Sensitivity of the breeding values for growth rate and worm egg count to environmental worm burden in Australian Merino sheep

1. Body shape and carcass composition have been measured in a dated series of Romney-Southdown cross and Australian Merino sheep foetuses.2. Large differences in shape exist between the two breed groups and these result from growth rate differences in certain components of the bone and muscle tissue.3. Carcass composition at any particular foetal weight, however, is more uniform. In relation to body weight, the Merino has a higher proportion of bone in the body but the proportion of muscle is the same in both breed groups. Nevertheless, the distribution of muscle tissue is changed as there s i a higher proportion of muscle in the hind limb of the Romney-Southdown cross.

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Genome-wide association study of body weight in Australian Merino sheep reveals an orthologous region on OAR6 to human and bovine genomic regions affecting height and weight

Genetics Selection Evolution ◽

10.1186/s12711-015-0142-4 ◽

2015 ◽

Vol 47 (1) ◽

Cited By ~ 40

Author(s):

Hawlader A. Al-Mamun ◽

Paul Kwan ◽

Samuel A. Clark ◽

Mohammad H. Ferdosi ◽

Ross Tellam ◽

...

Keyword(s):

Body Weight ◽

Association Study ◽

Genome Wide Association Study ◽

Genome Wide Association ◽

Orthologous Region ◽

Merino Sheep ◽

Genome Wide ◽

Genomic Regions ◽

Australian Merino

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A putative resistant DNA marker for wool yellowing susceptibility in sheep

Genetics and Molecular Biology ◽

10.1590/s1415-47572000000200017 ◽

2000 ◽

Vol 23 (2) ◽

pp. 341-346

Author(s):

M.V. Benavides ◽

S. Damak ◽

A.P. Maher

Keyword(s):

Candidate Genes ◽

Differential Display ◽

Dna Sequences ◽

Dna Markers ◽

Dna Marker ◽

Transmembrane Signalling ◽

Breeding Values ◽

Wide Range ◽

Resistant Group ◽

Australian Merino

An Australian Merino flock was screened for low (resistant) and high (susceptible) yellow predictive colour (YPC) breeding values in order to compare extreme individuals using the differential display of mRNA technique. One differentially expressed cDNA band was visualised only in the resistant group. This band showed no identity with the DNA sequences of public databases; however, they showed short homologies with three database sequences related to transmembrane signalling functions. The use of these candidate genes as DNA markers needs to be confirmed against sheep with a wide range of susceptibility to wool yellowing to verify the results.

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Genetic variation within and between subpopulations of the Australian Merino breed

Animal Production Science ◽

10.1071/an14560 ◽

2016 ◽

Vol 56 (1) ◽

pp. 87 ◽

Cited By ~ 16

Author(s):

Andrew A. Swan ◽

Daniel J. Brown ◽

Julius H. J. van der Werf

Keyword(s):

Genetic Variation ◽

Variance Components ◽

Additive Genetic Variance ◽

Genetic Correlations ◽

Fibre Diameter ◽

Genetic Group ◽

Additive Variance ◽

Breeding Values ◽

Genetic Groups ◽

Australian Merino

Genetic variation within and between Australian Merino subpopulations was estimated from a large breeding nucleus in which up to 8500 progeny from over 300 sires were recorded at eight sites across Australia. Subpopulations were defined as genetic groups using the Westell–Quaas model in which base animals with unknown pedigree were allocated to groups based on their flock of origin if there were sufficient ‘expressions’ for the flock, or to one of four broad sheep-type groups otherwise (Ultra/Superfine, Fine/Fine-medium, Medium/Strong, or unknown). Linear models including genetic groups and additive genetic breeding values as random effects were used to estimate variance components for 12 traits: yearling greasy and clean fleece weight (ygfw and ycfw), yearling mean and coefficient of variation of fibre diameter (yfd and ydcv), yearling staple length and staple strength (ysl and yss), yearling fibre curvature (ycuv), yearling body wrinkle (ybdwr), post-weaning weight (pwt), muscle (pemd) and fat depth (pfat), and post-weaning worm egg count (pwec). For the majority of traits, the genetic group variance ranged from approximately equal to two times larger than the additive genetic (within group) variance. The exceptions were pfat and ydcv where the genetic group to additive variance ratios were 0.58 and 0.22, respectively, and pwec and yss where there was no variation between genetic groups. Genetic group correlations between traits were generally the same sign as corresponding additive genetic correlations, but were stronger in magnitude (either more positive or more negative). These large differences between genetic groups have long been exploited by Merino ram breeders, to the extent that the animals in the present study represent a significantly admixed population of the founding groups. The relativities observed between genetic group and additive genetic variance components in this study can be used to refine the models used to estimate breeding values for the Australian Merino industry.

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Chronic locomotor dysfunction, associated with a thalamic-cerebellar neuropathy, in Australian Merino sheep

Australian Veterinary Journal ◽

10.1111/j.1751-0813.1993.tb03315.x ◽

1993 ◽

Vol 70 (6) ◽

pp. 232-233 ◽

Cited By ~ 3

Author(s):

CA BOURKE ◽

MJ CARRIGAN ◽

CHR DENT

Keyword(s):

Merino Sheep ◽

Australian Merino

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Effects of inbreeding on four families of Peppin Merinos

Australian Journal of Agricultural Research ◽

10.1071/ar9570299 ◽

1957 ◽

Vol 8 (3) ◽

pp. 299 ◽

Cited By ~ 16

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.

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

Australian Journal of Agricultural Research ◽

10.1071/ar9810657 ◽

1981 ◽

Vol 32 (4) ◽

pp. 657 ◽

Cited By ~ 2

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.

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

Australian Journal of Agricultural Research ◽

10.1071/ar98099 ◽

1999 ◽

Vol 50 (6) ◽

pp. 1099 ◽

Cited By ~ 15

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.

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