Albers, GAA

Kloosterman, A

Osterlee, CC

Genetics Selection Evolution

English

PubMed

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ceptibility 
" 
to experimental infection with one source of agent is controlled by a single gene and
that the dominant allele confers " susceptibility ". There is evidence that scrapie agent may
replicate in some " resistant " sheep but at a slower rate than in 
" 
susceptible " sheep. For this
reason, 
" resistance " is best regarded in terms of an extended incubation period. Also, " resis-
tance 
" 
to one strain of agent does not mean " resistance " to all strains. A " resistant " flock
of Swaledale sheep is being developed by experimentally infecting all animals and breeding from
the survivors. There have been extensive outbreaks of natural scrapie in the " susceptible 
"
flocks of Cheviot and Heydwick sheep.
Investigations of these outbreaks might be able to show whether or not sheep selected for
" resistance " could be used to limit the spread of infection in flocks with a serious scrapie problem.
RESISTANCE OF CALVES TO GASTROINTESTINAL PARASITES
C. C. OSTERLEE, A. KLOOSTERMAN G. A. A. ALBERS
Dep. of Animal Production of the Agvicultuval University
Wageningen, Duivendaal 5, the Netherlands
Control of enzootic diseases is possible by hygienic measures and by increasing resistance
of;!the animals. The resistance of calves to gastrointestinal nematodes is discussed as an example
where the reaction of animals to a certain dose of infective larvae can be measured by serological
as well as parasitological parameters. This resistance vary considerable in calves of the same
age and feeding condition, and part of it is genetically determined. The question what this
resistance means for the growth performance of the calf under various conditions of infection
remains to be answered.
IMMUNOGENETICS STUDIES ON CATTLE TWINS
J. SELLEI
Dep. of Animal Breeding and Genetics
Swedish University of Agvicultuval Sciences,
S - 750 07 U!!sala, Sweden
Some components which are essential factors in the immune mechanism were quantified
(titre tested) in the sera from cattle twins. It was found that in monozygous twins the kinetics
of antibody formation against red cell antigens was under close genetic control. This phenome-
non indicates that not only the amount but also the start, the raise and the persistence of antibody
formation is genetically controlled. These results were obtained in twins which had never before
been confronted with these antigens and where the dosage and route of injection was carefully
controlled. When the contact with the antigen as in the case of the ubiquitously occuring J-
substance could not be controlled genetic variation in the anti-I antibody titres was not demons-
trable. The titre tests revealed considerable genetic variation also in the relative activity of
complement (Ci trough C3) and konglutinin in the twin sera.
GENETIC ANALYSIS OF HEALTH DISTURBANCES IN PIGS
N. LUNDEHEIM
(Sweden)
Since the beginning of 1973 every pig from the Swedish Pig progeny testing stations pass a
special post-mortem examination where any disease in the thoracic cavity or in the snout is regi-
stered. The diseases which are thereby recorded are different kinds of pneumonia, pleurisy and
atrophic rhinitis (AR).
Data from this post-mortem examination during 1973-5 were merged with the ordinary
progeny testing records. This merging could not be done for those animals or groups which for


Resistance of calves to gastrointestinal parasites

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