The Effect of Fat-enriched Diets on the Perirenal Fat Quality and
Transcript
The Effect of Fat-enriched Diets on the Perirenal Fat Quality and
MearScience,Vol.47, No. l/2, 9s-103, 1997 0 1997Elsevier Science Ltd All rights reserved. Printed in Great Britain PII: so309-1740(97)00041-7 0309-I 740/97 $17.00 + 0.00 ELSEVIER The Effect of Fat-enriched Diets on the Perirenal Fat Quality and Sensory Characteristics of Meat from Rabbits MaAngels Oliver,“* Luis Guerrero,a Isabel Diaz,” Marina Gispert,” Marcia1 Plab & Agustin Blascob OInstitut de Recerca i Tecnologia Agroaliment&ies (IRTA), Centre de Tecnologia de la Carn, Granja Camps i Armet, 17121, Monells, Girona, Spain bDepartamento de Ciencia Animal, Universidad Politecnica de Valencia, Camino de Vera, 14, 46020, Valencia, Spain (Received 5 August 1996; revised version received 14 April 1997; accepted 20 April 1997) ABSTRACT Two hundred and eighty four medium sized young rabbits were fed ad libitum with two fat-enriched experimental diets (V: vegetable fat, A: animal fat) and a control diet (C). Diet had a significant effect on the ultimate pH (pHu) of the Longissimus dorsi muscle and on the colour, weight and fatty acid composition of the perirenal fat. The carcasses from diet C had significantly less perirenal fat (14.2~) compared to the carcasses from group A and V (24.4 and 23.Og) using carcass weight and age of the animals as covariables. Supplementing the diet with animal fat produced perirenal fat which was richer in oleic acid (41%) than In groups V (20.9O%) and C (27.9%). The P:S ratio was higher in group V (2.45) compared with groups A and C (0.53 and 0.42). Diet also affected the organoleptic quality of the loin meat. The meat from groups V and C was considered to have a more aniseedfiavour than that from group A. In contrast the loin meat from group A had more liverjlavour. Both groups V and A were considered juicier than group C. No d@erences were found in hardness, chewiness and fibrousness. These results suggest than from a human health point of view, the use of a diet supplemented with animalfat is useful on the basis of the nutritional index, P:S of the perirenal fat. However the amount of fat added in the diets V and A should be less than used in this study if the carcass is sold whole in order to avoid excessive perirenal fat. From an organoleptic point of view, the greater aniseed and grass Jlavour of group V compared to group A may give meat of better sensory quality. 0 1997 Elsevier Science Ltd INTRODUCTION In Europe, the most important countries producing rabbit meat are Italy, France and Spain. Average consumption in Spain is around 2.5 kg per person per year according to 1992 data (Carnica 2000, 1996). Traditional shops sell over 50% of the total rabbit meat *To whom correspondence should be addressed. 95 A. Oliver et al. 96 in Spain, usually as whole carcasses. Supermarkets sell about 15% as cuts. Where rabbit meat is sold as whole carcasses, excessive amounts of perirenal fat is a drawback from both appearance and dietary considerations, since it is the largest deposit of fat in the rabbit (Ouhayoun et al., 1987). Also, in monogastric animals including the rabbit, it has been demonstrated that the quantity and composition of the fatty acids in the fat and meat can be manipulated by diet. Many studies have confirmed this and it appears that the majority of ingested fatty acids are incorporated directly into the fat (Raimondi et al., 1975; Fraga et al., 1983; Ouhayoun et al., 1987). One of the main aims in producing healthy meat is to reduce the saturated fatty acids and increase the unsaturated fatty acids in the fat. The nutritional quality of fat has been assessed by the ratio of P:S (C18:2+C18:3/C14:0+C16:0+C18:0). For a whole diet P:S ratios of 0.45 or higher are recommended (Enser et al., 1996). High levels of oleic acid in the diets of rabbits leads to an increase of this acid in the fat and a decrease in palmitic acid, which is regarded as beneficial from the point of view of human health (Ouhayoun et al., 1987). Feeding rabbits with diets containing considerable amounts of linoleic acid brings about an increase in the amount of this acid in the perirenal fat, though only up to a certain point (Ouhayoun et al., 1987; Cobos et al., 1993). Various studies suggest that rabbit meat has less fat and calories than beef, chicken, lamb and pork and also a lower cholesterol content (Lee and Ahn, 1977; Rao et al., 1978; Holmes et al., 1984; Lukefahr et al., 1989; Youssef et al., 1994). These characteristics, together with the possibility of manipulating the composition of the fatty acids through diet, means that rabbit meat could be valuable in human nutrition. With this in mind, the use of industrial by-products (soya full-fat, soya oil and animal or vegetable fat) which reduce feeding costs is of great interest, provided these do not impair the organoleptic or nutritional quality of the meat. Cobos et al. (1995) found no effect on the composition of the fatty acids of rabbit meat using 15% sugar beet pulp instead of barley in the feed. However other authors have shown that diet may affect the organoleptic quality of rabbit meat (Ouhayoun et al., 1987). The aim of this study was to examine the effect of adding vegetable and animal fat to the diet of rabbits, on the quantity and nutritional quality of the perirenal fat and the organoleptic quality of the meat. MATERIALS AND METHODS Two hundred and eighty-four medium sized young rabbits of the same genetic type (a three-way cross, males and females) were divided into three groups at the weaning stage and fed ad libitum on three different diets. Two experimental and one control diet were used. The control diet (C) was a commercial diet (ether extract 2.6%). The experimental diets contained either vegetable fat (V, ether extract, 9.9%) or animal fat [a commercial mixture, 65% lard, 25% tallow and 10% poultry fat (Chillinach and Ballester, Carpesa, Valencia) (A), ether extract 11.7%]. At the age of 65 &3 days, 60 animals from each group, weighing 1.75-2.25 kg, were slaughtered on the same day at the farm, thereby avoiding stress caused by transportation. No fasting procedure was used. Chemical analysis of the diet The diets were formulated to include all essential nutrients to ensure the proper growth of the animals (Lebas, 1979). The feed ingredients used for the various diets in the experiment are shown in Table 1 together with their chemical and fatty acid compositions and digestible energy. Moisture, ash, crude fibre, crude protein, ether extract and digestible 97 Effect of fat enriched diets TABLE 1 Main Ingredients (% of Diet), Chemical Composition (% DM), Main Fatty Acid Composition (% of Fatty Acids) and Digestible Energy (MJ kg-’ MS) of Experimental Diets (V and A) and Control Diet (C) Diet” A c 24 50 2.5 0.1 2.8 0.4 0.2 20 18 50 8.5 0.1 2.8 0.4 0.2 35 12 50 0.1 2.8 0.4 0.2 Chemical composition Moisture Ash Crude protein Ether extract Crude fibre 9.28 10.7 20.0 9.9 16.9 9.30 10.7 18.9 11.7 16.9 9.24 10.7 18.9 2.6 16.9 Fatty acids 14:o 16:0 16:l 18:O 18:l 18:2 18:3 0.2 13.0 0.3 4.3 18.7 53.7 9.8 1.9 23.0 2.8 12.4 36.9 18.7 4.3 0.7 24.4 1.2 4.0 11.6 43.6 14.5 Digestible energy Ratio P:S* Ratio U:S* Total 18:2* 12.7 2.42 3.36 5.31 12.4 0.52 1.77 2.18 11.2 0.42 1.16 1.14 V Ingredients Barley Soya meal Soya full-fat Alfalfa hay Soya oil Animal fat DL-metionine Bicalcium phophat Salt Mixture 20 “V =experimental diet by addition of vegetable fat (ether extract 9.9%). A=experimental addition of animal fat (ether extract 11.7%). C =control diet (ether extract 2.6%). *P:S=(C18:2+C18:3/C14:0+C16:0+C18:0). *U:S=(C18:1 +C18:2+C18:3/C14:0+C16:0+C18:0). *Total 18:2: expressed as a percentage of DM. diet by by the method of Santoma et al. (1987). The digestible energy was similar for diets V and A. For fatty acid composition, the fat was extracted by the method of Folch et al. (1957). Methyl esters of fatty acids (FAMES) were obtained by the following procedure: an aliquot (100mg extractable fat) was evaporated and 1 ml of 14% BF3/methanol added and the mixture heated at 70°C for 20min. After cooling, lOm1 of a saturated solution of NaCl was added and FAMES were extracted with 2ml of hexane; one ~1 of this solution was injected and analysed by capillary GC under the following conditions: FSOT capillary column 50% cyanopropylsilicone (25 m x 250 pm, width film energy were determined A. Oliver et 98 al. 0,250 CL);temperature program: 150”C-3”Cmin-‘-21O”C (5 min), injector and detector temperature 250°C injection mode split (40mlmini), carrier gas helium at 30cm s-i, detector FID. A Dani HR-3800 gas chromatrograph was used. Meat quality measurements and fatty acid composition The ultimate pH at 24 h (pHu) post mortem (p.m.) was determined using a Crison pH meter with a combined electrode by penetrating 3 mm into the longissimus dorsi (LD) muscle. The colour was assessed in a transversal cut of loin and at the surface of the perirenal fat at 24 h p.m., using a MINOLTA CR200 calorimeter. The perirenal fat was collected from the carcass, weighed and frozen at -20°C until analysed. The fatty acid composition was determined as described above. Sensory evaluation of the rabbit meat loin A quantitative descriptive analysis (Stone et al., 1974) was carried out by eight trained tasters of rabbit meat in 16 sessions. First four sessions of generation, selection and description of attributes were undertaken. The parameters retained were: aniseed flavour, grass flavour, liver flavour, sweet taste, toughness, juiciness, chewiness and fibrousness. The sensory analysis was carried out on samples of the longissimus dorsi muscle following a complete block design (Steel and Torrie, 1980). Samples were cooked in an electric oven for 22min at 180°C cut into four pieces and distributed in such a way to the panellists to eliminate any location effect within the loin. To prevent cooling, samples were served on preheated plates. Statistical analysis A least squares analysis was performed using the General Linear Model program of the SAS statistical package (Statistical Analysis Systems Institute, SAS, 1988). The effect of the interaction diet xsex was analysed and found not to be significant for any of the variables studied, so the definitive model was as follows: Y,, Y,, = = _ p+Di+Sj+bW+CA+egk where: ijkth observation; general average; 1 diet effect (i= V, A, CT); sex effect (j = 1,2,); carcass weight covariable; W= A = age at slaughter covariable; residual random term. Li Sj = The carcass weight and age at slaughter were used as covariables. RESULTS Analysis of diets With regard to the chemical composition of the diets (Table l), the ether extract was the variable that differed most. As far as the fatty acid composition was concerned, experimental diet V contained 5.31% linoleic acid (C18:2), corresponding to 53.7% of all the 99 Effect of fat enriched diets fatty acids analysed. The unsaturated: saturated fat ratio (U:S = Cl 8: 1 + Cl 8:2 + Cl 8:3/ C14:O + C16:O + C18:O) was very high (3.36). Diet A, which had animal fat incorporated, had a linoleic acid content amounting to 2.18%, corresponding to 18.7% of the total fatty acids and its U:S ratio was 1.77. The C diet had a similar level of palmitic acid (C16:O) as diet A (24.4% and 23.0% respectively). The linoleic acid of C diet was 1.14%, which was 43.6% of the total amount of fatty acids and its US ratio was 1.16. The effect of the diet on the meat and perirenal fat The sex of the rabbits did not affect any of the variables studied. The results of pH (pHu) and colour measurements on the LD muscle and perirenal fat measurements are shown in Table 2. Diet had a significant effect on the pHu of the LD muscle. Carcasses of the animals fed with diet A displayed a significantly higher pHu (5.77) than carcasses of animals fed diets V (5.70) and C (5.66). No significant differences in L* value of the LD were observed between the three groups. The a* and b* values were higher in group V. Significant differences in the lightness of the perirenal fat was observed. Perirenal fat of the carcasses from group V(L* = 63.97) was darker than from groups A and C (70.18 and 69.12) . The b* values of the fat in the carcasses from group A were lower. Table 3 shows the weight in grams of the perirenal fat and the fatty acid composition of the total lipids of the perirenal fat of rabbits fed with the three diets. Significant differences were observed in the amounts of perirenal fat between the carcasses of the three different groups using the carcass weight and age of the animals as covariables. Carcasses from group C had less fat (14.15 g) compared to carcasses from groups A and V (24.36 g and 22.99 g respectively). There was a dietary effect on the fatty acids of the perirenal fat. The perirenal fat of the carcasses from group V had a significantly lower proportion of myristic (C14:0), palmitic (C16:0), palmitoleic (C16:1), stearic (C18:O) and oleic acid (C18:l) and a higher proportion of linoleic acid (C18:2, 48.91%) and linolenic acid (C18:3, 6.36%), in comparison to groups A and C. As a result the P:S ratio was higher in group V (2.45) compared to groups A and C (0.53 and O-42). The perirenal fat in the carcasses from group C had a significantly higher percentage of myristic acid (4.23) palmitic acid (35.72) and palmitoleic acid (6.27) compared with the TABLE 2 Meat Quality Measurements (Least-squares Means and Standard Errors) of Longissimus dorsi (LD) and Perirenal Fat of Rabbits Fed Three Different Diets V LSM pH LD Colour LD L* * ;* Colour perirenal fat L* a* b* SE Group (I) A LSM SE LSM C SE 5.70b 0.014 5.77a 0.015 5.66b 0.015 51.71 3.86a 3.35a 0.259 0.148 0.116 52.11 3.38b 2.7313 0.287 0.164 0.129 51.53 3.39b 2.76b 0.259 0.148 0.116 63.97b 3.42b 4.21b 0.378 0.227 0.202 70.18a 2.94b 3.14c 0.417 0.251 0.223 69.12a 5.80a 5.06a 0.378 0.228 0.203 Least squares means with different letters are significantly different, p < 0.05. 1-Group V = rabbits fed with diet added vegetal fat. Group A = rabbits fed with diet added animal fat. Group C = rabbits fed on control diet. A. Oliver et al. 100 TABLE 3 Least-squares Means and Standard Errors of the Fatty Acid (%) Composition of the Total Lipids of Perirenal Fat and Perirenal Fat (g) from Rabbits Fed with Three Different Diets Fatty acid c-14:0 C-16:0 C-16:1 C-18:0 C-18:1 C-18:2 C-18:3 Ratio US Ratio P:S Perirenal fat Group (I) A V 1.33b 16.8lb 0.92~ 4.72~ 20.94c 48.91a 6.36a 3.40a 2.45a 22.99a 0.06 0.28 3.42~ 25.97~ 3.95b 6.73a 41 .OOa 16.20b 2.88~ 1.78b 0.53b 24.36a 0.06 0.28 0.10 0.09 0.23 0.24 0.08 0.03 0.02 0.59 C 4.23a 35.72a 6.27a 6.26b 27.90b 15.65b 3.92b 1.17c 0.42b 14.15b 0.10 0.09 0.24 0.24 0.08 0.03 0.02 0.61 0.06 0.28 0.10 0.09 0.24 0.24 0.08 0.03 0.02 0.60 Least squares means with different letters are significantly different, p < 0.05. l-Group V = rabbits fed with diet added vegetable fat. Group A = rabbits fed with diet added animal fat. Group C = rabbits fed on control diet. others groups. The highest percentage of oleic acid (41%) was found in the perirenal fat from the carcasses from group A although the percentage of linoleic acid in the fat did not differ significantly between carcasses from groups A and C. The effect of the diet on the sensory characteristics of the loin meat Table 4 shows the least squares means and standard errors of the sensory characteristics of cooked loin. There was a significant effect of diet on the occurrence of aniseed flavour, liver flavour and grass flavour in the cooked loin meat. The meat from groups V and C TABLE 4 Least Squares Means and Standard Errors of Sensory Characteristics of Cooked Loin from Rabbits Fed Three Different Diets Group (I) c V A Flavour Aniseed Grass Liver sweet 2.3a 3.4a 1.2b 2.0 1.5b 2.8b 1.9a 1.8 2.3a 3.4a I.lb 2.1 0.188 0.168 0.207 0.213 Texture Hardness Juiciness Chewiness Fibrousness 2.9 3.0a 3.8 2.5 3.6 2.9a 3.9 2.7 3.4 2.lb 4.0 2.6 0.273 0.224 0.122 0.120 Sensory evaluation SE Least squares means with different letters are significantly different, p < 0.05. l-Group V = rabbits fed with diet added vegetable fat. Group A = rabbits fed with diet added animal fat. Group C = rabbits fed on control diet. Effect of fat enricheddiets 101 was considered to have more aniseed and grass flavour than that from group A. In contrast the loin meat from group A had more liver flavour. Both groups V and A were considered juicier than group C. No differences were found in hardness, chewiness and fibrousness between the groups. DISCUSSION The effect of the diet on the meat quality and perirenal fat The diets used to feed the rabbits had a significant effect on the muscle pH (Table 2) though these differences are within the limits considered normal for pHu. These values are similar to those found by Holmes et al. (1984), Blasco and Piles (1990) and Xiccato et al. (1994). In the study carried out by Xiccato et al. (1994) the L*, a* and b* values were slightly higher than recorded in our study, probably because the results are an average colour of two muscles Biceps femoris and Longissimus dorsi and also the rabbits were older. As the colour of rabbit meat is affected mainly by pre-slaughter treatment, stress and age we did not expect differences in L* value (Battaglini et al., 1994; Xicatto et al., 1994). However, fat colour was affected by diet being lighter in group V (lower L* values) as a consequence of the different fatty acid compositions of the fat between the three groups (Ouhayoun et al., 1987). This significant difference in the colour of the fat could affect consumer acceptance at the point of purchase because the colour of the fat is used as an index of freshness. This subject has been discussed recently by Issanchou (1996) in relation to meat and meat products. The perirenal fat is the main source of dissectable fat in the rabbit (Ouhayoun et al., 1987). Rabbit meat is normally consumed in Spain, as in other countries, by cooking the whole rabbit, that is, with the perirenal fat included. There is an effect of diet on the weight of the perirenal fat, which was significantly higher in the carcasses of the animals fed with diets supplemented with fat (V and A). The greater quantity of perirenal fat found in groups V and A could be a disadvantage from the dietary point of view and could also downgrade the appearance of the rabbit meat. However, when rabbit meat is sold as joints, the problem does not arise. The effect of the diet on the fatty acid composition of the perirenal fat and the sensory quality of the loin meat It is of particular interest to consider what level and composition of fat can be included in the diet of rabbits, in order to avoid human health and organoleptic problems. In our study, as expected, supplementing the diet with soya full-fat (Diet V) caused the production of additional perirenal fat with a greater degree of unsaturation than obtained using animal fat. A percentage of lincleic acid of 48.91% of the total fatty acids (Table 3) has been observed in group V. These results agree with those of Ouhayoun et al. (1981) who found that soya full fat can increase the proportion of linoleic acid in the adipose tissue to 30% of the total fatty acids. Therefore, the fat in groups A and C can be considered fat with a good nutritional P:S ratio (0.53 and 0.42 respectively). The P:S ratio recently reported by Enser et al. (1996) for retail samples of beef, lamb and pork muscle were 0.11, 0.15 and O-58, respectively. Cobos et al. (1993) noted that enriching the diet of rabbits with soya, sunflower oils or soya bean oil increased the proportion of unsaturated fatty acids compared to those obtained using conventional diets, this was considered an important nutritional benefit to the consumer. Xiccato et al. (1994) also observed a high level of unsaturation in rabbit fat. A. Oliver et al. 102 Diet also affected the organoleptic quality of the loin meat; meat from rabbits fed diets with animal fat (A) was considered to have more liver taste. From the sensory point of view the increase in liver flavor in the meat from group A could be explained by the incorporation of an aromatic liposoluble compound associated with the animal fat. Font et al. (1995) discovered the same descriptor in beef. The greater intensity of this attribute, though significant, appears to be of little importance since it is a common descriptor in meat flavour. The same can be said about aniseed flavour or grass flavour. However we think that these slightly aromatic notes (positive at this level of intensity) together with a reduction of the liver flavour could have a positive effect on consumer acceptability. To confirm the practical significance of this effect it would be necessary to undertake a consumer study. The more aniseed flavour (found in groups V and C) may be an important qualitative attribute from the consumers point of view. With regard to the texture attributes diets V and A produced an increase in juiciness, which could be attributed to the greater lipid content of these carcasses. No significant differences were observed between diets for the other texture parameters. CONCLUSION This work confirms that there is a clear effect of the composition of the diet on the fatty acid composition of rabbit fat. Fat colour was affected by diet, being less white in the group V with lower L* values. From a human health point of view, the use of the diet supplemented with animal fat could be considered on the basis of the nutritional index P:S of the perirenal fat. However, we feel that the amount of fat added to these diets (vegetable and animal fat) should be lower if the carcass is sold whole in order to avoid excessive amounts of perirenal fat. From an organoleptic viewpoint, these results suggest that diet V could produce meat with better sensory characteristics (greater aniseed and grass flavour) than diet A. It would be advisable to select the by-products used in the rabbit’s diet on the basis of the composition of fatty acids in order to achieve rabbit meat of optimal quality. ACKNOWLEDGEMENTS This work was supported in part by the Ministerio de Education y Ciencia (CICYT). The authors wish to acknowledge Ma Angels Rius and Dolors Guardia for technical assistance. REFERENCES Battaglini, M. B., Castellini, C. and Lattaioli, P. (1994) Rabbit carcass and meat quality: effect of strain, rabbitry and age. Italian Journal of Food Science 2, 157-166. Blasco, A. and Piles, M. (1990) Muscular pH of the rabbit. Annales Zootechnie 39, 133-136. Camica 2000 (1996) El consume de came de conejo en Espaiia. Carnica 2000, Anuario Camico, 5558. Cobos, A., Cambero, M. I., Ordotiez, J. A. and de la Hoz, L. (1993) Effect of fat enriched diets on rabbit meat fatty acid composition. Journal of the Science of Food and Agriculture 62, 83-88. Cobos, A., de la Hoz, L., Cambero, M. I. and Ordoiiez, J. A. (1995) Sugar-beet pulp as an alternative ingredient of barley in rabbit diets and its effect on rabbit meat. Meat Science 39, 113-l 2 1, Enser, M., Hallet, K., Hewitt, B., Fursey, G. A. J. and Wood, J. D. (1996) Fatty acid content and composition of english beef, lamb and pork at retail. Meat Science 4, 443-456. Eflect of fat enriched diets 103 Folch, J., Len, M. and Stanley, G. H. S. (1957) A simple method for the isolation and purification of total lipids from animal tissues. Journal of Biological Chemistry 226,497-509. Font, M., Pi, F., Garcia-Macias, J. A., Guerrero, L., Oliver, M. A. (1995) Calidad de la canal y de la came de 10s tipos geneticos “Bruna dels Pirineus” y “Charolais X Bruna” en las condiciones de production de montafia” IV. Jornadas de Produccibn Animal (II), 60&602. Fraga, M. J., De Bias, J. C., Perez, E., Rodriguez, J. M., Perez, C. J. and Galvez, J. F. (1983) Effect of diet on chemical composition of rabbits slaughtered at fixed body weights. Journal of Animal Science 56, 1097-l 104. Holmes, A. A., Wei, S. F., Harris, D. J., Cheeke, P. R. and Patton, N. M. (1984) Proximate composition and sensory characteristics of meat from rabbits fed three levels of alfalfa meal. Journal of Animal Science 58(l), 62-67. Issanchou, S. (1996) Consumer expectations and perceptions of meat and meat product quality. Meat Science 43(S), S5. Lebas, F. (1979) Nutrition and alimentation du lapin: les besoins. Cuniculture, 6, 159-160. Lee, Y. C. and Ahn, H. S. (1977) Studies on lipids and proteins of rabbit meat. I. Emphasis of lipid components of rabbit meat. Korean Journal of Nutrition 10, 78-82. Lukefahr, S. D., Nwosu, C. V. and Rao, D. R. (1989) Cholesterol level of rabbit meat and trait relationships among growth, carcass and lean yield performances. Journal of Animal Science 67, 2009-2017. Ouhayoun, J., Demarne, Y., Delmas, D. and Lebas, F. (1981) Utilization de pellicules de colza dans l’alimentation du lapin en croissance. II. Effect sur la qualite des carcasses. Annales Zootechnie 30,325-333. Ouhayoun, J., Kopp, J., Bonnet, M., Demarne, Y. and Delmas, D. (1987) Influence de la composition des graisses alimentaires sur les propietes des lipides peririnaux et la qualite de la viande de lapin. Sciences des Aliments 7(4), 521-534. Raimondi, R., de Maria, C., Auxilia, M. A. and Masoero, G. (1975) Effetto della grassatura dei mangimi sulla produzione della came di coniglio. III. Contenuto in acidi grassi delle cami e de1 grass0 perirenale. Annali dell Znstituto Sperimentale per la Zootechnia 8, 167-181. Rao, D. R., Chen, C. P., Sunki, G. R. and Johnson, W. M. (1978) Effect of weaning and slaughter ages on rabbit meat production. II. Carcass quality composition. Journal of Animal Science 46, 578-583. Santoma, G., De Bias, J. C., Caraballo, R. and Fraga, M. J. (1987) The effects of different fats and their inclusion level in diets for growing rabbits. Animal Production 45, 291-300. SAS (1988) SASSTAT User’s Guide: Statistics. Institute Inc., Cary, N.C. Steel, R. G. and Torrie, J. H. (1980) Principles and Procedures of Statistics. McGraw-Hi11 Book Co., New York. Stone, H., Sidel, J., Oliver, S., Woolsey, A. and Singleton, R. C. (1974) Sensory evaluation by quantitative descriptive analysis. Food Technology 28( 1l), 24-34. Youssef, M. K. E., Abou el Hama, S. H., El Rifly, M. N. and Khalifa, A. H. (1994) Effect of sex, age, cut and processing methods on chemical composition and caloric value of rabbit meat. Proceedings of the ZCoMST. The Hague. S-5 P25. Xiccato, G., Parigi-Bini, R., Dalle Zotte, A. and Carazzolo, A. (1994) Effect of age, sex and transportation on the composition and sensory properties of rabbit meat. Proceedings of the 40th ZCoMST. The Hague. W-2.02.Z