INSTRUMENTAL ESTIMATION OF THE LEVEL OF C ARCASS PARAMETERS IN PIGS

The objective of the paper was to test possibilities of in vivo instru mental prediction of some parameters of carcass value. In the first pa rt of experiment, these parameters were determined in 184 breeding gil ts of the cross combination BM x D by three instruments (PIGLOG 105, R ENCO LM and ALOKA SSD 210 DX II): backfat thickness between the 3rd an d 4th last lumbar vertebrae 6 to 7 cm laterally froin the midline, mm (PIGLOG 1, RENCO 1, ALOKA 1 parameters in Tabs. I and II); backfat thi ckness at the level of the 3rd to 4th last but one rib 6 to 7 cm later ally from the midline, mm (PIGLOG 2, RENCO 2, ALOKA 2 measures); eye-m uscle thickness (m.l.d.) at the 3rd to 4 th last but one rib 6 to 7 cm laterally from the midline, mm (PIGLOG MLD, ALOKA MLD); percentage of lean cuts ill the carcass in vivo by PIGLOG 105 instrument (PIG-MASO parameter). The above parameters were measured by identical operators during the whole experiment. The experimental gilts received uniform g ranular mixture (digestible crude protein content 17.4%, lysine conten t 0.9%, fiber content 4.3%) In the second part of experiment, the same measures as in the first part of experiment were determined by the in struments PIGLOG 105 and ALOKA SSD 210 DX II a day before slaughter in 138 hybrid pigs of the cross combination used on the largest scale in Slovakia (at the parity sex ratio of gilts : barrows). The hybrid pig s received a commercial feed mix (digestible crude protein 13.9%, lysi ne content 0.7%, fiber 4.6%). The pigs were slaughtered under standard conditions, and the carcass dissection into the basic cuts was execut ed on the second day after cooling. The percentage of valuable lean cu ts (neck, shoulder, loin and ham) and the percentage of fatty parts (s eparable fat + kidney fat) in the weight of the side of pork were dete rmined. All measures of backfat thickness and/or muscle that had been found out in vivo instrumentally a day before slaughter were determine d post mortem at the same time. The results in Tabs. I and II show tha t the reliability of instrumental estimates of the measures of backfat thickness and/or muscle thickness was highest in the weight categorie s up to 100 kg and/or 100 to 120 kg. At the higher live weight (above 120 kg) it was relatively difficult to determine m.l.d. thickness by t he PIGLOG 105 instrument. Decreasing accuracy of m.l.d. thickness dete rmination with the growing live weight by the instruments is documente d by the correlation coefficients for this parameter determined by PIG LOG 105 instrument and by ALOKA echocamera at the weight of 100 and/or above 120 kg (r = 0.71 and 0.38, resp.). Within a planned schedule of instrument use iii the breeding pigs it is advantageous to use instru ments to increase the accuracy of prediction of the evaluated measures of the carcass; it is necessary to consider the fact that the estimat e reliability has a decreasing nature with the growing live weight. Ta bs. III and IV show the characteristics of the investigated parameters and their relationships in hybrid pigs. At the average slaughter weig ht of approximately 122 kg, daily live weight gain was 604 g and the p ercentage of valuable lean cuts made 48.7% in the weight segment from 30 kg. The correlation between the PIGLOG 105 value and the actual per centage of VLC determined by carcass dissection was calculated at the level of r = 0.83 for the evaluated set. The percentage of VLC was in closest correlation with the percentage of fatty parts (r = -0.90). St atistically highly significant relationships (r = 0.74) were determine d between backfat thickness at the level of the 3rd to 4th lumbar vert ebrae post mortem and/or in vivo, as well as for backfat thickness at the level of the 3rd to 4th last but one rib (r = 0.79 to 0.81). A dif ferent level of correlation coefficients was calculated for m.l.d. thi ckness at the 3rd to 4th last but one rib post mortem and/or after sla ughter (r = 0.27 to 0.29). We believe that the closeness of the relati onships would be better at a possibility of the eye-muscle area determ ination, which indicates the importance and need of eye-muscle area de termination when carcass parameters of pigs are evaluated.