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Epidemiological studies on gastro-intestinal nematode infections in chickens

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Epidemiological studies on gastro-intestinal nematode infections in chickens

On farm establishment, host genetics and fluctuations in nematode egg excretion

Kalyakorn Wongrak (Autor)


Inhaltsverzeichnis, PDF (61 KB)
Leseprobe, PDF (330 KB)

ISBN-13 (Printausgabe) 9783954048182
ISBN-13 (E-Book) 9783736948181
Sprache Englisch
Seitenanzahl 120
Umschlagkaschierung glänzend
Auflage 1. Aufl.
Erscheinungsort Göttingen
Promotionsort Göttingen
Erscheinungsdatum 29.09.2014
Allgemeine Einordnung Dissertation
Fachbereiche Land- und Agrarwissenschaften
Schlagwörter poultry, free-range, mobile stall, nematode infections, mortality rate, parasitology, genetics, egg excretion, faecal collection, natural and experimental infections, Kalyakorn Wongrak

The study results indicated a high prevalence (>99%) of nematode infections with the most prevalent species beingthe caecal worm Heterakis gallinarum (98.5%), followed by the roundworm Ascaridiagalli(96.2%) and the hairworms Capillaria spp. (86.1%). Capillaria spp. were composed of C. obsignata, C. caudinflataand C. bursata. It can be concluded that chickens kept in free-range systems are exposed to a higher risk of nematode infections, even if the animals are kept in a rotational system and/or in small herd sizes. However, no obvious link between high mortality rates and nematode infections could be determined. The high genetic correlation between counts of closely related worm species (e.g., A. galliand H. gallinarum) may indicate the existence of similar/same genetically determined mechanism(s) for controlling these nematodesin chickens. High heritabilities for total worm burden suggest that it is feasible to select hens for nematode resistance. Nematode egg excretion in both naturally occurring and experimental infections follows repeatable diurnal fluctuations which may indicate adaptive strategies of the nematodes to both internal and external environmental factors. Since the analytic sensitivity of egg counts suffers from low faecal egg concentrations, results from the present study suggests that faeces samples taken during daytime hours have a higher diagnostic value.