Parâmetros genéticos para as produções de leite no dia do controle e da primeira lactação de vacas da raça Holandesa

Melo, Cláudio; Packer, Irineu Umberto; Costa, C. N.; Machado, Paulo Fernando

doi:10.1590/s1516-35982005000300011

Cited by 28 publications

(36 citation statements)

References 24 publications

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“…However, comparison in terms of the trend in values between test days shows that the genetic correlations estimated using the multiple-trait model are similar to those reported in studies on test-day milk yield (El Faro and Albuquerque, 2003;Ferreira et al, 2003;Melo et al, 2005;Bignardi et al, 2008).…”

Section: Resultssupporting

confidence: 79%

Genetic parameters for first lactation test-day milk flow in Holstein cows

Laureano

Bignardi

Faro

et al. 2012

Animal

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Genetic parameters for test-day milk flow (TDMF) of 2175 first lactations of Holstein cows were estimated using multiple-trait and repeatability models. The models included the direct additive genetic effect as a random effect and contemporary group (defined as the year and month of test) and age of cow at calving (linear and quadratic effect) as fixed effects. For the repeatability model, in addition to the effects cited, the permanent environmental effect of the animal was also included as a random effect. Variance components were estimated using the restricted maximum likelihood method in single-and multiple-trait and repeatability analyses. The heritability estimates for TDMF ranged from 0.23 (TDMF 6) to 0.32 (TDMF 2 and TDMF 4) in single-trait analysis and from 0.28 (TDMF 7 and TDMF 10) to 0.37 (TDMF 4) in multiple-trait analysis. In general, higher heritabilities were observed at the beginning of lactation until the fourth month. Heritability estimated with the repeatability model was 0.27 and the coefficient of repeatability for first lactation TDMF was 0.66. The genetic correlations were positive and ranged from 0.72 (TDMF 1 and 10) to 0.97 (TDMF 4 and 5). The results indicate that milk flow should respond satisfactorily to selection, promoting rapid genetic gains because the estimated heritabilities were moderate to high. Higher genetic gains might be obtained if selection was performed in the TDMF 4. Both the repeatability model and the multiple-trait model are adequate for the genetic evaluation of animals in terms of milk flow, but the latter provides more accurate estimates of breeding values.Keywords: functional trait, genetic correlation, heritability, milkability ImplicationsThe milk flow trait can be considered as functional, of great importance in dairy cattle, both related to udder health on the efficiency of labor. A increased milk flow is associated with a decrease in occupancy time of labor and thus a decrease in spending on it. In addition, a faster milking implies a reduction in electricity costs and maintenance of machines. Studies investigating milk flow are still limited and the best approach for analyzing this trait has not been well defined.

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Section: Resultssupporting

confidence: 79%

Genetic parameters for first lactation test-day milk flow in Holstein cows

Laureano

Bignardi

Faro

et al. 2012

Animal

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“…Estimates obtained from the ASME1, ASME4, ASME29, LEW þ W and W* models were the most similar to the estimates obtained by Melo et al (2005). Their estimates for test day yields from single-character analyses ranged from 0.22 to 0.36.…”

Section: Discussionsupporting

confidence: 62%

Genetic parameters for test day milk yields of first lactation Holstein cows by random regression models

Melo

Packer²,

Costa³

et al. 2007

Animal

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Covariance components for test day milk yield using 263 390 first lactation records of 32 448 Holstein cows were estimated using random regression animal models by restricted maximum likelihood. Three functions were used to adjust the lactation curve: the five-parameter logarithmic Ali and Schaeffer function (AS), the three-parameter exponential Wilmink function in its standard form (W) and in a modified form (W*), by reducing the range of covariate, and the combination of Legendre polynomial and W (LEG þ W). Heterogeneous residual variance (RV) for different classes (4 and 29) of days in milk was considered in adjusting the functions. Estimates of RV were quite similar, rating from 4.15 to 5.29 kg 2 . Heritability estimates for AS (0.29 to 0.42), LEG þ W (0.28 to 0.42) and W* (0.33 to 0.40) were similar, but heritability estimates used W (0.25 to 0.65) were highest than those estimated by the other functions, particularly at the end of lactation. Genetic correlations between milk yield on consecutive test days were close to unity, but decreased as the interval between test days increased. The AS function with homogeneous RV model had the best fit among those evaluated.

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“…Additionally, economic gains for producers can be observed, because lower productivity cows may be culled or replaced before completing their lactations. Correlations of high magnitude between consecutive milk weights taken from the 6th milk recording, close to 183 days of lactation, were also verified by Melo et al (2005).…”

Section: Resultsmentioning

confidence: 61%

Adjustment of Lactation Curves of Holstein Cows from Herds of Minas Gerais, Brazil

Azevedo¹,

Gonçalves²,

Souza³

et al. 2018

JAS

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Random regression models (RRM) differ in terms of the functions used to describe the shape of lactation curves. The aim was to compare random regression models under different functions to describe the lactation curves from Holstein cows in herds of the state of Minas Gerais. A database of 28,118 production records was analyzed using the test-day records of 4,230 first parity cows from five herds. The Wilmink, Ali & Schaeffer and Legendre polynomial (orders 4, 5 and 6) functions were adjusted in RRM to model the mean production trend (fixed) and genetic and permanent environmental (random) effects. The residual variances were assumed to be constant throughout lactation. Analyses were performed using the AIREMLF90 program. Except for the model with the polynomial function of order 5, all models converged. The Wilmink function showed lower values for criteria based on the -2log (L), AIC and BIC. The model with the Legendre polynomial of order 6 showed lower residual variance. Heritability estimates were similar between functions, ranging from 0.07 to 0.18 and were higher from 215 days of lactation. From 155 days of lactation, genetic and permanent environmental correlations between successive controls are of high magnitude. The Wilmink function is the most suitable for the study of milk yields from primiparous Holstein cows. The selection of animals is possible from 155 days of lactation on. Permanent environmental effects have greater influence on the milk production at the end of lactation of primiparous cows and should be considered since they are important and may be cumulative throughout lactation.

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Parâmetros genéticos para as produções de leite no dia do controle e da primeira lactação de vacas da raça Holandesa

Cited by 28 publications

References 24 publications

Genetic parameters for first lactation test-day milk flow in Holstein cows

Genetic parameters for first lactation test-day milk flow in Holstein cows

Genetic parameters for test day milk yields of first lactation Holstein cows by random regression models

Adjustment of Lactation Curves of Holstein Cows from Herds of Minas Gerais, Brazil

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