James Mich
Thu, Jul-13-06, 06:23
Dtsch Tierarztl Wochenschr. 2006 May;113(5):178-81.
Influence of sex on the resistance of sheep lambs to an
experimental Haemonchus contortus infection.
Gauly M, Schackert M, Hoffmann B, Erhardt G.
Institute of Animal Breeding and Genetics, University of
Gottingen, Germany
36 intact male and 69 female lambs of two breeds (n = 63
Merinoland; n = 42 Rhon) aged 12 weeks were orally infected
with 5000 infective-stage larvae, L3, of the nematode
Haemonchus contortus. After 4 and 8 weeks faecal egg counts
(FEC), haematocrit values and plasma testosterone levels were
determined. All lambs were slaughtered at 20 weeks of age. The
gastrointestinal tracts were examined for the presence of
adult stages of
H. contortus. Male lambs showed significantly higher log FEC
(p < 0.001), higher mean establishment rates (p < 0.05),
higher worm burdens (p < 0.01) and lower haematocrit values
(p < 0.001) when compared with female lambs. Correlations
between economically important traits (body weight, daily
weight gain) and parasitological parameters were
significantly higher in male animals. Testosterone level
was 4 weeks after infection significantly positive
correlated with worm burden. The results suggest that
female lambs are more resistant against an experimental H.
contortus infection when compared with male lambs.
Testosterone seems to play an important role in resistance.
This approach can be of importance if parasite resistance
is incorporated into breeding programs and the estimated
breeding values for rams are only based on male offspring
information. Therefore male breeding values are probably
not representative for the whole population.
Influence of sex on the resistance of sheep lambs to an
experimental Haemonchus contortus infection.
Gauly M, Schackert M, Hoffmann B, Erhardt G.
Institute of Animal Breeding and Genetics, University of
Gottingen, Germany
36 intact male and 69 female lambs of two breeds (n = 63
Merinoland; n = 42 Rhon) aged 12 weeks were orally infected
with 5000 infective-stage larvae, L3, of the nematode
Haemonchus contortus. After 4 and 8 weeks faecal egg counts
(FEC), haematocrit values and plasma testosterone levels were
determined. All lambs were slaughtered at 20 weeks of age. The
gastrointestinal tracts were examined for the presence of
adult stages of
H. contortus. Male lambs showed significantly higher log FEC
(p < 0.001), higher mean establishment rates (p < 0.05),
higher worm burdens (p < 0.01) and lower haematocrit values
(p < 0.001) when compared with female lambs. Correlations
between economically important traits (body weight, daily
weight gain) and parasitological parameters were
significantly higher in male animals. Testosterone level
was 4 weeks after infection significantly positive
correlated with worm burden. The results suggest that
female lambs are more resistant against an experimental H.
contortus infection when compared with male lambs.
Testosterone seems to play an important role in resistance.
This approach can be of importance if parasite resistance
is incorporated into breeding programs and the estimated
breeding values for rams are only based on male offspring
information. Therefore male breeding values are probably
not representative for the whole population.