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Ces 3 travaux, qui démontrent que la viande d'animaux élevés en paturage a moins de gras et de cholesterol que celle des animaux élevés par fourrage et grains, ont été présentés au 38ème Congrés International dela Viande, de la Science et de la Technologie de Clermont-Ferrand.

 
  • Lipides dans les muscles Longissimus provenant des animaux élevés en pâturage ou au grain

  • (Traduction partielle et texte complet en anglais)
  • Lipides dans les morceaux de viande argentine

  • (Traduction partielle et texte complet en anglais)
  • Etude comparative entre la graisse intramusculaire et celle "extramusculaire" des animaux élevés en pâturage.

  • (Traduction partielle et texte complet en anglais)


    Pâturages argentins - herbages principaux

    Liens vers d'autres informations sanitaires:

    INRA (Institut National de Recherche Agronomique)

    Page Officielle de la Vache Folle (en anglais)

    INTA (Instituto Nacional de Tecnologia Agropecuaria)

    AFSA (Association Française de Securité Alimentaire)

    CIV (Centre d'Information des Viandes)



    Lipides dans les muscles Longissimus provenant des animaux élevés en pâturage ou au grain
    (Traduction partielle et texte complet en anglais)

    P. T. GARCIA and J. J. CASAL
    Instituto de Tecnologia de Carnes, CICV,INTA.
    CC 77, 1708 Moron, Buenos Aires, Argentina.
    Introduction

    Les opinions médicales voient dans la composition du régime l'un des facteurs qui augmente le risque du développement de certaines maladies par son influence sur le niveau de cholestérol dans le sang. Le potentiel hypercholestérolemique-atherogenique d'un mets est lie à son contenu en cholestérol et en graisses saturées. Plusieurs études ont démontré que les tissus des animaux élevés au fourrage sont plus maigres que celui provenant des animaux élevés au grain (Crouse et al. , 1984). Des études ont été menées démontrant que la composition des acides gras dans la graisse bovine dépend de leur régime (Rumsey et al. ,1972 ; Marmer et al., 1984).


    Résultats et débats

    Certains particularités des carcasses sont résumées sur le tableau 1. Les animaux élevés au pâturage étaient plus gros (p.<.05) que ceux élevés au grain d'après l'épaisseur de la graisse sous cutanée et le pourcentage des animaux classifies comme FD2.
    Les pourcentages de graisse intramusculaire étaient plus élevés parmi les LD élevés au grain que dans ceux élevés en pâturage (p.<0.05) (tableau 2 ) Ces résultats sont similaires a ceux de Marmer et al. (1984) et Crouse et al. (1984) et démontrent les effets du régime sur la déposition de la graisse intramusculaire .
    Le contenu du cholestérol dans les muscles des LD élevés en pâturage était plus bas que dans les muscles des LD élevés au grain (p.<0.05) (tableau 2). Rhee et al. (1982) n'ont pas trouve des différences significatives dans le contenu en cholestérol des steaks crus avec des différents niveaux de marbrage, sauf que les steaks "pratiquement dépourvus" de marbrage contenaient beaucoup moins de cholestérol que les steaks avec des pourcentages divers de marbrage.


    Conclusions

    L'énergie du régime a une influence sur la graisse intramusculaire (marbrage) et le cholestérol des muscles Longissimus des animaux. Les Longissimus des animaux élevés au pâturage ont moins de graisse intramusculaire et du cholestérol que ceux des animaux élevés au grain.
    Les lipides du Longissimus provenant des animaux élevés au pâturage ont un niveau plus élevé de PUFA et un rapport n-6/n-3 inférieur a ceux élevés au grain.

    Table 1. Some characteristics of the steers
      Grain Grass
    n 32 32
    Live weight, kg
    Initial 360 360
    Final 436 465
    Gain, g/day .65 .59
    Fat thickness
    12th rib, cm .76 .92
    Fat degree 1, (%) 31 22
    Fat degree 2, (%) 69 78


    Table 2. Total intramuscular fat and cholesterol in LD muscle. Mean and SD
      Grain Grass
    IMF 3.9 + / - 1.1 2.9 + / - 0.9*
    Cholesterol mg % 72.2 + / -13.7 66.6 + / - 8.8*
    * p < .05


    Références

    BOHAC C. E., RHEE K. S., 1988. Influence of animal diet and muscle location on cholesterol content of beef and pork muscles. Meat Sci. 23, 71-75.

    BROWN H. J., MELTON S. L., RIEMANN H. J., BACKUS W. R., 1979. Effects of energy intake and feed source on chemical changes and flavor of ground beef during frozen storage. J. Ani. Sci. 48, 338-342.
    CROUSE J.D., CROSS H. R., SEIDEMAN J., 1984. Effects of a grass or grain diet on the quality of three beef muscles. J. Ani. Sci. 58, 619-625.

    FOLCH J., LEES H., STANLEY G. H. S., 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226, 497-509.

    LARICK D. K., TURNER B.E., 1989. Influence of finishing diet on the phospholipid composition and fatty acid profile of individual phospholipids in lean muscle of beef cattle. J. Ani. Sci. 67,2282-2293.
    MARMER W. N., MAXWELL R. J., WILLIAMS E. J., 1984. Effects of dietary regime and tissue site on bovine fatty acid profiles. J. Ani. Sci., 59, 109-121..

    RHEE K. S., DUTSON T. R., SMITH G. C., 1982. Effect of changes in intramuscular and subcutaneous fat levels on cholesterol content of raw and cocked beef steaks. J. Food Sci. 47, 1638-1642.

    ROSCHLAN P., BERNARD E. and GRUBER W., 1975. 9th Int. Congress on Clin. Chem. Toronto. Abstr. No 1.

    RUMSEY T. S.. OLTJEN R. R., Bovard K. P., Priode B. H., 1972. Influence of widely diverse finishing regimens and breeding on depot fat composition in beef cattle. J. Ani. Sci. 35, 1069-1074.

    TU C., POWRIE W. D., FENNEMA 0., 1967. Free and esterified cholesterol content of animal muscles and meat products. J. Food Sci. 32, 30-34.

    38th ICoMST Clermont-Ferrand France 1992 pag.53 - 56


    Lipids in longissimus muscles from grass or grain fed streer
    (Texte complet en anglais)

    P. T. GARCIA and J. J. CASAL
    Instituto de Tecnologia de Carnes, CICV, INTA.
    CC 77, 1708 Moron, Buenos Aires, Argentina.

    Summary

    The effect of grass or grain dietary regimen on Longissimus intramuscular fat and cholesterol was examined using two groups of Angus steers slaughtered at similar level of finishing. Carcasses were graded and after a 24 hs chill the Longissimus muscle was removed for analysis. Total intramuscular fat content, its fatty acid composition and total muscle cholesterol were determined. Grass steers were fatter than grain steers (fat thickness at 12th rib were .92 and .76 cm respectively). Grain fed Longissimus were fatter than that of grass fed (3.9 vs. 2.9%, p<.05) and with more cholesterol (73 vs. 66 mg%, p<.05). Grass fed Longissimus lipids presented more n-3 fatty acids and a lower relation n-6/n-3 (1.6 vs. 2.1, p< 0.05).


    Introduction

    The composition of the diet is seen by most medical opinion as one factor increasing the risk of the development of certain diseases via its influence on the level of blood cholesterol. The hypercholesterolaemic-atherogenic potential of a food is related to its cholesterol and saturated fat content. Several studies have shown that tissue from forage-fed beef is leaner than tissue from grain-fed beef (Crouse et al., 1984; Brown et al., 1979; Marmer et al., 1984). Studies have been conducted that show that fatty acid composition of bovine fat is influenced by dietary regimen (Rumsey et al. , 1972 ; Marmer et al. , 1984). There are conflicting reports in the literature regarding the effect of lipid composition modifications of animal diets on the muscle cholesterol content (Bohac & Rhee, 1988). The low correlation found between marbling score and cholesterol content suggests that a large proportion of the cholesterol is present in structural lipids (Rhee et al., 1982).

    The objectives of the present study were to determine the effects of grass or grain diets on the intramuscular fat and cholesterol contents and in the fatty acid composition of Longissimus muscles from Angus steers.


    Materials and Methods

    Sixty-four steers Angus, at an average live-weight of 360 kg, were assigned to two dietary treatments (32 steers each). one group was placed on a mixed pasture and the other was fed with sorghum grain and corn silage ad-libitum. At similar level of finishing appraised by experts the steers were slaughtered. The steers were graded in fat degree 1 or 2 (FD1 or FD2) according to Argentine National Meat Board standard regulations. Samples of Longissimus muscle at 10-12th ribs were obtained, the lean tissue was finely chopped and aliquot samples were dried and extracted with hexane during 16 h to determine the weight of chemical fat or extracted with the Folch et al.(1957) method for fatty acid analysis. Aliquot samples from the chloroform extract were saponified and used for total cholesterol determinations with an enzymatic-calorimetric method ( Roschlan et al., 1975).

    The data were analyzed using the "Lineal General Program" (SYSTAT 1987) with intramuscular fat percentages as principal fixed effect and carcass weight as lineal covariate, and cholesterol mg% as principal fixed effect and intramuscular fat percentage as lineal covariate.


    Results and Discussion

    Some carcass traits are summarized in Table 1. The grass-fed steers were fatter (p <.05) than the grain fed ones according to the subcutaneous fat thickness and the percentage of steers classified as FD 2. The percentages of intramuscular fat were higher in the grain-fed LD than in the grass-fed (p < 0.05) (Table 2). This results were similar to the findings of Marmer et al. ( 1984) and Crouse et al .(1984) and shows the dietary effects on the intramuscular fat deposition. The intramuscular fat % were lower than the values for LD. The cholesterol content in the grass-fed LD muscles were lower than in the grain-fed LD muscle (p < 0.05) (Table 2). Rhee et al. (1982) found no significant differences in cholesterol content in raw steaks with different amounts of marbling except that steaks with "Practically devoided" marbling contained significantly less cholesterol than did steaks with any other marbling scores. Tu et al .(1967) indicated that the total cholesterol content of muscle increases very little as the percent lipid value arose. The cholesterol content in muscle is lower than in intermuscular or subcutaneous fats (Rhee et al., 1982) then total cholesterol intake from beef may be reduced by trimming off the separable fat. The fatty acid composition from total LD lipids in grass and grain-fed steers is presented in Fig. 1. Significant differences were detected only for 15:0, 17:1, 18:3 and 20:3. Marmer et al. (1984) and Larick & Turner (1989) found similar results. Rumsey et al.(1972) show that cattle fed forage diets have more saturated fatty acid in their fat than cattle fed a concentrate diet. In our case, 14:0 and 16:0 decrease but 18:0 increases in grass-fed compared to grain-fed. It can be seen that a small but significant difference in n-3 fatty acids between grass and grain-fed steers was detected. In grass-fed steers the diet contain high amounts of linolenic acid (n-3). Though most linolenic acid is partly or completely hydrogenated a small amount escapes hydrogenation and is absorbed and converted to n-3 PUFA. In contrast in grain-fed steers the seed's lipids contain mainly linolenic acid (n-6) and there is a very low intake of n-3 PUFA. In Fig. 2 are presented the total saturated, monounsaturated and PUFA fatty acids and the n-6/n-3 relation in grain and grass steer Longissimus lipids.


    Conclusions

    Dietary energy affects the intramuscular fat (marbling) and cholesterol of steer Longissimus muscles. Longissimus for grass fed steers have less intramuscular and cholesterol than grain fed steers. The Longissimus lipids from grass fed steers have higher levels of PUFA and a lower relation n-6/n-3 than the grain ones.


    Table 1. Some characteristics of the steers.
      Grain Grass
    n 32 32
    Live weight, kg
    Initial 360 360
    Final 436 465
    Gain, g/day .65 .59
    Fat thickness
    12th rib, cm .76 .92
    Fat degree 1, (%) 31 22
    Fat degree 2, (%) 69 78


    Table 2. Total intramuscular fat and cholesterol in LD muscle. Mean and SD
      Grain Grass
    IMF 3.9 + / - 1.1 2.9 + / - 0.9*
    Cholesterol mg % 72.2 + / -13.7 66.6 + / - 8.8*
    * p < .05


    References

    BOHAC C. E., RHEE K. S., 1988. Influence of animal diet and muscle location on cholesterol content of beef and pork muscles. Meat Sci. 23, 71-75.

    BROWN H. J., MELTON S. L., RIEMANN H. J., BACKUS W. R., 1979. Effects of energy intake and feed source on chemical changes and flavor of ground beef during frozen storage. J. Ani. Sci. 48, 338-342.

    CROUSE J.D., CROSS H. R., SEIDEMAN J., 1984. Effects of a grass or grain diet on the quality of three beef muscles. J. Ani. Sci. 58, 619-625.

    FOLCH J., LEES H., STANLEY G. H. S., 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226, 497-509.

    LARICK D. K., TURNER B.E., 1989. Influence of finishing diet on the phospholipid composition and fatty acid profile of individual phospholipids in lean muscle of beef cattle. J. Ani. Sci. 67,2282-2293.

    MARMER W. N., MAXWELL R. J., WILLIAMS E. J., 1984. Effects of dietary regime and tissue site on bovine fatty acid profiles. J. Ani. Sci., 59, 109-121..

    RHEE K. S., DUTSON T. R., SMITH G. C., 1982. Effect of changes in intramuscular and subcutaneous fat levels on cholesterol content of raw and cocked beef steaks. J. Food Sci. 47, 1638-1642.

    ROSCHLAN P., BERNARD E. and GRUBER W., 1975. 9th Int. Congress on Clin. Chem. Toronto. Abstr. No 1.

    RUMSEY T. S.. OLTJEN R. R., Bovard K. P., Priode B. H., 1972. Influence of widely diverse finishing regimens and breeding on depot fat composition in beef cattle. J. Ani. Sci. 35, 1069-1074.

    TU C., POWRIE W. D., FENNEMA 0., 1967. Free and esterified cholesterol content of animal muscles and meat products. J. Food Sci. 32, 30-34.

    38th ICoMST Clermont-Ferrand France 1992 pag.53 - 56

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