The present study was conducted on sheep which were slaughtered in the main El-Mansaura
abattoir, where they were exposed to antimortem examination for detecting any
parasitological or signs of disease. Also the sheep were subjected to postmortem
examination for detecting any parasitological infections. The sheep which were completely
free from any parasitological infections were considered as control group. The sheep which
proved to be infected with abomasal nematodes served as infected or parasitized group.
Blood samples were taken from all animals (control and parasitized animals) with or without
anticoagulant for haematological and biochemical investigations. After postmortem
examination, the stomach worms were collected, identified as H. contortus and counted to
estimate percentage of the infection. The prevalence of H. contortus was 44.12% among
examined sheep, young animals were non susceptible to infection than adults and seasonal
dynamics of H. contortus in sheep revealed that infection rate reached its peak during
winter season (61.9%) while the lowest rate was in summer (20%). Laboratory investigations
in the present study proved that; presence of high significant decrease in TRBCs count, PCV
and very high significant decrease in Hb concentration. Also, the study showed significant
decrease in MCV value while the decrease was highly significant for MCH and MCHC values
in parasitized group. TWBCs count showed very high significant increase. On the other side,
the lymphocytes showed high significant decrease. Serum biochemical analysis illustrated
high significant and very high decrease in total protein and albumin respectively, on the
contrary it was observed high and very high significant increase B. urea, creatinine and liver
enzymes (S.AST & S.ALT) levels respectively. The level of Calcium, Phosphorus and
Magnesium decreased significantly, while the significant decrease was very high in the level
of Iron and Copper in parasitized group when compared with control one.