The post-natal development of the skin follicle population of a strain of Merino sheep.

1955 ◽  
Vol 6 (1) ◽  
pp. 68 ◽  
Author(s):  
PG Schinckel
Keyword(s):  
Normal Skin ◽  
Primary Follicle ◽  
Progressive Decline ◽  
Skin Expansion ◽  
Rate Of Development ◽  
Merino Sheep ◽  
Sigmoid Curve ◽  
Australian Merino

Observations are reported on the development of the follicle population during post-natal life in three groups of sheep from a strain of Australian Merino. The primary follicle number is complete by birth, and changes in density thereafter merely reflect the normal skin expansion accompanying growth. This constancy with time of the primary follicle number validates the use of the ratio of secondary to primary follicles (S/P) as a measure of the development of the secondary follicles. The S/P ratio followed a sigmoid curve characterized by a small increase in the ratio during the first week, a large increase in the second, and a progressive decline in the rate of development of secondary follicles thereafter.

Genetic studies of South Australian Merino sheep. 4. Genetic, phenotypic and environmental correlations between various wool and body traits

1982 ◽  
Vol 33 (2) ◽  
pp. 363 ◽  
Author(s):  
IP Gregory
Keyword(s):  
Great Increase ◽  
Fibre Diameter ◽  
Skin Thickness ◽  
Primary Follicle ◽  
Genetic Studies ◽  
Environmental Correlations ◽  
Merino Sheep ◽  
Selection For ◽  
Fleece Weight ◽  
Australian Merino

Genetic, phenotypic and environmental correlations were estimated between 23 quantitative and qualitative wool and body traits of South Australian Merino sheep. Clean fleece weight was significantly correlated genetically with greasy fleece weight (0.62), yield (0.47), staple length (0.41), crimps per inch (-0.34), secondary/primary follicle ratio (0.37) and skin thickness (0.39). No significant half-sib genetic correlation was found between clean fleece weight and fibre diameter and the dam-offspring correlation was quite low, although significant (0.16, P < 0.05). This indicates that selection for clean fleece weight should not lead to any great increase in fibre diameter. Skin thickness is discussed as a possible early indicator of clean fleece weight.

Genetic studies of South Australian Merino sheep. 3. Heritabilities of various wool and body traits

1982 ◽  
Vol 33 (2) ◽  
pp. 355 ◽  
Author(s):  
IP Gregory
Keyword(s):  
Body Weight ◽  
Fibre Diameter ◽  
Skin Thickness ◽  
Production Traits ◽  
Primary Follicle ◽  
Merino Sheep ◽  
Main Production ◽  
Fleece Weight ◽  
Australian Merino ◽  
Staple Length

Heritabilities have been estimated for a large number of quantitative and qualitative wool and body traits recorded on two flocks of South Australian Merino sheep over a 12-year period. Data were unadjusted for fixed environmental effects and so the estimates are applicable to the heterogeneous populations found in most practical situations. Dam-offspring heritabilities of quantitative traits ranged from 0.15 for primary follicle number to 0.63 for body weight. Greasy and clean fleece weights, percentage clean yield, staple length, crimps per inch, fibre diameter, secondary and total follicle number, skin thickness, coefficient of variation of fibre diameter and secondary/primary follicle ratio had moderate to high heritabilities. Dam-offspring heritabilities of qualitative traits ranged from 0.12 for weather damage of the fleece to 0.75 for birthcoat. Total folds, face cover and hocks had high heritabilities, and wool character, type of staple formation and wool quality had moderate heritabilities. The main production traits (body weight, greasy fleece weight, yield, clean fleece weight, staple length, fibre diameter and total follicle number) were corrected for variation due to type of birth and age of dam and their heritabilities re-estimated. No change occurred in the half-sib heritabilities; dam-offspring heritabilities increased by an average of 0.05.

Effects of ova transfer on the birthcoats of lambs

1972 ◽  
Vol 78 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Marca Burns
Keyword(s):  
Growth Rate ◽  
Meat Production ◽  
Transfer Experiment ◽  
Primary Follicle ◽  
Skin Expansion ◽  
Foetal Growth ◽  
Short Period ◽  
Selection For ◽  
Almost All ◽  
Size At Birth

SUMMARYBirthcoat samples from Lincoln and Welsh Mountain lambs born in an ova transfer experiment (Weiner & Slee, 1965) were examined to determine the fibre type arrays and any effect of ova transfer on manifestation of the prenatal check or the base (Dry, 1965).In the Lincoln breed arrays were Truncated Ravine or Truncated Valley thus showing central checking. Pre-curly tip fibres were mainly confined to central primary follicles. Post-natal medullation was plentiful, especially in peak curly-tips, but kemp was absent. In the Welsh lambs all identifiable arrays were either Plateau or Saddle, with the lateral primary fibres more checked than the centrals. Pre-curly tip fibres occupied almost all the primary follicles, with only a few curly-tips in primary laterals. Post-natal medullation was strongest in pre-curly tips and their successors.The effect of ova transfer was to decrease the manifestation of check in Lincoln-in-Welsh and increase it in Welsh-in-Lincoln, without affecting the base. Although this, in each case, changed the check of the lamb in the direction of that of the foster breed, it is suggested that this may not be due to any influence of maternal check on foetal check. The effect on pre-natal check may be due to foetal size, and in particular skin expansion, during a short period immediately following completion of primary follicle initiation. As compared to their respective controls, the Welsh transfer lambs had a higher S/P ratio at birth, whilst that of the transferred Lincolns was reduced.If increased prenatal fibre check is associated with increased foetal growth rate at the relevant period, it may also be correlated with increased lamb size at birth and therefore have been favoured in selection for meat production, at least in some breeds.

Effects of inbreeding on four families of Peppin Merinos

1957 ◽  
Vol 8 (3) ◽  
pp. 299 ◽  
Author(s):  
JM Doney
Keyword(s):  
Fibre Diameter ◽  
Genetic Effect ◽  
Direct Consequence ◽  
Specific Gene ◽  
Single Strain ◽  
Merino Sheep ◽  
Fibre Number ◽  
Per Se ◽  
Fleece Weight ◽  
Australian Merino

The influence of inbreeding on several fleece and body characters in a strain of Australian Merino sheep is reported. The four families from which data were taken were derived from a single strain of Peppin Merinos. Inbreeding without selection has been carried on since the foundation of the families between 1939 and 1944. Inbreeding is responsible for a reduction in body size, fertility, greasy and clean fleece weight, and wrinkle score, but has relatively little influence on the fleece components (yield, staple length, fibre diameter, and density of fibre population). It follows that the reduction in fleece weight is a direct consequence of a decrease in total fibre number. Since the reduction in fibre number is likely to be a correlated effect of low pre-natal and early post-natal growth rates, it is suggested that the inbreeding has had no genetic effect on the several independent systems involved in adult wool production but has affected only those associated with fitness and vigour. The depression due to inbreeding therefore may not be caused by specific gene fixation but by increased homozygosity per se.

Genetic studies of South Australian Merino sheep. 2. Environmental effects on wool and body traits at 15-16 months of age

1981 ◽  
Vol 32 (4) ◽  
pp. 657 ◽  
Author(s):  
IP Gregory ◽  
RW Ponzoni
Keyword(s):  
Body Weight ◽  
Surface Area ◽  
Multiple Birth ◽  
Production Traits ◽  
Merino Sheep ◽  
Main Production ◽  
The Difference ◽  
Fleece Weight ◽  
Main Components ◽  
Australian Merino

The effects of years, sex, type of birth (i.e. whether or not multiple birth) and age of dam on 26 wool and body traits of South Australian Merino sheep were estimated by least-squares analysis. Years and sex had highly significant effects on all traits. Of the main production traits, type of birth had a significant effect on body weight, greasy and clean fleece weight and total wool follicle number, while age of dam only had a significant effect on body weight and greasy fleece weight. The possible consequences of failing to correct body weight and greasy and clean fleece weights for type of birth and age of dam were considered and it was concluded that, although in some years correction of these traits may not be warranted, in other years correction may be necessary to prevent selection against fecundity and an increase in the generation interval. The main components contributing to the 6.0 % difference between fleece weights of singles and twins were surface area, total follicle number and wrinkle score. The difference between fleece weights of animals from older ewes and animals from maidens was only 1.5 %; surface area was the main contributor to this deviation.

The Agouti gene: a positional candidate for recessive self-colour pigmentation in Australian Merino sheep

1999 ◽  
Vol 50 (6) ◽  
pp. 1099 ◽  
Author(s):  
Y. M. Parsons ◽  
M. R. Fleet ◽  
D. W. Cooper
Keyword(s):  
Comparative Mapping ◽  
Economic Importance ◽  
The Self ◽  
Positional Candidate ◽  
Chromosome 13 ◽  
Merino Sheep ◽  
Merino Wool ◽  
Agouti Gene ◽  
Mapping Information ◽  
Australian Merino

The occurrence of self-colour pigmentation in the Australian Merino wool flock is of considerable economic importance. The Agouti gene is believed to be responsible for the recessive expression of pigmented fleece. Using comparative mapping information we have investigated the putative homologous ovine map positon of the Agouti gene for linkage to the recessive self-colour phenotype of Australian Merino sheep. Significant results were observed with microsatellites previously mapped to ovine chromosome 13. Comparative data suggest that the ovine Agouti gene would map to the same chromosome, making the Agouti gene a positional candidate for the self-colour phenotype.

Neuronal ceroid lipofuscinosis in Australian Merino sheep: a new animal model

2001 ◽  
Vol 5 ◽  
pp. 37-41 ◽  
Author(s):  
Imke Tammen ◽  
Roger W. Cook ◽  
Frank W. Nicholas ◽  
Herman W. Raadsma
Keyword(s):  
Animal Model ◽  
Neuronal Ceroid Lipofuscinosis ◽  
Merino Sheep ◽  
Ceroid Lipofuscinosis ◽  
Australian Merino

Microsatellite-based genetic variation and differentiation of selected Australian Merino sheep flocks

2016 ◽  
Vol 136 ◽  
pp. 137-144 ◽  
Author(s):  
R. Al-Atiyat ◽  
W. Flood ◽  
I. Franklin ◽  
B. Kinghorn ◽  
A. Ruvinsky
Keyword(s):  
Genetic Variation ◽  
Merino Sheep ◽  
Australian Merino
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