Análisis del Sistema de Control Interno para el Proceso de Facturación

Being a fat-soluble vitamin, absorption and bioavailability of VE depend highly on the properties of dietary fat. Piglets fed with 5% choice white grease showed better absorption and deposition of VE in terms of α-tocopherol content in serum, liver, heart, and adipose tissues compared to piglets fed diets without fat supplementation (Moreira and Mahan, 2002). Another example of this fact was illustrated recently in the study of Prévéraud et al. (2014), where dietary fat sources affected α-tocopherol concentrations in plasma and tissues of pigs. The α-tocopherol concentrations in plasma and tissues decreased when pigs were fed higher PUFA diets (from linseed and safflower oil) than the

Based on those results, they suggested that the profile of dietary FA is one of the key factors to determine VE status and bioavailability in plasma and tissues. Similarly, Lauridsen et al. (2013) reported that dietary fatty acid composition and VE supplementation influenced the α-tocopherol stereoisomer composition in the liver, less proportion of the RRR- α- tocopherol was observed in pigs provided fish oil and the highest dose of VE in comparison with other dietary treatments of tallow and sunflower oil. Expression of α-TTP in the liver, which is a key protein in VE metabolism, was higher in pigs fed 5% fish oil than pigs fed 5% tallow and sunflower oil (Lauridsen et al., 2013).

2.6.2 Antioxidant status and shelf life of pork

Serum VE content was generally reduced, and serum TBARS content was increased when pigs were fed peroxidized lipids based on a review of 16 published studies (Hanson et al., 2014). At the same time, dietary VE supplementation above the requirement increased serum VE, and decreased tissue TBARS as reviewed in section 2.5. These research suggests that feeding lipids of low quality and supra-nutritional VE affect the metabolic oxidative status of pigs in opposite directions, their interaction should be promising. However, it is unclear if antioxidants are useful additions to lipids to maintain optimal nutritional value, or if their addition to swine diets is beneficial in overcoming an oxidative metabolic challenge from low-quality dietary fat.

Besides, the ability to be deposited into different tissues of both VE and different fatty acids and the different chemical property of UFAs and VE provide an opportunity for both dietary constituents to counteract each other in tissues. On the one hand, as an essential micronutrient for pigs, VE plays important roles in reducing oxidative stress as an antioxidant, improving the oxidative stability of pork and prolonging fresh pork shelf life (Boler et al., 2009). On the other hand, the susceptibility of pork to lipid peroxidation and rancidity may increase when high levels of PUFA and degree of unsaturation were presented due to dietary FA profile (Mitchaothai et al., 2007; Okrouhlá et al., 2010; Browne et al., 2013a). Therefore, improving dietary VE levels could increase lipid stability of increasing UFAs in tissues caused by the change in dietary fatty acids (Guo et al., 2006). Wang et al. (2012) found that supplementation with high levels of VE decreased TBARS

value of meat produced with high DDGS diet (30% highest ) on 4, 7, 10 and 13 d post slaughter. The study also indicated that the high content of UFAs in DDGS favored lipid oxidation by increasing PUFA content in the muscle, while increased dietary VE supplementation from 10 to 210 IU/kg slowed the oxidation down (Wang et al., 2012).

The protective effect on lipid oxidation by increasing dietary VE seems not to work well in pigs fed extremely oxidized unsaturated fat. When pigs were fed diets containing 30% peroxidized DDGS (5.2 ng malondialdehyde/mg oil, the peroxide value of 84.1 mEq/kg oil, and 0.95% S content), although increasing dietary VE content by ten times from NRC (2012) requirement estimates of 11 IU/kg diet increased tissue VE concentration linearly with increasing dietary VE supplementation, it failed to counteract the negative effect caused by peroxidized DDGS. The negative effects included higher TBARS content in the muscle, increased PUFA and iodine value. (Song et al., 2014).

To improve oxidative stability in the feed and pigs as well as the resultant pork, depending on the types and levels of fats in diets, different levels of antioxidants such as VE or synthetic antioxidants are needed more/less. In the case of the abuse use of DDGS around 30%, supranutrional VE supplementation up to 200 ppm may be necessary to eliminate their negative effect in pork quality, especially the lost in shelf life caused by the increasing UFA in the resultant pork product. There have been rare reported study that investigated the interactions among dietary fat sources, and supplementation level or isoforms of VE associated with heavy SLW.

2.6.3 Immunity

High levels of PUFA in the diet are thought to increase VE requirements, and interactions between high PUFA diets and VE to affect immune function have been reported (Bendich et al., 1985; Lauridsen, 2010). Reduction in inflammatory response can be observed in terms of decreasing serum TNF-α concentration after an immune challenge by decreasing the n-6:n-3 ratio (Meyer, 2003; Beaulieu, 2011). Additionally, increasing

The beneficial effect of both n-3 fatty acids and VE in the immune system were all previously reported, and an additive effect between them was expected. In an E. coli LPS challenged grow-finishing pig study, prostaglandin E2, which is largely responsible for

neurological infection responses such as anorexia and fever, was reduced by supplementation with either VE or n-3 fatty acids, while no additive effects on serum concentrations of pro-inflammatory cytokines were observed (Upadhaya et al., 2015b). Similar results were reported in weaning pigs also, where pigs were fed with 3×3 treatment of fat sources (tallow, sunflower oil, and fish oil) and VE levels (85, 150, and 300 mg/kg all rac-α-tocopheryl acetate), the interaction between fat sources and VE supplementation on immunity were not observed (Lauridsen, 2010).

Even though the published data has not demonstrated an interaction on immune response between fat sources and VE supplementation in pigs, research in humans and fish showed some evidence of the additive effect or interactions. Based on a randomized control trial, dietary n-3 PUFAs plus VE restored immune-competence and prolonged survival for severely ill patients with generalized malignancy (Gogos et al., 1998). In another study in humans consuming diets with 15% PUFA, and with or without 80 mg tocopheryl acetate/day, increasing dietary levels of PUFA to 15% may adversely affect some indices of DNA stability in human lymphocytes, while increasing the dietary intake of VE by 80 mg/day ameliorates the damaging effects of PUFA (Jenkinson et al., 1999). When rainbow trout were fed with diets containing three levels of dietary VE (0, 100 or 1000 ppm ATA) and n-3 PUFA either at 20 or 48% of dietary lipid, both humoral and cellular immune functions deteriorated in fish fed VE deficient diets whereas improvement in most parameters corresponding to supplementation of supra-nutritional levels of VE were observed, and the research clearly indicated the role of VE in maintaining the immune functions in fish in relation to dietary n-3 PUFA (Puangkaew et al., 2004).