الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Sheep and goats play an essential role in the socio economy, Moreover; providing many benefits as source of animal protein and wool production such as cashmere and mohair production.Gastrointestinal tract nematodes are considered one of the most prevalent helminth groups affecting small ruminants worldwide especially members of the family Trichostrongylidae. Adult worms in their hosts can cause urgent economic losses as diarrhea, odaema, anaemia, reduced production and even death of animal. Haemonchus contortus can cause haemorragic anemia, dark colour in faeces, restlessness, reduced production and sudden death which are signs of Haemonchiosis disease, followed by Ostertagia leptospicularis in its pathogencity and also Teladorsagia circumcincta that not recordred before in Egypt.Many papers have been puplished about anthelmintic resistance that raised in trichostrongyle species.Because of similarities of different trichostrongyle eggs in addition to traditional methods for microscopic differentiation of 3rd stage larvae depended on their morphology involve cultivation of 3rd stage larvae; this method is more labor and time consuming.The advances in molecular biology of nematodes eggs are more diagnostic than the methods have commonly used in the past; ITS2 sequence is useful to identify specific species of nematodes. So, the current study was performed to identify the prevalence of trichostrongyle species infecting sheep and goats in relation to age and sex of animals, Moreover; molecular characterization and genetic diversity of these parasites.The results showed that the overall incidence of trichostrongyles infection in sheep was 33.2% and in goat was 14.7%.Concerning the prevalence, the highest infection rate in sheep was in El Mahalla -Elkubra (92.5%) followed by Talkha (34.3%) then Dekernes (30%) then Nabrouh (21.6%) and Biyala (10%). In goats, the highest infection rate was in El Mahalla -Elkubra (27.8%) followed by Nabrouh (16.6%) then Dekernes (14.2%), Talkha (13.2%) and no infection recordrd in Biyala. Regarding the relationships of age and sex of animal and the infection rate; sheep that aged less than one year (78.35%) was more susceptible to the infection than sheep that aged more than one year (15.22%). Also, in goats the infection rate was higher in goat that aged less than one year (20.27%) than goats that aged more than one year (4.87%). Concerning animal sex, females (36% and 20.27% in sheep and goats, respectively) were more susceptible to the infection than males (8.57% and 4.87% in sheep and goats, respectively).With respect to molecular biology; genomic DNA of 41 samples of trichostrongyle eggs were extracted utilizing conventional PCR by using species specific primers to amplify ITS2 gene.DNA fragments were run on agarose gel; the results of PCR reaction was recorded to be 15 out of 25 sheep samples showed mixed infections and the majority (14/16) of goats samples displayed mixed infections. The single infection was recorded in 10 out of 25 sheep samples and 2 out of 16 goats. Samples were infected with H. contortus as a noted single species, also the incidence of Haemonchus contortus was 96% and 100% in sheep and goats, respectively while Ostertagia leptospicularis was 4% and 0% in sheep and goats, respectively. Teladorsagia circumcincta was 28% and 0% in sheep and goats, respectively. Trichostrongylus axei was 64% and 87,5% in sheep and goats, respectively. Trichostrongylus colubriformis was 8% and 0% in sheep and goats, respectively. No infection with Cooperia curticei is recorded in sheep and goats on using purification of PCR products by QIquick PCR product Kits, Qiagen for sequencing reaction. Purified PCR products of 16 samples in sheep and 5 samples in goats obtained from trichostrongyle species DNA were sequenced in one direction only. The analysis of data was applied by using BLAST analysis software to identify the sequence identity to Gene bank accession number. The results of sequencing revealed that Haemonchus contortus, genotyping in sheep; two haplotypes; the first haplotype; Ha1 was identical with these accession numbers (KU891853, KY305783, KP101382, MH481598, LC360162) in Gene Bank. The second haplotype; Ha2 was identical with the sequences of Ha1 but in identity percent (98%) in Gene Bank. While Haemonchus contortus, genotyping in goats; two haplotypes; the first one; Ha3 was identical with these accession numbers (LS997564, LC275896, LC278594, KU891899 (in Gene Bank, while the second one; Ha4 was identical with these accession numbers (LC275896, MG699349, MF398452) in Gene Bank. Trichostrongylus axei, genotyping revealed in sheep two haplotypes; the first haplotype; Trax1 was identical with these accession numbers (AY439026, KC998726) in Gene Bank. The second one; Trax2 was identical with these accession numbers (KF204574, KC998726) in Gene Bank.Trichostrongylus axei, genotyping revealed in goat was one haplotype; Trax3 being identical with these accession numbers (KF204574, KC998726) in Gene Bank.Teladorsagia circumcincta, genotyping showed in sheep two haplotypes; the first haplotype; Te1 was identical with these accession numbers (KU891918, KC998708, JF747153) in Gene Bank. The second one; Te2; It showed additional nucleotide substitution(s) with KC998712 (A19G & C20T). It displayed similiarity with these accession numbers (AY439025, KF989498) in Gene Bank.