scholarly journals Genetic Analysis of Fitness Traits of Kashmir Merino Sheep at Organized Farms of Kashmir

2021 ◽  
Author(s):  
Mubashir Ali Rather ◽  
Ambreen Hamadani ◽  
Tariq Ahmad Malik ◽  
Imran Bashir ◽  
Ishfaq Ahmad
Keyword(s):  
Maximum Likelihood ◽  
Sex Ratio ◽  
Litter Size ◽  
Genetic Factors ◽  
Mixed Model ◽  
Reproductive Efficiency ◽  
Sheep Breeding ◽  
Merino Sheep ◽  
Fitness Traits ◽  
Estimate Number

Background: Fitness traits include measures of reproductive efficiency of sheep. The improvement in reproductive efficiency has significant impact on overall economy of sheep. Methods: Data spanning over 21 years (1997-2017) were collected from two sheep breeding farm and analyzed with mixed model least-squares maximum likelihood (LSMLMW) computer (PC-2) programme designed by Harvey (1990) to estimate number of lambs born per ewe (NLBE), number of lambs weaned per ewe (NLWE), litter size (LS) and sex ratio (SR) of Kashmir Merino sheep. Result: Overall estimates of 3.56±0.11, 3.20±0.10, 48.32±0.04 and 1.06±0.01 for number of lambs born per ewe (NLBE), number of lambs weaned per ewe (NLWE), litter size (LS) and sex ratio (SR), respectively were observed in the present study. The period of birth had significant (p less than 0.05) effect on NLBE and NLEE. The effect of sire was highly significant on all the traits under study whereas effect of all the non-genetic factors considered had non-significant effect on LS and SR.

scholarly journals Effect of non-genetic factors on prolificacy and pre-weaning kid mortality of Khari goats in Nawalpur, Nepal

2021 ◽  
Vol 4 (1) ◽  
pp. 87-95
Author(s):  
Nirajan Bhattarai
Keyword(s):  
Maximum Likelihood ◽  
Computer Program ◽  
Selective Breeding ◽  
Genetic Factors ◽  
Mixed Model ◽  
Coat Color ◽  
Fixed Effect ◽  
Least Square ◽  
Sources Of Variation

Present study was carried out mainly aiming at studying the effect of non-genetic factors on prolificacy and pre-weaning kid mortality of Khari goats in Nawalpur, Nepal. The traits were recorded for 1005 does were measured and analyzed using fixed effect Least Square Mixed Model and Maximum Likelihood Computer Program (LSMMML PC-2). Results revealed that overall mean prolificacy and pre-weaning kid mortality in this study were 145 and 6.2%, respectively. According to the results, non-genetic factors such as altitude, coat color and dam’s parity were the important sources of variation with respect to pre-weaning kid mortality and prolificacy of Khari goats in this study. Thus, the results of present study suggested the scope of improvement in prolificacy and pre-weaning kid mortality through selective breeding.

Problems in the accurate recording of lambing data

1983 ◽  
Vol 23 (123) ◽  
pp. 361 ◽  
Author(s):  
G Alexander ◽  
D Stevens ◽  
B Mottershead
Keyword(s):  
Litter Size ◽  
Pedigree Data ◽  
Once Daily ◽  
Sheep Breeding ◽  
Merino Sheep ◽  
Size Data

Continuous observations of a Merino flock comprising representatives from 15 strains or studs, lambing together in a drift system, showed that data on litter size and identity of offspring obtained at once-daily inspections were likely to be incorrect for 12% of ewes producing singles, 30% producing twins and 60% producing triplets. Correspondingly, the pedigree data for approximately 9% of single lambs, 15% of twins and 24% of triplets would be incorrect and the litter size data incorrect for another 3, 15 and 36% of singles, twins and triplets respectively. These potential errors were due to failure of ewes to keep their litters together, desertion of lambs, and lamb 'stealing' by ewes about to lamb. The use of an examination of afterbirths to resolve doubts about litter size is presented it1 an appendix. Of lambs separated from their mothers, 43% of singles, 34% of twins and 9% of triplets were reared to weaning by foster ewes; the others died. At least 19% of twin-bearing ewes in each of the main strain groups became separated from at least one twin, indicating that failure of ewes to keep their litter together during the first day or so after birth is a characteristic of Merino sheep generally. These results have important implications for the collection of lambing data in sheep breeding and husbandry experiments aimed to increase fecundity.

Estimation of genetic parameters for early reproduction traits in Beetal goat

Zygote ◽  
2021 ◽  
pp. 1-6
Author(s):  
Yogesh C. Bangar ◽  
Ankit Magotra ◽  
A.S. Yadav ◽  
Ashish Chauhan
Keyword(s):  
Litter Size ◽  
Genetic Parameters ◽  
Genetic Factors ◽  
Least Square ◽  
Reproductive Efficiency ◽  
Managerial Practices ◽  
Litter Weight ◽  
Reproduction Traits ◽  
Estimate Variance ◽  
Beetal Goat

Summary The evaluation of early reproduction traits in Beetal goat was performed for possible effects of genetic and non-genetic factors on litter size at birth (LSB), litter size at weaning (LSW), litter weight at birth (LWB), litter weight at weaning (LWW) and age at first kidding (AFK). The data records consisted of information of pedigree and targeted traits pertained to 223 does born to 25 sires and 122 dams between the years 2004 to 2019. A general linear model was used for assessment of non-genetic factors such as period of birth, type of birth and dam’s weight at kidding on studied traits. Genetic evaluation of targeted traits was done to estimate variance components and genetic parameters under dyadic mixed modelling. The estimates of least-square means for LSB, LSW, LWB, LWW and AFK were observed as 1.27 ± 0.03, 1.25 ± 0.03, 3.24 ± 0.07 kg, 13.08 ± 0.30 kg and 27.56 ± 0.58 months, respectively. Only the period of birth showed significant (P < 0.05) effects for targeted traits in this study. The estimates of direct heritability for LSB, LSW, LWB, LWW and AFK were low in magnitude as 0.08, 0.03, 0.10, 0.03 and 0.06, respectively. The moderate to high genetic and phenotypic correlations among litter traits indicate simultaneous improvement for these traits. It was concluded that low ranged direct heritability estimates for targeted traits indicated modest scope for genetic improvement of reproductive efficiency in Beetal goat through selection and, therefore, adoption of improved managerial practices is necessary to improve reproductive efficiency of Beetal goat.

scholarly journals Systematic factors and individual variation affecting litter size of Boer and Jawarandu goat cross

2021 ◽  
Vol 902 (1) ◽  
pp. 012009
Author(s):  
N K Agustin ◽  
T Nugroho ◽  
R Setiaji ◽  
S Prastowo ◽  
N Widyas
Keyword(s):  
Maximum Likelihood ◽  
Linear Model ◽  
Litter Size ◽  
Individual Variation ◽  
Mixed Model ◽  
Restricted Maximum Likelihood ◽  
Individual Data ◽  
Individual Variations ◽  
The Individual ◽  
Boer Goats

Abstract We studied the systematic factors and individual variation affecting litter size in the crossbreds between Boer and Jawarandu goat. The data were obtained from the records of litter size of Boerja goats from 2012 to 2015. The systematic factors consisted of season and year of birth, doe breeds and the kid’s sex; along with individual data including pedigree, date of birth, and parental breeds. The data consisted of 107 Boer does, 687 Jawarandu does, and 495 Boerja does with a total of 3804 kids. A linear model was developed to account the effect of systematic factors on litter size of Boerja goats. Later, a mixed model was solved with Restricted Maximum Likelihood (REML) method to estimate the individual variations on litter size. The results showed that litter size trait in goat was influenced by doe breed (P<0.05). Individual variation of this trait was also high (46%). Based on this research, it can be concluded that litter size of Boer goats and their crosses were affected by the doe’s breed with high individual variation. Doe’s selection is potential to improve liter size in goat crossbred population in the future.

scholarly journals Maximum Likelihood Analysis of Rare Binary Traits Under Different Modes of Inheritance

Genetics ◽  
1996 ◽  
Vol 143 (4) ◽  
pp. 1819-1829 ◽  
Author(s):  
G Thaller ◽  
L Dempfle ◽  
I Hoeschele
Keyword(s):  
Maximum Likelihood ◽  
Mixed Model ◽  
Major Gene ◽  
Likelihood Ratio Statistic ◽  
Information Criterion ◽  
Genetic Models ◽  
Parameter Estimates ◽  
Gene Effects ◽  
Binary Traits ◽  
Deterministic Algorithms

Abstract Maximum likelihood methodology was applied to determine the mode of inheritance of rare binary traits with data structures typical for swine populations. The genetic models considered included a monogenic, a digenic, a polygenic, and three mixed polygenic and major gene models. The main emphasis was on the detection of major genes acting on a polygenic background. Deterministic algorithms were employed to integrate and maximize likelihoods. A simulation study was conducted to evaluate model selection and parameter estimation. Three designs were simulated that differed in the number of sires/number of dams within sires (10/10, 30/30, 100/30). Major gene effects of at least one SD of the liability were detected with satisfactory power under the mixed model of inheritance, except for the smallest design. Parameter estimates were empirically unbiased with acceptable standard errors, except for the smallest design, and allowed to distinguish clearly between the genetic models. Distributions of the likelihood ratio statistic were evaluated empirically, because asymptotic theory did not hold. For each simulation model, the Average Information Criterion was computed for all models of analysis. The model with the smallest value was chosen as the best model and was equal to the true model in almost every case studied.

scholarly journals Response transformations for random effect and variance component models

2020 ◽  
pp. 1471082X2096691
Author(s):  
Amani Almohaimeed ◽  
Jochen Einbeck
Keyword(s):  
Maximum Likelihood ◽  
Random Effects ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Random Effect ◽  
Statistical Technique ◽  
Response Distribution ◽  
Level Data ◽  
Variance Component Models ◽  
Response Transformation

Random effect models have been popularly used as a mainstream statistical technique over several decades; and the same can be said for response transformation models such as the Box–Cox transformation. The latter aims at ensuring that the assumptions of normality and of homoscedasticity of the response distribution are fulfilled, which are essential conditions for inference based on a linear model or a linear mixed model. However, methodology for response transformation and simultaneous inclusion of random effects has been developed and implemented only scarcely, and is so far restricted to Gaussian random effects. We develop such methodology, thereby not requiring parametric assumptions on the distribution of the random effects. This is achieved by extending the ‘Nonparametric Maximum Likelihood’ towards a ‘Nonparametric profile maximum likelihood’ technique, allowing to deal with overdispersion as well as two-level data scenarios.

Ambient Temperature and Rainfall: An Effect on Sex Ratio and Litter Size in Deer Mice

1985 ◽  
Vol 66 (2) ◽  
pp. 289-298 ◽  
Author(s):  
P. Myers ◽  
L. L. Master ◽  
R. A. Garrett
Keyword(s):  
Sex Ratio ◽  
Ambient Temperature ◽  
Litter Size ◽  
Deer Mice

Evaluation of genetic markers for litter size in Meishan synthetic and Large White pigs

1996 ◽  
Vol 1996 ◽  
pp. 18-18
Author(s):  
O.I. Southwood ◽  
S. Hoste ◽  
T.H. Short ◽  
A.J. Mileham ◽  
D. Cuthbert-Heavens
Keyword(s):  
Litter Size ◽  
Fixed Effects ◽  
Oestrogen Receptor ◽  
Mixed Model ◽  
Receptor Gene ◽  
Large White ◽  
Service Type ◽  
Sib Families ◽  
Natural Service ◽  
Size Data

A significant relationship between the oestrogen receptor gene (ESR) and litter size has been detected in USA populations of Large White and a synthetic comprising 50% Meishan (Rothschild et al., 1995). Animals carrying two copies of the favourable allele (B) had an extra pig born per litter than those that did not have the allele. This paper reports on results observed in a UK 50% Meishan synthetic and four UK Large White lines.Litter size data from 50% Meishan synthetic (L93) full-sib females where more than one ESR genotype was segregating. Data were analysed using a mixed model with full relationships and including the fixed effects of season of farrowing, parity, ESR genotype (AA, AB or BB) and service type (AI or natural service). Heritiability and permanent environmental effects for litter size were assumed as 0.09 and 0.11, repectively. A total of 27 full-sib families were represented and included 62 sows and 139 litter records. Hypothesis testing used the option in PEST under a mixed model (Groeneveld et al., 1991).

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