الفهرس 
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Abstract
The present study was conducted during the period extending from May 2011 to April 2013 to investigate the prevalence and identification of abomasal nematodes of small ruminants slaughtered at different abattoirs at Sharkia province; using light and electron microscope as well as molecular biological studies on Haemonchus species infecting these hosts.
A total of 208 abomasa from slaughtered sheep and goats (105 sheep and 103 goats) were examined for the presence of abomasal nematodes at 3 localities at Sharkia province (Belbies, Menya Al Qamh and Zagazig). The results revealed that 43.3% haboured abomasal nematodes. Sheep showed higher infection rate 60.9% than goats 25.2%. No hypobiotic larvae were detected in sheep and goats during the study period. Four species were recovered from abomasa in sheep including Haemonchus contortus 51.4%, Trichostrongylus axei 22.9%, Ostertagia circumcincta 7.6% and Parabronema skrjabini 11.4% ; while only three species were recorded in goats including H. contortus 16.5%, T. axei 7.8% and P. skrjabini 3.9%.
Concerning single and mixed infections with abomasal nematodes in sheep, the result showed that single infection was higher than mixed infection with 2 or 3 species in both sheep and goats.
Dealing with mean worm burden of abomasal nematodes species in sheep and goats, it was found that, the mean worm burden of H. contortus 18.8 and 10.7 per animal in infected sheep and goats respectively, T. axei mean worm burden was 18.5 and 19.3 per animal in infected sheep and goats respectively. While, O. circumcincta mean worm burden was 7.5 per animal in sheep. P. skrjabini mean worm burden was 8.4 and 7 per animal in infected sheep and goats respectively.
It was noticed that the prevalence of abomasal nematodes in female and young animals was higher than in male and adults in both sheep and goats.
Seasonal prevalence of abomasal nematodes in sheep and goats showed that the highest prevalence was in winter 50%, followed by spring 44% then summer 42.5%; while the lowest season was autumn 34.9%. Seasonal prevalence of the collected abomasal nematodes in sheep revealed that, the highest prevalence was in winter 76.2%, followed by summer 57.1% and spring 50%, while the lowest one was in autumn 45.8%. While in goats, the results showed that the highest prevalence was in spring 28.6%, followed by autumn 28.2%, summer 26.3%, then winter 21.1%.
Dealing with the prevalence of abomasal nematodes species in different seasons in sheep, H. contortus was the highest prevalent in summer 57.1% and the lowest in spring 44.4%. T. axei was the highest prevalent in winter 42.9%, lowest prevalent in autumn 12.5% and not recorded in summer season. O. circumcincta was the highest prevalent in winter 14.3 %, the lowest prevalent in autumn 4.2% and not found in summer season. P. skrjabini was the highest prevalent in autumn 20.8%, the lowest prevalent in winter 7.1% and not recorded in spring. In goats; H. contortus was the highest prevalent in autumn 23.1% and the lowest prevalent in winter 10.5%. T. axei was the highest prevalent in winter 10.5%, the lowest prevalent in summer 5.3% and not recorded in spring season. P. skrjabini was the highest prevalent in spring 14.3% and the lowest prevalent in autumn and winter 2.6%.
Morphological features of the detected abomasal nematodes were described using light microscope. Also, scanning electron microscopy was done to clarify the different morphs of H. contortus. Regarding distribution of the H. contortus vulvar morphology in sheep & goats, in both sheep and goats, the knobbed type was encountered as the most predominant type of vulvar morphology followed by liguiform morph and the lowest form was smooth morph.
Dealing with the molecular characterization of H. contortus female morphotypes using PCR-RFLP technique, based on amplification of ITS region, the Length of PCR products for knobbed vulvar morph, linguiform A vulvar morph and linguiform I vulvar morph was 700 bp. No variation in the size of PCR products was detected for the different H. contortus female morphotypes. Restriction with Rsa1 produced two fragments for linguiform A morph and linguiform І morph of 500 and 200 bp. While, there was no digestion occurred in knobbed vulvar morph, indicating variability between these morphs. No variation in the restriction patterns was detected for linguiform A morph and linguiform І morph.