The effect of the operator on the accuracy of the estimates of lean meat share in pigs

The aim of the study followed the determination of operator error, ie repeatability, or influence of the measuring point on the accuracy of the estimate of lean meat share (LMP). It was a FOM-SFK instrument measured at prescribed locations the backfat thickness, muscle depth, and thus their LMP in their carcass realization in SEUROP system. For this purpose a total of 71 hybrid pigs (Dan-Bred) were measured at the Velvary slaughterhouse. In order to determine the error from incorrectly determined place of measurement, the following six classification insertions were done per one animal, thus 1. 2nd -- 3rd last rib 7 cm off the midline (right point), 2. 2nd -- 3rd last rib 7 cm off the midline (repeat in the same hole), 3. 2nd -- 3rd last rib 1 cm caudal to the right point, 4. 2nd -- 3rd last rib 1 cm cranial to the right point, 5. 3rd -- 4th last rib 1 cm medial to the right point, 6. 1st --2nd last rib 1 cm lateral to the right point. Measurements were performed on the carcass that insertion 2 should be identical with insertion 1, insertions 3 and 4 were moved 1 cm off insertion 1 in the cranial or caudal direction and insertions 5 and 6 were moved by 1 rib from insertion 1 in the cranial or caudal direction respectively. Classification was held by FOM instrument, for further comparison also by ZP method. For the above classifications following regression equations were used. For: - FOM y= 81,8909+0,2006*M+14,1911*ln S, kde M=MLLT depth, S =backfat thickness, - ZP y= 76,6722--1,0485*M+0,00794*M2--0,002884*S2+9,0151*ln (M/S), kde M = MLLT depth, S= backfat thickness. Calculation and comparison of the results was performed by statistical program SAS Propriety Software Release 6.04, differences were tested by analysis of variance. Based on the results we can say that a given hypothesis was confirmed. Also, in the realization of slaughter pigs in SEUROP system can be stated that - by invasive technique FOM - precise LMP determination of the carcass is a function of the need for precise determination of the puncture site of operator, - accuracy of the backfat thickness as well as LMP estimate is affected by repeated punctures, - more reliably is measured the backfat thickness with repeated injection than the muscle depth due to its possible deformation, - inaccuracy of repeated measurements (repeatability) will not significantly affect the carcass classification into classes at the slaughterhouse; any errors will occur to the detriment of the supplier, - the injection shift 1 rib cranially respectively caudally affect the overall carcass classification more than shift the injection 1 cm medially or laterally away from the spine, - in the case of an unsuccessful measurement the best is to repeat the puncture or the second puncture shift 1 cm caudal or repeat puncture between the 2nd and the 3rd thoracic vertebra 1 cm towards the spine, - non-invasive technique ZP, compared to FOM, underestimates the LMP estimate by about 1,4%