LACTATION CURVES IN ANGUS, BROWN SWISS AND THEIR CROSSBRED COWS: I. COMPARISON OF PARAMETER ESTIMATION PROCEDURES

LACTATION CURVES IN ANGUS, BROWN SWISS AND THEIR CROSSBRED COWS: I. COMPARISON OF PARAMETER ESTIMATION PROCEDURES

A good prediction of cow lactation curves permits the improvement of cow/calf production efficiency, by defining management and breeding strategies. The objective of this study was to compare two procedures, linear (L) and nonlinear (N), to estimate parameters of lactation curves in cows of Angus (A), Brown Swiss (P) and their reciprocal crosses AP (A x P, and P x A). The possibility of using a weighted least squares estimation procedure was also studied. Milk production data (297 lactations) taken weekly for 180 days postpartum were recorded using the weigh-suckleweigh technique. The two procedures were evaluated for each lactation using the following equations: 1) Yt = atbe-ct; 2) Yt = ae-ct; 3) Yt = t/aect; and 4) Yt = ae(bt+ct²). For L, parameters of the four equations were estimated by least squares regression using logarithmic transformations; and for N, parameters were estimated using nonlinear least squares regression. For both, L and N, the patterns of residuals were analyzed. The residual mean squares (CMR) were used as a criterion to evaluate estimation of the curves. The CMR were analyzed, within genotype and lactation number, by a model that includes the effects of estimation procedure and cow. There were no differences (p>0.10) in CMR between L and N, except for Equation 3 where six out of 16 comparisons were significant (p

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Main Authors: Ramírez-Valverde, Rodolfo, Ramírez-Valverde, Gustavo, Núñez-Domínguez, Rafael, Tewolde-Medhin, Assefaw
Format: Digital revista
Language:spa
Published: Colegio de Postgraduados 1998
Online Access:https://www.agrociencia-colpos.org/index.php/agrociencia/article/view/1562
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spelling oai:ojs.pkp.sfu.ca:article15622020-05-14T06:12:00Z LACTATION CURVES IN ANGUS, BROWN SWISS AND THEIR CROSSBRED COWS: I. COMPARISON OF PARAMETER ESTIMATION PROCEDURES CURVAS DE LACTANCIA EN VACAS ANGUS, SUIZO PARDO Y SUS CRUZAS: I. COMPARACION DE PROCEDIMIENTOS PARA ESTIMAR PARAMETROS Ramírez-Valverde, Rodolfo Ramírez-Valverde, Gustavo Núñez-Domínguez, Rafael Tewolde-Medhin, Assefaw Dairy cattle Angus and Brown Swiss cows estimation procedures animal science milk production Ganado lechero vacas Angus y Suizo Pardo procedimientos de estimación ciencia animal producción de leche A good prediction of cow lactation curves permits the improvement of cow/calf production efficiency, by defining management and breeding strategies. The objective of this study was to compare two procedures, linear (L) and nonlinear (N), to estimate parameters of lactation curves in cows of Angus (A), Brown Swiss (P) and their reciprocal crosses AP (A x P, and P x A). The possibility of using a weighted least squares estimation procedure was also studied. Milk production data (297 lactations) taken weekly for 180 days postpartum were recorded using the weigh-suckleweigh technique. The two procedures were evaluated for each lactation using the following equations: 1) Yt = atbe-ct; 2) Yt = ae-ct; 3) Yt = t/aect; and 4) Yt = ae(bt+ct²). For L, parameters of the four equations were estimated by least squares regression using logarithmic transformations; and for N, parameters were estimated using nonlinear least squares regression. For both, L and N, the patterns of residuals were analyzed. The residual mean squares (CMR) were used as a criterion to evaluate estimation of the curves. The CMR were analyzed, within genotype and lactation number, by a model that includes the effects of estimation procedure and cow. There were no differences (p>0.10) in CMR between L and N, except for Equation 3 where six out of 16 comparisons were significant (p La predicción adecuada de las curvas de lactancia en bovinos permite mejorar la eficiencia de producción vaca/ becerro, mediante la definición de estrategias de manejo y de combinaciones raciales. El objetivo de esta investigación fue comparar dos procedimientos, lineal (L) y no lineal (N), para estimar parámetros en curvas de lactancia de vacas Angus (A), Suizo Pardo (P) y sus cruzas recíprocas AP (A x P y P x A). Asimismo, se consideró la posibilidad de estimar a los parámetros por el procedimiento de cuadrados mínimos ponderados. Los datos de producción de leche (297 lactancias) se colectaron semanalmente durante 180 días postparto, utilizando la técnica de pesaje de becerros antes y después del amamantamiento. Para cada lactancia se evaluaron los dos procedimientos en las ecuaciones siguientes: 1) Yt = atbe-ct; 2) Yt = ae-ct; 3) Yt = t/aect; y 4) Yt = ae(bt+ct²). Los parámetros de las cuatro ecuaciones se estimaron para L por regresión de cuadrados mínimos lineales usando transformaciones logarítmicas, y para N por regresión, de cuadrados mínimos no lineales. En los dos procedimientos se analizaron las formas de los patrones de los residuales. Los cuadrados medios de residuales (CMR) se usaron como criterio para evaluar la estimación de las curvas. Los CMR se analizaron dentro de genotipo y número de lactancia, mediante un modelo que incluyó el efecto de procedimiento y vaca. Generalmente no hubo diferencia (p>0.10) en CMR entre L y N, excepto para la Ecuación 3 donde seis de 16 comparaciones fueron significativas (p Colegio de Postgraduados 1998-12-31 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion application/pdf https://www.agrociencia-colpos.org/index.php/agrociencia/article/view/1562 Agrociencia; Vol. 32 No. 4 (1998): 1998-oct-dic; 317-323 Agrociencia; Vol. 32 Núm. 4 (1998): 1998-oct-dic; 317-323 2521-9766 1405-3195 spa https://www.agrociencia-colpos.org/index.php/agrociencia/article/view/1562/1562
institution COLPOS
collection OJS
country México
countrycode MX
component Revista
access En linea
databasecode rev-agrociencia-mx
tag revista
region America del Norte
libraryname Departamento de documentación y biblioteca de COLPOS
language spa
format Digital
author Ramírez-Valverde, Rodolfo
Ramírez-Valverde, Gustavo
Núñez-Domínguez, Rafael
Tewolde-Medhin, Assefaw
spellingShingle Ramírez-Valverde, Rodolfo
Ramírez-Valverde, Gustavo
Núñez-Domínguez, Rafael
Tewolde-Medhin, Assefaw
LACTATION CURVES IN ANGUS, BROWN SWISS AND THEIR CROSSBRED COWS: I. COMPARISON OF PARAMETER ESTIMATION PROCEDURES
author_facet Ramírez-Valverde, Rodolfo
Ramírez-Valverde, Gustavo
Núñez-Domínguez, Rafael
Tewolde-Medhin, Assefaw
author_sort Ramírez-Valverde, Rodolfo
title LACTATION CURVES IN ANGUS, BROWN SWISS AND THEIR CROSSBRED COWS: I. COMPARISON OF PARAMETER ESTIMATION PROCEDURES
title_short LACTATION CURVES IN ANGUS, BROWN SWISS AND THEIR CROSSBRED COWS: I. COMPARISON OF PARAMETER ESTIMATION PROCEDURES
title_full LACTATION CURVES IN ANGUS, BROWN SWISS AND THEIR CROSSBRED COWS: I. COMPARISON OF PARAMETER ESTIMATION PROCEDURES
title_fullStr LACTATION CURVES IN ANGUS, BROWN SWISS AND THEIR CROSSBRED COWS: I. COMPARISON OF PARAMETER ESTIMATION PROCEDURES
title_full_unstemmed LACTATION CURVES IN ANGUS, BROWN SWISS AND THEIR CROSSBRED COWS: I. COMPARISON OF PARAMETER ESTIMATION PROCEDURES
title_sort lactation curves in angus, brown swiss and their crossbred cows: i. comparison of parameter estimation procedures
description A good prediction of cow lactation curves permits the improvement of cow/calf production efficiency, by defining management and breeding strategies. The objective of this study was to compare two procedures, linear (L) and nonlinear (N), to estimate parameters of lactation curves in cows of Angus (A), Brown Swiss (P) and their reciprocal crosses AP (A x P, and P x A). The possibility of using a weighted least squares estimation procedure was also studied. Milk production data (297 lactations) taken weekly for 180 days postpartum were recorded using the weigh-suckleweigh technique. The two procedures were evaluated for each lactation using the following equations: 1) Yt = atbe-ct; 2) Yt = ae-ct; 3) Yt = t/aect; and 4) Yt = ae(bt+ct²). For L, parameters of the four equations were estimated by least squares regression using logarithmic transformations; and for N, parameters were estimated using nonlinear least squares regression. For both, L and N, the patterns of residuals were analyzed. The residual mean squares (CMR) were used as a criterion to evaluate estimation of the curves. The CMR were analyzed, within genotype and lactation number, by a model that includes the effects of estimation procedure and cow. There were no differences (p>0.10) in CMR between L and N, except for Equation 3 where six out of 16 comparisons were significant (p
publisher Colegio de Postgraduados
publishDate 1998
url https://www.agrociencia-colpos.org/index.php/agrociencia/article/view/1562
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