Effect of dietary n-3/n-6 ratio on fatty acid composition of liver, meat and perirenal fat in rabbits

Abstract

The metabolic pathways of dietary fatty acids were studied in rabbits by analysing the fatty acid profile of different tissues (liver, perirenal fat,longissimus lumborummuscle). Four groups of 24 hybrid males each were assigned to four semi-purified diets, varying in the source oflipids which differed in n-3/n-6 ratios: 180 g/kg sunflower (S), 80 g/kg flaxseed + 90 g/kg sunflower (SF), 160 g/kg flaxseed (F) and 60 g/kg fish oil (FI). The liver showed a very important rôle in fatty acid syntheses and was the tissue richest in long-chain (≥20 C) polyunsaturated fatty acids (LCP) of n-3 and n-6 series. The S diet gave the highest mono-unsaturated fatty acids and n-6 LCP (respectively, 201·9 and 384·9 g/kg,P< 0·01) also showing a clear antagonism v. n-3 LCP; the FI diet determined the highest enrichment of n-3 LCP (179·5 g/kg,P< 0·01). a-linolenic acid was efficiently converted into n-3 LCP mainly when п-ЗІп-6 ratio was high (Σn-3/С20: 4n-6: 2·74 and 3.61,P< 0·01 in flaxseed and fish-oil diet, respectively). The same trend occurred in the muscle but in a less consistent way. The adipose tissue more closely reflected the composition of the dietary fatty acids, showing variations mainly concerning polyunsaturated fatty acids (S diet), and LCP n-3 (FI diet: 44·9 g/kg,P< 0·01). Results showed the possibility of modifying the fatty acid profile of rabbit meat by dietary means and that the n-3/n-6 ratio of the food is crucial in regulating the relative presence of LCP n-3 or n-6 in meat products.

Dietary n-6- or n-3-rich vegetable fats and α-tocopheryl acetate: effects on fatty acid composition and stability of rabbit plasma, liver and meat

“…In our study in rabbits, increased amounts of EPA and DHA were found in plasma and liver due to the addition of LO to feeds (Tables 1 to 3), as it had been found in meat . This is in accordance with other studies in rabbit (Bernardini et al, 1999;Dal Bosco et al, 2004;Maertens et al, 2008) and other animals (Enser et al, 2000;Bou et al, 2006b). However, the effectiveness of the synthesis of DHA from linolenic acid in animals and humans is controversial, as it has been reported to be limited (Cherian and Sim, 1995;D'Arrigo et al, 2002;Hoz et al, 2003;Burdge and Calder, 2005b;Nuernberg et al, 2005).…”

“…Changes in the FA composition of tissues from rabbit (Bernardini et al, 1999), other animals (Wood and Enser, 1997;Enser et al, 2000;Bou et al, 2006b) and humans (Arterburn et al, 2006) have been reported as a result of varying the FA profile of diets. In our study in rabbits, the content of trans FA in plasma and liver and the content of MUFA in liver decreased, while total PUFA in liver increased (Tables 1 and 2) as BT in feeds was replaced by increasing doses of n-6-or n-3-rich vegetable fat .…”

“…A similar effect of increasing doses of LO in feeds was found in meat FA composition ; however, due to the higher biosynthetic activity of liver, the increases in long-chain n-3 PUFA in liver were greater than in meat, as were the decreases in long-chain n-6 FA. In other animal and human studies, concomitant reductions have also been reported in the content of long-chain n-6 PUFA, as a result of increased biosynthesis of n-3 FA in several tissues due to dietary LO (Cherian et al, 1996;Bernardini et al, 1999;Nuernberg et al, 2005;Arterburn et al, 2006).…”

“…Attempts have been made to increase the long-chain n-3 polyunsaturated fatty acids (PUFA) content in animal tissues by enriching diets with fats that have a high linolenic acid content (Bernardini et al, 1999;Enser et al, 2000;Bou et al, 2006b). However, the increase in dietary long-chain n-3 PUFA, achieved for instance by adding marine fat sources to the diet, has been reported to be more effective (Nettleton, 1991;Wood and Enser, 1997).…”

“…Fewer studies in the literature deal with rabbit feeding, although recently the number of studies conducted with rabbit has increased (Pla and Cervera, 1997;Bernardini et al, 1999;Castellini et al, 2001;Dalle Zotte, 2002;Dal Bosco et al, 2004;Lo Fiego et al, 2004;Corino et al, 2007;Gigaud and Combes, 2008;Maertens et al, 2008;Zsedely et al, 2008). Most of them are focused on rabbit meat due to its nutritional value, but there is a lack of comprehensive studies dealing, at the same time, with rabbit plasma, meat and other tissues more involved in the animal's metabolism, such as the liver.…”