TESTING OF THE GLUCOPLASTIC PREPARATION K ETOBION USED FOR PREVENTIONOF DFD MEAT OCCURRENCE IN SLAUGHTER BULLS

Dark beef (DFD, DCB meat) of slaughter animals can be characterized by the high terminal pH value and changed sensory and technological prop erties. The cause of its origin is depletion of muscular glycogen befo re slaughter due to different stresses, while physical stress is the m ost important. Effective organizational measures to reduce the frequen cy of occurrence of DFD meat in practical conditions are known (Franc, Bartos, 1987) but they have not been implemented on a larger scale fo r various reasons until now. As the occurrence of DFD meat is related to the energy metabolism of the skeletal muscles in the ante-mortem pe riod, administration of various easily digestible sugars shortly befor e slaughter or after transport is tested as a preventive measure (Haur ez, 1988; Wajda, Wichlacz, 1987; Fostier, 1992). The glucoplastic prep aration KETOBION with the active ingredient propylene glycol was succe ssfully administered to the cows with energy metabolism disorders Krok avec et al., 1989). The objective of our trial was to test its effect in the prevention of DFD meat occurrence in slaughter bulls of the Slo vak Pied cattle at the average live weight of 485 kg. KETOBION was adm inistered to the bulls of experimental group at a rate of 500 ml per h ead and day at morning feeding for five days before slaughter, it was mixed the concentrate feed. On the last day, four hours after KETOBION administration, samples from the m. semitendinosus were taken by harp oon biopsy SB-1 to determine glycogen content, as well as a blood samp le from the v. jugularis to determine glucose content. Muscle biopsy w as repeated just before slaughter while blood was sampled instantly af ter slaughter, all this followed bull transport to a meat packing plan t to a distance of 35 km and twenty-hour joint loose housing of experi mental and control animals. Meat samples from the m. longissimus dorsi were taken in 24 hours post mortem, their pH values was determined in 48 hours p.m., along with meat color, free water content, shearing fo rce of the muscle and cooking loss. KETOBION administration slightly i ncreased glucose content in the blood (4.09 against 3.66 mmol/l). No d ifference in the blood content of glucose was found out a slaughter (3 .10 and 3.13 mmol/l, resp.). KETOBION did not influence the content of muscular glycogen before transport to a slaughterhouse (94.76 and 94. 05 mumol/g, resp.) nor did it prevent a steep fall of glycogen content due to the night loose housing in all bulls of the experimental and c ontrol group (7.60 and 12.86 mumol/g). The high terminal pH value abov e 6.2 (7.16 and 6.86, resp.) was found in all animals, which confirmed the occurrence of DFD meat. The above-mentioned findings as well as t he values of qualitative analyses of meat - meat color (% reflectance) (5.83 and 5.83, resp.), content of free water (22.83 and 26. 10 %, re sp.), cooking losses (25.21 and 28.44 %, resp.) and shearing force of cooked meat (3.31 and 5.21 kg/cm2, resp.) were in the range of values typical of the DFD syndrome. The results document that KETOBION was no t an effective preparation in the prevention of DFD meat occurrence in slaughter bulls.