<?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>S1659-13212019000100014</article-id>
<article-id pub-id-type="doi">10.15517/am.v30i1.33430</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Factores que afectan la producción en primera lactancia de vacas lecheras de Costa Rica]]></article-title>
<article-title xml:lang="en"><![CDATA[Factors that affect the production in first lactation of dairy cattle of Costa Rica]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Castillo-Badilla]]></surname>
<given-names><![CDATA[Gloriana]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Vargas-Leitón]]></surname>
<given-names><![CDATA[Bernardo]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Hueckmann-Voss]]></surname>
<given-names><![CDATA[Frank]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Romero-Zúñiga]]></surname>
<given-names><![CDATA[Juan José]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad Nacional  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad Nacional  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,Consultor independiente  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<aff id="Af4">
<institution><![CDATA[,Universidad Nacional  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Costa Rica</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>04</month>
<year>2019</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>04</month>
<year>2019</year>
</pub-date>
<volume>30</volume>
<numero>1</numero>
<fpage>209</fpage>
<lpage>227</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_arttext&amp;pid=S1659-13212019000100014&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_abstract&amp;pid=S1659-13212019000100014&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_pdf&amp;pid=S1659-13212019000100014&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen Introducción. El método de crianza que se brinda a una ternera, determina la vaca productora del futuro. Por lo tanto, las técnicas de salud, nutrición y alimentación pueden afectar el inicio y rendimiento de la vida productiva de una hembra bovina. Objetivo. El objetivo de este trabajo fue determinar el efecto de los factores del animal y del ambiente, modificables y no modificables, sobre la producción de la primera lactancia (PPL) en hatos lecheros especializados de Costa Rica. Materiales y métodos. Se realizó un estudio de cohorte retrospectivo. Se incluyeron 2747 vacas de razas Jersey y Holstein, con primer parto entre los años 2013 y 2015, de veintidós hatos lecheros especializados de diferentes zonas ecológicas de Costa Rica, con datos en el programa VAMPP Bovino. Se analizaron los datos mediante estadística descriptiva y un modelo lineal generalizado. Resultados. La PPL promedio a 305 días fue de 5485,8 kg (± 1547,8). Las variables no modificables del individuo, como la raza, presentaron efectos significativos sobre la PPL, con valores de 5360,1 kg (IC95%: 5158,2-5562,1) y 4694,1 kg (IC95%: 4578,5-4809,7) en la raza Holstein y Jersey, respectivamente. Se observó una tendencia a incrementar los niveles de producción conforme se aumentó la edad al primer parto hasta los veintiséis meses (P&lt;0,001), después de lo cual se mantuvo estable. Se determinó un efecto significativo de la variable modificable de manejo (P&lt;0,0001); fincas con protocolos de alta calidad de crianza de terneras produjeron 213,9 kg (PPL: 5809,0; IC95%: 5570,6-6047,4) más de leche en su primera lactancia, que las novillas con una crianza media, y 1133,7 kg más que las de sistemas de baja calidad de manejo (PPL: 4676,3; IC95%: 4158,3-5194,3). Conclusión. Estos resultados evidencian la influencia que tienen los métodos de crianza de terneras sobre el rendimiento productivo posterior del animal en sistemas tropicales. Las condiciones del medio ambiente tropical, incluyendo temperatura, humedad y precipitación, afectan de manera considerable el comportamiento productivo de las vacas lecheras.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract Introduction. The young calf rearing method, determines the dairy cow of the future. Therefore, health, feeding and housing techniques, influence the start and performance of the productive life of a dairy cow. Objective. The aim of this work was to determine the effect of animal and environmental factors, modifiable and non-modifiable on the first lactation milk yield (FLM) in specialized dairy farms from Costa Rica. Materials and methods. A cohort retrospective study was conducted. A total of 2747 Jersey and Holstein cows, with age at first calving (AFC) between the years 2013 and 2015, belonging to twenty-two specialized dairy herds located in different ecological zones of Costa Rica, with data in the Bovine VAMPP program, were included in the study. All data in the present research was analyzed by descriptive analysis and a generalized linear model. Results. The average FLM at 305 days was 5485.8 kg (±1547.8). Non-modifiable variables, like breed, had significant effects over FLM, with 5360.1 kg (CI95%: 5158.2-5562.1) and 4694.1 (CI95%: 4578.5-4809.7; P&lt;0.001) for Holstein and Jersey breeds respectively. AFC, had a significant effect over FLM, were a tendency to increased milk production with higher AFC was found until twenty-six month of AFC, after that milk yield remain stable (P&lt;0.001). Furthermore, the results showed a significant effect of management as a modifiable variable (P&lt;0.0001) revealing that farms with high quality calf rearing protocols produced 213.9 kg (FML: 5809.0; CI95%: 5570.6-6047.7) more milk in their first lactation than heifers raised under medium quality rearing and 1133.7 kg more milk than animals from low quality rearing programs (FML: 4676.3; CI95%: 4158.3-5194.3). Conclusion.These results show that rearing factors affect the productive life time of dairy cows in tropical operations. Tropical environmental conditions, including temperature, humidity and precipitation, significantly affect the productive behavior of dairy cows.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[edad a primer parto]]></kwd>
<kwd lng="es"><![CDATA[factor modificable]]></kwd>
<kwd lng="es"><![CDATA[manejo de ganado]]></kwd>
<kwd lng="es"><![CDATA[producción de leche]]></kwd>
<kwd lng="en"><![CDATA[age at first calving]]></kwd>
<kwd lng="en"><![CDATA[livestock management]]></kwd>
<kwd lng="en"><![CDATA[milk production]]></kwd>
<kwd lng="en"><![CDATA[modifiable factor]]></kwd>
</kwd-group>
</article-meta>
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