A. Daugschies et al., Growth performance, meat quality and activities of glycolytic enzymes in the blood and muscle tissue of calves infected with Sarcocystis cruzi, VET PARASIT, 88(1-2), 2000, pp. 7-16
Growth performance and the pattern of glycolytic enzymes in the blood plasm
a were assessed during experimental Sarcocystis cruzi infection (1 x 10(5)
sporocysts per calf) in six calves; five calves served as noninfected contr
ols. At slaughter (68 or 88 days post infection), carcass weight, dressing
percentages and several parameters of meat quality (pH, color brightness, r
igor, water absorbing capacity, water binding capacity) were recorded. More
over, enzyme activities were measured in muscle homogenates. Weight gain wa
s significantly impaired by the infection. Activities of lactate dehydrogen
ase (LDH) and aldolase (ALD) significantly increased in the blood plasma of
the infected calves during the chronic stage of the disease, while glucose
-6-phosphate dehydrogenase (G6PDH) and isocitrate dehydrogenase (ICDH) were
not significantly altered. This was accompanied by a significant decrease
of enzyme activities in the Musculus longissimus dorsi (LDH, ALD), in the d
iaphragmatic musculature (ALD, G6PDH) and in the heart (LDH, ALD). Activiti
es of LDH, ALD, ICDH and G6PDH were visualized by enzyme histochemistry wit
hin the developing sarcosporidial cysts. However, isoenzymes of parasite or
igin could not be demonstrated by agar-gel electrophoresis of muscle homoge
nates or blood plasma. It is concluded that sarcocystiosis of even moderate
severity alters the performance of calves but not meat quality. Leakage of
glycolytic enzymes from the affected muscles is the probable cause of incr
eased plasma enzyme activities. Although these enzymes are also synthesized
by the parasite, the contribution of parasite-derived enzymes to the obser
ved changes of enzyme patterns remains in question. (C)2000 Elsevier Scienc
e B.V. All rights reserved.