Genetic and environmental dispersion parameter estimationby test interval method in dairy sheep

Komprej, Andreja; Kompan, D.; Kovač, Milena

doi:10.2478/v10014-011-0008-6

Cited by 4 publications

(10 citation statements)

References 24 publications

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“…Protein content ranged from 5.45% to 6.76% (with an average value of 5.90%). Fat and protein content of Tsigai sheep were slightly higher or almost the same than those reported for Slovenian breeds ( Komprej et al, 2011 ) and Greek Sfakia dairy sheep ( Volanis et al, 2002 ). Protein content of Spanish Manchega breed ( Serrano et al, 2001 ) was higher than protein content of Tsigai sheep, even though milk yield of Tsigai sheep was lower than that of Manchega breed.…”

Section: Resultssupporting

confidence: 50%

“…The comparison of heritability and variance ratios estimated for fat and protein content in Tsigai sheep with those found in literature is not easy since different models are reported. The exception, in part, is a study of Komprej et al (2011) who used a similar model as the Model 2 here (differences only in fixed part of the model). As an additional difference to our research, these authors analysed eight months of lactation.…”

Section: Resultsmentioning

confidence: 99%

“…Restriction was due to fact that most of test day measurements were taken in these six months. Each ewe had at most one record with fat and protein content in each month ( Komprej et al, 2011 ). Following the procedure indicated by these authors, if a ewe had more than one record in one month, only one was kept within this month and the other was moved to a different month.…”

Section: Methodsmentioning

confidence: 99%

“…There can be found two different strategies of using of test day measurements of sheep milk ( Oravcová, 2014 ): repeatability animal models in which daily milk yield is treated as repeated measures of the same trait and analyses of single test day records separately using multivariate animal models which treat daily milk yield in individual months of lactation as a different trait. For dairy sheep, such modelling is known not only for daily milk yield, but also for separate analyses of protein content ( Serrano et al, 2001 ) or fat and protein content ( Volanis et al, 2002 ; Komprej et al, 2011 ). In addition to heritability estimates, the second approach enables estimates of genetic correlations between daily milk yields grouped by month of lactation (fat contents and protein contents, respectively) which tend to be higher between adjacent months ( Ali and Schaeffer, 1987 ; Komprej et al, 2011 ).…”

Section: Introductionmentioning

confidence: 99%

“…For dairy sheep, such modelling is known not only for daily milk yield, but also for separate analyses of protein content ( Serrano et al, 2001 ) or fat and protein content ( Volanis et al, 2002 ; Komprej et al, 2011 ). In addition to heritability estimates, the second approach enables estimates of genetic correlations between daily milk yields grouped by month of lactation (fat contents and protein contents, respectively) which tend to be higher between adjacent months ( Ali and Schaeffer, 1987 ; Komprej et al, 2011 ). The animal model treating milk yield in individual months of lactation as a different trait was applied for Tsigai breed in Slovakia ( Oravcová, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

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Variance Components and Genetic Parameters Estimated for Fat and Protein Content in Individual Months of Lactation: The Case of Tsigai Sheep

Oravcová

2015

Asian Australas. J. Anim. Sci

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The objective of this study was to assess variance components and genetic parameters for fat and protein content in Tsigai sheep using multivariate animal models in which fat and protein content in individual months of lactation were treated as different traits, and univariate models in which fat and protein content were treated as repeated measures of the same traits. Test day measurements were taken between the second and the seventh month of lactation. The fixed effects were lactation number, litter size and days in milk. The random effects were animal genetic effect and permanent environmental effect of ewe. The effect of flock-year-month of test day measurement was fitted either as a fixed (FYM) or random (fym) effect. Heritabilities for fat content were estimated between 0.06 and 0.17 (FYM fitted) and between 0.06 and 0.11 (fym fitted). Heritabilities for protein content were estimated between 0.15 and 0.23 (FYM fitted) and between 0.10 and 0.18 (fym fitted). For fat content, variance ratios of permanent environmental effect of ewe were estimated between 0.04 and 0.11 (FYM fitted) and between 0.02 and 0.06 (fym fitted). For protein content, variance ratios of permanent environmental effect of ewe were estimated between 0.13 and 0.20 (FYM fitted) and between 0.08 and 0.12 (fym fitted). The proportion of phenotypic variance explained by fym effect ranged from 0.39 to 0.43 for fat content and from 0.25 to 0.36 for protein content. Genetic correlations between individual months of lactation ranged from 0.74 to 0.99 (fat content) and from 0.64 to 0.99 (protein content). Fat content heritabilities estimated with univariate animal models roughly corresponded with heritability estimates from multivariate models: 0.13 (FYM fitted) and 0.07 (fym fitted). Protein content heritabilities estimated with univariate animal models also corresponded with heritability estimates from multivariate models: 0.18 (FYM fitted) and 0.13 (fym fitted).

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Section: Resultssupporting

confidence: 50%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Variance Components and Genetic Parameters Estimated for Fat and Protein Content in Individual Months of Lactation: The Case of Tsigai Sheep

Oravcová

2015

Asian Australas. J. Anim. Sci

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Genetic parameters for reproduction and growth traits in Boer goats in Brazil

Menezes

Sousa

Cavalcanti-Filho

et al. 2016

Small Ruminant Research

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Estimation of environmental effects on test day milk yield in Patch-faced Maritza sheep

Zhelyazkova¹,

Dimov²

2022

AST

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Abstract. The aim of this study was to estimate environmental effects on test day milk yield (TDMY) in Patch-faced Maritza sheep breed. Database includes 12 955 milk yield records in the test day. Milk yield recordings were made in 18 flocks and test day milk yields were obtained from 1992 to 2015 (24 years). In the structuring of the database, the following environmental effects were differentiated: animal; flock; year-season of lambing effect (YS); parity effect (Par); litter size at birth (LS); age of ewe at lambing (AgeL); age of ewe at test day (AgeTD); suckling period (Suck); ewe test day (ETD); flock test day (FTD); flock-year-test day (FYTD); stage of lactation period (DIM); stage of lactation period defined at 3-day intervals (DIM3). Average TDMY was 748.59±416.22 mL. The highest test day milk yield was in the first test day of ewes (1015.80±457.67 mL) and gradually decreased to seventh test day (267.50±120.05 mL). All mentioned environmental effects have influence on TDMY and have significant effect (p <0.001). The FYTD had the largest proportion (41.57%) on the total phenotypic variation. A large part of the total phenotypic variation had the following effects: Animal (31.11%), AgeTD (30.95%), DIM (27.85%), DIM3 (27.14%) and ETD (21.92%). Considering the significant influence of the described environmental effects on the TDMY in the population of Patch-faced Maritza sheep breed, they should be taken into account when estimating the genetic parameters.

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Genetic and environmental dispersion parameter estimationby test interval method in dairy sheep

Cited by 4 publications

References 24 publications

Variance Components and Genetic Parameters Estimated for Fat and Protein Content in Individual Months of Lactation: The Case of Tsigai Sheep

Variance Components and Genetic Parameters Estimated for Fat and Protein Content in Individual Months of Lactation: The Case of Tsigai Sheep

Genetic parameters for reproduction and growth traits in Boer goats in Brazil

Estimation of environmental effects on test day milk yield in Patch-faced Maritza sheep

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