Additive genetic and permanent environmental variance components for test day milk traits in Black-White cattle

Strabel, T.; Szwaczkowski, T.

doi:10.1016/s0301-6226(97)00005-5

Cited by 22 publications

(19 citation statements)

References 22 publications

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“…Since, information on daily milk yield is not dependent on lactation length, inherent biases arising from culling of heifers before completion of lactation are eliminated (Pander et al, 1992). Daily milk yield records provide a substantial amount of data compared with complete lactation within the interval of evaluation thus improving on the accuracy of cow evaluation (Strabel and Szwaczkowski, 1997;Rekaya et al, 1999;Misztal et al, 2000). Even for completed lactations, selection on a properly weighted index of TD records could be more accurate than selecting based on phenotypic records of total lactation production (Pander et al, 1992).…”

Section: Resultsmentioning

confidence: 99%

Genetic and phenotypic parameters for test day milk yield of Sahiwal cattle in the semi-arid tropics

Ilatsia

Muasya

Muhuyi

et al. 2007

Animal

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A total of 19 376 test day (TD) milk yield records from the first three lactations of 1618 cows daughters of 162 sires were used to estimate genetic and phenotypic parameters and determine the relationship between daily milk yield and lactation milk yield in the Sahiwal cattle in Kenya. Variance components were estimated using animal models based on a derivative free restricted maximum likelihood procedure. Variance components were estimated using various univariate and multi-trait fixed regression test day models (TDM) that defined contemporary groups either based on the year-season of calving (YSCV) or on the year-season of TD milk sampling (YSTD). Variance components were influenced by CG which resulted in differences in heritability and repeatability estimates between TDM. Models considering YSTD resulted in higher additive genetic variances and lower residual variances compared with models in which YSCV was considered. Heritability estimates for daily yield ranged from 0.28 to 0.46, 0.38 to 0.52 and 0.33 to 0.52 in the first, second and third lactation, respectively. In the first and second lactation, the heritability estimates were highest between TD 2 and TD 4. Genetic correlations among daily milk yields ranged from 0.41 to 0.93, 0.50 to 0.83 and 0.43 to 86 in the first, second and third lactation, respectively. The phenotypic correlations were correspondingly lower. Genetic correlations were different from unit when fitting multi-trait TDM. Therefore, a multiple trait model would be more ideal in determining the genetic merit of dairy sires and bulls based on daily yield records. Genetic and phenotypic correlations between daily yield and lactation yields were high and positive. Genetic correlations ranged from 0.84 to 0.99, 0.94 to 1.00 and 0.94 to 0.97 in the first, second and third lactations, respectively. The corresponding phenotypic correlation estimates ranged from 0.50 to 0.85, 0.50 to 0.83 and 0.53 to 0.87. The high genetic correlation between daily yield and lactation yield imply that both traits are influenced by similar genes. Therefore daily yields records could be used in genetic evaluation in the Sahiwal cattle breeding programme.

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Section: Resultsmentioning

confidence: 99%

Genetic and phenotypic parameters for test day milk yield of Sahiwal cattle in the semi-arid tropics

Ilatsia

Muasya

Muhuyi

et al. 2007

Animal

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“…Strabel and Szwaczkowski (1997) found that BC transformation of milk, fat and protein yield data in dairy cattle, when compared with untransformed data, resulted in lower estimates of the additive genetic and error variances. Reduction of error variances was, however, proportionally higher than in additive genetic variances resulting in higher heritability estimates.…”

Section: Parameter Estimates For Milk Yieldmentioning

confidence: 98%

“…Deviations from a normal distribution increase the error variance estimates and in consequence the functions of variance components are biased (Banks et al 1985). Logarithmic or BC transformation are usually employed when dealing with unbalanced data to overcome non-normal fitting of the data (Strabel and Szwaczkowski 1997) and heterogeneity of variances between groups (Everett and Keown 1984;Boldman and Freeman 1990;Vissher et al 1991).…”

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confidence: 99%

Genetic parameters for milk yield and litter size in Boutsico dairy sheep

Kominakis¹,

Rogdakis²,

Koutsotolis³

1998

Can. J. Anim. Sci.

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Kominakis, A., Rogdakis, E. and Koutsotolis, K. 1998. Genetic parameters for milk yield and litter size in Boutsico dairy sheep. Can. J. Anim. Sci. 78: 525-532. Lactation and litter size records (n = 2553) of Boutsico dairy sheep were used to estimate direct additive, maternal genetic, maternal and animal's permanent environmental variance components for milk yield and litter size by restricted maximum likelihood under a repeated records animal model. Raw milk yield data were transformed by log and Box-Cox (BC) transformations. Heritability estimates of direct additive effects were between 0.21 and 0.30, 0.18 and 0.24 and 0.21 and 0.27 for untransformed, log transformed and BC transformed data, respectively. Only maternal and animal's environmental effects were important for milk yield. Direct-maternal genetic covariance did not significantly (P > 0.05) influence milk yield. Repeatability for milk yield ranged from 0.32 to 0.38. Only additive genetic effects were important for litter size. Heritability and repeatability for litter size were 0.07 and 0.11, respectively. Genetic and phenotypic correlations between yield and litter size were 0.13 and 0.19, respectively.

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“…Observaram-se, na maioria dos trabalhos, grandes desigualdades para as estimativas de herdabilidade (Swalve, 1995;Reents et al, 1995;Rekaya et al, 1999;Strabel & Szwaczkowski, 1997;Ferreira et al, 2002;Melo, 2003;Cruz, et al, 2006), as quais ocorrem principalmente pela grande diferença existente entre as populações estudadas, e também pelos diferentes métodos de análises utilizados. A tendência dos valores de herdabilidade envolvendo animais de raças européias, é apresentar maiores valores na metade da lactação devido à menor variação nas produções nesta fase, e à menor influência do meio ambiente (Ledic et al, 2002b).…”

Section: Figure 1 Heritability Estimates For Test-day Milk and Fat Yunclassified

“…Utilizando modelos de repetibilidade, Strabel & Szwaczkowski (1997) obtiveram maiores estimativas de herdabilidade para produção de leite e de gordura (0,29 e 0,20), que as estimativas obtidas para a produção acumulada e ajustada para 305 dias (0,15 e 0,10).…”

Section: Introductionunclassified

Análise genética de bovinos Sindi utilizando-se as produções de leite e de gordura no dia do controle

Cruz

Ribeiro

Filho

et al. 2008

Agraria

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Análise genética de bovinos Sindi utilizando-se as produções de leite e de gordura no dia do controle 1 R E S U M OObjetivando-se estimar os parâmetros genéticos e predizer os valores genéticos para a produção de leite (PLDC) e de gordura (PGDC) no dia do controle, e comparar a classificação dos animais por estimativas obtidas mediante análises unicaracterísticas utilizaram-se dados referentes a 373 lactações e 4.476 controles de bovinos da raça Sindi, registrados entre 1986 e 2004. O PLDC e PGDC foram analisadas por meio de um modelo animal, em análises unicaracterísticas, considerando-se as quatro primeiras lactações (modelo de repetibilidade). Nos modelos estatísticos para essas análises se incluíram os efeitos genético aditivo direto e de ambiente permanente, como aleatórios, o efeito fixo de grupo contemporâneo, formado pelo ano e mês do controle, e a idade da vaca ao parto como covariável, regressão linear e quadrática. De maneira geral, as herdabilidades (0,36 e 0,47) estimadas e as correlações de ordem (0,74 e 0,68) entre os valores genéticos para PLT e as PLDC e entre a PGT e a PGDC, foram maiores na fase intermediária da lactação, indicando possibilidade de resposta à seleção em substituição à produção total. Palavras-chave: bovinos leiteiros, parâmetros genéticos, seleção, ZebuGenetic analysis of Sind cows using test day milk and fat yield A B S T R A C TData were used from 373 lactation of 4.476 controls of the Sind cows, controlled between 1986 and 2004 with the objectives of estimating the genetic parameters and to predict the genetic values for the production of milk (PLDC) and fat (PGDC) on the day of the control and to compare to the classification of the animals, for estimates obtained by ordinary test-day model. PLDC and PGDC were analyzed through an animal model, in ordinary test-day model, considering the first four lactations (repeatability model). The statistical models to analyze PLDC and PGDC included the genetic effects direct and of permanent ambient, as random, the fixed effect of contemporary group, formed by the year and month of the control, and covariances the age of dam at kidding as, linear and quadratic regression. In general way, the dear herdabilidades (0,36 and 0,47) estimated and the order of correlations (0,74 and 0,68) among the genetic values for PLT and PLDC and between PGT and PGDC were larger in the intermediate phase of the lactation indicating response possibility to the selection in substitution to the total production.

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Additive genetic and permanent environmental variance components for test day milk traits in Black-White cattle

Cited by 22 publications

References 22 publications

Genetic and phenotypic parameters for test day milk yield of Sahiwal cattle in the semi-arid tropics

Genetic and phenotypic parameters for test day milk yield of Sahiwal cattle in the semi-arid tropics

Genetic parameters for milk yield and litter size in Boutsico dairy sheep

Análise genética de bovinos Sindi utilizando-se as produções de leite e de gordura no dia do controle

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