<?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>2007-0705</journal-id>
<journal-title><![CDATA[Nova scientia]]></journal-title>
<abbrev-journal-title><![CDATA[Nova scientia]]></abbrev-journal-title>
<issn>2007-0705</issn>
<publisher>
<publisher-name><![CDATA[Universidad de La Salle Bajío A. C., Coordinación de Investigación]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S2007-07052020000200110</article-id>
<article-id pub-id-type="doi">10.21640/ns.v12i25.2585</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Efecto de la concentración de proteína en la dieta sobre rendimiento productivo, características de la canal y composición química de carne de pollos de engorda en el trópico seco]]></article-title>
<article-title xml:lang="en"><![CDATA[Effect of protein concentrations in the diet on productive performance, carcass characteristics, and meat chemical composition of broiler chickens in the dry subtropics]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Infante Rodríguez]]></surname>
<given-names><![CDATA[Fidel]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Domínguez Muñoz]]></surname>
<given-names><![CDATA[Miguel Ángel]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Montaño Gómez]]></surname>
<given-names><![CDATA[Martín Francisco]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Hume]]></surname>
<given-names><![CDATA[Michael E.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Anderson]]></surname>
<given-names><![CDATA[Robin C.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Manríquez Núñez]]></surname>
<given-names><![CDATA[Olga Maritza]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[López Acevedo]]></surname>
<given-names><![CDATA[Edgar Alberto]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Bautista Martínez]]></surname>
<given-names><![CDATA[Yuridia]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Salinas Chavira]]></surname>
<given-names><![CDATA[Jaime]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad Autónoma de Tamaulipas Instituto de Medicina Veterinaria y Ciencias Animales Departamento de Nutrición Animal]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad Autónoma de Baja California Instituto de Investigaciones en Ciencias Veterinarias Departamento de Nutrición y Biotecnología en Rumiantes]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,United States Department of Agriculture Agricultural Research Service, Southern Plains Agricultural Research Center Food and Feed Safety Research Unit, College Station]]></institution>
<addr-line><![CDATA[ Texas]]></addr-line>
<country>USA</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>00</month>
<year>2020</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>00</month>
<year>2020</year>
</pub-date>
<volume>12</volume>
<numero>25</numero>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S2007-07052020000200110&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S2007-07052020000200110&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S2007-07052020000200110&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen  Introducción: Las dietas actuales de pollos de engorda, tienden a incrementar los niveles de proteína para obtener variables productivas altas que son logradas en forma conjunta con mejoras genéticas, de manejo, sanitarias, entre otras. Sin embargo, el incremento en los niveles de proteína en la dieta no siempre acompaña el incremento en eficiencia productiva de los pollos de engorda debido a múltiples factores que intervienen en el sistema de producción. El objetivo de esta investigación fue evaluar el efecto de niveles crecientes de proteína cruda (PC) en las dietas sobre el comportamiento productivo, las características de la canal y la composición química de la carne de pechuga y muslo de pollos de engorde en el trópico seco.  Método: El estudio incluyó 200 pollos de engorde Ross de 1 día de edad. Las dietas de tratamientos (T) para las fases de inicio y finalizado tuvieron concentración de proteína cruda (PC; %) de: 21 y 18.1 (T1); 21.4 y 18.5 (T2); 21.8 y 18.9 (T3); 22.2 y 19.3 (T4), respectivamente. Dentro de cada una de las fases de alimentación, las cuatro dietas de tratamiento fueron formuladas con niveles similares de energía metabolizable aparente. En un diseño completamente aleatorio, las aves fueron asignadas a los cuatro tratamientos con cinco réplicas (corrales de piso) de 10 aves cada una. El ensayo se dividió en dos fases (inicio y finalizado) de 21 días cada una (42 días en total).  Resultados: La concentración de proteínas no tuvo ningún efecto (P &gt; 0.05) en el aumento de peso, mientras que el consumo de alimento fue mayor en T1 (P &lt; 0.05) que en T2 y T3. La conversión alimenticia fue mejor en T2 y T4 (P &lt; 0.05) que en T1. No hubo influencia del tratamiento en el peso o en los cortes de la canal (P &gt; 0.05). El rendimiento de la canal fue mayor (P &lt; 0.05) en T1 que en T3. La materia seca y el extracto etéreo de la carne de la pechuga y el muslo fueron similares (P &gt; 0.05) entre los tratamientos. La proteína cruda de la pechuga fue mayor (P &lt; 0.05) en T2 que en T3. La menor (P &lt; 0.05) concentración de PC en la carne de muslo fue en T3.  Discusión o Conclusión: Estos resultados indican que en la zona subtropical del noreste de México los aumentos de PC sobre los valores de T2 (21.4% y 18.5% PC en dietas de inicio y finalizado, respectivamente) no mejoraron el rendimiento productivo, las características de la canal o la composición química de la carne de pollos de engorde.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract  Introduction: Current diets of broiler chickens tend to increase protein levels to obtain high productive variables that are achieved in combination with genetic, management, and sanitary improvements, among others. An increase in dietary crude protein levels does not always accompany an increase in broiler productive efficiency due to multiple factors involved in the production system. The objective of this study was to evaluate the effect of increasing levels of dietary crude protein (CP) on productive performance, carcass characteristics, and chemical composition of breast and thigh meat in broiler chickens raised in the dry subtropics of northeastern Mexico.  Method: The study used 200, 1-day-old male Ross broiler chicks. In a completely randomized design, birds were allocated to the four treatments with five replicates (floor pens) of ten birds each. The trial was divided in two phases (starter and finisher) of 21 days each (42 days total). Treatment diets (T) for starter and finisher phases had crude protein concentrations (CP; %) of 21 and 18.1 (T1), 21.4 and 18.5 (T2), 21.8 and 18.9 (T3), and 22.2 and 19.3 (T4), respectively. Within each feeding phase, the four treatment diets were formulated to similar levels of apparent metabolizable energy.  Results Protein concentrations had no effect (P &gt; 0.05) on weight gain, while feed intake was greater in T1 (P &lt; 0.05) than in T2 and T3. Feed conversion was better in T2 and T4 (P &lt; 0.05) than in T1. There was no influence of treatment on carcass weight or carcass cuts (P &gt; 0.05). Carcass yield was greater in T1 than in T3 (P &lt; 0.05). Breast and thigh dry matter and ether extracts were similar (P &gt; 0.05) between treatments. Breast crude protein was greater (P &lt; 0.05) in T2 than in T3. The lowest (P &lt; 0.05) CP concentration in thigh meat was in T3.  Discussion or Conclusion: These results indicated that in the dry subtropics area of northeastern Mexico increases in CP above the level of T2 (21.4% and 18.5% CP in starter and finisher diets, respectively) did not improve broiler chicken productive performance, carcass characteristics or meat chemical composition.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[alimento]]></kwd>
<kwd lng="es"><![CDATA[nutrientes]]></kwd>
<kwd lng="es"><![CDATA[aves]]></kwd>
<kwd lng="es"><![CDATA[producción]]></kwd>
<kwd lng="es"><![CDATA[harina de soya]]></kwd>
<kwd lng="es"><![CDATA[proteína]]></kwd>
<kwd lng="es"><![CDATA[dieta]]></kwd>
<kwd lng="es"><![CDATA[eficiencia productiva]]></kwd>
<kwd lng="es"><![CDATA[pollos]]></kwd>
<kwd lng="es"><![CDATA[peso]]></kwd>
<kwd lng="es"><![CDATA[consumo de alimento]]></kwd>
<kwd lng="es"><![CDATA[comportamiento productivo]]></kwd>
<kwd lng="es"><![CDATA[carne]]></kwd>
<kwd lng="es"><![CDATA[materia seca]]></kwd>
<kwd lng="es"><![CDATA[extracto etéreo]]></kwd>
<kwd lng="es"><![CDATA[zona subtropical de México]]></kwd>
<kwd lng="es"><![CDATA[composición química]]></kwd>
<kwd lng="en"><![CDATA[feed]]></kwd>
<kwd lng="en"><![CDATA[nutrients]]></kwd>
<kwd lng="en"><![CDATA[poultry]]></kwd>
<kwd lng="en"><![CDATA[production]]></kwd>
<kwd lng="en"><![CDATA[soybean meal]]></kwd>
<kwd lng="en"><![CDATA[protein]]></kwd>
<kwd lng="en"><![CDATA[diet]]></kwd>
<kwd lng="en"><![CDATA[productive efficiency]]></kwd>
<kwd lng="en"><![CDATA[chickens]]></kwd>
<kwd lng="en"><![CDATA[weight]]></kwd>
<kwd lng="en"><![CDATA[food consumption]]></kwd>
<kwd lng="en"><![CDATA[productive performance]]></kwd>
<kwd lng="en"><![CDATA[meat]]></kwd>
<kwd lng="en"><![CDATA[dry matter]]></kwd>
<kwd lng="en"><![CDATA[ether extract]]></kwd>
<kwd lng="en"><![CDATA[subtropical area of Mexico]]></kwd>
<kwd lng="en"><![CDATA[chemical composition]]></kwd>
</kwd-group>
</article-meta>
</front><back>
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<surname><![CDATA[Awad]]></surname>
<given-names><![CDATA[E. A.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Effects of low-protein diets on acute phase proteins and heat shock protein 70 responses, and growth performance in broiler chickens under heat stress condition]]></article-title>
<source><![CDATA[Poultry Science]]></source>
<year>2018</year>
<volume>97</volume>
<numero>4</numero>
<issue>4</issue>
<page-range>1306-14</page-range></nlm-citation>
</ref>
</ref-list>
</back>
</article>
