Breed and ageing extent on carcass and meat quality of beef from adult steers (oxen)

Livestock Science 107 (2007) 62 – 69 www.elsevier.com/locate/livsci

Breed and ageing extent on carcass and meat quality of beef from adult steers (oxen) C. Vieira a,⁎, A. Cerdeño b , E. Serrano b , P. Lavín b , A.R. Mantecón b a

Estación Tecnológica de la Carne, ITACyL, Apdo. 58, 37770 Guijuelo, Salamanca, Spain b Estación Agrícola Experimental, CSIC, Apdo. 788, 24080 León, Spain

Received 29 March 2006; received in revised form 31 August 2006; accepted 5 September 2006

Abstract In Spain, there is increasing demand, mainly by restaurants and specialty markets, for beef from adult steers (oxen). Therefore, this study assessed the quality of meat from three breeds which show large differences in meat production, but were reared under the same production system and slaughtered at 42 months of age. The breeds evaluated include a specialized meat breed, Limousine (LIM), a dual-purpose breed, Brown Swiss (BS), and a local breed, Asturiana de los Valles (AV). Effect of ageing extent (14 vs. 28 days) was also evaluated. LIM showed the highest dressing percentage and best conformation score while AV oxen provided the lowest carcass weights. BS and LIM adult steers produced fatter carcasses and BS animals had the highest intramuscular fat content. With the exception of juiciness, which had slightly higher values in BS, breed had little effect on sensory parameters. Shear force values were slightly lower in meat aged for 28 days than in meat aged for 14 days. Regarding sensory parameters, ageing extent beyond 14 days just influenced odour intensity which had higher values in meat aged for 28 days. © 2006 Elsevier B.V. All rights reserved. Keywords: Adult steers beef; Meat quality; Carcass quality; Breed; Ageing extent

1. Introduction The changes in the world meat markets over the past decade and the improvement in the educational and economical conditions of most consumers have increased the demands in meat they consume. As a consequence, consumers are searching for meat that has characteristics that differ from the most commonly consumed meat. Today, consumers are better informed and more

⁎ Corresponding author. Tel.: +34 923 59 06 88; fax: +34 923 58 03 53. E-mail address: [email protected] (C. Vieira). 1871-1413/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2006.09.004

concerned about production systems and the environment and animal welfare requirements (Andersen et al., 2005). Given those developments, beef production using adult castrated male animals (oxen) might provide an interesting and profitable alternative. Historically, oxen were used for draught power; today, however, the only objective of adult steer production is to provide high quality meat that can be differentiated from other types of beef. Recently, in several developed countries, oxen meat has become an appreciated product that is sold at high prices in specialty markets and restaurants. The use of adult steers for beef production might be profitable in mountainous areas of Europe, such as those that exist in north-western Spain. In those areas, the use of pasture and a diet supplemented with dried forages and

C. Vieira et al. / Livestock Science 107 (2007) 62–69

small amounts of cereals might provide a way to achieve sustainable meat production, meet the production system requirements of the European Union, extensification and territory use to contribute to the livelihood of rural population. To produce a high quality meat, however, it is necessary to evaluate variables related to animal production, such as genetic and management properties, as well as variables associated with the processing of meat (Short et al., 1999). Breed is an important factor that can influence the characteristics of the finished product; therefore, a comparative study of the most common breeds in Spanish mountain areas is needed. Given the particular characteristics of beef from adult animals, it is plausible that meat processing parameters, such as extent of the ageing period might influence the quality of oxen meat. Although studies have described the carcass and meat characteristics of castrated males in a large number of breeds, most of the studies are based on animal slaughtered at less than 3 years of age and few have examined these characteristics in older animals. The objective of this experiment was to determine the breed-specific characteristics of meat produced in a production system that is based on the maximum use of natural resources, and to determine the optimum ageing period required to produce high quality meat from oxen. 2. Materials and methods 2.1. Animals and experimental design The experiment was conducted at the Agricultural Experimental Station of the Spanish Council for Scientific Research (CSIC) in León, Spain, and involved 24 animals of three genotypes: 12 male Brown Swiss (BS), a dual-purpose breed, 6 male Limousine (LIM), a specialized meat production breed, and 6 male Asturiana de los Valles (AV), a local Spanish beef breed. The animals were born in spring and reared on pasture with their dams until early October, when calves were weaned and the 3-year experiment began. At that time, the animals were, on average, 8 months old and their weights ranged from 220 to 260 kg. Once they arrived at the Agricultural Experimental Station, the animals were housed together and subjected to the same production system, which was similar to the system commonly used on Spanish farms that raise oxen for beef. The animals occupied a 900 m2 indoor area that had straw bedding on a concrete floor and the adjacent 1500 m2 open area of ground, which served as an exercise yard. Additionally, between June and October, the animals had access to an irrigated pasture where they could graze. To maximize forage intake in the growth and fattening phases, the feeding regime

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took into account the natural resources available in each season. To achieve a desirable fatness grade at slaughter, animals were fed larger amounts of concentrate during the finishing phase. Specifically, the daily ration of concentrate was 3 kg/animal in the first year, 6 kg/animal in the second year, and 10 kg/animal in the third year of the experiment. Between November and January, animals were offered alfalfa hay ad libitum; between February and May, animals received 10 kg/animal of medium quality silage and 4 kg/animal of alfalfa hay each day; and between June and October, the animals grazed irrigated pasture for 10 h/day. The concentrate consisted of 35% corn, 32% barley, 12% soybean meal, 10% lupin, 5% molasses, 3% by-pass fat, and 3% vitamin and mineral premix. The concentrate contained (% DM) crude fibre (5.1%), acid detergent fibre (6.5%), neuter detergent fibre (13.7%), sugars (4.7%), starch (39.2%), crude protein (14.8%), ether extract (5.5%), and ash (5.3%). Throughout the experiment, the animals were weighed at 2-month intervals, and average daily weight gain was estimated using linear regression. At 10 months old, the animals were castrated. At 42 months old, when the maximum fatness grade in each genotype is expected, the animals were slaughtered. The transport of animals from the experimental station to an EUauthorised commercial slaughterhouse lasted 1 h and the animals were slaughtered within 12 h after arriving at the slaughterhouse. A summary of the animal performance and live weight at slaughter is given in Table 1. 2.2. Carcass characteristics and rib dissection Once the animals were slaughtered, carcasses were weighed at about 1 h post-mortem and graded visually for conformation and fatness using the EUROP beef-carcass grading system. Conformation scores ranged from 1 (P, very poor conformation) to 5 (E, very good conformation). Fatness scores ranged from 1 (very low) to 5 (very Table 1 Growth rate through the experimental period and weight at slaughter in oxen from the three breeds studied AV ADG1 1st and 2nd years (kg/day) ADG finishing phase (kg/day) SBW2 (kg)

LIM

BS

RSD

p

0.75

0.74

0.82

0.12

ns

0.50a

0.68b

0.68b

0.12

⁎

88.49

⁎

826.9 a

909.8a,b

941.0b

a, b: values with different superscripts indicate significant differences between breeds. ⁎p b 0.05; ns: p N 0.1. 1 ADG: average daily gain. 2 SBW: slaughter body weight.

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Table 2 Carcass characteristics, fat color, and meat color of three breeds of oxen slaughtered at 42 months old AV Hot carcass weight (kg) Hot dressing percentage (%) Cooling shrinkage (%) Carcass assessment Conformation score Fatness score Carcass length (cm) Blockiness (kg/cm) pH 24 semimembranous pH 24 longissimus lumborum Color of subcutaneous fat L⁎ b⁎ Color longissimus thoracis L⁎ a⁎ b⁎

LIM

BS

RSD

p

499.31a 590.52b 557.50b 52.540 ⁎ 60.31a 64.92b 59.31a 1.705 ⁎⁎⁎ 3.20

4.11

2.90

4.00 b 3.00 a 3.17 a 2.67 a 4.17 b 4.77 b 148.1 147.5 152.8 3.91b 3.52 a 3.30 a 5.56 5.53 5.51 5.59 5.79 5.67

0.425 ns 0.195 0.811 6.765 0.241 0.091 0.270

⁎⁎⁎ ⁎⁎⁎ ns ⁎ ns ns

66.4a 13.79 a

61.1b 10.26 b

62.0 b 11.45 b

3.320 ⁎ 1.190 ⁎⁎⁎

37.23 19.08 7.09

38.49 17.73 6.80

38.84 19.51 8.51

2.127 ns 2.067 ns 1.561 ns

⁎⁎⁎p b 0.001; ⁎p b 0.05; ns: p N 0.1. a, b: values with different superscripts indicate significant differences between breeds.

high). Dressing proportion was calculated as the ratio between hot carcass weight and slaughter body weight. After the carcasses were cooled for 24 h at 4 °C, the longissimus thoracis muscle between the 6th and 11th ribs was removed from the left carcass side. A Metrohm 704 pH-meter with a ‘penetration’ pH-electrode was used to record pH in longissimus thoracis muscle at the 6th rib level. To measure carcass length (De Boer et al., 1974) and calculate blockiness (kg/cm), the left carcass side was used. To estimate carcass tissue composition, the 6th rib was kept frozen (− 20 °C) before being thawed and dissected into bone, muscle, subcutaneous fat, intermuscular fat, and other tissues (vessels, tendons, fascia, and ligamentum nuchae). The weight of each type of tissue was expressed as a proportion (%) of the total weight of dissected tissue. The weight of longissimus thoracis muscle (LT) was expressed as a proportion (%) of the total weight of dissected muscle. The area (cm2) of the longissimus thoracis muscle was measured at the 7th rib section using a planimeter (Area Meter MK2), and was scaled for carcass weight (cm2/kg). Fat color scores were based on the subcutaneous fat between the 6th and 10th ribs and muscle color was estimated using the m. longissimus thoracis muscle at the 6th rib, after the newly cut surface was exposed to artificial light for 90 min at 10 °C. Measurements were made using a Minolta CM2002 spectrophotometer in the CIEL⁎a⁎b⁎ space under D65, 10°, and SCI conditions.

2.3. Meat quality To determine the chemical composition of muscle, the longissimus thoracis muscle from the 6th rib was minced and freeze-dried. The amounts of dry matter, ash, ether extract, and crude protein were determined using standard procedures (A.O.A.C., 1993). To determine Gross energy (GE), an adiabatic calorimetric bomb was used. To determine the effects of ageing on meat quality, each section of longissimus thoracis between the 7th and 11th ribs was divided into two pieces, which were vacuum-packed separately and aged for 14 or 28 days. At the time of analysis, each vacuum-packed section was divided into two sub-samples, each about 2 cm thick; one sample was used for measurements of cooking weight loss and textural analyses, and the other was used for sensory analyses. Losses due to cooking were determined after heating the samples in a water bath at 70 °C (Honikel, 1997). Those samples were subjected to the Warner-Bratzler Shear Force test (Honikel, 1997) using a Texture Analyser TA-XT2 texturemeter. Each sample provided a minimum of 8 strips that had a 1 cm × 1 cm cross-section and fibre parallel to the longest dimension of at least 2 cm, so that the fibre axis was perpendicular to the blade of the Warner-Braztler device. For the sensory analyses, steaks were wrapped in aluminium foil and cooked to an internal temperature of 70 °C in a convection oven that was preheated to 220 °C for 10 min. A trained eight-member panel evaluated the sensory characteristics of 2 cm × 2 cm cooked samples, which were kept hot until testing. Using a scale from 1 (low intensity) to 9 (high intensity), panel members evaluated the samples for odour intensity, tenderness, juiciness, chewiness, flavour intensity, and overall palatability.

Table 3 Tissue composition of the 6th rib section of the three breeds of oxen studied

6th rib weight (kg) Bone (%) Muscle (%) Subcutaneous fat (%) Intermuscular fat (%) Other tissues (%) Longissimus thoracis area (cm2) LT area/carcass weight (cm2/kg)

AV

LIM

BS

RSD

p

5.05 13.4 62.7 a 5.65 a 16.7 1.54 64.7b

5.13 11.9 61.3 a 8.13b 17.2 1.53 79.7 a

5.14 13.5 57.1b 8.39 b 18.9 2.02 69.5 a,b

0.867 1.817 2.780 2.396 2.661 1.035 10.80

ns ns ⁎⁎ ⁎ ns ns ⁎

13.38

13.90

12.87

ns

⁎⁎p b 0.01; ⁎p b 0.05; ns: p N 0.1. a, b: values with different superscripts indicate significant differences between breeds.

C. Vieira et al. / Livestock Science 107 (2007) 62–69 Table 4 Composition of the longissimus thoracis muscle of the three breeds of oxen studied

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⁎⁎⁎p b 0.001; ⁎⁎p b 0.01. a, b: values with different superscripts indicate significant differences between breeds.

breeds. Dressing percentage, conformation score, and blockiness were significantly higher in the LIM breed than in the BS and AV breeds. Mean fatness score was significantly lower in AV oxen than in the BS and LIM breeds. The pH values of the meat from the three breeds fell within the normal range and did not differ significantly. The color of the longissimus thoracis muscle did not differ significantly among breeds; however, the colorimetric parameters L⁎ and b⁎ of the subcutaneous fat in carcasses of the AV breed were significantly higher than those observed in the BS and LIM breeds.

2.4. Statistical analyses

3.2. Tissue composition

To determine whether growth rate, slaughter weight, carcass quality, and chemical muscle composition differed significantly among breeds, the data were subjected to one-way analysis of variance using the GLM procedure. Regarding cooking loses, texture, and sensorial parameters, data were subjected to analysis of variance using GLM procedure of SAS to examine the effect of breed and ageing period. We used a two factor model (2 × 2) with repeated measures on one factor (time) as described by Cody and Smith (1991). Single animals were considered as experimental units. Differences between means were separated by PDIFF procedure of SAS. Results are presented as least-squared mean values with S.E. Statistical analyses were performed using SAS 9.1 software.

The tissue composition of the 6th rib section in the three breeds is presented in Table 3. Although the three breeds did not differ significantly in most measures of tissue composition, the mean proportion of muscle was significantly lower in the BS breed, and the mean proportion of subcutaneous fat was significantly lower in the AV breed than in the BS and LIM breeds. The surface area of the longissimus thoracis muscle was significantly higher in LIM than in AV adult steers, but the mean value in BS oxen was intermediate to and did not differ significantly from the values of the AV and LIM breeds. When the area of the longissimus thoracis muscle was scaled for carcass weight, the three breeds did not differ significantly.

AV Dry matter (%) Ash (% DM) Crude protein (% DM) Ether extract (% DM) Gross energy (Mcal/kg)

LIM a

28.80 3.95a 70.29 a 24.53a 6.34a

BS a

27.04 4.03a 74.90 a 20.32 a 6.26 a

b

31.40 3.16 b 59.10 b 35.91b 6.84b

RSD

p

2.380 0.412 7.175 6.906 0.282

⁎⁎ ⁎⁎⁎ ⁎⁎⁎ ⁎⁎⁎ ⁎⁎

3.3. Meat quality 3. Results The proportions of dry matter, fat and the gross energy content of the longissimus thoracis muscle were significantly higher in BS oxen than in AV and LIM oxen while protein and ash content were lower in BS than in AV and LIM (Table 4). Water-holding capacity presented a tendency to be higher in LIM beef than in AV beef ( p b 0.1), but the mean value of proportion of

3.1. Carcass characteristics The carcass characteristics of three breeds of oxen are presented in Table 2. Hot carcass weight was significantly lower in AV oxen than in BS and LIM oxen. Cooling shrinkage did not differ significantly among

Table 5 Effect of breed and ageing extent on shear force, cooking losses, and sensorial parameters in oxen meat (lsmeans and standard errors) Breed

Warner-Bratzler (kg) Cooking losses (%) Odour Tenderness Juiciness Chewiness Flavour Acceptability

Ageing

ANOVA

AV

LIM

BS

14 days

28 days

B

A

6.99 ± 0.535 23.36a ± 1.030 5.75 ± 0.123 5.77 ± 0.398 4.77 ± 0.398a 4.91 ± 0.298 5.75 ± 0.146 5.25 ± 0.264

7.50 ± 0.535 19.96 b ± 1.132 5.41 ± 0.137 5.16 ± 0.445 4.31a ± 0.318 4.34 ± 0.333 5.49 ± 0.094 4.58 ± 0.299

7.45 ± 0.313 22.18a,b ± 0.630 5.72 ± 0.079 5.48 ± 0.257 5.00b ± 0.183 4.95 ± 0.192 5.66 ± 0.094 5.13 ± 0.172

7.54 ± 0.214 21.24 ± 0.634 5.48 ± 0.094 5.29 ± 0.175 4.67 ± 0.119 4.59 ± 0.143 5.65 ± 0.110 4.90 ± 0.127

6.90 ± 0.194 22.42 ± 0.598 5.78 ± 0.096 5.66 ± 0.180 4.72 ± 0.121 4.87 ± 0.146 5.62 ± 0.112 5.08 ± 0.130

ns † ns ns † ns ns ns

† ns ⁎ ns ns ns ns ns

⁎p b 0.05; †p b 0.1; ns: p N 0.1. a, b: values with different superscripts indicate significant differences between breeds.

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cooking losses in BS beef was intermediate to and did not differ significantly from the values of the AV and BS breeds (Table 5). Warner-Braztler shear test values did not differ significantly among breeds, but meat aged for 28 days tend to be lower than meat aged for 14 days ( p b 0.1). With the exception of juiciness which tend to be higher in BS than in AV and LIM ( p b 0.1), none of the sensorial parameters examined in the study differed among the breeds studied. Only the odour was affected by the extent of ageing, corresponding the higher values to meat aged 28 days ( p b 0.05). 4. Discussion 4.1. Carcass quality: differences among breeds In cattle breeds, live weight is largely the result of size at maturity, biological type, and growth rate (HovingBolink et al., 1999; Short et al., 1999; Chambaz et al., 2003; Albertí et al., 2005). The relatively lower carcass weight of the AVoxen used in this study might be due, at least partially, to breed-specific differences in mature size. Piedrafiata et al. (2003) reported that when AV and BS animals were slaughtered as yearlings, BS animals had higher slaughter and carcass weights than did AV animals. In our study, the mean carcass weight of BS oxen was within the range of values reported by Serra et al. (2004), who define the breed as “medium-big framed”. The mean slaughter weight of the LIM oxen used in our study is within the range (600–700 kg) reported by Robelin and Tulloh (1992). In our study, breed-specific differences in growth rate might have affected carcass weight. In that respect, breed-specific differences in growth rate were significant during the finishing phase, only, when BS and LIM animals had higher growth rates than did AS animals. As in our study, Sañudo et al. (2004) recorded significantly lower fatness scores in AV than in LIM young bulls, and Albertí et al. (1998) showed that AV animals had fat cover scores that were lower than those of six other beef breeds when young bulls were slaughtered at an average live weight of 460 kg. As in the study by Sañudo et al. (2004), we found that carcass fatness score was reflected in the tissue composition at the 6th rib, which indicated that the proportion of subcutaneous fat was lower in AV than in LIM. The percentages of fat cover and dissectible fat observed in our study might be considered too high since nowadays an excess in carcass fat is viewed as a negative attribute and the commonly used grading system would downgrade them. Although the commonly used beef grading system treats levels of carcass fat as high as those observed in our study as a

negative attribute and would lower the grade of the meat, in the commercialization of oxen beef, high fat content is desirable because it is one of the characteristics that differentiates it from other meat products. Indeed, the AV fatness scores observed might be a distinct disadvantage in oxen beef production given that meat from adult steers needs a fat cover thick enough to protect the carcasses during the long ageing period that is required for oxen meat to develop desirable characteristics. The significant differences in the carcass characteristics of the breeds studied in our work are similar to those reported elsewhere (Keane et al., 1989; Sañudo et al., 2004; Albertí et al., 2005), in which continental meat breeds and their crosses are generally better conformed than dairy or traditional breeds. It is interesting to note that the Limousine breed has been genetically selected over all long period to produce a breed that is highly specialized for meat production. Numerous studies have demonstrated that the LIM breed produces better conformation scores and carcass yields than do other beef breeds and, of course, dual-purpose and dairy breeds (e.g., Keane et al., 1989; Chambaz et al., 2003; Sañudo et al., 2004). The relatively high dressing percentage observed in LIM was expected because other studies (Keane et al., 1989; Sañudo et al., 2004) have reported high values for this trait, which is a result of the breed's low percentage of visceral fat and lower values in most of weights taken from fifth quarter. The relatively low dressing percentage in BS was expected given that it is a dual-purpose breed and, in dairy cattle, the coefficients of growth for non-carcass fat are higher than those for carcass fat (Geay, 1978; Kempster et al., 1982; Keane et al., 1990). As in previous studies (Keane et al., 1989; Chambaz et al., 2003), the surface area of the longissimus thoracis muscle was higher in the LIM breed than in the other breeds. That result is important because, in the commercialization of oxen meat, rib steaks are most demanded and valuable joints in specialized restaurants and markets. The finding that LIM carcasses were relatively leaner than those of breeds not specialized for meat production, such as BS, are similar to the results of studies that compared LIM crossbred steers with Friesian steers (Keane et al., 1989; Steen and Kilpatrick, 1995). Those studies showed that the area of LT muscle, saleable meat in high-priced joints, lean content in the fore-rib joint, and estimated lean content in the carcasses were greater for LIM than for Friesian steers. In addition, Purchas et al. (1992) reported that carcasses from the large framed and late maturing breeds have less fat, higher conformation scores, dressing percentages, and proportion of first category cuts.

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In terms of fat and muscle color, the three breeds in our study differed in the degree of yellowness and lightness of subcutaneous fat. Note, however, that all of the values are within the range of dark muscles and yellow fat, which are characteristic of adult steers carcasses. Generally, the intensity of muscle and fat color increases as animals became older (Morgan and Everitt, 1969; Renerre, 1982; Boleman et al., 1996). In our study, the values for L⁎ and a⁎ in longissimus thoracis muscle were higher than those reported in Limousine steers slaughtered at about 20 months of age (38.1, 14.7 and 4.9 for L⁎, a⁎ and b⁎, respectively; Chambaz et al., 2003) and closer to the values observed in Simmental mature cows (36.7, 18.7 and 10.4 for L⁎, a⁎ and b⁎, respectively; Hoffman, 2005). 4.2. Meat quality: effect of breed and ageing extent In our study, the chemical composition of oxen beef mirrored tissue composition given that BS meat had the highest fat content. In this sense, a higher ether extract of BS with respect to LIM and AV were expected since BS is a dual-purpose breed whereas AV and LIM are considered beef specialized breeds. In the line of our results, Cuvelier et al. (2006) have reported breed differences in fat content among Limousine, Aberdeen Angus and Belgian Blue slaughtered as young bulls, corresponding higher values for Aberdeen Angus, followed by Limousine and Belgian Blue. Given the relatively high Warner-Braztler shear force values recorded in our study, beef from these breeds can be classified as slightly tough meat because Bruce et al. (2004) classified meat with values over 6 kg as tough. Although meat aged for 28 days had slightly lower Warner-Braztler shear force values than did meat aged for 14 days, the trained sensory panel did not report differences in tenderness. In addition, no significant effect of ageing extent was observed on the other sensorial parameters, including tenderness, chewiness, and acceptability, which theoretically should improve as the length of the ageing period increases. The studies carried out by Campo et al. (2000) and Monson et al. (2004) showed that ageing reduced differences between breeds and increased tenderness. Those authors reported that the desirable tenderness in meat from adult animals might not be reached until after several weeks of ageing, but the highest percentage (75–80%) of the potential improvement in tenderness occurs during the first 10 days of ageing, when resistance to cutting decreases exponentially. On the other hand, studies have shown that the older the animal is at slaughter, the longer the ageing period has to be (Koomaraie et al., 2002; Vieira et al.,

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2002; Kolczak et al., 2003). Taking into account low tenderness scores together with higher Warner-Braztler shear force values, it seems that although ageing periods studied could be enough to reduce breed differences, meat from animals slaughtered as oxen might need ageing periods longer than 28 days to achieve a desirable degree of tenderness. Nevertheless, our results might be partially explained by the cooking process used in preparing samples for the Warner-Braztler tests and sensorial analyses and the structure of muscles from animals slaughtered as adults. King et al. (2003) used Warner-Braztler shear force tests to compare meat previously cooked at different cooking rates, 90 °C (slow) and 260 °C (fast), and reported that slower cooking rates produced greater tenderness. Additionally, others (Møller, 1981; Powell et al., 2000; Tornberg, 2005) have shown that the contribution of connective tissue to shear force is primarily influenced by a heating temperature between 50 and 65 °C, when the maximum weakening of collagen occurs, and the time during which steaks remain in this temperature range is extended in slow cooking treatments. Given the oven temperature used in our study, the cooking rate was fast. Although we did not determine the content of connective tissue, we assume that meat from animals older than 3 years have high amounts of collagen (McCornick, 1994; Boleman et al., 1996; Avery et al., 1998). Thus, in the types of adult animals studied, slower cooking rates will likely favour greater tenderness of the meat. Unlike the study of Monson et al. (2005), differences in the tenderness of the meat of the three breeds were not detected in our study; however, both studies detected breed-specific differences in the juiciness of beef. As in the study by Destefanis et al. (1996), the higher juiciness values we observed in BS meat were expected because of its relatively high intramuscular fat content. Regarding odour, Campo et al. (2003) indicated that the delayed increase in aromatic characteristics is a result of the accumulation of products, which can be considered aromatic precursors, derived from proteolysis that occurs after long periods of ageing. 5. Conclusion In our study, Limousine oxen provided the best carcass value given the higher dressing percentage and conformation score compared to the AV and BS breeds. Given current consumer preferences and market standards, a high degree of fatness in oxen meat is desirable; thus, Limousine and Brown Swiss might be more advantageous to produce because of the higher fat content of the meat and the very little difference in the sensory traits of the

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