Bayesian estimation of genetic parameters of litter size at birth in crossbred Mule ewes using repeatability and multiple trait threshold models

2007 ◽  
Vol 2007 ◽  
pp. 66-66
Author(s):  
W. Mekkawy ◽  
R. Roehe ◽  
R. M. Lewis ◽  
M. H. Davies ◽  
A. M. Van Heelsum ◽  
...  
Keyword(s):  
Litter Size ◽  
Reproductive Performance ◽  
Genetic Parameters ◽  
Reproductive Traits ◽  
Threshold Models ◽  
Multiple Trait ◽  
Repeated Observations ◽  
Improvement Programs ◽  
Size At Birth ◽  
Estimation Of Genetic Parameters

The reproductive performance of ewes is a major factor influencing the economic success of lowland flocks. Even so reproductive traits have not often been included in sheep genetic improvement programs because of their low heritabilities compared with other performance traits like body weight and carcass merit. Litter size is one of the most important traits affecting reproductive performance. There are two important factors to be considered in the genetic analysis of litter size. First, several authors have suggested that litter size in different parities is controlled in part by different genes, and therefore should be treated as different traits. Second, ignoring the categorical nature of litter size and analysing it using a linear model does not account for its non-normal distribution. As a consequence, threshold models are likely to be more appropriate for the analysis of categorical traits (Gianola and Foulley, 1983). Therefore, the objective of the current study was to estimate the genetic parameters for litter size of Mule ewes using both repeatability and a multiple trait threshold models for repeated observations of litter size across four different parities.

REPRODUCTIVE PERFORMANCE OF GILTS FROM LINES SELECTED FOR FEED UTILIZATION AND CARCASS SCORE

1972 ◽  
Vol 52 (2) ◽  
pp. 267-271
Author(s):  
M. H. FAHMY ◽  
C. S. BERNARD
Keyword(s):  
Least Squares ◽  
Litter Size ◽  
Reproductive Performance ◽  
Reproductive Traits ◽  
Feed Utilization ◽  
Gestation Length ◽  
Litter Weight ◽  
Yorkshire Pigs ◽  
Score Line ◽  
Size At Birth

Eight reproductive traits were studied on 751 gilts of 3 lines of Yorkshire pigs derived from a common population by selecting for feed utilization (line 1), carcass score (line 2), and for both traits combined (line 3) during 10 generations. Least squares means for the traits were as follows: gestation length 115.2 days; litter size at birth 9.0 pigs (total) and 8.4 pigs (alive); litter size at weaning 6.8 pigs; number of teats 13.4; and litter weight at birth, 21, and 56 days, 9.3, 32.6, and 92.6 kg, respectively. Heritability estimates were calculated for each line by half-sib correlation and intra-sire regression of offspring on dam. The pooled estimate for the above eight traits was 0.45, 0.11, 0.09, 0.15, −0.12, 0.08, 0.14, and 0.14, respectively. Line effect was highly significant for all traits except litter size at birth. Means and heritabilities for line 3 were higher than those for lines 1 and 2, which did not differ greatly from each other. Variation from year to year had significant effects only on litter weight at different ages. The within years–within line regressions of the eight traits on inbreeding were not significant. The within line phenotypic correlations between each of feed utilization and carcass score and the eight traits were generally low and nonsignificant.

Estimation of genetic parameters for litter size in sheep: a comparison of a repeatability and a multivariate model

1998 ◽  
Vol 66 (3) ◽  
pp. 685-688 ◽  
Author(s):  
M. J. de Vries ◽  
E. H. van der Waaij ◽  
J. A. M. van Arendonk
Keyword(s):  
Animal Model ◽  
Genetic Correlation ◽  
Litter Size ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Multivariate Model ◽  
Phenotypic Variance ◽  
Multiple Trait ◽  
Environmental Correlations ◽  
Estimation Of Genetic Parameters

AbstractGenetic parameters were estimated for litter size in two prolific sheep breeds, i.e. the Zwartbles and the synthetic breed Swifter. Genetic parameters and breeding values for litter size in different parities were estimated using both a repeatability and a multivariate animal model. The estimated heritability from the repeatability model was 0·10 for the Zwartbles and 0·12 for the Swifter. For the multivariate model, heritability of litter size in first, second and third parity was 0·05, 0·07 and 0·10 for the Zwartbles and 0·09, 0·12 and 0·09 for the Swifter. Genetic correlation for litter size in Swifter was 0·81 between parity 1 and 2 and 0·99 between parity 2 and 3. For the Zwartbles genetic correlations were all very close to unity. Environmental correlations between litter size in subsequent parities were not constant over parities. Phenotypic variance in litter size in both breeds was 0·309 in first parity and was almost 50% higher in later parities. Based on the results it is recommended to apply a multiple trait model.

THE ACCUMULATIVE EFFECT OF FINNSHEEP BREEDING IN CROSSBREEDING SCHEMES: REPRODUCTIVE PERFORMANCE

1988 ◽  
Vol 68 (1) ◽  
pp. 69-81 ◽  
Author(s):  
MOHAMED H. FAHMY ◽  
JACQUES J. DUFOUR
Keyword(s):  
Body Weight ◽  
Mortality Rate ◽  
Key Words ◽  
Litter Size ◽  
Reproductive Performance ◽  
Conception Rate ◽  
Ovulation Rate ◽  
Genetic Groups ◽  
Linear Regressions ◽  
Size At Birth

Reproductive performance and body weight were studied on 361 ewes, representing Finnsheep (F), DLS (a population of 1/2 Dorset, 1/4 Leicester, 1/4 Suffolk) and seven combinations ranging from 1/8 to 7/8 Finnsheep breeding. Conception rate in yearlings was 61.5% for DLS compared to 89.0% for F with the crosses being intermediate. Conception rate in older ewes was similar in the different genetic groups (avg. 94%). Ovulation rate and litter size at birth of DLS ewes were 1.72 and 1.44 lambs, which was less than half those of F ewes (3.51 and 2.86 lambs, respectively). Both traits increased progressively with an increase in F breeding in crosses and with advances in age. DLS ewes weaned 1.22 lambs compared to 2.03 lambs for F ewes and 1.84 lambs for 4/8 F ewes. The heaviest litters at weaning (31.7 kg) were raised by 4/8 F ewes, followed by 7/8 F (30.8 kg) while those raised by DLS ewes weighed 23.0 kg and F ewes 29.1 kg. Percentage of ova lost per ewe mated averaged 24% and ranged between 18% (DLS and 1/8 F) and 29% (6/8 F). About 3.6% of lambs were born dead and a further 13.8% died before weaning. Preweaning mortality rate was highest in F (22.9%) and lowest in 3/8 F (9.4%). Average kilograms of lambs weaned per ewe exposed was highest in 4/8 F (27.6 kg) followed by F (26.0 kg), whereas that of DLS was the lowest at 18.1 kg. The 4/8 F cross showed 25% heterosis in kg of lambs weaned per ewe exposed and 52.5% increase over DLS. Significant positive linear regressions were calculated for ovulation rate, litter size and preweaning mortality rate on proportion of Finnsheep breeding in crosses. The relation was quadratic for percent ova lost and lamb mortality at weaning. Yearling DLS females weighted 36 kg compared to 44 kg for F yearlings. However, at 5 yr of age DLS ewes weighed 62 kg, 5 kg heavier than F ewes. The heaviest ewes at all ages were the 4/8 F (45 kg at 1 yr, 65 kg at 5 yr). Key words: Reproduction, DLS sheep, Finnsheep, crossbreeding, heterosis, repeatabilities

Estimates Of Genetic Parameters For Economic Traits In West African Dwarf Goat

2021 ◽  
Vol 19 ◽  
pp. 114-119
Author(s):  
I. K. Odubote ◽  
J. O. Akinokun
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Genetic Parameters ◽  
West African ◽  
Economic Traits ◽  
West African Dwarf ◽  
West African Dwarf Goat ◽  
Heritability Estimates ◽  
Size At Birth ◽  
Birth Body Weight

Records of 848 West African Dwarf goat kids and 220 kiddings over a period of eight years (1982-1989) were analysed. The records were used to provide heritability and repeatability estimates for litter size at birth, kidding interval (repeatability estimate alone) and body weight at birth, weaning, 3 months, 6 months, 9 months and 1 year of age. Heritability estimates of 0.28±0.005, 0.18±0.003, 0.14±0.003, 0.29±0.005, 0.11±0.003 and 0.17±0.004 were obtained for litter size at birth, body weight at birth, and at weaning, 3 months, 6 months, and 9 months of age respectively. Corresponding repeatability estimates were slightly higher than the heritability estimates. However, repeatability estimates of 0.04±0.030 was obtained for kidding interval.

scholarly journals Estimation of Genetic Parameters for Peak Yield, Yield and Persistency Traits in Murciano-Granadina Goats Using Multi-Traits Models

Animals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 411
Author(s):  
Judith C. Miranda ◽  
José M. León ◽  
Camillo Pieramati ◽  
Mayra M. Gómez ◽  
Jesús Valdés ◽  
...  
Keyword(s):  
Multivariate Analysis ◽  
Selection Criteria ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Multiple Trait ◽  
Lactation Curve ◽  
Derivative Free ◽  
Selection For ◽  
Estimated Breeding Values ◽  
Estimation Of Genetic Parameters

This paper studies parameters of a lactation curve such as peak yield (PY) and persistency (P), which do not conform to the usual selection criteria in the Murciano-Granadina (MG) breed, but are considered to be an alternative to benefit animal welfare without reducing production. Using 315,663 production records (of 122,883 animals) over a period of 24 years (1990–2014), genetic parameters were estimated with uni-, bi- and multivariate analysis using multiple trait derivative free restricted maximum likelihood (MTDFREML). The heritability (h2)/repeatability (re) of PY, yield (Y) and P was estimated as 0.13/0.19, 0.16/0.25 and 0.08/0.09 with the uni-trait and h2 of bi- and multi-traits analysis ranging from 0.16 to 0.17 of Y, while that of PY and Y remained constant. Genetic correlations were high between PY–Y (0.94 ± 0.011) but low between PY–P (–0.16 ± 0.054 to –0.17 ± 0.054) and between Y–P (–0.06 ± 0.058 to –0.05 ± 0.058). Estimates of h2/re were low to intermediate. The selection for Y–PY or both can be implemented given the genetic correlation between these traits. PY–P and Y–P showed low to negligible correlation values indicating that if these traits are implemented in the early stages of evaluation, they would not be to the detriment of PY–Y. The combination of estimated breeding values (EBVs) for all traits would be a good criterion for selection.

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