<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>1659-1321</journal-id>
<journal-title><![CDATA[Agronomía Mesoamericana]]></journal-title>
<abbrev-journal-title><![CDATA[Agron. Mesoam]]></abbrev-journal-title>
<issn>1659-1321</issn>
<publisher>
<publisher-name><![CDATA[Universidad de Costa Rica]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S1659-13212021000100034</article-id>
<article-id pub-id-type="doi">10.15517/am.v32i1.43184</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Caracterización multivariada de la eficiencia productivo-reproductiva y edad al primer parto en vacas Holstein]]></article-title>
<article-title xml:lang="en"><![CDATA[A multivariate characterization of productive-reproductive efficiency and age at first calving in Holstein cows]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Marini]]></surname>
<given-names><![CDATA[Pablo Roberto]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Biga]]></surname>
<given-names><![CDATA[Pablo]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Di-Masso]]></surname>
<given-names><![CDATA[Ricardo José]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad Nacional de Rosario (UNR)  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Argentina</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad Nacional de Rosario (UNR)  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Argentina</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,Centro Latinoamericano de Estudios de Problemáticas Lecheras (CLEPL)  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Argentina</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>04</month>
<year>2021</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>04</month>
<year>2021</year>
</pub-date>
<volume>32</volume>
<numero>1</numero>
<fpage>34</fpage>
<lpage>44</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_arttext&amp;pid=S1659-13212021000100034&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_abstract&amp;pid=S1659-13212021000100034&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_pdf&amp;pid=S1659-13212021000100034&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen Introducción. La evaluación de la eficiencia productiva debe estar acompañada por indicadores integrales para valorar el comportamiento de las vacas lecheras en los sistemas de pastoreo. Objetivo. Identificar en un rodeo de vacas lecheras Holstein agrupadas por su edad al primer parto, las de mayor eficiencia en sistemas de pastoreo, con base en una caracterización multivariada en indicadores productivos y reproductivos. Materiales y métodos. Se utilizaron datos retrospectivos de 1785 vacas primíparas de raza Holstein entre los años 1999-2016, en dos establecimientos comerciales pertenecientes a la empresa Los Ángeles - Argentina, las que se dividieron en tres grupos por su edad al primer parto: Grupo 1 - 750 días, Grupo 2 - 840 días y Grupo 3 - 1098 días. Las variables vida productiva total, producción total de leche, índice de leche e intervalo entre partos promedio se utilizaron asociadas a la edad al primer parto mediante la técnica multivariada de componentes principales. Resultados. No se observaron agrupamientos asociados al grupo de edad al primer parto. Los dos primeros componentes principales explicaron el 92,9 % de la variancia total observada. Se pudo definir cuatro cuadrantes representando todas las combinaciones entre los valores positivos y negativos. La distribución de las vacas de los tres grupos en los cuatro cuadrantes resultó homogénea (x2=6,291; p=0,391). La distribución por cuadrante, independientemente del Grupo de edad al primer parto fue de: Cuadrante I (52/150, 34,7 %), Cuadrante II (42/150; 28,0 %), Cuadrante III (28/150; 18,7 %) y Cuadrante IV (28/150; 18,7 %). Conclusión. Las vacas ubicadas en el Cuadrante II (valores negativos de la CP1 y positivos de la CP2), fueron las eficientes al sistema de pastoreo, mostraron mayor longevidad con niveles productivos compatibles con las limitaciones del sistema y un eficiente comportamiento reproductivo.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract Introduction. The evaluation of productive efficiency must be accompanied by comprehensive indicators to assess the behavior of dairy cows in grazing systems. Objective. To identify in a herd of Holstein dairy cows grouped by age at first calving, those with the highest efficiency in grazing systems, based on a multivariate characterization of productive and reproductive indicators. Materials and methods. Retrospective data from 1785 primiparous cows of the Holstein breed, registered between the years 1999-2016 in two commercial establishments belonging to the Los Angeles-Argentina company, were used. Cows were categorized into three groups according to their age at first calving: Group 1 - 750 days, Group 2 - 840 days, and Group 3 - 1098 days. The variables total productive life, total milk production, milk index, and average calving interval were used associated with the age at first calving using the multivariate principal components technique. Results. No groupings associated with age group at first birth were observed. The two first principal components explained 92.9 % of the total variance observed. It was possible to define four quadrants representing all the combinations between the positive and negative values. Cows distribution of the three groups in the four quadrants was homogeneous (x2=6.291; p=0.391). The distribution per quadrant, regardless of the age group at first calving was: Quadrant I (52/150, 34.7 %); Quadrant II (42/150, 28.0 %); Quadrant III (28/150; 18.7 %); Quadrant IV (28/150; 18.7 %). Conclusion. Cows located in Quadrant II (negative values of PC1 and positive values of PC2), were efficient in the grazing system, showed greater longevity with productive levels compatible with the limitations of the system, and with an efficient reproductive behavior.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[sistema de pastoreo]]></kwd>
<kwd lng="es"><![CDATA[indicadores]]></kwd>
<kwd lng="es"><![CDATA[longevidad]]></kwd>
<kwd lng="es"><![CDATA[producción de leche]]></kwd>
<kwd lng="es"><![CDATA[reproducción]]></kwd>
<kwd lng="en"><![CDATA[grazing system]]></kwd>
<kwd lng="en"><![CDATA[indicators]]></kwd>
<kwd lng="en"><![CDATA[longevity]]></kwd>
<kwd lng="en"><![CDATA[milk production]]></kwd>
<kwd lng="en"><![CDATA[reproduction]]></kwd>
</kwd-group>
</article-meta>
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