Data/hora: 17/06/2024 09:12:13

Biblioteca(s): | Embrapa Pantanal.
Data corrente: | 31/08/1995
Data da última atualização: | 31/08/1995
Autoria: | ALTAIF, K. I.; DARGIE, J. D.
Título: | Genetic resistance to helminths. The influence of breed and haemoglobin type on the response of sheep to primary infections with Haemonchus contortus.
Ano de publicação: | 1978
Fonte/Imprenta: | Parasitology, v.77, n.2, p.161-175, Out. 1978.
Idioma: | Inglês

Conteúdo:

The possible existence of strain and breed differences in the response of sheep to priama-
ry infections with Haemonchus contortus was examined by comparing the establishment 
and pathogenic effects of the parasite in Scottish Blackface and Finn Dorset sheep grou-
ped according to haemoglobin type and infected with 7-10 000 3rd-stage larvae. Homozy-
gous haemoglobin A-type sheep of both breeds had lower worm burdens and faecal egg
outputs, and suffered less severe clinical and pathophysiological distrubances than  ani-
mals homozygous for haemoglobin B. In addition, Scottish Blackface sheep displayed si-
milar advantages over Finn Dorsets with the same haemoglobin type and variations in the
severity of the disease as judged by s variety of pathophysiological factors, this was con-
trolled by the immune response elicited. The nature of this response is unknown, but ap-
peared to operate only against the larval stages, since the size and metabolic activities of
the surviving worms were similar in all animals. In a subsequent experiment, designed to
examine the response of Scottish Blackface sheep to heavy infection (45 000 larvae),
there was no correlation between worm establishment and haemoglobin type. This was
possibly due to a delayed immune response arising from exposure to excessive amounts
of antigen.

Palavras-Chave: | Infeccao primaria; Parasita; Parasite; Primary infection.
Thesagro: | Carneiro; Haemonchus Contortus; Helminto; Resistência Genética.
Thesaurus Nal: | genetic resistance; sheep.
Categoria do assunto: | --
Registro original: | Embrapa Pantanal (CPAP)
Exemplares: | CPAP - (29551-1) - ADC - SP - -- - SP1083 -  - 1083 - DIS