<?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>2007-1124</journal-id>
<journal-title><![CDATA[Revista mexicana de ciencias pecuarias]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. de cienc. pecuarias]]></abbrev-journal-title>
<issn>2007-1124</issn>
<publisher>
<publisher-name><![CDATA[Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S2007-11242016000100001</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Análisis genético para vida productiva en ganado Holstein de México]]></article-title>
<article-title xml:lang="en"><![CDATA[Genetic analysis of productive life in Holstein cattle in Mexico]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Abadía Rojas]]></surname>
<given-names><![CDATA[José R.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Ruíz López]]></surname>
<given-names><![CDATA[Felipe de Jesús]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Vega Murillo]]></surname>
<given-names><![CDATA[Vicente E.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Montaldo]]></surname>
<given-names><![CDATA[Hugo H.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad Veracruzana Facultad de Medicina Veterinaria y Zootecnia ]]></institution>
<addr-line><![CDATA[ Veracruz]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,INIFAP Centro Nacional de Investigación Disciplinaria en Fisiología y Mejoramiento Animal ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>México</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,INIFAP Centro de Investigación Regional Golfo Centro ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>México</country>
</aff>
<aff id="Af4">
<institution><![CDATA[,Universidad Nacional Autónoma de México  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Mexico</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>03</month>
<year>2016</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>03</month>
<year>2016</year>
</pub-date>
<volume>7</volume>
<numero>1</numero>
<fpage>1</fpage>
<lpage>14</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S2007-11242016000100001&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S2007-11242016000100001&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S2007-11242016000100001&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen: Se usó la metodología de análisis de supervivencia con un modelo de riesgos proporcionales de Weibull para estudiar la duración de vida productiva funcional (DVPF) de ganado Holstein en México, usando un modelo padre-abuelo materno con el software Survival Kit V3.12. La DVPF se calculó como el número de días entre la fecha de primer parto y la fecha de desecho o censura, con un crédito máximo de 305 días por lactación. Los datos analizados se obtuvieron de la Asociación Holstein de México. El archivo final constó de 36,507 registros para DVPF de vacas que parieron por primera vez entre 1995 y 2008. El modelo incluyó la función de riesgo basal de Weibull y los siguientes efectos fijos: edad al primer parto, número de lactación por fase de lactación con cortes en los días 29, 249 y 305 y nivel de producción estandarizado con 10 clases con cambios en cada lactación, incluidas como variables tiempo dependientes y los efectos aleatorios de hato-año de parto y efectos genéticos de padre y abuelo materno. El porcentaje de censura fue de 25.54 %. Todos los efectos fijos analizados fueron significativos (P &lt;0.0001) y tuvieron una influencia importante en el riesgo de desecho de los animales. Las heredabilidades calculadas en escalas logarítmica, original, efectiva y equivalente resultaron de 0.08, 0.13, 0.12 y 0.10 respectivamente, indicando que este carácter se puede integrar efectivamente a los programas de mejoramiento genético como se ha hecho en otras poblaciones de ganado Holstein.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract: Methodology survival analysis model with Weibull proportional hazards was used to study Holstein cattle duration of functional productive life (FPL) in Mexico, using a model sire-maternal grandsire with Survival Kit V3.12 software. The FPL was calculated as the number of days between the date of first calving and the date of culling or censored, with a maximum credit of 305 d per lactation. The FPL was defined as the length of time between first calving and date of culling or death and a maximum of 305 d lactation. The data analyzed were obtained from the Holstein Association of Mexico. The final file consisted of 36,507 records for FPL of cows that calved for the first time between 1995 and 2008. The model included baseline hazard function of Weibull and the following fixed effects: age at first calving, lactation number by stage of lactation with cuts 29, 249 y 305 and standardized production level, with 10 classes with changes in each lactation period included as dependent variables and random effects of herd-year of calving and genetic effects of sire and maternal grandsire. Percentage of censored data was 25.54 %. All analyzed fixed effects were significant (P&lt;0.0001) and had a significant risk of animal culling influence. The heritability calculated logarithmic, original, effective and equivalent scales were 0.08, 0.13, 0.12 and 0.10 respectively, indicating that this character can effectively integrate breeding programs as has been done in other locations of Holstein cattle.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[Análisis de supervivencia]]></kwd>
<kwd lng="es"><![CDATA[Modelo de Weibull]]></kwd>
<kwd lng="es"><![CDATA[Variable tiempo dependiente]]></kwd>
<kwd lng="es"><![CDATA[Heredabilidades]]></kwd>
<kwd lng="en"><![CDATA[Survival analysis]]></kwd>
<kwd lng="en"><![CDATA[Weibull model]]></kwd>
<kwd lng="en"><![CDATA[Variable time dependent]]></kwd>
<kwd lng="en"><![CDATA[Heritability]]></kwd>
</kwd-group>
</article-meta>
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