The inheritance of faecal egg count following natural Ostertagia circumcinctainfection in Scottish Blackface lambs

1996 ◽  
Vol 1996 ◽  
pp. 117-117
Author(s):  
S.C. Bishop ◽  
K. Bairden ◽  
Q.A. McKellar ◽  
M. Park ◽  
M.J. Stear
Keyword(s):  
Genetic Selection ◽  
Live Weight ◽  
Gastrointestinal Parasites ◽  
Sheep Industry ◽  
Environment Effects ◽  
Faecal Egg Count ◽  
Genetic And Phenotypic Correlations ◽  
Selection For ◽  
The Uk ◽  
Production Losses

The use of genetic selection as a means of reducing the welfare and production losses caused by gastrointestinal parasites has hitherto been ignored by the UK sheep industry. The aim of this study is to assess the potential for selection for reduced faecal egg count, as an indicator of parasitism, and to establish relationships with live weight.Faecal egg counts and live weights were measured on approximately 200 predominantly twin born Scottish Blackface lambs each year for three years following natural, predominantly Ostertagia circumcincta , infection on pasture. Measurements were made from one to six months of age, at four week intervals, following anthelmintic treatment. Heritabilities, maternal common environment effects, genetic and phenotypic correlations were calculated using Residual Maximum Likelihood techniques.

The inheritance of faecal egg count following natural Ostertagia circumcinctainfection in Scottish Blackface lambs

1996 ◽  
Vol 1996 ◽  
pp. 117-117
Author(s):  
S.C. Bishop ◽  
K. Bairden ◽  
Q.A. McKellar ◽  
M. Park ◽  
M.J. Stear
Keyword(s):  
Genetic Selection ◽  
Live Weight ◽  
Gastrointestinal Parasites ◽  
Sheep Industry ◽  
Environment Effects ◽  
Faecal Egg Count ◽  
Genetic And Phenotypic Correlations ◽  
Selection For ◽  
The Uk ◽  
Production Losses

The use of genetic selection as a means of reducing the welfare and production losses caused by gastrointestinal parasites has hitherto been ignored by the UK sheep industry. The aim of this study is to assess the potential for selection for reduced faecal egg count, as an indicator of parasitism, and to establish relationships with live weight.Faecal egg counts and live weights were measured on approximately 200 predominantly twin born Scottish Blackface lambs each year for three years following natural, predominantly Ostertagia circumcincta , infection on pasture. Measurements were made from one to six months of age, at four week intervals, following anthelmintic treatment. Heritabilities, maternal common environment effects, genetic and phenotypic correlations were calculated using Residual Maximum Likelihood techniques.

A genetic analysis of wool characteristics and lamb performance traits in Scottish Blackface sheep

2003 ◽  
Vol 77 (3) ◽  
pp. 355-362 ◽  
Author(s):  
J. Conington ◽  
A. Murphy
Keyword(s):  
Genetic Correlations ◽  
Live Weight ◽  
Scoring Systems ◽  
Production Traits ◽  
Genetic And Phenotypic Correlations ◽  
Selection For ◽  
Heritability Estimates ◽  
Wool Quality ◽  
Fleece Weight ◽  
The Uk

AbstractGenetic parameters were estimated for wool quality, fleece characteristics and lamb production traits for Scottish Blackface sheep reared under extensive hill conditions in the UK. In two separate studies, heritabilities and genetic correlations were estimated for wool quality traits measured on lambs at 5 months of age and again on the shorn fleece a year later. The wool traits included birth coat length (BCT), 10-point scores for proportion of grey and kemp fibres present in the fleece (grey, kemp), British Wool Marketing Board (BWMB) recommendation (REC), greasy fleece weight (FLWT), BWMB fleece grade (FLGR), and average staple length (ASL). Genetic and phenotypic correlations were estimated between lamb wool traits and lamb live weights at birth (BWT), marking (at mid lactation with an average age of 7 weeks) (MWT), weaning (at an average age of 17 weeks) (WWT) and slaughter (SLWT), average fat depth (AVFD) and average muscle depth (MD). Individual lamb carcass measurements included Meat and Livestock Commission (MLC) conformation score (CONF) and fat class (FATC). Heritability estimates measured on 2524 or more live lambs were 0·69, 0·52, 0·26, 0·42 and 0·31 for BCT, ASL, grey, kemp and REC respectively. Heritability estimates for traits measured on the shorn fleece a year later for 1415 ewes were 0·37, 0·02, 0·57, 0·43, 0·46 and 0·14 for ASL, grey, kemp, REC, FLWT and FLGR respectively. Genetic correlations between FLWT in hoggets and other wool were positive and moderate to high in magnitude, ranging from 0·22 for kemp in lambs to 0·48 for grey in hoggets. Genetic correlations between REC and live-weight traits were 0·39 for MWT, 0·37 for WWT and 0·44 for SLWT. Genetic correlation between ASL and ultrasonic fat depth was 0·15 and for ASL and ultrasonic muscle depth was -0·30. The results indicate that the simple scoring systems derived to assess these traits are useful indicators of fleece quality, are highly repeatable over time and are a good gauge of likely future wool production. The results indicate that selection for heavier, leaner lambs should not compromise fleece quality, as assessed in this study.

Associations of PrP genotypes with live weight and slaughter traits in an experimental flock of Swaledale sheep in Great Britain

2006 ◽  
Vol 82 (5) ◽  
pp. 607-614 ◽  
Author(s):  
W. Y. N. Man ◽  
S. Brotherstone ◽  
B. G. Merrell ◽  
W. A. Murray ◽  
B. Villanueva
Keyword(s):  
Great Britain ◽  
Maternal Effects ◽  
Mixed Models ◽  
Fixed Effects ◽  
Genetic Selection ◽  
Live Weight ◽  
Eradication Programme ◽  
Gene Encoding ◽  
Significant Relationships ◽  
Selection For

AbstractPolymorphisms at codons 136, 154 and 171 of the gene encoding the prion protein (PrP) are associated with susceptibility to classical scrapie in sheep. Genetic selection for scrapie resistance based on PrP genotypes is central to the scrapie eradication programme in Great Britain but there are concerns about how this may affect other economically important traits. The objective of this study was to evaluate associations of PrP genotypes with live weight and slaughter traits in a hill sheep breed in Great Britain. Data used were from an experimental flock of Swaledale sheep in which the alleles ARR, ARQ, AHQ and VRQ were present. About 1450 genotyped lambs with birth, marking and weaning weights, and 620 with slaughter records were used for the study. Mixed models with various fixed effects and random direct genetic and maternal effects were tested to determine the appropriate model to use for each trait. None of the differences in lamb performance between PrP genotypes consistently reached significance. Therefore, this study does not support existence of significant relationships between PrP genotype and lamb performance traits in this breed.

Genetic Selection for Enhanced Health Characteristics

2007 ◽  
Vol 4 (6) ◽  
Author(s):  
Andy Miah
Keyword(s):  
Genetic Information ◽  
Genetic Selection ◽  
Regulatory Framework ◽  
Genetic Tests ◽  
Selection For ◽  
The Uk ◽  
Moral Stance ◽  
Human Genetic Commission

AbstractThis paper examines the UK regulatory framework and the ethical arguments surrounding the use of genetic tests, specifically considering how they would apply to selecting for enhanced health characteristics. It discusses the Human Genetic Commission reports on the use of genetic information more broadly, identifying the implied values and concerns arising from their conclusions. It argues that the HGC conflates the concepts of ‘best’ and ‘enhancement’ and this limits the persuasiveness of their moral stance

Genetics of food intake, live weight, condition score and energy balance

1999 ◽  
Vol 24 ◽  
pp. 63-73 ◽  
Author(s):  
R. F. Veerkamp ◽  
E. P. C. Koenen
Keyword(s):  
Energy Balance ◽  
Food Intake ◽  
Weight Change ◽  
Genetic Selection ◽  
Metabolic Stress ◽  
Live Weight ◽  
Food Utilization ◽  
Score Change ◽  
Condition Score ◽  
Selection For

AbstractThe objectives of this study were to investigate genetic variation for traits that are part of the food utilization complex and to investigate the scope for future genetic improvement of traits possibly linked to metabolic stress: live weight (change), condition score (change) and energy balance. Many aspects of the food utilization complex appear to be heritable and are affected by genetic selection for yield. In general, genetic selection for yield increases intake and body tissue mobilization and energy balance is expected to decrease. However, unfavourable effects of genetic selection can be compensated for by measuring additional traits to be included in breeding programmes. Food intake, live weight (change) and condition score (change) are all potential options. Which traits should be measured, at what lactation stages and in which (nutritional) environment will merely depend on the coheritability with health and fertility, the genetic correlation with milk yield and the cost of measuring the trait effectively in a breeding programme.

Selection for high or low backfat depth in Coopworth sheep: juvenile traits

1997 ◽  
Vol 65 (1) ◽  
pp. 93-103 ◽  
Author(s):  
C. A. Morris ◽  
J. C. McEwan ◽  
P. F. Fennessy ◽  
W. E. Bain ◽  
G. J. Greer ◽  
...  
Keyword(s):  
Animal Model ◽  
Maximum Likelihood ◽  
Random Sample ◽  
Live Weight ◽  
Control Line ◽  
Selection Experiment ◽  
Initial Screening ◽  
Genetic And Phenotypic Correlations ◽  
Selection For ◽  
Subsequent Selection

AbstractA selection experiment was established in Coopworth sheep in 1981 to breed for increased or reduced ultrasonic backfat depth (scan C). Foundation females came from four flocks recorded for scan C and live weight, with weight-adjusted scan C data within flock being used for initial screening and subsequent selection. Three groups of animals per source flock, comprising proportionally the fattest 0·12, a random sample, and the leanest 0·12, were used to establish the F, control and L lines, respectively. Ewe flock numbers from 1981 to 1992 averaged 51 per line. Foundation rams were selected in the same manner from four different farms (two sources each in 1981 and 1982) to provide F line (proportionally the fattest 0·04), control line and L line (leanest 0·04) rams for use in 1981 and 1982, with four mated per line per year. Thereafter homebred rams were selected, with 41 or 42 homebred rams being used per line until 1992. Average generation intervals were 2·13 years and annual inbreeding rates per line 0·004. Bivariate heritability estimates for log scan C and log live weight, and a univariate estimate for log scan C using restricted maximum likelihood with an animal model, were 0·28, 0·22 and 0·38, respectively (all with s.e. 0·03). There was a suggestion of lower heritabilities in the L line for log scan C after adjustment for live weight. Realized heritabilities in the F and L lines were 0·34 (s.e. 0·07) and 0·26 (s.e. 0·03), respectively. Deviations of back-transformed weight-adjusted scan C in the last 2 years ofF and L data analysed (1991 and 1992 birth years) from the control flocks were 2·08 and −0·85 mm, which corresponded to responses of +2·50 and −1·03 phenotypic standard deviations, respectively. In addition there were relatively large responses in live weight taken at scanning, with F and L lines averaging 34·0 and 40·2 kg, compared with 38·0 kg for controls in the 1991 and 1992 birth years. The genetic and phenotypic correlations between log scan C and log live weight at scanning were 0·16 (s.e. 0·07) and 0·46 (s.e. 0·01) respectively.

Options to reduce vulnerability to metabolic stress by genetic selection

1999 ◽  
Vol 24 ◽  
pp. 119-127 ◽  
Author(s):  
J. E. Pryce ◽  
P. Løvendahl
Keyword(s):  
Milk Production ◽  
Genetic Selection ◽  
Metabolic Stress ◽  
Live Weight ◽  
Genetic Merit ◽  
Condition Score ◽  
Breeding Programmes ◽  
Selection For ◽  
Breeding Goals ◽  
High Yields

AbstractGenetic selection for milk production has been very successful. However to achieve high yields, the metabolic load on dairy cows is believed to be substantial. If the size of this load is large enough then the animal may become ‘metabolically stressed’. Signs of this may include some sort of distortion of normal physiological function. There is evidence from both population studies and research herds to suggest that intense selection for milk yield has led to a deterioration in some aspects of health and fertility. Genetic correlation estimates between production and measures of fertility are unfavourable. As an example, calving intervals of high merit animals from Langhill are on average 12 days longer than those of average genetic merit, which is mostly due to a delay in days to first heat. It is suggested that some aspects of health and fertility problems in high genetic merit animals are a consequence, in part, of so-called metabolic stress. Future breeding goals should be broadened to include a broad spectrum of traits related to efficient milk production, in addition to either health and fertility traits themselves, or traits believed to be precursors of them, such as those related to metabolic stress. The complexity and subjectivity of metabolic stress and its components makes it very difficult to include in future breeding goals. However, traits related to energy balance, such as some measures of condition score, dry-matter intake and live weight may be useful in breeding programmes where one of the goals is to alleviate metabolic stress.

scholarly journals Genetic parameters for faecal egg count following mixed, natural, predominantly Ostertagia circumcincta infection and relationships with live weight in young lambs

1996 ◽  
Vol 63 (3) ◽  
pp. 423-428 ◽  
Author(s):  
S. C. Bishop ◽  
K. Bairden ◽  
Q. A. McKellar ◽  
M. Park ◽  
M. J. Stear
Keyword(s):  
Genetic Parameters ◽  
Genetic Correlations ◽  
Live Weight ◽  
Gastrointestinal Parasites ◽  
Phenotypic Correlations ◽  
Selection Decisions ◽  
Faecal Egg Count ◽  
Resistance To Infection ◽  
Faecal Egg Counts ◽  
Small Measurement Error

AbstractFaecal egg counts and live weights were measured on approximately 200 predominantly twin-born Scottish Blackface lambs each year for 3 years, from 1 to 6 months of age. Measurements were made at 4-week intervals following anthelmintic treatment. Heritability estimates (with s.e.s) of log transformed faecal egg count at each age were 0·01, 0·00, 0·12 (0·10), 0·14 (0·12), 0·15 (0·07) and 0·22 (0·13), for ages 1 to 6 months respectively. Therefore, genetic variation exists for acquired but apparently not for innate resistance to infection. Maternal common environmental effects (with s.e.s) were 0·36 (0·11), 0·20 (0·05), 0·27 (0·09), 0·06 (0·08), 0·15 (0·09) and 0·16 (0·08), for ages 1 to 6 months respectively. Genetic correlations between faecal egg counts in lambs older than 3 months were not significantly less than 1·0, indicating that faecal egg counts at different ages are expressions of the same trait. Phenotypic correlations between faecal egg counts were generally positive but small. Measurement error contributed one-third of the observed variation for individual egg counts. The heritability of mean faecal egg count from 3 to 6 months was 0·33 (s.e. 0·15), indicating that selection decisions can be made more accurately using multiple egg counts per animal. Phenotypic correlations between faecal egg counts and live weight were generally negative but close to zero. However, genetic correlations between faecal egg counts and live weight in lambs older than 3 months were close to -1·0, indicating that resistance to gastrointestinal parasites may be an important genetic determinant of growth rate in this environment.

scholarly journals Wooden breast and white striping: comparative occurrence in three poultry companies

2021 ◽  
Vol 41 ◽  
Author(s):  
Sabrina T. Fraga ◽  
Fátima R.F. Jaenisch ◽  
Jane O. Peixoto ◽  
Arlei Coldebella ◽  
Karen A. Borges ◽  
...  
Keyword(s):  
Growth Rate ◽  
Pectoralis Major Muscle ◽  
Genetic Selection ◽  
Live Weight ◽  
Economic Losses ◽  
White Striping ◽  
Processing Plants ◽  
Poultry Processing ◽  
Selection For ◽  
Wooden Breast

ABSTRACT: To increase the amount of meat produced, researchers have promoted intensive genetic selection for growth rate and muscling and have improved nutrition and management conditions. However, there has been an increase in the number of reports of breast muscle myopathies observed in poultry processing plants, including white striping (WS) and wooden breast (WB). This study aimed to evaluate and to compare the occurrence of WS and WB myopathies in three poultry processing plants and to perform an anatomopathological characterization, including macroscopic and microscopic analyses. A total of 408,334 carcasses were condemned or downgraded due to the presence of WB or WS, which represents 0.73% of the total number of slaughtered animals during the evaluated period. WB was more frequent than WS, but the occurrence of each myopathy varied significantly according to each establishment. WB was more frequent in the establishment which includes only male flocks, an average age of 45 days, and an average live weight of 2775g (B). WS was more frequent in establishment with male, female and mixed flocks, average ages ranging from 41 to 44 days, and average live weight 1731g-2830g (A). It is probably related with specific condition of each poultry company, including genetics, age, nutrition and management conditions. Macroscopically, WB and WS lesions are characterized by hypertrophy and stiffness of the pectoralis major muscle. Under microscopy, the myopathies showed similarities regarding the detected histological abnormalities, characterized by a process of myodegeneration, although the connective tissue infiltrate was more severe in the breasts with WB than in those with WS myopathy. The results found in this study demonstrate that the rates of condemnation for these myopathies are high, vary significantly among the analyzed companies and may cause major economic losses for the productive sector in the region.

Selection for ultrafine Merino sheep in New Zealand: heritability, phenotypic and genetic correlations of live weight, fleece weight and wool characteristics in yearlings

2001 ◽  
Vol 72 (2) ◽  
pp. 241-250 ◽  
Author(s):  
T. Wuliji ◽  
K. G. Dodds ◽  
J. T. J. Land ◽  
R. N. Andrews ◽  
P. R. Turner
Keyword(s):  
New Zealand ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Live Weight ◽  
Production Traits ◽  
Genetic And Phenotypic Correlations ◽  
Selection For ◽  
Staple Strength ◽  
Fleece Weight ◽  
Staple Length

AbstractMerino yearling records from 1988 to 1992 birth years in ultrafine wool selection and random control flocks at Tara Hills High Country Station, New Zealand were analysed for live weight, fleece weight and wool characteristics. Estimates of heritability, genetic and phenotypic correlations among traits using REML methods are presented. Heritabilities (h2) of birth, weaning, autumn, spring and summer live weights and greasy and clean fleece weights were estimated as being 0·35, 0·34, 0·44, 0·43, 0·49, 0·24 and 0·28 respectively; while h2 of yield, fibre diameter, coefficient of variation in fibre diameter, staple crimp, staple length, staple strength, position of break, resistance to compression, bulk, CIE Y and CIE Y-Z were estimated to be 0·58, 0·59, 0·60, 0·45, 0·71, 0·13, 0·18, 0·46, 0·38, 0·38 and 0·42 respectively. Genetic correlations were found to be high among the live weights but low to moderate among fleece weight and wool characteristics. Heritability estimates of fibre diameter, fibre diameter variation and staple length were found to be higher in New Zealand fine wool Merinos than most of those reported in the literature. The results indicate that selection for reduced fibre diameter will have little effect on other major production traits such as live weight and fleece weight.

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