Založba Univerze v Ljubljani / University of Ljubljana Press
Doi
Abstract
Computer tomography (CT) is a tool used to determine body composition in live animals. However, only at limited numbers of institutions CT is available for animal investigations. Long distance transport may alter the body composition of animals. Therefore, scanning carcasses (chilled, frozen or thawed) could be the solution to extend the possibilities. In two experiments, pigs (at 60 and 105 kg live weight in exp. 1 and exp 2 resp., n = 10 and n = 12 resp., equal ratios of barrows and gilts) were CT scanned, first alive in the evening. Next day pigs were slaughtered and left carcasses were kept at + 4 °C for 36 hours. After CT scanning, the chilled carcasses were put into a freezer for 48 hours, where the ultimate temperature was – 12 °C. Carcasses were CT scanned and put back into the cooling room at + 4 °C for 48 hours to thaw gently for the final CT scanning. Our results indicate that both the tissue position in the body and the temperature affect the Hu (Hounsfield unit) value of muscle and fatty tissue. However, in the case of frozen tissues it is not systematic. The CT is applicable for the detection in changes of fatty tissue volume at any stage of carcass (r = 0.95–0.99). In the case of muscle, the correlation as high as 0.90–0.98 with live measurements was found, while in frozen carcasses just r = 0.10 was achieved for Hu value of weighed muscle volume. The results show that chilled or thawed carcasses can be used for CT based tissue separation without losing information. This could extend the number of potential users of computer tomography.Računalniška tomografija (CT) se uporablja pri določevanju sestave telesa živih živalih. Vendar ima CT za raziskovanje živali le omejeno število ustanov. Dolgi prevozi lahko spremenijo sestavo telesa živali, zato preiskave klavnih polovic (ohlajenih, zamrznjenih ali odtajanih) predstavljajo drugo možnost. V dveh poskusih smo prašiče (60 in 105 kg telesne mase v prvem oz. drugem poskusu, n = 10 oz. n = 12, enaka deleža kastratov in svinjk) preiskali s CT, najprej zvečer še žive. Naslednji dan so bile živali zaklane, klavne polovice pa smo 36 ur hranili na temperaturi + 4°C. Po pregledu s CT smo ohlajene klavne polovice dali v zamrzovalnik z najnižjo temperaturo – 12 °C za 48 ur. Nato smo klavne polovice pregledali s CT in jih premestili v hladilnico s temperaturo + 4°C za 48 ur, da so se počasi odtalile in jih nato še zadnjič pregledali s CT. Dobljeni rezultati kažejo, da položaj tkiv v telesu in temperatura vplivata na Hu (Hounsfieldova enota) vrednost mišičnih in maščobnih tkiv. Pri zamrznjenih klavnih polovicah vpliv ni sistematičen. CT se lahko uporablja pri določanju sprememb v prostornini maščobnega tkiva v kateremkoli stadiju (r = 0,95–0,99). Pri mišični smo ugotovili korelacijo od 0,90 do 0,98 pri živih živalih, pri zamrznjenih klavnih polovicah pa le r = 0,10 za Hu težo mišične. Rezultati kažejo, da ohlajene ali odtaljene klavne polovice lahko pregledujemo s CT zaradi ločevanja tkiv, ne da bi pri tem izgubili pomembne informacije. Število uporabnikov računalniške tomografije se tako lahko precej poveča
