Amélioration du profil des matières grasses de la viande de poulet et du foie gras de canard par l’ajout de graines de lin extrudées dans l’alimentation
Improving the fatty acid pattern of chicken meat and duck foie gras by an extruded linseed feed supplement
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Table 1: Fatty acid composition of chicken (thigh) intramuscular fat according to diet - Table 2 : Fatty acid pattern of foie gras and intramuscular fat in ducks.
Amélioration du profil des matières grasses de la viande de poulet et du foie gras de canard par l’ajout de graines de lin extrudées dans l’alimentation
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Context
The nutritional advantages of a higher proportion of essential fatty acids of the omega-3 family in human food are now well established. Much research focuses on techniques for increasing the omega-3 fatty acid content of animal products (milk, meat and eggs). Adding linseed to animal feed offers a natural means of achieving this aim.Objectives
Two trials were conducted, one with broilers and the other with force-fed ducks, in order to investigate the effects of adding extruded linseed to their diet upon the composition of the intramuscular fat and foie gras. The first trial looked at the effect of the time from addition of extruded linseed (3.25 % of the diet) to slaughter on the composition of the intramuscular fat in broilers. The second trial focused on the impact of extruded linseed (2 % and 4 % of the diet) added during force feeding on the fatty acid composition of the foie gras and intramuscular fat in ducks.Results obtained
The “broiler” trial comprised 900 chickens. Three different feeding systems were tested during the period of the experiment (age between 46 and 73 days): control diet fed throughout the period (R0); control diet from age 46 to 59 days followed by the linseed diet from age 59 to 73 days (R14); linseed diet fed throughout the period (R27). A significant increase in the proportion of n 3 fatty acids was observed with the linseed supplement, with the biggest rise occurring with the longest period of supplementation (27 days compared to 14 days before slaughter) (Table 1). The mean daily weight gain, feed conversion rate and dressing percentage were similar for the different diets. Likewise, no significant differences in meat quality were observed according to the parameters considered (tenderness, juiciness). The “duck” trial comprised 30 hybrid drakes during the force-feeding period (13 days). The test subjects were divided into three groups according to diet: maize grain only (control diet -T-); maize grain with 2 % extruded linseed (L2%) and maize grain with 4% extruded linseed (L4%). The fatty acid pattern results are presented in Table 2. Linseed supplementation improves the fatty acid pattern by increasing the omega 3 fatty acids in the liver and intramuscular fat and lowering the n-6/n-3 fatty acid ratio. Despite the higher alpha-linolenic acid level in the diets, the proportion of that fatty acid remains relatively low in the liver of force-fed ducks (Table 2). Diet has a more significant effect on n 3 fatty acid levels in intramuscular fat. However, some differences in the fatty acid pattern emerge according to type of muscle (thigh or breast) (Table 2). A sensory test was carried out on lumps of foie gras reconstituted according to a neighbour-design with border plots. The test involved an assessment by a panel of experts of the following criteria: colour, flavour, juiciness, texture, granularity and appearance. This sensory test revealed that the L2% diet has a positive effect on the appearance of foie gras. The L4% diet makes for a juicier product with a more granular appearance. Visual attractiveness is closely linked to colour (r=0.77) and flavour correlates negatively with granularity (r=-0.42). Lipid melting is a key indicator of the technological quality of foie gras. A higher omega-3 fatty acid level in the liver due to linseed could lead to greater cell membrane elasticity and thus reduce lipid melting. Further research is required to verify this hypothesis. Partners
University of Ghent Catholic University of Louvain Agricultural University of Gembloux UPIGNAC Moulin Hick MR-W, Department of Development and Extension CRAW off coordinator
BARTIAUX-THILL Nicole (Inspecteur général scientifique) Rue de Liroux, 8 B-5030 Gembloux Téléphone direct :62 67 71 Téléphone département :+ 32 (0) 81/61.27.39 - 61.27.40 Fax département :+ 32 (0) 81/61.58.68 E-mail :bartiaux@cra.wallonie.be Funding
