA absorption is lower in comparison with that of SFA (Powles et al, 1993). Thus, acid palm oils may be an economically interesting alternative to native palm oils, provided they have a moderate amount of FFA and a low percentage of moisture, impurities and unsaponifiable matter, as we have also observed in weaning piglets (Vilarrasa et al, 2015).…”

“…The same results were found by DeRouchey et al (2004), who examined the effects of different levels of FFA in choice white grease in weaning piglets. In contrast, Powles et al (1993) reported that the FFA content of fats appeared to be one of the major determinants of the digestible energy values of fats when given to growing/finishing pigs. One possible explanation for the lack of differences between PN and PA oils could be related to the particular FA positional distribution of these fat sources.…”

“…Thus, its use in fattening pig diets is attractive because it may be associated with a positive influence on fat firmness (Wiseman and Agunbiade, 1998). However, its high SFA content impairs its nutritive value (Powles et al, 1993). Besides the importance of the fat degree of saturation, the fat acylglycerol structure also plays an important role in the nutritive value of fats.…”

Unsaturated to Saturated Fatty Acids Ratio Adjustmentin Diets on Digestibility and Performance of Growing Pigs

“…This finding seems to suggest that the lower digestibility might be due to the higher saturated fatty acids in the tallow, suggesting that an optimal U:S ratio in dietary fat could be an important consideration. Similarly, Powles et al (1993) reported that DE content improved exponentially as a function of the U:S ratio. Gatlin et al (2005) also reported that the apparent digestibility of dietary fat in finishing swine improved with increasing values of the U:S ratio.…”