Study on the continuity of farmer`s breeding activity with Patch Faced Maritza sheep breed

Zhelyazkova, P.; Петрова, Виктория Владимировна; Dimov, D.

doi:10.15547/10.15547/ast.2018.04.054

Cited by 3 publications

(4 citation statements)

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“…lificacy of the White Maritza sheep breed established in this study (1.39) was similar to that of the competing synthetic dairy sheep population in the Plovdiv region at 1.34(Dimov and Kuzmanova, 2007) and 1.36(Zhelyazkova et al, 2014). The average age at lambing was 1382.53 d (3.79 years) with P.…”

supporting

confidence: 71%

“…When constructing the linear models in this study, this specificity of the TDMY database was highlighted, where the milk recordings in the flocks were of different durations over the years. The comparatively long period (24 years) in which the data from the milk recordings were accumulated in a database and the short period of the continuity of breeding activity by the individual farmers (4.99 years) (Zhelyazkova et al, 2018) made it necessary to concatenate the flock-yeartest-day factor.…”

Section: Methodsmentioning

confidence: 99%

“…The production systems in which the White Maritza sheep breed and other sheep breeds in Bulgaria which are suitable for milk production are kept have two distinctive features. The first distinguishing feature is that, in all native breeds in the early phase of lactation, lambs suckle from their mothers -that is, there is a suckling period, where the duration for White Maritza sheep is 67.5 d (Dimov, 2011), for the synthetic population of dairy sheep it is 63.5 d (Zhelyazkova et al, 2014), and for Patch-faced Maritza sheep it is 62.5 d (Zhelyazkova and Dimov, 2022). The second distinguishing feature is that, during the second half of pregnancy and the first months of lactation, the sheep are reared indoors, and during most of the milking period, they graze.…”

Section: Introductionmentioning

confidence: 99%

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Genetic-parameter estimation of milk yield in White Maritza sheep breed using different test day models

Zhelyazkova,

Dimov,

Andonov

2023

Arch. Anim. Breed.

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Abstract. The aims of this study were to estimate the genetic parameters of the test day milk yield (TDMY) of the White Maritza sheep breed population and to choose the most appropriate linear models for genetic-parameter estimation of test day milk yield. The White Maritza sheep breed is a multipurpose native sheep breed in Bulgaria. Test day milk yield data were collected from 1992 to 2015 (24 years). Milk yield recordings were made in 18 flocks according to the AC method (official milk recording by ICAR regulations). The database includes 8768 test day milk yield records belonging to 987 ewes. The pedigree file includes 1937 animals. Nine test day models (TDMs) were formulated and tested for the estimation of the genetic parameters of milk yield. The first three models were repeatability models (REP models), the second three were random regression models (RRMs), and the last three models were also random regression models with an added Ali and Schaeffer regression to describe the lactation curve using first-, second- and third-order polynomials. The average TDMY was 764.47 mL. There were no significant differences in the values of heritability (h2) calculated by the three REP models: REP1 0.355 ± 0.060, REP2 0.344 ± 0.047 and REP3 0.347 ± 0.060. The same applied to the repeatability coefficients, which, for the three REP models, were 0.384 ± 0.065, 0.376 ± 0.051 and 0.378 ± 0.065, respectively. Based on REP model 1, three models with random regression RRM1, RRM2 and RRM3 were constructed, which is associated with the use of first-, second- and third-order polynomials (for the random effects of both the animal and the permanent environment). The trajectories of h2 calculated by the three RRMs were not similar and demonstrated some differences, both at the beginning and in the middle of the milking period. The RRM with third-order polynomials demonstrated more genetic diversity until the 165th day of lactation, but Akaike information criterion (AIC), Bayesian information criterion (BIC) and log-likelihood (LogL) estimates were higher. The regression models with first- and second-degree polynomials were insufficient to reveal genetic diversity to a higher degree than REP model 1. The trend in the trajectories of h2 calculated by the three random regression models with Ali and Schaeffer regression models (ASRMs) was similar to that of random regression models without the Ali and Schaeffer regression incorporated. Although the noted advantages of the random regression models revealed, to a greater extent, the genetic diversity of test day milk yield, AIC, BIC and LogL estimates indicated that repeatability models achieved a better balance between complexity and fitness and a smaller prediction error compared to random regression models.

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supporting

confidence: 71%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Genetic-parameter estimation of milk yield in White Maritza sheep breed using different test day models

Zhelyazkova,

Dimov,

Andonov

2023

Arch. Anim. Breed.

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“…Всички тези животни са родени в периода 2019-2023 г., което предполага, че от 2024 година в педигрето ще се увеличава дялът на животните с 4 пълни пояса. При друга българска порода -Бяла Маришка овца, където е изследвано педигре с 3 038 индивида, съставено от животни родени от 1992 до 2015 година, с данни за млечната продуктивност и техните прародители (Zhelyazkova et al, 2023), средният брой пълни пояси е 2.05, което е между стойността за цялото педигре на Среднородопската овца -1.47 и тази за периода 2019-2023 г. -2.17.…”

Section: материал и методиunclassified

Estimation of the Central Rhodope Sheep pedigree quality in 2005-2023

Duchev,

Todorov

2024

BJAH

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The aim of this study was to estimate the quality of the Central Rhodope Sheep pedigree data in years 2005-2023. The data was provided by the Association for breeding Central Rhodope sheep, Karakachan sheep and Rhodope Cigay sheep, which is keeping the breed’s herdbook. The herdbook has 18 720 records for the studied period. Along with the individuals registered only as sires or dams, there were 22686 individuals in total in the pedigree file. The pedigree was processed by the OptiSel software package and then checked for errors with the PedigreeViewer software. All the inconsistencies found in the pedigree, cycles and the gender discrepancies, were solved by erasing the conflicting data. In total 565 sires and 12 156 dams were identified in the pedigree file. The maximum number of generations traced for an animal in the pedigree were six. Since 2014, the average pedigree completeness index is over 98% for the first generation, and for second and third increases from 58% to 100%, and from 38% to 94%, respectively. In the recent five years, the average number of equivalent generations by year of birth is between 2.145 to 3.159, and the average number of full generations 1.839 to 2.537. These results indicate that the cumulated pedigree data might be used for analyses of the population structure and genetic diversity of the Central Rhodope Sheep breed.

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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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Study on the continuity of farmer`s breeding activity with Patch Faced Maritza sheep breed

Cited by 3 publications

References 1 publication

Genetic-parameter estimation of milk yield in White Maritza sheep breed using different test day models

Genetic-parameter estimation of milk yield in White Maritza sheep breed using different test day models

Estimation of the Central Rhodope Sheep pedigree quality in 2005-2023

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

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