Correlation of ultrasonic measured ribeye area and fat thickness to the certain traits measured on slaughtered bulls (Short Communication)

The aim of this study was to test accuracy of measurements done by Falco 100 (Pie Medical) ultrasonic equipment. 10 Angus, 10 Hungarian Simmental, 10 Limousin and 10 Charolais fattening bulls were measured at the feedlot just before slaughtering. Fat thickness at the rump (P8) and ribeye area (REA) were realized from each animal. After slaughtering, the data of slaughter and carcass weights were collected and carcasses were judged on the base of EUROP system. The database was examined by SPSS 9.0 for Windows. Average liveweight of Angus was 645 ± 41.5 kg, of Hungarian Simmental was 676 ± 41.8 kg, of Limousin was 655 ± 50.8 kg and of Charolais was 694 ± 42.3 kg at the measurement. REA measured with ultrasound was 102.9 ± 8.9 cm2, 102.7 ± 10.4 cm2, 111.2 ± 9.6 cm2 and 106.4 ± 9.5 cm2, respectively. P8 was 1.05 ± 0.28 cm, 0.62 ± 0.13 cm, 0.62 ± 0.09 and 0.61 ± 0.18 cm, respectively. Correlation between ultrasonic and carcass REA in case of mentioned breeds was 0.74, 0.74, 0.94 and 0.80. Correlation between P8 and EUROP fat score was 0.51, 0.73, 0.56 and 0.28, respectively. Overall correlation between ultrasonic and carcass REA was 0.83 (P≤0.01), and between P8 and EUROP fat score was 0.69 (P≤0.01).


Introduction
New methods such as ultrasonic technics for the measurement of the body composition in vivo (or post mortem) need to be evaluated before routine use in livestock research or performance testing (SCHOLZ & FÖRSTER 2006).KALLWEIT et al. (1994) reported that magnetic resonance imaging (MRI) is an excellent non invasive method to study morphological structures in live animals and these estimation results can serve as a reference for other evaluation methods.However, ultrasound is easier to use in daily practice and have lower costs than MRI.WILD (1950) was the first who described that A-Mode ultrasound can be used for investigating live fat and muscle tissues of animals.He found that ultrasound is non destructive and humane.The technology continued to progress until today B-Mode (brightness modulation) is a widely used technology for imaging tissue.While A-Mode is onedimensional and is limited to measuring depth of tissue, B-Mode allows characterization of tissue with different densities.Real-time ultrasound is a specialized version of B-Mode ultrasound-producing images almost instantaneously thereby creating »live«, moving objects (GRESHAM 2004).An other specialized version of ultrasound is VOS used mainly in France (TŐZSÉR et al. 2001). PRICE et al. (1958) was one of the pioneers who used ultrasound on farm animals.The development of the equipments allowed the wide use of real-time ultrasound in the animal production (HOUGHTON & TURLINGTON 1992).PFEIFFER et al. (1985) found that ultrasonic measurements could improve the effectiveness of performance testing.They recommended to relate the quotient of ultrasonic fat thickness and ultrasonic muscle thickness to the carcass trait values in further studies.TŐZSÉR et al. (2003) found that subcutan fat thickness of Red Angus and Angus breed didn't differ from each other.
Many researchers reported that accuracy of ultrasonic measured subcutan fat thickness and REA is quite good (BRETHOUR 1990, DUELLO et al. 1990, SMITH et al. 1992, PERKINS et al. 1992a, PERKINS et al. 1992b, WALDNER et al. 1992, BRETHOUR 1992, ROBINSON 1992, RÖSLER et al. 1996, MAY et al. 2000, GREINER et al. 2003).HARTJEN et al. (1993) investigated a total of 648 young bulls of different breeds just before slaughter.The relationship between the musculus longissimus dorsi area measured by ultrasound and the corresponding measurement on the carcass ranged from r =0.68 (1st trial) to r =0.80 (2nd trial).

Material and methods
Ultrasonic and some slaughter data of 10 Angus, 10 Hungarian Simmental, 10 Limousin and 10 Charolais fattening bulls were investigated.Animals were kept at the same feedlot, under the same conditions.Their diet was corn silage and sugar beet pulp with concentrate with small amount of hay.Animals were slaughtered at nearly the same age in 4 groups.Ultrasonic measurements were taken by the same person with a Falco 100 (Pie Medical) ultrasonic equipment with 18 cm linear array probe (3,5 MHz) at the feedlot just before slaughtering.Fat thickness was measured at the rump (P8 site): the perpendicular intersection of the line from the third sacral vertebrae with a line from the inside of the pin bone.Ultrasonic REA (UREA) was measured between the 12-13th ribs, near to the spine, parallel to the ribs.Liveweight was measured by digital scale just after taking the ultrasonic measurements, at the feedlot.After slaughter, carcass REA (CREA) was measured, carcass weights were taken and carcasses were judged on the base of EUROP system.The database was processed with ANOVA (LSD test) by breed and analysis of correlation were proceeded by SPSS 9.0 for Windows.

Results and discussion
Preslaughter and postslaughter results of the animals (average and standard deviation) can be seen in Table 1 and Table 2.There were significant differences between breeds in daily gain during fattening period, moreover slaughter weight, P8, UREA, killing out percentage and CREA.Differences between breeds as for slaughter age were not significant.Results of the analysis of correlation can be seen in Table 3. Correlation between ultrasonic and carcass REA at Angus, Hungarian Simmental, Limousin and Charolais bulls was 0.74, 0.74, 0.94 and 0.8, respectively.These results are similar (PERKINS et al. 1992a;ROBINSON 1992, GREINER et al. 2003) or a little bit better (SMITH et al. 1992, PERKINS et al. 1992b, MAY et al. 2000) than values mentioned in the Introduction and in Table 4.
Correlation between P8 and EUROP fat score was 0.51, 0.73, 0.56 and 0.28 at each breed, respectively.Overall correlation between ultrasonic and carcass REA was 0.83 (P≤0.01), and between P8 and EUROP fat score was 0.69 (P≤0.01).Correlation between EUROP fat score and fat thickness is lighter than between ultrasonic and carcass fat thickness reported by other authors can be seen in Table 4.In conclusion it is obvious from the results of the study that REAcan be estimated quite exactly by in vivo ultrasonic measurements.Correlation between P8 and EUROP fat score is looser than correlation between ribeye measurements.Correlation between ribeye measurements and EUROP muscle score is not so high, mainly not significant.The result mentioned above shows the difficulties of the use of EUROP carcass scoring system.Exact accuracy of ultrasonic fat thickness measurement (comparision to the real fat thickness value) have to be investigated in a later experiment.