Genetic and phenotypic parameters between yearling, hoggetand adult reproductive performance and age of first oestrus in sheep

2014 ◽  
Vol 54 (6) ◽  
pp. 753 ◽  
Author(s):  
J. E. Newton ◽  
D. J. Brown ◽  
S. Dominik ◽  
J. H. J. van der Werf
Keyword(s):  
Reproductive Performance ◽  
Evaluation System ◽  
Genetic Correlations ◽  
High Standard ◽  
Genetic Evaluation ◽  
Standard Errors ◽  
Adult Performance ◽  
Genetic And Phenotypic Correlations ◽  
Heritability Estimates ◽  
Lamb Survival

The aims of this study were to quantify the relationship between age of first oestrus and yearling reproductive performance in maternal-cross ewes in the Information Nucleus Flock data and to estimate genetic and phenotypic correlations between early and later reproductive performance defined as three ages, yearling, hogget and adult in both Merino and maternal-cross ewes. Information on 2218 yearling records, 2047 hogget records and 910 age of first oestrus records were used in the analysis of maternal-cross ewes, whereas 3286 hogget and 2518 adult reproductive records were used in analysis of Merino ewes. Heritability estimates for yearling reproductive performance in maternal-cross ewes ranged from 0.08 ± 0.09 for ewe fecundity to 0.16 ± 0.05 for number of lambs born and were generally higher than hogget heritability estimates for both maternal-cross and Merino ewes. Age at first oestrus was found to have a low heritability, 0.02 with standard errors of 0.07 and 0.06 with and without weight fitted as a covariate. Genetic correlations between age at first oestrus with and without weight fitted as a covariate and yearling reproductive performance were positive, ranging from 0.07 ± 0.49 with lamb survival to 0.94 ± 0.39 with number of lambs born, which was unexpected. Correlations between traits from the same age class were high in both breed groups. Genetic correlations between yearling and hogget performance in maternal-cross ewes were generally lower than one, ranging from 0.46 ± 0.68 for lamb survival and 0.79 ± 0.50 for fertility suggesting that yearling and later reproductive performance are related but genetically different traits. In Merino ewes, the genetic correlations between hogget and adult performance followed a similar pattern. The small number of records in this study generated high standard errors for estimates, which restricts the conclusions that can be drawn. Overall, this study supports current practice used by ‘Sheep Genetics’, the Australian genetic evaluation system for sheep, in considering yearling reproductive performance as a trait separate from later parities for genetic evaluation purposes.

scholarly journals Genetic and genomic relationship between methane production measured in breath and fatty acid content in milk samples from Danish Holsteins

2016 ◽  
Vol 56 (3) ◽  
pp. 298 ◽  
Author(s):  
J. Lassen ◽  
N. A. Poulsen ◽  
M. K. Larsen ◽  
A. J. Buitenhuis
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Content ◽  
Genetic Correlations ◽  
High Standard ◽  
Standard Errors ◽  
Genomic Relationship Matrix ◽  
Relationship Matrix ◽  
Genomic Relationship ◽  
Milk Fatty Acids ◽  
Heritability Estimates

In this study the objective was to estimate the genetic and genomic relationship between methane-related traits and milk fatty acid profiles. This was done using two different estimation procedures: a single nucleotide polymorphism-based genomic relationship matrix and a classical pedigree-based relationship matrix. Data was generated on three Danish Holstein herds and a total of 339 cows were available for the study. Methane phenotypes were generated in milking robots during milking over a weekly period and the milk phenotypes were quantified from milk from one milking. Genetic and genomic parameters were estimated using a mixed linear model. Results showed that heritability estimates were comparable between models, but the standard error was lower for genomic heritabilities compared with genetic heritabilities. Genetic as well as genomic correlations were highly variable and had high standard errors, reflecting a similar pattern as for the heritability estimates with lower standard errors for the genomic correlations compared with the pedigree-based genetic correlations. Many of the correlations though had a magnitude that makes further studies on larger datasets worthwhile. The results indicate that genotypes are highly valuable in studies where limited number of phenotypes can be recorded. Also it shows that there is some significant genetic association between methane in the breath of the cow and milk fatty acids profiles.

scholarly journals Realized Sampling Variances of Estimates of Genetic Parameters and the Difference Between Genetic and Phenotypic Correlations

Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1409-1416 ◽  
Author(s):  
Kenneth R Koots ◽  
John P Gibson
Keyword(s):  
Genetic Correlation ◽  
Genetic Parameters ◽  
Genetic Parameter ◽  
Genetic Correlations ◽  
Phenotypic Correlation ◽  
Parameter Estimates ◽  
Sampling Variance ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Heritability Estimates

Abstract A data set of 1572 heritability estimates and 1015 pairs of genetic and phenotypic correlation estimates, constructed from a survey of published beef cattle genetic parameter estimates, provided a rare opportunity to study realized sampling variances of genetic parameter estimates. The distribution of both heritability estimates and genetic correlation estimates, when plotted against estimated accuracy, was consistent with random error variance being some three times the sampling variance predicted from standard formulae. This result was consistent with the observation that the variance of estimates of heritabilities and genetic correlations between populations were about four times the predicted sampling variance, suggesting few real differences in genetic parameters between populations. Except where there was a strong biological or statistical expectation of a difference, there was little evidence for differences between genetic and phenotypic correlations for most trait combinations or for differences in genetic correlations between populations. These results suggest that, even for controlled populations, estimating genetic parameters specific to a given population is less useful than commonly believed. A serendipitous discovery was that, in the standard formula for theoretical standard error of a genetic correlation estimate, the heritabilities refer to the estimated values and not, as seems generally assumed, the true population values.

Genetic parameter estimates (full sib and half sib analysis) of fertility and hatchability in two strains of Rhode Island chickens

2021 ◽  
Vol 38 (1) ◽  
pp. 14-22
Author(s):  
M. Orunmuyi ◽  
I. A. Adeyinka ◽  
O.O Oni
Keyword(s):  
Rhode Island ◽  
Additive Genetic Variance ◽  
Genetic Parameter ◽  
Genetic Correlations ◽  
Reproductive Traits ◽  
Parameter Estimates ◽  
Phenotypic Correlations ◽  
Poultry Breeding ◽  
Genetic And Phenotypic Correlations ◽  
Heritability Estimates

A study was conducted to estimate the genetic parameters of fertility and hatchability in two strains of Rhode Island Red (RIR) Chickens denoted as Strain A and Strain B respectively using the full-sib (sire +dam variance) and maternal half-sib (dam variance) components. The birds were obtained from the selected populations of RIR Chickens kept at the poultry breeding programme of National Animal Production Research Institute, Shika, Zaria, Nigeria. Settable eggs were collected from mating 28 cocks to 252 hens in a ratio of 1cock:9 hens from each strain. Eggs were pedigreed according to sire and dam. Results showed that values obtained for number of egg set (EGGSET), number of fertile eggs (NFERT), number of hatched chicks (NHATCH), percentage of chicks hatched from total eggs set (PHATCH) and percentage of chicks hatched from fertile eggs (PHATCHBL) were all higher in strain A than strain B. Heritability estimates obtained from the full-sib and maternal half-sib analysis ranged from medium to high for the two strains (0.24-0.96). The maternal half sib estimates were higher (0.40-0.96) than the estimates obtained from full sibs (0.24- 0.48). Genetic and phenotypic correlations obtained for both strains were positive and similar regardless of method of estimation. Genetic correlations between EGGSET and PFERT were low in strain A using both full-sib and maternal half-sib analyses (0.09-0.14). Phenotypic correlations between EGGSET and PFERT, PHATCH and PHATCHBL were also low in both strains and regardless of method of analyses. Moderate to high heritability estimates suggest that genetic improvement can be obtained by selection of these reproductive traits. The full-sib analysis for estimating heritability will be preferred since it is assumed that only additive genetic variance contributes to the covariance between family members.

Phenotypic and genetic parameters for reproductive performance in a synthetic line of sheep

1981 ◽  
Vol 96 (1) ◽  
pp. 107-113 ◽  
Author(s):  
T. G. Martin ◽  
D. Nicholson ◽  
C. Smith ◽  
D. I. Sales
Keyword(s):  
Reproductive Performance ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Reproductive Traits ◽  
Direct Selection ◽  
Sex Distribution ◽  
Regression Methods ◽  
Litter Weight ◽  
Heritability Estimates ◽  
Synthetic Line

SUMMARYData on 902 ewes (1755 records) bom over 7 years in the synthetic ABRO Dam Line were analysed by least squares. Reproductive traits of the ewe were not affected by whether she was a single or a twin or by the age of her dam. Ewe age had major effects on all reproductive traits. Litter weight traits were affected by the sex distribution and the age of the litter when weighed.Heritability estimates, both by half sib and regression methods, were low for litter size, low to moderate for litter weights, and higher for ewe and fleece weights. Genetic correlations among the litter-weight traits were high. Together with the heritability estimates, they indicated that selection on litter weight at birth (and perhaps other traits) might give a greater change in total litter weight at weaning, the main measure of ewe productivity and the objective in improvement, than would direct selection.

scholarly journals Host Genetics of Response to Porcine Reproductive and Respiratory Syndrome in Sows: Reproductive Performance

2021 ◽  
Vol 12 ◽  
Author(s):  
Felipe M. W. Hickmann ◽  
José Braccini Neto ◽  
Luke M. Kramer ◽  
Yijian Huang ◽  
Kent A. Gray ◽  
...  
Keyword(s):  
Reproductive Performance ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Reproductive Traits ◽  
The Other ◽  
Nucleotide Polymorphisms ◽  
Host Genetics ◽  
Other Hand ◽  
Selection For ◽  
Heritability Estimates

Porcine Reproductive and Respiratory Syndrome (PRRS) is historically the most economically important swine disease worldwide that severely affects the reproductive performance of sows. However, little is still known about the genetic basis of reproductive performance in purebred herds during a PRRS outbreak through the comparison of maternal and terminal breeds. Thus, the objective of this work was to explore the host genetics of response to PRRS in purebred sows from two breeds. Reproductive data included 2546 Duroc and 2522 Landrace litters from 894 and 813 purebred sows, respectively, which had high-density genotype data available (29,799 single nucleotide polymorphisms; SNPs). The data were split into pre-PRRS, PRRS, and post-PRRS phases based on standardized farrow-year-week estimates. Heritability estimates for reproductive traits were low to moderate (≤0.20) for Duroc and Landrace across PRRS phases. On the other hand, genetic correlations of reproductive traits between PRRS phases were overall moderate to high for both breeds. Several associations between MARC0034894, a candidate SNP for response to PRRS, with reproductive performance were identified (P-value < 0.05). Genomic analyses detected few QTL for reproductive performance across all phases, most explaining a small percentage of the additive genetic variance (≤8.2%, averaging 2.1%), indicating that these traits are highly polygenic. None of the identified QTL within a breed and trait overlapped between PRRS phases. Overall, our results indicate that Duroc sows are phenotypically more resilient to PRRS than Landrace sows, with a similar return to PRRS-free performance between breeds for most reproductive traits. Genomic prediction results indicate that genomic selection for improved reproductive performance under a PRRS outbreak is possible, especially in Landrace sows, by training markers using data from PRRS-challenged sows. On the other hand, the high genetic correlations with reproductive traits between PRRS phases suggest that selection for improved reproductive performance in a clean environment could improve performance during PRRS, but with limited efficiency due to their low heritability estimates. Thus, we hypothesize that an indicator trait that could be indirectly selected to increase the response to selection for these traits would be desirable and would also improve the reproductive performance of sows during a PRRS outbreak.

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.

ALTERNATIVE SELECTION CRITERIA FOR THE GENETIC IMPROVEMENT OF FEED EFFICIENCY IN BROILER CHICKENS

1988 ◽  
Vol 68 (3) ◽  
pp. 611-618
Author(s):  
L. N. IRWIN ◽  
G. W. FRIARS ◽  
R. J. JULIAN
Keyword(s):  
Feed Intake ◽  
Feed Efficiency ◽  
Genetic Improvement ◽  
Broiler Chickens ◽  
Genetic Correlations ◽  
High Standard ◽  
Abdominal Fat ◽  
Feed Consumption ◽  
Standard Errors ◽  
Compensatory Gain

A hierarchical mating of 25 sires and 192 dams produced 862 progeny that yielded complete records to market age in two hatches of broiler chickens. These progeny were housed in two levels of cages. Half of the birds were subjected to a compensatory feed treatment which was used as an indicator of appetite. Increased feed consumption, following fasting, resulted in increased deposition of abdominal fat. Various approaches were investigated with respect to maximizing the genetic improvement of feed efficiency. Estimates of the heritabilities of feed:gain, gain:feed, total feed intake, compensatory feed intake and compensatory gain were all low (0.24 or less), with generally high standard errors. The estimated heritabilities of gain and gain corrected for feed intake at 0.46 suggests that selection for the latter trait has potential for improving gain at a statistically fixed feed intake. The standard errors on estimates of genetic correlations were too wide to allow predicted selection changes in correlated traits, and thus these correlations were not presented. Key words: Broiler chickens, feed efficiency, compensatory feed intake, abdominal fat deposition

Genetic evaluation of maternal behaviour and temperament in Australian sheep

2016 ◽  
Vol 56 (4) ◽  
pp. 767 ◽  
Author(s):  
D. J. Brown ◽  
N. M. Fogarty ◽  
C. L. Iker ◽  
D. M. Ferguson ◽  
D. Blache ◽  
...  
Keyword(s):  
Genetic Relationships ◽  
Genetic Correlations ◽  
Genetic Evaluation ◽  
Pedigree Information ◽  
Maternal Behaviour ◽  
Production Traits ◽  
Contributing Factors ◽  
Combined Analysis ◽  
Heritability Estimates ◽  
Behaviour Score

The temperament of ewes and maternal behaviour at lambing has been implicated as contributing factors to lamb survival. Some 14 054 records of maternal behaviour score (MBS, 1 = good, 5 = poor) were collected at lamb tagging from 32 breeds of sheep over several years in a variety of environments. Records for two objectively scored temperament traits, flight time from a weighing crate (FT) and agitation score in an isolation box test (IBT) were available on 19 151 and 17 159 animals, respectively. These data were pooled from three sources, which included research and commercial ram breeding flocks. The combined data were also split into three subsets based on breed groups (Merino, Maternal and Terminal) for analyses. Records of weights and number of lambs weaned (NLW), as well as pedigree information was available from the national genetic evaluation database. The heritability estimates from the combined analyses were 0.20 ± 0.02 for MBS, 0.18 ± 0.02 for FT and 0.26 ± 0.02 for IBT, with a repeatability of 0.24 ± 0.01 for MBS. There were some small differences between the breed groups in the heritability estimates. The genetic correlations between FT and MBS were negative (favourable) and consistent across the datasets (–0.47 ± 0.12, combined analysis). The genetic correlations between IBT and MBS were positive (favourable) but not significant (0.12 ± 0.11, combined analysis). The genetic correlations between IBT and FT were also favourable, but small and generally not significant. There were small favourable genetic correlations between MBS and various bodyweights (–0.17 ± 0.07, yearling) and NLW (–0.25 ± 0.07). However, there were no significant genetic relationships between the temperament and production traits. The moderate heritability and repeatability of MBS indicate maternal behaviour could be improved by selection, and that it could be a useful additional trait in breeding programs for improved reproduction.

Reproductive performance and genetic parameters for Australian Dorset Sheep

1994 ◽  
Vol 45 (2) ◽  
pp. 427 ◽  
Author(s):  
LD Brash ◽  
NM Fogarty ◽  
AR Gilmour
Keyword(s):  
Litter Size ◽  
Reproductive Performance ◽  
Genetic Improvement ◽  
Genetic Correlations ◽  
Reproductive Traits ◽  
Reproductive Rate ◽  
Parameter Estimates ◽  
Reproduction Traits ◽  
Component Traits ◽  
Lamb Survival

Reproductive performance of ewes in a large Dorset stud flock is reported. The data included 2488 ewes with 10016 joining records over 25 years. Average performance for reproductive traits were: fertility 92%, litter size 1.31, neonatal lamb survival 91%, lamb survival to weaning 85%, with overall lambs born 1.20 and lambs weaned 1.02 per ewe joined. Differences between breeds (Poll Dorset and Dorset Horn), season of birth (spring and autumn) and season of joining (spring and autumn) were significant for most reproduction traits. Linear and quadratic regressions for age of ewe at joining were highly significant for all traits (P < 0.001) with maximum performance between three and six years of age. Estimates of heritability for ewe reproductive traits were: 0.062 � 0-02 for number of lambs born and 0.04 � 0.01 for number of lambs weaned per ewe joined, and component traits, 0.02 �0 -01 for fertility, 0 08 � 0 -02 for litter size and 0.00 � 0.01 for lamb survival. Estimates of repeatability were less than 0.14 for all the reproduction traits, which resulted in substantially higher predicted heritabilities when repeated records were used. Heritability estimates for average ewe lifetime performance, with approximately four records, were 0.08 � 0 06 for lambs born, 0.12 � 0.05 for lambs weaned, 0.08 � 0.04 for fertility, 0.l9 � 0 -04 for litter size and zero for lamb survival. The genetic correlations between litter size and lambs born and weaned were close to unity, whereas those for fertility were lower and declined from lambs born (0.6l � 0.22) to lambs weaned (0-45 � 0.30). The estimated heritability for ewe longevity, defined as the number of years the ewe remained in the breeding flock, was 0.00 � 0.03. The potential for genetic improvement in reproductive rate is discussed in relation to other reports in the literature and in the context of the roles of the Dorset breed in the Australian lamb industry. Increased reproductive rate in Dorset flocks impacts on stud profitability and the rate of genetic improvement from selection for other traits such as liveweight. The parameter estimates derived will be used in compiling breed-specific parameter sets for genetic evaluation in LAMBPLAN.

GENETIC AND PHENOTYPIC PARAMETERS OF EARLY GROWTH TRAITS OF LAMBS REARED ARTIFICIALLY IN A CONTROLLED ENVIRONMENT

1985 ◽  
Vol 65 (1) ◽  
pp. 37-49 ◽  
Author(s):  
J. N. B. SHRESTHA ◽  
D. P. HEANEY
Keyword(s):  
Body Weight ◽  
Genetic Correlations ◽  
Research Centre ◽  
Breeding Cycle ◽  
Parameter Estimates ◽  
Controlled Environment ◽  
Phenotypic Correlations ◽  
Solid Diet ◽  
Genetic And Phenotypic Correlations ◽  
Heritability Estimates

This study involved body weights of 6078 lambs from 525 sires of two synthetic dam strains developed at the Animal Research Centre with 50% Finnish Landrace background. Breeding was practiced in flocks A and B for lambing at 4-mo intervals under an 8-mo breeding cycle. Lambs were housed indoors in a controlled environment on expanded metal floors in windowless barns, reared artificially with milk replacer and solid diet from birth to weaning at 21 days of age. Thereafter, all lambs were fed solid diet to 70 days of age. Paternal half-sib estimates of heritability for lamb weights at birth, weaning, 49 and 70 days of age were 0.25–0.26. Heritability estimates in the two synthetic dam strains were in close agreement (P > 0.05). Genetic and phenotypic parameter estimates did not demonstrate any significant linear trends across lambing periods. The moderate levels of heritability estimates for lambs reared artificially under a controlled environment suggest that genetic response to selection could be enhanced by selecting lambs independent of potential maternal effects and competition among litter mates for a fixed quantity of milk. Estimates of genetic and phenotypic correlations among various lamb weights ranged from 0.60 to 1.00, and from 0.51 to 0.93, respectively. Lamb weights having closer proximity in time showed higher correlations. Moderate to high genetic correlations between body weight of lambs at different ages indicated that selection for weight at one age should cause no adverse effects on body weight at other ages. Key words: Sheep, artificial rearing, lamb weights, heritability, genetic and phenotypic correlations

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