Phenotypic and genotypic analysis of a barebreech trait in Merino sheep as a potential replacement for surgical mulesing

2009 ◽  
Vol 49 (1) ◽  
pp. 56 ◽  
Author(s):  
N. M. Edwards ◽  
M. Hebart ◽  
P. I. Hynd
Keyword(s):  
Genetic Correlations ◽  
Rapid Progress ◽  
Immune Rejection ◽  
Histological Evidence ◽  
Merino Sheep ◽  
Wide Channel ◽  
Lower Weight ◽  
Genotypic Analysis ◽  
Genetic Mechanisms ◽  
System 1

The potential for adopting a genetic solution to protect sheep from blowfly strike on the breech was investigated in a flock of sheep that contained several animals expressing a trait characterised by low wool coverage over the breech and through a wide channel from the anus to the udder or scrotum. A scoring system (1, bare to 5, woolly) was developed and used to determine the heritability of the trait and its phenotypic and genetic correlations with other traits of importance in a sheep enterprise. In comparison to animals with woolly breeches, the skin in the breech of animals with a low bareness score was characterised by a low density of follicles producing short, medullated fibres, with histological evidence of immune rejection and follicular atrophy. The bareness score of progeny was influenced by the score of their respective sires suggesting a strong genetic component. The heritability of bareness score was moderate to high (h2 = 0.45 ± 0.02, 0.53 ± 0.01 and 0.38 ± 0.02 at lamb, hogget and adult ages, respectively). The lactation status and age of ewes influenced their bareness score, resulting in a low repeatability (0.42) of the trait between ages in females. Genetic correlations between bareness score and most other economically important traits were low. The weight of belly wool and the weight of skirtings was genetically related to bareness score (rg = +0.52 and +0.48 respectively), indicating that animals with barer breeches tend genetically towards lighter belly wool weights and lower weight of skirtings at wool classing. Selection and breeding for bareness score should achieve relatively rapid progress towards fixing the trait in a flock and without adverse effects on other important traits. Caution should be exercised in extrapolating these results to other bloodlines and environments where genetic mechanisms or environmental influences may be different.

Genetic and phenotypic parameters for reproduction, production and bodyweight traits in Australian fine-wool Merino sheep

2018 ◽  
Vol 58 (2) ◽  
pp. 207 ◽  
Author(s):  
S. Dominik ◽  
A. A. Swan
Keyword(s):  
Genetic Relationships ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Careful Consideration ◽  
Production Traits ◽  
Merino Sheep ◽  
Wool Production ◽  
Phenotypic Correlations ◽  
Reproduction Traits ◽  
Definition Of

The present study estimated phenotypic and genetic relationships between wool production, reproduction and bodyweight traits in Australian fine-wool Merino sheep. The data for the study originated from the CSIRO Fine Wool Project, Armidale, Australia. Data on wool characteristics, measured at ~10 and 22 months of age, bodyweight and several reproduction traits across consecutive lambing opportunities were analysed. The genetic correlations were moderately negative between fibre diameter measured as yearling and adult, and lamb survival (rg = –0.34 ± 0.15 and rg = –0.28 ± 0.14 respectively) and total number of lambs weaned (rg = –0.32 ± 0.21 and rg = –0.40 ± 0.21 respectively). The genetic correlations of yearling and adult greasy and clean fleece weights with number of lambs weaned and fecundity showed moderately to highly negative relationships and a moderately negative correlation with the number of fetuses at pregnancy scanning. Phenotypic correlations between reproduction and wool production traits were estimated to be zero, with the exception of bodyweight showing low to moderate positive phenotypic correlations with total number of lambs born and weaned. Genetic variances were generally low for the reproduction traits and resulted in low heritability estimates (from h2 = 0.03 ± 0.01 to h2 = 0.12 ± 0.13), with the exception of total number of lambs born (h2 = 0.25 ± 0.03). The study indicated that parameter estimation and trait definition of lifetime reproduction records require careful consideration and more work in this area is required.

scholarly journals Genetic correlations among and between wool, growth and reproduction traits in Merino sheep

2007 ◽  
Vol 124 (2) ◽  
pp. 65-72 ◽  
Author(s):  
E. Safari ◽  
N.M. Fogarty ◽  
A.R. Gilmour ◽  
K.D. Atkins ◽  
S.I. Mortimer ◽  
...  
Keyword(s):  
Genetic Correlations ◽  
Merino Sheep ◽  
Wool Growth ◽  
Reproduction Traits ◽  
Growth And Reproduction

Can we breed Merino sheep with softer, whiter, more photostable wool?

2010 ◽  
Vol 50 (12) ◽  
pp. 1089 ◽  
Author(s):  
S. Hatcher ◽  
P. I. Hynd ◽  
K. J. Thornberry ◽  
S. Gabb
Keyword(s):  
Genetic Parameters ◽  
Selection Index ◽  
Genetic Correlations ◽  
Genetic Selection ◽  
Phenotypic Selection ◽  
Quality Traits ◽  
Current Generation ◽  
Merino Sheep ◽  
Initial Cohort ◽  
Selection For

Genetic parameters (heritability, phenotypic and genetic correlations) were estimated for a range of visual and measured wool traits recorded from the 2008 shearing of the initial cohort of Merino progeny born into the Sheep CRC’s Information Nucleus Flock. The aim of this initial analysis was to determine the feasibility of selectively breeding Merino sheep for softer, whiter, more photostable wool and to quantify the likely impact on other wool production and quality traits. The estimates of heritability were high for handle and clean colour (0.86 and 0.70, respectively) and moderate for photostability (0.18), with some evidence of maternal effects for both handle and photostability. The phenotypic correlations between handle and clean colour and between handle and photostability were close to zero, indicating that achieving the ‘triple’ objective of softer, whiter, more photostable wool in the current generation through phenotypic selection alone would be difficult. There was evidence of an antagonistic relationship between handle and photostability (–0.36), such that genetic selection for softer wool will produce less photostable wool that will yellow on exposure to UV irradiation. However genetic selection for whiter wool is complementary to photostability and will result in whiter wool that is less likely to yellow. Genetic selection to improve handle, colour and photostability can be achieved with few detrimental effects on other visual and measured wool traits, particularly if they are included in an appropriate selection index.

Selection for economic characters in Australian Merino sheep. V. Further estimates of phenotypic and genetic parameters.

1955 ◽  
Vol 6 (1) ◽  
pp. 77 ◽  
Author(s):  
FHW Morley
Keyword(s):  
Genetic Correlations ◽  
Minor Importance ◽  
Agricultural Experiment Station ◽  
Genetic Progress ◽  
Sheep Population ◽  
Merino Sheep ◽  
Agricultural Experiment ◽  
Selection For ◽  
Fleece Weight ◽  
Genetic Homeostasis

Estimates of heritability, genetic correlations, phenotypic correlations, and other parameters among eight characteristics were obtained from Merino sheep at Trangie Agricultural Experiment Station. One set of estimates was obtained by parent-offspring regressions from data obtained between 1943 and 1952. Another set was obtained by half-sib analyses from data from sheep with first adult shearings in 1953. Estimates of heritability were: greasy fleece weight, 0.40 ± 0.06; yield (per cent.), 0.39 ± 0.07; clean fleece weight, 0.47 ± 0.07; staple length, 0.56 � 0.07; crimps per inch, 0.47 ± 0.11; folds, 0.50 ± 0.07; body weight, 0.36 ± 0.08; birthcoat, 0.80 ± 0.10. The most important genetic correlation limiting genetic improvement in clean fleece weight is that between this trait and crimps per inch. Because of this the rate of improvement in fleece weight could be reduced by about 30 per cent. whenever crimps per inch is also selected. Other genetic correlations indicate antagonisms between characteristics, but these antagonisms appear to be of minor importance except that between clean fleece weight and crimps per inch. This sheep population does not appear to have reached a state of genetic homeostasis, a t least with respect to the characteristics studied. However, the findings emphasize the necessity for careful evaluation of the economic importance of different traits, and for accurate measurement, if maximum genetic progress is to be achieved.

scholarly journals Genetic correlations between pain phenotypes and depression and neuroticism

2019 ◽  
Vol 28 (3) ◽  
pp. 358-366 ◽  
Author(s):  
Weihua Meng ◽  
Mark J. Adams ◽  
Parminder Reel ◽  
Aravind Rajendrakumar ◽  
Yu Huang ◽  
...  
Keyword(s):  
Depressive Symptoms ◽  
Depressive Disorders ◽  
Genetic Correlations ◽  
The Body ◽  
Uk Biobank ◽  
Major Depressive ◽  
Genetic Mechanisms ◽  
Major Depressive Disorders ◽  
The Uk ◽  
Shared Genetic

Abstract Correlations between pain phenotypes and psychiatric traits such as depression and the personality trait of neuroticism are not fully understood. In this study, we estimated the genetic correlations of eight pain phenotypes (defined by the UK Biobank, n = 151,922–226,683) with depressive symptoms, major depressive disorders and neuroticism using the the cross-trait linkage disequilibrium score regression (LDSC) method integrated in the LD Hub. We also used the LDSC software to calculate the genetic correlations among pain phenotypes. All pain phenotypes, except hip pain and knee pain, had significant and positive genetic correlations with depressive symptoms, major depressive disorders and neuroticism. All pain phenotypes were heritable, with pain all over the body showing the highest heritability (h2 = 0.31, standard error = 0.072). Many pain phenotypes had positive and significant genetic correlations with each other indicating shared genetic mechanisms. Our results suggest that pain, neuroticism and depression share partially overlapping genetic risk factors.

Are breech strike, dags and breech wrinkle genetically the same trait in crutched, uncrutched and mulesed Merino sheep?

2019 ◽  
Vol 59 (10) ◽  
pp. 1777
Author(s):  
J. C. Greeff ◽  
L. J. E. Karlsson ◽  
A. C. Schlink
Keyword(s):  
Genetic Correlation ◽  
Standard Error ◽  
Lower Risk ◽  
Genetic Correlations ◽  
High Standard ◽  
Breeding Value ◽  
Strongly Correlated ◽  
Merino Sheep ◽  
Skin Wrinkles ◽  
Indicator Traits

Breech strike is caused by the infestation of maggots from Lucilia cuprina on the skin of susceptible sheep. Crutching and mulesing modify the potential expression of breech strike, because crutched and mulesed sheep have a lower risk of being struck than uncrutched sheep. The inheritance of and genetic correlations among breech strike from birth to hogget shearing, and dags (breech soiling) and skin wrinkles scored at yearling age were estimated in unmulesed and crutched, unmulesed and uncrutched, and in mulesed and uncrutched Merino sheep to determine whether these traits were genetically the same under these three husbandry systems. The heritability estimates of breech strike in uncrutched, crutched and mulesed sheep were very similar (0.11 ± 0.02, 0.09 ± 0.02 and 0.08 ± 0.05 respectively). Breech strike in uncrutched sheep is genetically strongly correlated with breech strike in crutched sheep (0.80 ± 0.16). The genetic correlation between breech strike in uncrutched and in mulesed sheep was high (0.98 ± 0.40), but the high standard error makes this estimate unreliable. Dags and wrinkles are genetically moderately to strongly correlated with breech strike, which confirms that they are indicator traits for breech strike. Dags in uncrutched sheep was genetically strongly correlated with dags in mulesed sheep (0.84 ± 0.11). Breech wrinkle in uncrutched and crutched sheep, and tail wrinkle in mulesed sheep were not genetically strongly correlated with each other, as the correlations varied between zero and 0.48 (±0.18). The key outcome from this study indicates that all breech strike, wrinkle and dag data in mulesed, crutched or uncrutched flocks may be used in future to estimate a breeding value directly for breech strike.

Genetic correlations between wool traits and meat quality traits in Merino sheep

2017 ◽  
Vol 0 (0) ◽  
pp. 0
Author(s):  
S. I. Mortimer ◽  
S. Hatcher ◽  
N. M. Fogarty ◽  
J. H. J. van der Werf ◽  
D. J. Brown ◽  
...  
Keyword(s):  
Meat Quality ◽  
Genetic Correlations ◽  
Quality Traits ◽  
Merino Sheep ◽  
Meat Quality Traits

Response to selection in Australian Merino sheep. VI. Inheritance of abnormal staple crimp; estimates of phenotypic and genetic parameters

1975 ◽  
Vol 26 (2) ◽  
pp. 375 ◽  
Author(s):  
N Jackson ◽  
RE Chapman
Keyword(s):  
Body Weight ◽  
Unit Area ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Phenotypic Variance ◽  
Correlated Responses ◽  
Environmental Correlations ◽  
Merino Sheep ◽  
Phenotypic Correlations ◽  
Fibre Number

The heritability of abnormal crimp in wool at various ages and the genetic and phenotypic cotreiations of crimp abnormality with several wool and body characters were estimated for Peppin Merino sheep. When examined by half-sib analyses of variance, the heritability of abnormal crimp scored at ages less than 4.5 years was low, whereas abnormality at 5.5 years and older was highly inherited. Heritabilities estimated by intra-sire dam-daughter regression analyses with fewer degrees of freedom did not show such a clear-cut pattern, although the estimates tended to increase with age. The genetic correlations of crimp abnormality scores at ages up to 4.5 years with scores at older ages were mainly low. Crimp abnormality scores at most ages had genetic correlations with wool and body characters at 15–16 months of age as follows: strong positive with fibre diameter, weak positive with greasy and clean wool weight, wrinkle score and staple length, and weak negative with fibre number. Genetic correlations with body weight, percentage clean yield, face cover score and crimp frequency were inconsistent. The phenotypic variance of crimp abnormality increased with age, owing almost entirely to an increase in the additive genetic variance. The environmental variance was approximately the same at all ages. Phenotypic correlations among crimp abnormality scores were generally higher between scores at close ages, and particularly at older ages. Crimp abnormality scores at all ages had positive phenotypic correlations with fibre diameter and wrinkle score and negative correlations with fibre number per unit area of skin and percentage clean yield.Crimp abnormality at old ages also had positive phenotypic correlations with greasy and clean wool weights. Environmental correlations of crimp abnormality with greasy wool weight, clean wool weight body weight and fibre number per unit area of skin were negative, and those with percentage clean yield and fibre number positive. Predicted correlated responses in crimp abnormality differed in some respects from correlated responses observed previously in groups of Peppin Merino sheep selected for high and low values of percentage clean yield, clean wool weight, fibre number per unit area of skin and fibre diameter. Methods of selection of sheep which would be expected to reduce crimp abnormality are outlined.

Genetic evaluation of production traits between and within flocks of Merino sheep. II. Component traits of the Hogget fleece

1993 ◽  
Vol 44 (7) ◽  
pp. 1523 ◽  
Author(s):  
SI Mortimer ◽  
KD Atkins
Keyword(s):  
Agricultural Research ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Matter Content ◽  
Research Centre ◽  
Production Traits ◽  
Merino Sheep ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Fleece Weight

Components of the fleece and wool quality traits were measured or assessed on Merino hogget ewes in an unselected multiple-bloodline flock over a 7-year period at Trangie Agricultural Research Centre, N.S.W. The traits recorded were face cover score (FC), leg cover score (LC), neck fold score (NF), body fold score (BF), wax content (W), suint content (S), vegetable matter content (VM), dust penetration (D), follicle density (N) and follicle ratio (RA). Genetic differences within and between flocks of Merino sheep were examined for the traits, and estimates of heritability and within-flock genetic and phenotypic correlations and between-flock genetic correlations among the traits were obtained. Genetic and phenotypic correlations were also estimated between these traits and the major wool production traits: greasy fleece weight (GFW), clean fleece weight (CFW), fibre diameter (FD), body weight (BWT) and staple length (SL). Significant strain. flock within strain and flock effects were wresent for all traits. The influence of environmental effects (birth-rearing type, age at measurement and age of dam) on the traits was estimated, with the birth-rearing type being significant and the largest effect for most traits. Paternal half-sib heritability estimates were 0.44� 0.06 for FC, 0.35� 0.06 for LC, 0.24�0.05 for NF, 0.23�0.05 for BF, 0.38�0.07 for W, 0.42�0.07 for S, 0.06�0.04 for VM, 0.22�0.06 for D, 0.20� 0.07 for N and 0.21�0.07 for RA. Estimates of within-flock phenotypic and genetic correlations were in broad agreement with available published estimates. The implications of the results for Merino breeding programs are discussed.

Selection for weaning weight in Merino sheep. 2. Correlated responses in other production characters

1965 ◽  
Vol 5 (19) ◽  
pp. 361 ◽  
Author(s):  
WA Pattie
Keyword(s):  
Milk Protein ◽  
Survival Rates ◽  
Genetic Correlations ◽  
Negative Relationship ◽  
Weaning Weight ◽  
Merino Sheep ◽  
Selection For ◽  
The Difference ◽  
Fleece Weight ◽  
Lamb Growth

The heritabilities of seven production characters of Merino Sheep and their phenotypic and genetic correlations with corrected weaning weight have been calculated using half-sib and dam-daughter correlations. Realized genetic correlations calculated from responses in Weight Plus and Weight Minus selection flocks, which showed broad agreement with these correlations, were : 17-month body weight, 0.72 ; yield, 0.22 ; clean fleece weight, 0.24 ; and staple length, 0.17. There was zero relationship with greasy fleece weight and crimps per inch, and a large negative relationship between folds and high weaning weight. There were strong phenotypic correlations between lamb growth and milk production through the total weight of milk protein produced. The lamb's genotype was the most important contributor to the difference in weaning weight between the flocks. There were no differences in reproductive performance or survival rates between the flocks but twice as many twin rams and 20 per cent more twin ewes were mated in the Weight Minus flock over the selection period.

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