Comparison of the meat quality of Thai indigenous Upland Cattle and F2-crossbreds with 75% Charolais blood proportion

Abstract

The aim of the present study was to investigate the difference in meat quality between local Thai indigenous Upland Cattle (Bos indicus) and Charolais × generic Thai native cattle crossbreds (here: F2, 75% blood proportion of Charolais), an increasingly preferred option of farmers in Northern Thailand. Eight bulls of the F2-crossbred genotype and eight of the Upland Cattle genotype were fed ad libitum with grass and were supplemented with concentrate at 1.5% of body weight until they were on average 4 years old. In the Longissimus dorsi (LD) muscle, pH at 45 min and 24 h post-mortem as well as luminosity were lower and redness was higher in the F2-crossbreds than in the Upland Cattle. The beef of the F2-crossbreds also expressed lower drip, thawing and cooking losses. There was no difference in grilling loss. The LD of the F2-crossbreds contained less moisture and more protein, fat and cholesterol than that of the Upland Cattle, and was richer in total and soluble collagen. Still, the beef of the F2-crossbreds was scored as more tender and had a lower shear force. Additionally it was scored to have a higher intensity of beef flavour as well as off-flavour and an overall better acceptability. Overall this suggests that a clearly better meat quality can be achieved by the crossbreeding strategy, but this was associated with higher fat and cholesterol contents. Further studies have to show which part of the changes in meat quality resulted from the large differences in body size of the two genotypes. Consideration for or against crossbreeding have to include animal welfare and health aspects.

Keywords:

• beef quality
• Charolais
• crossbred
• Upland Cattle
• breed
• Thailand

Introduction

In Northern Thailand, the most prevalent indigenous breed is the Upland Cattle (Bos indicus), where the animals have a slow growth rate but high heat tolerance, disease resistance and fertility. With 150–200 kg mature body weight they are likely the smallest among the Thai native cattle breeds and, traditionally, the breed is a very important source of meat supply to the villages (Rattanaronchart 2008). Still for Thai meat production systems more productive breeds, namely those with high muscle mass and high slaughter weight, the so-called beef breeds (Koohmaraie et al. 2002), are of increasing interest. Therefore, Northern Thai cattle farmers increasingly prefer to fatten crossbreds with Charolais rather than other genotypes according to the big body frame (Boonmee et al. 2008). There are a number of advantages in crossbreeding that have driven its current adoption. The most significant reason to crossbred is to take advantage of the superior genotype in terms of higher and beef quantity of the exotic breed and of heterosis. Another advantage is that it is likely that heat and disease resistance of the native breed is not completely lost. The genotype of the animal considerably influences meat quality. However, other genetic traits may be responsible for meatiness, which is why a high meat proportion is not necessarily associated with high meat quality. In Charolais, a specific inactivated myostatin mutation, named Q204X, segregates and corresponds to a cytosine to thymine substitution in the second exon of the myostatin gene (Grobet et al. 1998; Dunner et al. 2003). Animals with a single copy of the inactivated myostatin gene have greater muscle mass than normal animal. In order to evaluate whether or not crossbreeding improves the performance at cost of meat quality, the objective of the present study was to compare the meat quality of two extremely different genotypes, Thai indigenous Upland Cattle (originating from the mountainous areas of Thailand; further on called Upland Cattle) and crossbreds with Charolais.

Materials and methods

Fattening and slaughter procedures

Eight bulls each of Upland Cattle genotype and Charolais × generic Thai native cattle genotype (F2, 75% Charolais and 25% Thai native cattle; further on called F2-crossbreds) were fed paragrass (Brachiaria mutica) ad libitum from weaning at 7 months of age. After weaning the cattle were treated for intestinal parasites and vaccinated against foot and mouth disease as well as haemorrhagic septicaemia. In our experiment we found no problem with health. At weaning body weight was 40–50 kg for Upland Cattle and 250–300 kg for F2-crossbreds. They were then reared on the research farm in individual pens and supplemented with concentrate at 1.5% of body weight per day. The concentrate was composed of corn, tapioca chips, rice bran, soybean meal, urea, dicalcium phosphate, salt and sulphur. At slaughter, animals of both genotypes were on average 4 years old following common Thai practices concerning cooking habits. This procedure excluded an age effect. The animals were slaughtered at the Huay Kaew slaughterhouse, Chiang Mai, Thailand. For that, animals were stunned by a bolt stunner and dressed according to commercial practices. Afterwards they were exsanguinated, eviscerated and separated into two carcass halves. All experimental procedures were carried out following the animal welfare standards of the Animal Care and Use Committee of the Thai Livestock Department which are based on the guidelines of the Federation of Animal Science Societies (1999). After slaughter, the pH was recorded at 45 min and 24 h post-mortem (p.m.) in the Longissimus dorsi muscle (LD). The carcasses were chilled for 24 h at 3°C before sample collection. Samples of the LD (sixth to twelfth rib) were prepared from the left carcass side for subsequent meat quality analysis.

Laboratory analyses

Meat pH (pH metre model HI 99163, Hanna Instrument, Nusfalau, Romania) was determined in the LD at 45 min and 24 h p.m. After dissection, the LD samples were cut into 2.5 cm thick slices, kept in polyethylene bags and chilled at 4°C for 48 h, was determined. Measurements of the colour characteristics (L*, a*,b*) were performed with the Chroma Meter (Minolta, CR-400, Osaka, Japan) applying the light source D65 after samples had been allowed to bloom for 1 h in a refrigerator at 4°C.

Water-holding capacity (WHC) was estimated by measuring substance losses occurring during different procedures. Drip loss was quantified as described by Honikel (1987). Thawing and cooking losses were determined in the 2.5 cm thick slices of LD frozen in polyethylene bags at −20°C. The percentage of thawing loss was evaluated based on weight change before and after thawing at 4°C for 24 h. After that, samples were cooked in plastic bags in a water bath (Korimat model 120/1.6, Christian Wanger, Esslingen, Germany) at 80°C until a meat core temperature of 70°C was reached. The temperature was controlled by a thermocouple (Consort T851, Cohasset, MA, USA). Samples were cooled to ambient temperature and weighed after drying the surfaces with tissue paper. For the determination of the grilling loss, 2.5 cm thick slices were grilled in a convection oven (model 720, Mara, Taipei, Taiwan) at 150°C until a meat core temperature of 70°C was reached.

Samples of the LD were minced and analyzed in duplicate for contents of moisture, fat and protein (Kjeldahl; 6.25 × N) according to AOAC (1996). Cholesterol concentrations were determined in samples after extraction of the fat (Folch et al. 1957) and its saponification (Abell et al. 1951). In the residual extract cholesterol was measured colorimetrically according to Jung et al. (1975).

Soluble, insoluble and total collagen contents were colorimetrically determined as described in detail in Jaturasitha et al. (2009) and based on Hill (1966) as well as AOAC (1996). Absorption was measured at 558 nm by a spectrometer (UV 1601, Shimadzu, Tokyo, Japan). The soluble collagen was calculated as 7.52 × hydroxyproline found in the supernatant of the preparation whereas insoluble collagen was 7.25 × hydroxyproline found in the natant.

The samples which had been boiled to an internal temperature of 70°C were used to determine shear force after cooling and drying with soft paper. A steel hollow-core device with a diameter of 1.27 cm was punched parallel to the muscle fibres to obtain six cores from each LD sample. Each core was sheared perpendicular to the fibre direction using a TA XT2 Texture Analyzer (Texture Technologies Corp., Scarsdale, NY) with a 25 kg load cell. Test speed was 4.2 mm/sec, travel distance was 55 mm. Calibration distances were taken and the average of the maximum forces was used for data analysis.

For sensory evaluation, a test panel of nine persons was selected from students and faculty members of the Animal Science and Aquaculture Department of Chiang Mai University, who had undergone sensory evaluation training following the methods of Wheeler et al. (2005). Slices of LD which were 2.5 cm thick were grilled until the internal temperature reached 70°C, cut into pieces of 1.5 cm × 1.5 cm and then served warm on a plate. With this standardized sample size the muscle sizes which largely differed between genotypes were not discernible by the panellists. Samples were graded by the panellists using a 9-point scale (1, low; 9, high) for flavour intensity, off flavour intensity, tenderness and overall acceptability. The 16 samples, 1 of each animal, were served subsequently in a randomized order with respect to group and animal. Each panellist received four samples per test day, this over four days.

Statistical analysis

The differences between the two genotypes were statistically analyzed using Student's t-tests. Treatment differences were tested for significance at the 5% level. Tables present arithmetic means, standard deviations (SD) as well as minimum and maximum values. All calculations were performed with SAS version 6.12 (SAS Institute, 1997).

Result and discussion

The live weights at slaughter with an age of about 4 years were extremely different between genotypes (Table 1). After that long fattening period the Upland Cattle did not even reach the expected target weight of 150–200 kg. By contrast, at slaughter the F2-crossbreds were in the weight range of 450–700 kg expected with 75% blood proportion of Charolais. The present study focused on specific meat quality properties independent of growth and slaughter performance or size of valuable cuts which was very different in these two contrasting genotypes as well.

Table 1. Effect of genotype type on live weight at slaughter, pH, meat colour and WHC of the LD muscle (mean + SD; in brackets: min-max).

Criteria	F2-crossbreds (75% Charolais × 25% Thai native cattle)	Upland Cattle	P-value
Live weight at slaughter (kg)	649 ± 20.6 (620–669)	120 ± 12 (90–148)	<0.001
Chilled carcass (kg)	381 ± 14 (369–412)	65 ± 5 (47–78)	<0.001
pH
45 min p.m.^a	6.84 ± 0.16 (6.52–7.00)	6.58 ± 0.27 (6.08–6.95)	0.035
24 h p.m.^a	5.71 ± 0.04 (5.65–5.80)	5.52 ± 0.04 (5.45–5.55)	<0.001
Meat color^b
L*	37.5 ± 5.4 (29.2–52.0)	43.2 ± 3.5 (36.3–48.9)	<0.001
a*	19.4 ± 5.4 (11.0–29.2)	12.4 ± 2.3 (8.4–16.3)	<0.001
b*	10.3 ± 2.6 (6.9–14.6)	9.4 ± 1.5 (6.7–11.7)	0.162
WHC (%)
Drip loss	3.2 ± 1.4 (1.1–5.1)	5.8 ± 1.9 (2.6–7.4)	0.012
Thawing loss	9.1 ± 3.5 (3.3–14.2)	12.9 ± 1.5 (10.0–14.3)	0.020
Cooking loss	19.7 ± 4.1 (10.6–23.3)	24.5 ± 3.8 (20.0–28.6)	0.035
Grilling loss	29.3 ± 5.9 (23.7–39.8)	31.7 ± 1.4 (30.3–33.3)	0.441

^a Post-mortem.

^b L* = lightness, white = 100, black = 0; a* = redness, green = −80, red = 100; b* = yellowness, blue = −50, yellow = 70.

Muscle colour is an important trait determining purchase decision by consumers as it was repeatedly shown that meat tenderness is related with ultimate pH and muscle colour (Page et al. 2001). There was a significant difference between genotypes in pH and colour (Table 1). The pH at 45 min and at 24 h p.m. was higher for the F2-crossbreds (P < 0.05). However, ultimate pH was never >5.8 which excluded the presence of dark firm dry meat. Meat luminosity (L*) was lower and redness (a*) was higher in the F2-crossbreds (P < 0.001). There was no difference in yellowness values (b*) between genotypes. This was opposite to findings by Wulf and Wise (1999) where Bos taurus carcasses had higher L* values and lower a* values than B. indicus carcasses. These authors explained this finding by the whiteness generated by intramuscular fat which was actually also higher in the F2-crossbreds of the present study. However, p.m. denaturation of the muscle proteins results in a release of intracellular water which increases luminosity by reflection and thus is an even more universal contributor to the overall luminosity than actual discoloration (Lawrie & Ledward 2006) or fat-dependent components. In addition, a higher muscle pH leads to a higher activity of enzymes that use oxygen, resulting in decrease oxygenation of the surface myoglobin and a darker colour (Ledward 1992). This is consistent with the higher pH and lower drip loss (P < 0.05) of the beef from the F2-crossbreds found in the present study.

The beef from the F2-crossbreds had lower drip, thawing and cooking losses (P < 0.05), but grilling losses did not differ (Table 1). The level of drip loss is affected by many factors, such as breed, age, sex and diet (Fennema 1990). Waritthitham et al. (2010a) reported that the WHC of meat from crosses of Charolais × generic Thai native cattle was better than that of Brahman × generic Thai native cattle, which was probably due to the lower moisture and higher fat contents of the meat of the first compared to other crossbreds. According to Huff-Lonergan et al. (1996) intramuscular fat content correlates with drip loss, WHC, cooking loss and tenderness of the meat. The traits related to WHC of the meat are typically determined by genotype and slaughter conditions (Jaturasitha et al. 2009). Early p.m. events, including rate and extent of pH decline, proteolysis and even protein oxidation, are key factors in influencing the ability of meat to retain moisture (Huff-Lonergan & Lonergan 2005). Moreover Ozawa et al. (2000) found a positive relationship between percentage of α red type fibre and cooking loss. Slow twitch fibre type percentage was positively correlated with grilling loss, whereas an inverse relation between fast twitch fibre type percentage and grilling loss was observed (Waritthitham et al. 2010b).

Even though the beef from both genotypes was in the range expected in terms of chemical composition, the LD from the F2-crossbreds had a lower moisture and higher protein and fat percentages than that of the Upland Cattle (P < 0.05; Table 2). Meat moisture content is inversely related to its lipid content (Padre et al. 2006). The higher intramuscular fat content of the beef of the F2-crossbreds, which was high even when compared to intensively fattened, but still much younger Charolais steers (Chambaz et al. 2003), compared to that of the indigenous B. indicus cattle was in agreement with reports by Waritthitham et al. (2010a) and Wheeler et al. (1990). Due to the slow maturation of the indigenous cattle the accretion of fat in muscles is also delayed. Instead, muscles of early maturing genotypes are able to accumulate fat early. This phenomenon is also responsible for differences in protein/moisture ratios among muscles (Owen et al. 2001). The cholesterol content was higher in the LD of the F2-crossbreds than in that of the Upland Cattle (P < 0.001). Salvatori et al. (2004) reported that breed seems to be the most important factor for differences in cholesterol content, thus also influencing the contribution of cholesterol to intramuscular adipose tissue. In agreement with Chizzolini et al. (1999), the cholesterol content in the muscle was higher in the genotype with the higher intramuscular fat content, the F2-crossbreds. Also Garcia et al. (2008) reported a clear breed difference in cholesterol content, with a higher content found in early-maturing Angus as compared to Holstein Argentine breed.

Table 2. Effect of genotype on composition, shear force and sensory grading of the LD muscle (mean + SD; in brackets: min-max).

Criteria	F2-crossbreds (75% Charolais × 25% Thai native cattle)	Upland Cattle	P-value
Composition (%)
Moisture	72.3 ± 2.6 (70.3–81.3)	76.4 ± 0.5 (75.2–76.8)	<0.001
Protein	23.2 ± 1.2 (20.7–25.7)	22.6 ± 0.8 (21.2–24.0)	0.043
Fat	4.60 ± 1.59 (2.2–6.9)	0.97 ± 0.03 (0.4–1.3)	<0.001
Cholesterol (mg/100 g meat)	95.5 ± 4.7 (52.7–133.6)	63.2 ± 5.4 (37.6–125.4)	<0.001
Collagen (g/100 g meat)
Soluble	0.35 ± 0.02 (0.30–0.38)	0.32 ± 0.05 (0.25–0.42)	0.045
Insoluble	0.98 ± 0.15 (0.67–1.17)	0.87 ± 0.19 (0.40–1.16)	0.079
Total	1.33 ± 0.16 (0.98–1.53)	1.19 ± 0.18 (0.82–1.49)	0.031
Shear force, N	45.8 ± 2.1 (28.7–88.0)	51.4 ± 4.7 (44.9–71.4)	0.018
Sensory evaluation^a
Beef flavour intensity	5.77 ± 1.24 (3–8)	5.24 ± 1.45 (3–8)	0.002
Off-flavour intensity	2.19 ± 1.48 (1–4)	1.83 ± 1.02 (1–3)	0.026
Tenderness	7.02 ± 1.14 (4–9)	5.75 ± 0.69 (4–8)	<0.001
Overall acceptability	6.96 ± 1.13 (5–9)	5.72 ± 0.69 (3–9)	<0.001

^a 1, low; 5, average; and 9, high.

Soluble and total collagen contents were higher in the beef of the F2-crossbreds than in that of the Upland Cattle (P < 0.05) while the content of insoluble collagen did not differ as clearly (P < 0.1; Table 2). Jurie et al. (2006) found clear breed differences in culled cows, where the meat of Salers and Charolais cows showed higher total and insoluble collagen contents than that of Aubrac and Limousin cows. This may be explained by differences in maturity as earlier maturing breeds tend to deposit more collagen, but this with a greater proportion of soluble collagen. This is consistent with the present results where the meat of the F2-crossbreds with high blood proportion of Charolais, an early maturing breed, had higher collagen levels than that of the Upland Cattle, a late maturing beef breed. Shear force of raw beef is closely correlated with its collagen content (r = 0.81, Kopp & Bonnet, 1987; r = 0.95, Dransfield et al. 2003). Additionally, a high correlation to beef tenderness has also been found with collagen solubility (0.77 < r < 0.81, Herring et al. 1967; quoted in the review by Lepetit 2008) soluble collagen is an important factor in meat tenderness. Also described a close correlation between tenderness and collagen solubility. Still shear force of the LD from the F2-crossbreds was lower and sensory scoring of tenderness was more favourable than for beef from the Upland Cattle (P < 0.05). Differences in contents of all categories of collagen, though significant, were numerically small thus likely having remained without real influence on meat tenderness. It cannot be excluded that especially some of the light Upland cattle carcasses suffered from cold shortening, but the range found in maximum shear force was even slightly lower with upland cattle (max: 71 N; F2-crossbreds, max. 88 N) suggesting that group differences were not primarily due to cold shortening. Waritthitham et al. (2010a) reported higher shear force values for crossbreds of Brahman and generic Thai native cattle than for the meat of Charolais crossed also with generic Thai native cattle. Apart from collagen properties, this may be explained by the inherently high calpastatin activity of B. indicus genotypes which results in a deceleration of the activity of proteolytic enzymes involved in p.m. tenderization of beef (Waritthitham et al. 2010a). In general, the level of shear force was rather high compared to the about 32 N found with Charolais steers by Chambaz et al. (2003).

Panel scores in beef flavour and overall acceptability were found to be more favourable (P < 0.01) in the beef of the crossbreds; however, off-flavour was stated more often, too (P < 0.05; Table 2). These differences between breeds might have at least partially reflected differences in intramuscular fat content and the associated appearance of marbling. According to Shackelford et al. (1995), B. indicus breeds have an inherent capacity to produce meat of an eating quality and tenderness comparable to that of British and continental breeds, but this was not the case in the present study.

Conclusions

The results show that, at very high differences in slaughter weight and muscle sizes, the F2-crossbreds of Charolais (75%) × generic Thai native cattle (25%) produced meat with a clearly higher physicochemical quality than the purebred Upland Cattle. This was obvious from differences in a number of quality traits. It can, however, not be excluded that at least part of the differences resulted from the largely differing body weights of the two genotypes. The few comparative advantages of the beef from the Upland cattle include fewer notifications of off-flavour and a lower content of cholesterol. An aspect favouring the maintenance of Upland cattle is that this strategy promotes livestock biodiversity. The beef quality is sufficiently high with Upland cattle to be suitable for Thai eating tradition.

Acknowledgements

The authors would like to express their gratitude to the National Research University under The Commission of Higher Education, Ministry of Education, Royal Thai Government, which funded the research.