Carcass and meat quality in double-muscled Belgian Blue bulls and cows

Carcass and meat quality of 37 bulls and 91 cows of the Belgian Blue breed (double-muscled type) were compared. Age at slaughter averaged 648±73 and 1820±689 days, respectively. Both groups of cattle were finished on maize silage supplemented with concentrate, and were slaughtered at about 750 kg live weight. Females had a lower (P=0.004) cold carcass weight (469.7 kg) in comparison with bulls (500.8 kg), due to a reduced dressing percentage (63.8 vs. 66.6; P <0.001). SEUROP conformation was better for bulls. SEUROP fat covering (P=0.007) and fat content in the carcass (16.4 vs. 12.9%; P <0.001) and in the M. longissimus thoracis (LT) muscle (2.3 vs. 1.1%; P <0.001) were higher for females than for males. The LT of cows was darker (lower L* and higher a*-value; P <0.001), had a better waterholding capacity (P?0.063) and was slightly more tender (P=0.120) than the LT of bulls. Increasing parity reduced dressing percentage and increased LT lightness (L*-value) in cows. Several carcass (SEUROP-grading, composition, LT-area) and meat quality traits (protein and fat contents, drip and cooking losses, a*-value) were better correlated with carcass weight than parity. It is concluded that meat quality of the aged LT of cows is not negatively affected by age, while some carcass quality traits decreased with advancing age. Carcass quality traits adjusted for age at slaughter were better for bulls, but LT meat quality characteristics were at least as good for females as for males.     

Effect of live weight and sex on physico-chemical and sensorial characteristics of Merino lamb meat

Forty-eight lamb carcasses were divided into four groups (n = 12) according to slaughter weight (24 and 29 kg) and sex (male and female). Colour, pH, moisture, and intramuscular fat were not affected (p > 0.05) by slaughter weight or sex. With respect to fatty acid composition, slaughter weight had significant effects on C12:0 (p < 0.01), C14:0, C16:0, and C18:1 n-9 (p < 0.05) in Longissimus lumborum (LL) muscle. The percentage of C12:0 and C14:0 decreased as slaughter weight increased, while C16:0 increased. In Semimembranosus (SM) m., only C18:3 n-3 and C20:2 n-6 were affected (p < 0.001) by slaughter weight. Total PUFA in LL m. was greater (p < 0.01) in females than in males. Although in general, sensorial quality was not significantly affected by slaughter weight or sex, meat from lighter lambs (24 kg) had greater general acceptability than meat from heavier lambs (29 kg).     

Effects of weight at slaughter and sex on the carcass characteristics of Florida suckling kids

The effect of slaughter weight and sex on some carcass traits of suckling kids of the Florida breed was evaluated. A total of 60 kids (30 male and 30 female), fed exclusively on milk replacers, were slaughtered at 7-8kg (group 1), 10-11kg (group 2) or 14-15kg (group 3) of liveweight (mean weights of 7.6kg, 10.8kg and 14.4kg, respectively). Higher slaughter weights decreased the percentage of subproducts (blood, skin, head, feet) and internal organs (lungs+traquea, heart, liver, spleen, thymus) but significantly increased the percentage of intestine and fat depots (omental fat and mesenteric fat). Higher slaughter weights also increased carcass measures (L 40.5 vs 49.1; F 22.5 vs 25.9; G 10.4 vs 14.2; Wr 10.1 vs 13.9; Wth 8.0 vs 10.5; Th 16.5 vs 199; B 32.3 vs 42.4; PT 41.5 vs 50.8), compactness carcass index (96.6 vs 152.3) and compactness leg index (27.5 vs 44.1). Sex only significantly affected the percentages of feet, internal organs, omental fat, measure L, carcass compactness index and hind limb compactness index. The meat colour and fat colour were mainly scored as pale and white respectively in the carcasses of the lightest animals, whereas heavier kids were scored as pink and cream. Slaughter weight also influenced significantly the carcass fatness (score 1 in lightest kids and 2 or 3 in heavier ones). There were no significant (p>0.05) differences between slaughter weight group and sex in dressing percentages. Percentages corresponding to the long leg, back and neck (30-33%, 18-19% and 8-10%, respectively) decreased when the slaughter weight increased, whereas the ribs (23-25%) and the flank (10-11%) increased slightly. The carcasses comprised 57-58% muscle, 22-25% bone, 5-6% subcutaneous fat and 9-12% intermuscular fat. The percentage muscle stayed the same with increasing slaughter weight, whereas the bone decreased and the fat increased. The carcasses of the heavier females contained less lean and more fat than the males. The bone percentage was significantly (p<0.05) lower in the females and the carcass fat percentage was significantly (p<0.05) higher than in the males.     

Effect of diet,slaughter weight and sex on instrumental and sensory meat characteristics in rabbits

The effect of the fattening diet, slaughter weight and sex on meat quality was studied in a total of 156 hybrid rabbits. After weaning, rabbits were divided into three groups of 52 animals each (50% male and 50% female), that were allocated for three weeks to one of three commercial diets containing low (14.28%, A), medium (18.04%, B) and high (20.48%, C) fibre content with decreasing energy levels. Animals were slaughtered at 2.0 and 2.3 kg after the consumption of a common pre-slaughter non-medicated concentrate and pH, colour, water-holding capacity (WHC), Warner–Bratzler shear test and sensory analysis were all measured. Meat from animals fed with low fibre and high energy was the least luminous. Rabbits slaughtered at 2.0 kg showed more yellowness than at 2.3 kg at 0 min. In both traits, these differences did not prevail after 15 min of blooming. Globally, meat from males was more coloured than that of the females, both at 0 and 15 min of blooming. No significant differences were found for pH, WHC or shear test for the individual effects. In the sensory analysis, rabbit and grass odours were more intense at 2.0 kg than at 2.3 kg of slaughter weight.     

Effect of housing system, slaughter weight and slaughter strategy on carcass and meat quality, sex organ development and androstenone and skatole levels in Duroc finished entire male pigs

This study aimed at evaluating the effect of housing system (HS), slaughter weight (SW) and strategy (SS) on carcass a nd meat quality, sexual organ development and boar taint in entire males. Twelve pens of 10 pigs were used (two trials). Half of male pens were allowed visual contact with females (MF) and half with males (MM). Half MM or MF were slaughtered at 105 or 130 kg in trial 1, or penwise or by split marketing in trial 2 at 120 kg. Housing system showed no significant effect on carcass or meat quality. MF presented significantly longer testicles and heavier bulbourethral glands compared to MM. The distribution of androstenone and skatole levels was affected by SW but not by HS or SS, samples with androstenone >1 μg/g of the different groups falling within the range of 16 to 22%. All correlations between androstenone and sex organs were significant. Housing system and slaughter strategy did not reduce the risk of boar tainted carcasses.     

Effect of gender and castration of females and slaughter weight on performance and carcass and meat quality of Iberian pigs reared under intensive management systems

A total of 360 Iberian dam × Duroc sire pigs was used to study the influence of gender and castration of females (CM, castrated males; CF, castrated females; IF, intact females) and slaughter weight (SW; 145 and 156 kg body weight, BW) on performance and carcass and meat quality. Each treatment was replicated four times (15 pigs). Intact females ate less, tended to have better feed conversion and had less carcass fat and more primal cuts yield than CM and CF. Pigs slaughtered at 156 kg BW ate more feed and had worse feed conversion than pigs slaughtered at 145 BW. An increase in SW improved carcass yield, but tended to decrease trimmed ham yield. Intact females are an alternative to castrated females for intensive production of Iberian pigs. Also, the reduction in slaughter weight from 156 to 145 kg BW is recommended for this type of production.     

The effect of increasing carcass weight of finishing boars and gilts on joint composition and meat quality

Two hundred and eighty-eight crossbred (3/4 Landrace × 1/4 Large White) pigs, comprising equal numbers of boars and gilts, were housed in single sex groups from 50 kg liveweight to slaughter at liveweights of 92, 105, 118 and 131 kg (carcass weights of 70, 80, 90 and 100 kg). Sample joints from the left longissimus dorsi muscle were obtained at slaughter for dissection and meat quality assessment. As carcass weight increased there were significant (p<0.001) increases in eye muscle area and subcutaneous fat content. Lean content decreased (p<0.001) with increasing carcass weight while intermuscular fat content was not affected. There was a significant interaction between carcass weight and gender with % drip loss in pork from gilts at 100 kg having a higher drip loss than boars and gilts at all other weights. There were small but significant (p<0.01) reductions in ultimate pH with increasing carcass weight. Cooking loss was also reduced (p<0.001) at the heavier weights. There was no effect of carcass weight on shear force or on intramuscular fat. Dry matter (DM) and crude protein (CP) contents of m. L. dorsi increased (p<0.001) at heavier weights while sarcomere length decreased (p=0.001). Compared with boars, gilts had greater eye muscle area (p<0.05), more subcutaneous fat (p<0.001). Meat from gilts in comparison with boars had higher % DM and % CP contents (p<0.001), higher intramuscular fat content and shear force (p<0.05). It is concluded that meat quality may be improved when carcass weight is increased from 70 to 100 kg. ?     

Relationships of fat-tail dimensions with fat-tail weight and carcass characteristics at different slaughter weights of Torki-Ghashghaii sheep

The purpose of this research was to investigate the relationship between fat-tail and carcass attributes in Torki-Ghashghaii sheep. Thirty ram lambs belonging to six weight groups (weighing from 25 to 50kg) were used. Fat-tail measurements were recorded on the live animals before slaughter. Hot and cold (after 24h in the cold room) carcass weights, and the weights of the tail and internal organs were recorded. The carcass was dissected into conventional cuts. Each cut was de-boned and the physically separable fat was removed from the meat. The bone, physical fat and trimmed meat were weighed separately. The weight of trimmed meat as a percentage of slaughter weight did not change significantly from 25 to 50kg live weights (23.4-25.3%). The weights of physically separated fat and the fat-tail as a percentage of live weight varied from 6.6% to 15.5% for various weight groups. The correlation coefficients between the tail weight and dimensions were large, positive, and significant. The highest correlation coefficient was found between the tail weight and upper circumference (r=0.88), and the lowest one was found between the tail weight and upper thickness (r=0.61). The upper and lower circumferences of the tail accounted for 85% of the total variation in the tail weight. The tail weight was positively correlated with the meat chemically determined fat (ether extract; r=0.43; P<0.05) and with the total body fat (r=0.70; P<0.01). Further studies are needed to see whether inclusion of fat-tail measurements in breeding programs would result in a decrease in body fat in this breed.     

Meat quality of "Galician Mountain" foals breed. Effect of sex, slaughter age and livestock production system

The effects of sex, slaughter age (9 vs. 12 months) and livestock production system (freedom extensive system (FES) vs. semi extensive system (SES)) of "Galician Mountain" foals breed on meat quality from the Longissimus dorsi (LD) muscle were investigated. Forty-two foals had been used for this study, 19 (11 females and 8 males) were reared in a semi extensive system and weaned three months prior to slaughtering (8 and 11 were slaughtered at 9 and 12 months, respectively) while the other 23 (11 females and 12 males) were reared together with its mothers in a system in freedom and were slaughtered at the age of 9 months. The obtained results showed that there were no significant differences between the sexes and the slaughter age whereas the livestock production system was a significant variation source on intramuscular fat content and meat tenderness because SES foals showed 51.6% more of IMF and the improved meat tenderness achieved a shear force of <3 kg. In general, the meat from foals of the study at hand showed very lean meat (<0.3% in IMF) with a high protein content (>20.5%) and heme-iron (1.62 mg/100g meat) comparable to veal meat. Furthermore, the meat samples showed a higher luminosity (L*>40), a very good water holding capacity, measured by cooking losses (<18.3%), and a tenderness less than 4 kg. Thus, it can be classified as "very tender" meat.     

Effects of genotype and slaughter weight on the meat quality of Criollo Cordobes and Anglonubian kids produced under extensive feeding conditions

Physicochemical and organoleptic characteristics of meat (longissimus muscle) from Criollo Cordobes (CC) and Anglonubian (AN) suckling kids were analysed to determine the effects of genotype and slaughter weight. Forty suckling entire male kids, 20 CC and 20 AN were assigned to two age/slaughter weight groups (I: 60 + 2 days old and ?11 kg, and II: 90 + 2 days old and >11 kg). Colour, shear force and cholesterol levels of meat were affected by breed. Tenderness decreased and cholesterol increased with age/slaughter weight. Fatty acid profiles were affected primarily by genotype. The sensory attributes were perceived as medium-high intensity, and meat from CC and AN goat kids was valued as tender. However, initial tenderness and connective tissue varied with genotype. The main effect due to the increase in age/slaughter weight was a decrease in tenderness (initial and overall), as observed for instrumental shear force.     

Effects of vitamin E supplementation on fattening performance, non-carcass components and retail cut percentages, and meat quality traits of Awassi lambs

This experiment was carried out to evaluate the effects of vitamin E supplementation on growth, non-carcass components and retail cut percentages, and meat quality traits of Awassi male lambs at approximately 8 months of age. The lambs were divided into two groups as control (CG, n=12) and experimental (VG, n=12) at the beginning of the fattening period. The CG and VG lambs were fed with a concentrate and grass hay close to ad-libitum by biweekly adjustment of the amount offered. In addition, the VG received a supplement of 45 mg vitamin E per lamb per day during a 75-day fattening period. Inital weight, final weight, daily weight gain and feed conversion efficiency were 31.8±1.40 kg, 45.5±1.37 kg, 183±13 g and 7.6 for CG, 32.5±1.45 kg, 46.7±1.42 kg, 189±15 g and 7.0 for VG, respectively. Vitamin E supplementation did not have a statistically significant effect on animal performance traits, non-carcass components and retail cut percentages, but produced an 8.1% improvement in feed conversion efficiency. After slaughter, carcasses were chilled at 4?°C for 24 h. Then, the carcasses were dissected into wholesale cuts, and m. longissimus dorsi (LD) muscles excised. The samples of muscle were subjected to moisture, protein, ether extract and ash analyses. Samples were cooked for shear test and cooking yield measurements. There were no significant differences between CG and VG lamb groups in chemical composition of meat samples from the LD muscles. Though the influence of vitamin E supplementation on color parameters (L*, a*, b*) was not statistically significant, the mean a* (redness) values decreased on days 2 and 4 and increased on days 7 and 12 of the storage period. However, the a* values of muscles from the VG were higher than those grouping CG. L* and a* values in LD muscle from vitamin E-treated lamb groups were also preserved for a period of 12 days of maturation. In this study, drip loss was relatively preserved by vitamin E supplementation to the diet of animals. The results showed that vitamin E supplementation to the diet of Awassi male lambs at an inclusion rate over the amount of nutritional recommendations relatively reduced lipid oxidation, drip loss and tended to maintain meat redness.     

Effect of slaughter weight and breed on instrumental and sensory meat quality of suckling kids

The effects of breed and slaughter weight on chemical composition, fatty acid groups, texture, and sensory characteristics of meat of 141 suckling male kids from 5 Spanish breeds were studied. There was a decrease in texture and lightness and hue angle with the increase of the slaughter weight. Fatty acid composition was correlated with the intramuscular fat content. All the breeds except MO had values of n-6/n-3 ratio below 4, which is the healthy limit recommended, and a low atherogenic index as well as a low intramuscular fat content. A multivariate analysis discriminated light kid, which had the most tender and juicy meat, from heavy kid which had more intense kid and milk odours. Blanca Andaluza and Pirenaica had most tender and juicy meat. The effect of slaughter weight on meat traits should be considered separately for each breed to find the most appropriate meat according to consumers preferences.     

Effects of diet and live weight at slaughter on kid meat quality

Forty male twin kids of the Majorera breed were used in a 2×2 design, in which the diet, suckled on dam (SD) or milk replacer (MR) and live weight at slaughter (6 or 10kg) were the main variables. Muscle pH and colour (CIE, L*a*b*) were determined in the longissimus (LD), semimembranosus (SM) and triceps brachii (TB) muscles, immediately after slaughter and chilling (24h). Water-holding capacity, shear force, chemical composition (moisture, fat, protein and collagen content and solubility) were determined. Muscle fibre populations were also studied. SD kid meat was slightly more tender and juicy, and the Chroma value was lower than in MR animals. The meat from the kids that were slaughtered at 10kg was significantly darker in all muscles tested and slightly less tender 6kg LWS kid meat had more moisture and less protein than that of 10kg LWS kids. Muscle fibre area was statistically higher in the 10-kg LWS kids. It was concluded that the meat quality of the heavier kids was not significantly different from that of the lighter kids and that slaughter at the greater weight would result in more meat being marketed.     

The significance of diet, slaughter weight and aging time on pork colour and colour stability

The objective of the present study was to investigate the effect of a diet with a low content of digestible starch, slaughter weight and subsequent aging time on meat colour and colour stability. Pork colour was determined as the extent of blooming of M. longissimus thoracis (LT) and M. semimembranosus (SM) after 1, 2, 4, 8 and 15 days postmortem and as colour stability during a subsequent storage period in air for 6 days. Compared to the control diet, the experimental diet resulted in a significantly lower postmortem muscle temperature (1°C; p<0.0001). Moreover, high slaughter weight (110kg) resulted in a higher postmortem temperature in LT (p<0.001) compared to low weight (85kg). Independent of feeding strategy and slaughter weight, the extent of blooming decreased during the first 2-4 days of aging in LT, however, the effect was more pronounced in meat from experimentally fed pigs and pigs with high slaughter weight. This effect was not seen in SM, where a gradual increase in blooming took place throughout the aging period. The colour stability was found to be superior in aged pork from experimentally fed pigs. The discoloration rate was faster in SM compared to LT. In conclusion, the present study shows that the diet composition can be used as a tool to control meat colour and colour stability in pork.     

Use of generalized Procrustes analysis (GPA) to test the effects of sex and carcass weight on sensory quality evaluations of Terrincho lamb meat

Generalized Procrustes analysis (GPA) was used to test the sensory attributes of Terrincho lamb meat, a product with Protected Designation of Origin (PDO) labelling. Effects of sex and carcass weight on the following sensory attributes: toughness, juiciness, flavour intensity, odour intensity, stringiness, and level of sweetness were tested. Tests were performed on 28 females and 29 males placed within three classes of carcass weight, 3 to 9 kg. Meat sensory quality was evaluated, within five sessions, by a trained taste panel. Meat was cooked in a conventional oven, cut into pieces, and delivered to the panel for evaluation. Data were analyzed using a GPA to minimize differences between assessors. Two factors explained 72.76% of the total variability. The panel did not clearly detect sex effects, yet could differentiate meat by carcass weight as heavier animals were toughest and had more intense odour and flavour, whilst light animals were most succulent.     

Live weight and sex effects on carcass and meat quality of "Borrego terrincho-PDO" suckling lambs

Fifty seven suckling lambs (28 males and 29 females) of the Churra da Terra Quente breed were used to evaluate the effects of live weight and sex on carcass composition and meat quality traits. Lambs were slaughtered at three weight classes (<8 kg, 8–11 kg and >11 kg) according to “Borrego Terrincho–PDO” specifications. The left sides of the carcasses were totally dissected. The longissimus thoracis and lumborum muscle was used for meat quality determination. Dressing proportion and carcass fatness were not affected by weight class or sex. Muscle proportion was similar in all carcass joints for the three weight classes. The percentage of bone decreased at the higher weight class, while that of subcutaneous and intermuscular fat increased. Female lambs had higher muscle proportions and greater muscle/bone ratios in the carcass side than males. Muscle pH, colour, cooking losses and tenderness were not affected by gender and weight class. Female lambs and weight classes 8–11 kg and >11 kg had higher proportions of intramuscular fat.     

Lamb meat quality of two breeds with protected origin designation. Influence of breed, sex and live weight

Lamb meat quality of two Portuguese products was examined. The influences of slaughter weight, sex and breed on eating quality were evaluated. Data were obtained from 72 lambs of two different breeds with protected designation origin. In accord with the normal slaughter weight in the region three classes were considered: A: 9–14 kg live weight; B: 14–19 kg live weight and C: 19–24 kg live weight. pH of M. longissimus thoracis et lumborum muscle (MTL) was measured 1 h and 24 h after slaughter. Meat colour was estimated in the M. longissimus thoracis et lumborum muscle (MTL) muscle on the 12th rib using the L* a* b* system. Shear force was evaluated 72 h after slaughter. Sensorial analysis was assessed by a trained taste panel of 12 members. The pH values found could be considered within the normal pH range, between 5.5 and 5.9. When the pH measurement was made 24 h after slaughter, the heavy lambs had significant higher value than the light lambs. In relation to colour variables, live weight, sex and breed had no effect on the red index (a*). Lightness (L) decreased with increasing live weight and the light lambs had higher yellow index (b*) than the heavier lambs. Shear force increased with live weight and the Bragançano breed had a greater mean shear force than the Mirandesa (7.8 vs. 6.8 kg/cm²). The heavy carcasses had more flavour intensity than the light ones. Mirandesa lambs had significantly lower values for toughness, stringy and odour intensity than Bragançana lambs.     

Effects of age and/or weight at slaughter on longissimus dorsi muscle: Biochemical traits and sensory quality in pigs

The effect of increasing either age alone through feed restriction, or both age and weight at slaughter, on the quality of the longissimus dorsi muscle (LM) was investigated. Starting at 83 days of age and 32 kg, 80 pigs were allotted within litter to four experimental groups. All pigs were free of RYR1 mutated gene. Pigs were fed either ad libitum (A100, A130) or restricted 30% (R100, R130) and slaughtered at either 100 kg (A 100, R100) or 130 kg (A130, R130) body weight. Restricting feed intake in order to increase age at the same weight resulted in slower growth, better feed efficiency and increased leanness, whereas increasing age and weight simultaneously elicited slower growth, reduced feed efficiency and fatter carcasses. Intramuscular fat (IMF) and muscle collagen concentration were reduced by restricted feeding. Increase in both age and weight of pigs resulted in lower water, and higher protein and IMF concentrations. Although pigs were free of RYR1 gene, the PSE condition (defined as pH1 ≤ 5.9) developed in 25 carcasses, with a higher incidence in restricted pigs. PSE animals were excluded from the subsequent analysis of meat quality data. Feed restriction resulted in higher drip loss and lower a^* and c^* (saturation index) values. Longer myofibril fragments in muscle of restricted pigs on day 1 post mortem are indicative of slower maturation, while longer fragments on day 4 in heavier pigs, suggest that the extent of post mortem tenderisation could be negatively affected by the elevation of slaughter weight. Feed restriction had no significant effect on meat sensory quality, whereas increase in both age and weight resulted in lower tenderness, chewiness and mouth coating scores. Our results indicate that increasing age at a given body weight, via feed restriction, reduced IMF and collagen concentrations, and the rate of post mortem proteolysis, however, this had no significant impact on pork quality assessed after 4 days of ageing. On the other hand, increasing both age and weight at slaughter could alter pork texture, in spite of elevated IMF concentration.     

Meat quality of wether lambs grazed on either saltbush (Atriplex nummularia) plus supplements or lucerne (Medicago sativa)

The meat quality of 42, 8 month-old cross-bred wether lambs that had been grazed on either predominantly saltbush (Atriplex nummularia) and supplemented with pasture hay (n=14) or oat grain (n=14) for 68 days was compared to lambs grazed predominantly on lucerne (Medicago sativa; n=14). The lambs used in the study ranged in un-fasted liveweight from 44.5 to 63.6kg pre-slaughter. There was no significant (p>0.05) difference between the treatments for liveweight, but there was a significant (p<0.05) treatment effect on hot carcass weight with those from the saltbush/hay group (SH) being lighter than those from the lucerne group. When the carcass measures of fatness or m. longissimus thoracis et lumborum area were adjusted to a common carcass weight of 22.4kg there was no difference between groups. There were no significant differences (p>0.05) between groups for pH or colour values (where L* indicates relative lightness, a* indicates relative redness and b* indicates relative yellowness). There was no significant difference (p>0.05) between groups for b(2)* values of subcutaneous fat. Treatment had a significant effect on aroma strength (p<0.05), samples from lambs in the SH group (n=10) and those in saltbush/grain (SG) group (n=10) having a stronger aroma than those from lambs grazed on lucerne (L; n=10). No treatment effect for liking of aroma was found. Flavour strength was not significantly (p>0.05) stronger for samples from groups SH and SG than for samples from group L. There was no effect of treatment on tenderness or juiciness and overall panellists ranked the samples similarly for acceptability. Finishing lambs on saltbush and either supplemented with hay or grain as used in this experiment did not present any apparent meat quality problems compared to lucerne fed lambs.     

Meat and fat quality of unweaned lambs as affected by slaughter weight and breed

Sixty-four male lambs of two Southern Spanish breeds, a dairy breed (Grazalema Merino) and a meat breed (Churra Lebrijana), were used to study the effects of slaughter weight and breed on meat traits and intramuscular and subcutaneous fat composition. Lambs were reared following a traditional production system without weaning and slaughtered when live weight reached 12 kg (suckling) or 20 kg (light). Meat from suckling lambs of both breeds had lower fat and myoglobin contents, and was more tender and had higher scores for sustained juiciness in the sensory analysis. Fat from light lambs had lower C12:0 and C14:0 levels than fat from suckling lambs. Grazalema Merino meat had higher fat and ash contents, and its fat had higher conjugated linoleic acid content than Churra Lebrijana meat.