scholarly journals Analysis of Ewe Longevity and Lamb Survival in Teleorman Black Head Sheep

2020 ◽  
Author(s):  
Rodica Stefania Pelmus ◽  
Horia Grosu ◽  
Mircea Cãtãlin Rotar ◽  
Mihail Alexandru Gras ◽  
Cristina Lazãr ◽  
...  
Keyword(s):  
Survival Analysis ◽  
Genetic Parameters ◽  
Breeding Value ◽  
Careful Monitoring ◽  
Breeding Programs ◽  
Sheep Population ◽  
Sheep Breeding ◽  
Productive Life ◽  
Black Head ◽  
Lamb Survival

Background: The aim of this paper was to estimate the genetic parameters for the longevity of ewes and lamb survival at 30 days in a Teleorman Black Head Sheep population. Methods: Data was analysed with survival model. Result: Mean length of productive life of ewes was 673.16 days. The heritability for longevity was 0.097 and for lambs’ survival at 30 days was 0.098. The breeding value of the best sheep for longevity as productive life ranged from 0.081 months to 0.129 months and for the best lambs for survival at 30 days ranged from 0.041 days to 0.127 days. The results obtained in survival analysis are showing that the improvement of environmental conditions will increase longevity of ewes and survivability of lambs. Daily and careful monitoring of the health of sheep was performed. It was ensured administration of feed and water in a proper state of hygiene, a suckling and milking hygienic and a proper microclimate. Regarding the utility, longevity is a trait that is recommended to be used in local sheep breeding programs in Romania.

scholarly journals Milk yield genetic parameters estimated using random regression model in Teleorman Black Head Sheep

2021 ◽  
Vol 24 (1) ◽  
pp. 44-52
Author(s):  
Florin Popa ◽  
Horia Grosu ◽  
Mircea-Cătălin Rotar ◽  
Rodica Ștefania Pelmuș ◽  
Cristina Lazăr ◽  
...  
Keyword(s):  
Milk Yield ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Random Regression ◽  
Breeding Value ◽  
First Year ◽  
Sheep Population ◽  
Random Regression Model ◽  
Regression Test ◽  
Black Head

Abstract Genetic parameters are important in breeding program of sheep. For the genetic evaluation of sheep was used the random regression test-day animal model. This model was better economic that another models because reduces generation interval and reduces the costs with test-days records. Data consisted of 1050 test-day of 403 ewes in first year (2017), 752 test-day of 374 ewes in second year (2018) and 1164 test-day of 319 ewes in third year (2019). The main goal to achieve the objectives of this research were the estimation of the genetic parameters important in obtaining the breeding value by calculation heritability for test-day milk yields and the correlations between test-days milk yields, for Teleorman Black Head Sheep population from Teleorman county in three different years. The heritability for test-day milk yield ranged from 0.150 to 0.237 in 2017, from 0.212 to 0.600 in 2018 and in 2019 from 0.186 to 0.403. Genetic correlations between sheep test-days milk yield in 2017 were positive and high.

Genetic relationships between internal parasite resistance and production traits in Merino sheep

2017 ◽  
Vol 57 (2) ◽  
pp. 209 ◽  
Author(s):  
D. J. Brown ◽  
N. M. Fogarty
Keyword(s):  
Genetic Parameters ◽  
Genetic Correlations ◽  
Production Traits ◽  
Parasite Resistance ◽  
Breeding Programs ◽  
Sheep Breeding ◽  
Breeding Values ◽  
Merino Sheep ◽  
Internal Parasite ◽  
Australian Sheep

Breeding Merino sheep that are resistant to internal parasites alleviates the high costs associated with treatment of worm infestation and loss of production, as well as mitigating the development of anthelmintic resistance among the major worm species. Faecal worm egg count ((cube root transformation), wec) can be used in sheep as a measure of internal parasite resistance. Accurate estimates of genetic parameters for wec are required for calculation of Australian Sheep Breeding Values and inclusion of worm resistance in sheep breeding programs. This study provides updated estimates of heritability for wec and its genetic correlations with production traits. Data were analysed from a wide range of Australian and New Zealand Merino sheep in the MERINOSELECT database, which included 141 flocks with 801 flock years and up to 217 137 animals with wec recorded in at least one of four ages (W = weaning, P = post weaning, Y = yearling, H = hogget). The heritability estimates ranged from 0.16 ± 0.01 for Ywec to 0.29 ± 0.01 for Wwec, with generally high genetic correlations between the ages. Bivariate analyses estimated genetic correlations between wec at the various ages and growth, carcass quality, reproduction and wool production traits at various ages. These genetic correlations were generally small or close to zero, albeit with some significantly different from zero. The moderate heritability for wec (0.2–0.3) and its high phenotypic variation (coefficient of variation >30%) shows that relatively rapid selection response for worm resistance could be achieved. Inclusion of wec in sheep breeding programs to increase worm resistance would be expected to have little if any impact on other important production traits. These genetic parameters have been incorporated into MERINOSELECT by Sheep Genetics to provide Australian Sheep Breeding Values for wec and appropriate indices for wool and meat production. There is evidence that genotype × environment interactions may be important in some environments by reducing the accuracy of Australian Sheep Breeding Values for wec. Hence it may be prudent for breeders to implement strategies that manage the risk of any impact of genotype × environment on their breeding program.

Genetic evaluation of productive life in Iranian Holstein using survival analysis

2005 ◽  
Vol 2005 ◽  
pp. 131-131 ◽  
Author(s):  
M. Dadpasand Taromsari ◽  
S. R. Miraei-Ashtiani ◽  
M. Moradi Shahrebabak ◽  
R. Vaez Torshizi
Keyword(s):  
Survival Analysis ◽  
Dairy Cattle ◽  
Genetic Parameters ◽  
Linear Models ◽  
Failure Time ◽  
Genetic Evaluation ◽  
Time Analysis ◽  
Productive Life ◽  
Analysis Methodology ◽  
Time Dependent Covariates

Improvement of herd life increases profitability due to lower replacement costs of heifers, higher proportion of mature cows that produce at their maximum potential and increased opportunity for voluntary culling. Functional productive life (PL) after adjustment for production is the ability of a cow to remain healthy and delay involuntary culling (Ducrocq et al 1988). Survival or failure time analysis has replaced linear model approaches for routine genetic evaluation of dairy cattle in several countries (Sewalem et. al. 2003). It allows proper treatment of censored data, inclusion of time-dependent covariates and skewed or non normal distribution of data. Approximate estimates of the heritability of longevity traits typically range from 0.05 to 0.10 and 0.15 to 0.20 using linear models and survival analysis, respectively (Vollema et al. 2000 and Caraviello et. al. 2004). The objective of this study was to apply survival analysis methodology for assessing the most important factor influencing PL, estimation of genetic parameters of productive life and genetic evaluation in Iranian Holstein dairy cattle.

scholarly journals Genetic Variability, Correlation among Agronomic Traits, and Genetic Progress in a Sugarcane Diversity Panel

Agriculture ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 533
Author(s):  
Fernanda Zatti Barreto ◽  
Thiago Willian Almeida Balsalobre ◽  
Roberto Giacomini Chapola ◽  
Antonio Augusto Franco Garcia ◽  
Anete Pereira Souza ◽  
...  
Keyword(s):  
Genetic Parameters ◽  
Mixed Model ◽  
Agronomic Traits ◽  
Average Increase ◽  
Genetic Progress ◽  
Breeding Programs ◽  
Future Studies ◽  
Diversity Panel ◽  
Adjusted Means ◽  
Historical Series

Sugarcane breeding programs require 15 years of experimentation to create more productive cultivars, and estimates of genetic progress can indicate the efficiency of breeding programs. In this study, we used a diversity panel, the Brazilian Panel of Sugarcane Genotypes (BPSG), with the following objectives: (i) to estimate, through a mixed model, the adjusted means and genetic parameters of ten traits evaluated over three harvest years; (ii) to estimate genotypic correlation among those traits; and (iii) to estimate genetic progress over six decades of breeding. The heritabilities ranged from 0.43 to 0.88, and we detected 42 significant correlations, 9 negative and 33 positive. Over six decades, the sucrose-related traits BRIX, POL%C, and POL%J showed an average increase per decade of 0.27 °Brix (0.26% and 0.31%, respectively). Stalk number, height, and weight of the plot, and cane and sucrose yields revealed average increases per decade of 3.27 stalks, 0.06 m, 9.42 kg, 11.22 t/ha, and 2.08 t/ha, respectively. The genetic progress of the main agronomic traits is discussed through a historical series of sugarcane genotypes present in the BPSG. The findings of this study could contribute to the management of new breeding strategies and allow for future studies of associative mapping.

scholarly journals A note on genetic parameters and accuracy of estimated breeding values in honey bees

2019 ◽  
Vol 51 (1) ◽  
Author(s):  
Evert W. Brascamp ◽  
Piter Bijma
Keyword(s):  
Honey Bees ◽  
Variance Components ◽  
Genetic Parameters ◽  
Additive Genetic Variance ◽  
Breeding Value ◽  
Phenotypic Variance ◽  
Breeding Values ◽  
Estimated Breeding Values ◽  
Additive Genetic Relationship ◽  
The Relationship

Abstract Background In honey bees, observations are usually made on colonies. The phenotype of a colony is affected by the average breeding value for the worker effect of the thousands of workers in the colony (the worker group) and by the breeding value for the queen effect of the queen of the colony. Because the worker group consists of multiple individuals, interpretation of the variance components and heritabilities of phenotypes observed on the colony and of the accuracy of selection is not straightforward. The additive genetic variance among worker groups depends on the additive genetic relationship between the drone-producing queens (DPQ) that produce the drones that mate with the queen. Results Here, we clarify how the relatedness between DPQ affects phenotypic variance, heritability and accuracy of the estimated breeding values of replacement queens. Second, we use simulation to investigate the effect of assumptions about the relatedness between DPQ in the base population on estimates of genetic parameters. Relatedness between DPQ in the base generation may differ considerably between populations because of their history. Conclusions Our results show that estimates of (co)variance components and derived genetic parameters were seriously biased (25% too high or too low) when assumptions on the relationship between DPQ in the statistical analysis did not agree with reality.

A simulation study of open nucleus and closed nucleus breeding systems in a sheep population

1995 ◽  
Vol 60 (1) ◽  
pp. 117-124 ◽  
Author(s):  
J. A. Roden
Keyword(s):  
Genetic Gain ◽  
Live Weight ◽  
Breeding Systems ◽  
Breeding Value ◽  
Linear Unbiased Prediction ◽  
Sheep Population ◽  
Best Linear Unbiased ◽  
Nucleus Breeding ◽  
Open Nucleus ◽  
Selection Of

AbstractStochastic simulation was used to compare the results of alternative breeding systems in a sheep population divided into 10 flocks of 120 ewes. The breeding systems compared were selection within closed flocks (CF), a closed nucleus system (CNS), an open nucleus system (ONS) and open nucleus systems with the selection of nucleus replacements being restricted to either nucleus born males (ONSRm) or nucleus born females (ONSRf). Selection was for a best linear unbiased prediction of breeding value for lamb live weight which had a heritability of 0·17. The open nucleus breeding systems (ONS, ONSRm, ONSRf) resulted in higher rates of genetic gain, more predictable selection responses and lower rates of inbreeding than either the closed nucleus system (CNS) or selection within closed flocks (CF). Initial genetic differences between flocks resulted in higher rates of genetic gain in the nucleus breeding systems due to the use of between flock genetic variance. In the ONS system up to 25% of nucleus sires and approximately 50% of nucleus dams were born in base flocks. Nevertheless if selection of either nucleus sires or dams was restricted to nucleus born animals there was very little change in genetic gain or rate of inbreeding.

PRODUCTION POTENTIAL AND BREEDING SCHEMES OF SOME MEDITERRANEAN DAIRY SHEEP BREEDS

1991 ◽  
Vol 8 ◽  
pp. 13-26 ◽  
Author(s):  
N. P. Zervas ◽  
J. Hatziminaoglou ◽  
J. Boyazoglu ◽  
A. Georgoudis
Keyword(s):  
Genetic Parameters ◽  
Management Practices ◽  
Reproductive Potential ◽  
Dairy Sheep ◽  
Phenotypic Characteristics ◽  
Production Potential ◽  
Sheep Population ◽  
Sheep Breeds ◽  
Breeding Schemes ◽  
The Mediterranean

SUMMARYExaminded are some of the most important dairy sheep breeds, among the great diversity of the Mediterranean sheep population, by focusing on their phenotypic characteristics, their productive and reproductive potential as well as on the management practices and systems of testing. Information is also given on their genetic parameters, with emphasis on heritability coefficients, and the range of respective selection and breeding schemes, applied under their particular husbandry conditions.

Genetic analysis of docility score of Australian Angus and Limousin cattle

2018 ◽  
Vol 58 (2) ◽  
pp. 213 ◽  
Author(s):  
S. F. Walkom ◽  
M. G. Jeyaruban ◽  
B. Tier ◽  
D. J. Johnston
Keyword(s):  
Adverse Effect ◽  
Animal Model ◽  
Genetic Analysis ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Production Costs ◽  
Breeding Value ◽  
Maternal Behaviour ◽  
Production Traits ◽  
Subjective Score

The temperament of cattle is believed to affect the profitability of the herd through impacting production costs, meat quality, reproduction, maternal behaviour and the welfare of the animals and their handlers. As part of the national beef cattle genetic evaluation in Australia by BREEDPLAN, 50 935 Angus and 50 930 Limousin calves were scored by seedstock producers for temperament using docility score. Docility score is a subjective score of the animal’s response to being restrained and isolated within a crush, at weaning, and is scored on a scale from 1 to 5 with 1 representing the quiet and 5 the extremely nervous or anxious calves. Genetic parameters for docility score were estimated using a threshold animal model with four thresholds (five categories) from a Bayesian analysis carried out using Gibbs sampling in THRGIBBS1F90 with post-Gibbs analysis in POSTGIBBSF90. The heritability of docility score on the observed scale was 0.21 and 0.39 in Angus and Limousin, respectively. Since the release of the docility breeding value to the Australian Limousin population there has been a favourable trend within the national herd towards more docile cattle. Weak but favourable genetic correlations between docility score and the production traits indicates that docility score is largely independent of these traits and that selection to improve temperament can occur without having an adverse effect on growth, fat, muscle and reproduction.

scholarly journals Review: Genetic diversity studies using microsatellite markers and their contribution in supporting sustainable sheep breeding programs

2017 ◽  
Vol 1 (01) ◽  
pp. 46-51
Author(s):  
OUMER SHERIFF ◽  
KEFYALEW ALEMAYEHU
Keyword(s):  
Genetic Diversity ◽  
Microsatellite Markers ◽  
Polymorphic Information Content ◽  
Domestic Sheep ◽  
Breeding Programs ◽  
Sheep Breeding ◽  
Population Structures ◽  
The Mean ◽  
Tree Building ◽  
Diversity Studies

Sheriff O, Alemayehu K. 2017. Review: Genetic diversity studies using microsatellite markers and their contribution in supporting sustainable sheep breeding programs. Asian J Agric 1: 46-51. Microsatellites have been widely accepted and employed as useful molecular markers for measuring genetic diversity and divergence within and among populations. The various parameters developed so far to measure genetic diversity within and among populations are observed and expected heterozygosities (Ho and He), the mean number of alleles per locus (MNA),polymorphic information content (PIC), genetic distance and phylogenetic or tree building approach.The objective of thisreview was therefore to quantifythe genetic diversity studies of domestic sheep populations using microsatellite markersand their contribution in supporting sustainable sheep breeding programs. From the review, it is possible to see that there was high within population genetic variations in all the studied sheep populations, poor level of population differentiations and high levels of inbreeding. On the other hand, low estimates of hetrozygosities and mean number of alleles and employing only few and weak markers were observed in some of the studies. The gaps observed in the previous genetic diversity studies of the sheep populations may demand further works to reveal more information on the population structures andto start appropriate and sustainable breeding programs.

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