Dtsch Tierarztl Wochenschr. 1994 Nov;101(11):434-9.

[The problems of spotted breeds of rabbits. 4. Morpho- and histometric findings in the CNS and thyroid glands and the hormone content in blood at slaughter of hybrid rabbits, and estimation of the heterosis effect].

[Article in German]

Flemming K, Kühnel C, Wieberneit D, Wegner W.

Source

Institut für Tierzucht und Vererbungsforschung der Tierärztlichen Hochschule Hannover.

Abstract

Morpho- und histometric investigations of brains, pituitary and thyroid glands as well as thyroid-related functional parameters in the blood of purebred and hybrid rabbits revealed a predisposition to hypothyreotic conditions in homozygous, megacolon-prone genotypes. 

In addition to this also a hypoganglionotic state in different gut wall localizations was confirmed; pituitary traits however did not indicate a primary contribution of this gland to the syndrome, though some alterations were found, which are interpreted as secondary sv. symptomatic. 

Gender influences varied hormonal characteristics and disease manifestations too: 

A dramatic fall in severely diseased does with respect to T3-concentration as well as a seemingly more inactive thyroid gland compared to bucks underline hormonal influences. 

As a consequence of these results it is concluded, that hybridisation within spotted rabbits does not amend the inclination to megacolon in animals homozygous for the K (En) gene, though it may influence its manifestation.

Zentralbl Veterinarmed A. 1995 Nov;42(9):549-59.

Pathophysiological and functional aspects of the megacolon-syndrome of homozygous spotted rabbits.

Bödeker D, Türck O, Lovén E, Wieberneit D, Wegner W.

Source

Institute of Animal Breeding and Genetics, Hannover School of Veterinary Science, Germany.

Abstract

The Megacolon-Syndrome is a hereditary disease of homozygous spotted rabbits (En En). 

Investigations have been performed on some special traits related to functional aspects of the gut in comparison to vital heterozygous spotted rabbits (En en). 

It was found that En En rabbits showed significantly reduced sodium absorption rates across the wall of the cecum. Consequently, the dry matter content of the ingesta was reduced at this location, whereas the content of the ashes was increased. 

These results indicate that a further important pathogenetic aspect of this hereditary disease is an undue liquification of ingesta in proximal parts of the large intestine. 

Severe clinical problems, however, resulted from obstipation. 

This is concluded to be a late complication due to and modified by different stressors of endogenic and exogenic origin. 

Thus, there are some indications that an early site of spot-gene related effects might be the small intestine. 

This segment of the bowel was shorter and had an increased dry matter proportion of its wall when compared with heterozygous spotted rabbits. 

But a decreased proportion of dry matter within the wall of the large intestine was found. 

The latter could be an effect of the hypothyreotic state of metabolism in En En rabbits.

Dtsch Tierarztl Wochenschr. 1991 Sep;98(9):352-4.

[The problems of spotted breeds of rabbits. 1. Fattening and body condition at slaughter, organ parameters].

[Article in German]

Wieberneit D, Mahdi N, Zacharias K, Wegner W.

Source

Institut für Tierzucht und Vererbungsforschung, Tierärztlichen Hochschule Hannover.

Abstract

Rabbits of the Giant German Spot Breed and of the English Spot Breed were bred, reared, fattened and evaluated under standardized conditions. 

A total of 50 animals (31 German spot = DRS; 19 English spot = ES; both derived from mating of heterozygotes) was tested, belonging to the three possible genotypes: 

Homozygous black (kk), heterozygous spotted (Kk, "standard animals") and homozygous spotted (KK, so-called "Chaplins").
As expected, breed differences consisted of better daily gains and higher carcass weights in DRS, but higher dressing percentages in ES. 

With respect to colour genotypes, only in DRS-KK depressions of daily gains and carcass weight were observed; food conversion efficiency however was even better in these animals (of both breeds), primarily because of lower feed uptake.
Very distinct differences in some important organ traits could be demonstrated for those genotypes: 

A significantly augmented intestine (abs. and rel.) in KK-animals, specially with reference to the gross intestine--indicating a tendency to motility disturbances and/or chronic obstipation. 

This predisposition was underlined by the premature loss of three KK-rabbits suffering from severe corresponding symptoms. 

Seemingly analogous syndromes (Megacolon) in man and other species are cited, though further investigations are needed to clarify the etiology in spot rabbits. 

Significance of lower heart weights was stated in DRS-KK-animals, probably induced by minor activities observed in this genotype. 

Thus the K-gene can be classified as a subvital one when homozygous though manifestations of the symptoms obviously vary with the genetic background (breed, line) and perhaps with the environment.

(ABSTRACT TRUNCATED AT 250 WORDS)

Dtsch Tierarztl Wochenschr. 1993 Jun;100(6):237-9.

[The problems of breeding spotted rabbits. 3. Variability of the pigmentation grade, ganglionic intestinal wall supply, relationship to pathogenesis--animal breeding and animal welfare aspects].

[Article in German]

Gerlitz S, Wessel G, Wieberneit D, Wegner W.

Source

Institut für Tierzucht und Verebungsforschung, Tierärztlichen Hochschule Hannover.

Abstract

In a total of 128 animals of the German Giant Spot und the English Spot Breed grade of pigmentation and spotting pattern were investigated by photography and planimetry. 

A clear cut binary distribution, representing homozygous (KK) or heterozygous spot rabbits (Kk), and a strong bilateral concordance was found as well as a broad variance within both genotypical groups. 

Thus only a small percentage of animals bred can be compatible with mandatory fancy breed standards. 

Measurements of intestinal layers and neural components in well pigmented and depigmented individuals revealed an enhancement of these histological structures but a relative hypoganglionosis in distal parts of the gut in animals with predisposition to megacolon (KK, so-called chaplins). 

It is not yet clear whether this is symptomatic or of primary pathogenetic relevance. 

There were no pleiotropic deleterious effects of the K-allele in heterozygous rabbits and no correlations between the degree of depigmentation and the severity of symptoms in homozygous spotted ones, thus indicating a mode of inheritance by an incompletely dominant gene K, acting as or being linked to a recessive semilethal when homozygous. 

A change in breeders' attitude and breeding practices is mandatory because neither the permanent elimination of animals not "fitting" a fancy standard nor the continuous production of defective genotypes is legal.

Dtsch Tierarztl Wochenschr. 1992 Mar;99(3):111-3.

[The problem of breeding for spots in rabbits. 2. Further results on the variation of characteristics in fattening and breeding animals].

[Article in German]

Mahdi N, Wieberneit D, Wegner W.

Source

Institut für Tierzucht und Verebungsforschung der Tierärztlichen Hochschule Hannover.

Abstract

The mode of inheritance of spotting in both breeds (ES and DRS) is compatible with incompletely dominant resp. intermediate segregation, though a broad variability of spotted areas exists, indicating the influence of minor genes or other ontogenetic factors. 

Additional findings support the conclusion, that there is a very distinct predisposition of homozygous KK animals to develop megacolon with growing age. 

This also has consequences for the relative organ weight of the heart and of the adrenals in this genotype. 

Sporadically encountered accessory adrenal cortical tissue however did not exhibit genotypic preferences.

Artikel av kanindomare Glenn Larsson - Engelsk Scheck, avelsarbete, utställningsförberedelser

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