The role of genotype on classification grades of beef carcasses produced under mexican tropical conditions Influencia del genotipo bovino en el grado de clasificación de canales generadas en el trópico mexicano José Manuel Zorrilla-Ríos,1* Phillip Lancaster,4 Carla Goad,3 Gerald Horn2 y Margarita Hernández-Gallardo1 Centro Universitario de Ciencias Biológicas y Agropecuarias Universidad de Guadalajara Camino Ing. Ramón Padilla Sánchez No. 2100 La Venta del Astillero, Zapopan, Jalisco, México (C. P. 45110). 2 Animal Science Department Oklahoma State University Stillwater, Okl. USA (74078). 3 Department of Statistics Oklahoma State University Stillwater, Okl. USA (74078). 4 Department of Animal Sciences University of Florida Range Cattle Research and Education Center 3401 Experiment Station Ona, FL, USA (33865). * Correspondence: [email protected] 1

Abstract

Resumen

The present study identified the distribution of 22,850 beef carcasses belonging to three genotypes according to a visual judgment of the height of the hump (large, indicative of Bos indicus; medium, Crosses between B. indicus and Bos taurus, and small, B. taurus) among the classification grades obtained under the Mexican norm NMX-FF-078-SCFI-2002, at the No 51 Federal Inspected Type abattoir, Tabasco State, southeastern Mexico. Chi-square analysis was used to determine the association and the proportion of hump classification with carcass grading criteria. Fifty four percent of the carcasses

El presente estudio identificó la distribución de 22,850 canales de bovino de diferentes genotipos. Éstos, en función del juzgamiento visual del tamaño de la giba (grande, representativa de un genotipo Bos indicus; mediana, genotipo producto de la cruza entre B. taurus y B. indicus y pequeña, considerada como genotipo B. taurus) en los grados de clasificación obtenidos bajo la norma mexicana NMX-FF-078-SCFI-2002, en el rastro Tipo Inspección Federal No. 51 de La Unión, Tabasco (México). Se determinó el grado de asociación y la proporción de canales, juzgados por el tamaño de su giba; y el criterio Avances en Investigación Agropecuaria • Zorrilla-Ríos et al. Aia. 2015. 19(2): 67-77 Issn 0188789-0

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The role of genotype on classification grades of beef carcasses produced under mexican tropical conditions

classified as large hump (B. indicus breeding), 35% as small hump (B. taurus breeding), and 10.70% as medium hump (Crossbred). B. taurus and Crossbred genotypes had greater (P < 0.0001) percentage of Select carcasses (17.90 and 18.50%, respectively) and Standard grades (55.20 and 60.10%, respectively) than B. indicus genotype (10.10% for Select and 39.30% for Standard). B. indicus genotype had greater (P < 0.0001) percentage of Commercial carcasses (36.20%) and Out of Grade (14.40%) grades. The three genotypes representing the overall beef herd for the Mexican tropics, B. taurus, B. indicus, and Crossbred were present at the Select beef carcass classification grade suggesting that genotype is not a factor introducing bias in the Mexican carcass classification norm NMX-FF-078-SCFI-2002.

Key words Bos indicus, Bos taurus, crosses, meat, evaluation, climate.

de clasificación de la canal, por el procedimiento analítico de Chi-Cuadrada. Cincuenta y cuatro por ciento de las canales correspondieron al tipo de giba grande (genotipo B. indicus), 35% al de pequeña (genotipo B. taurus) y el 10.70% al de mediana (genotipo producto de la cruza entre B. taurus y B. indicus). En los genotipos B. taurus y cruza se concentró un mayor número de canales con clasificación de selecta (P