The objective of this study was to determine post-mortem measurements for predicting carcass traits in growing rabbits. A total of 50 clinically healthy New Zealand White × Californian male rabbits with a body weight (BW) of 1351 ± 347 g between 60 to 80 days of age were used. Body weight was recorded 12 h before slaughtering. Data recorded at slaughtering included carcass weights (HCW). After cooling at 4 °C for 24 h, carcasses were weighed (CCW) and then were carefully split longitudinally with a band saw to obtain left and right halves. In the right half carcass, the following measurements were recorded using a tape measure: dorsal length (DL), thoracic depth (TD), thigh length (TL), carcass length (CL), lumbar circumference (LC). The compactness index (CCI) was calculated as the CCW divided by the CL. Thereafter, the right half carcass was weighed and manually deboned to record weights of muscle (TCM), and bone (TCB). The CCI explained of 93% of variation for TCM (R2 = 0.93 and a CV = 9.30%). In addition, the DL was the best predictor (p < 0.001) for TCB (R2 = 0.60 and a CV = 18.9%). Our results indicated that the use of carcass measurements could accurately and precisely (R2 = ≥ 0.60 and ≤0.95) be used as alternatives to predict the carcass tissues composition in growing rabbits.

El objetivo de este estudio fue evaluar la predicción del peso corporal (PC) del guajolote nativo mexicano (GNM) a partir de medidas morfométricas (MM) e índices morfológicos usando el análisis del árbol de clasificación y regresión (CART). Se tomaron medidas de 244 GNM, provenientes de los estados de Puebla, Chiapas y Campeche. Se recolectó el PC y diez MM, se estimaron tres índices morfológicos: masividad (IMA), solidez (ISO) y de condición corporal (ICC). Se analizó los estadísticos descriptivos y correlación de Pearson (r) de las variables y con ellas se construyó un árbol de regresión utilizando el método CART. Se obtuvieron coeficientes de variación <20% en las MM, un IMA de 13,50%, ISO de 111,12% y el ICC de 16,81%. Las correlaciones entre el PC y las MM variaron de moderadas a altas (r = 0,35 a r = 0,91; P < 0,0001). El ICC fue la variable con la mejor puntuación (100%) en el análisis de importancia normalizada, seguida de IMA (79,2%) y el perímetro torácico (52,8%). El diagrama del árbol de regresión óptimo formó un total de 13 nodos, de los cuales 7 fueron nodos terminales, demostrando que el ICC es suficiente para predecir el PC del GNM. Este estudio permitió definir un modelo de predicción con una varianza explicada observada de 86,4% e incluyó el ICC, la altura corporal y el ancho del ala, el cual puede ser aplicado por los productores para predecir el peso corporal de GNM de manera confiable.Palabras clave: CART, índices morfológicos, árbol de decisión, modelo de predicción.

El objetivo del presente trabajo fue comparar la rentabilidad de la engorda de corderos bajo dos tipos de alojamiento en el trópico subhúmedo de México. Se analizaron datos de parámetros productivos y costos de producción de 32 corderos, 16 alojados en corrales elevados y 16 en corrales a nivel del suelo, para determinar la relación costo-beneficio y la rentabilidad. La relación costo-beneficio y la rentabilidad en crianza en corrales elevados fueron superior en comparación con la crianza en corrales a nivel del suelo.

<p><strong>Background.</strong> The study of space allowance (m²) per animal is important, due in current production systems different group sizes are used throughout the year, without knowing their possible effects on daily weight gain and growth during the fattening period. <strong>Objective.</strong> The effect of space allowance on the growth of hair lambs in raised-slatted floor cages was determined. <strong>Methodology.</strong> Data from 527 daily weight gains (DWG) and weights adjusted at 60 (P60) days post-weaning of female lambs from commercial crossbreds between hair breeds were analyzed. The statistical model included fixed effects of space allowance (AL; 0.69, 0.64-0.60 and 0.56 m²/animal), year (A; 2012 and 2013), seasons of the year (EA; rainy and north) and the interaction on DWG and P60. The initial body weight was included as co-variate.<strong> Results.</strong> AL, A and interactions A × EA affected the dependent variables evaluated (P &lt;0.05). AL larger (0.69 m²) and intermediate (0.64-0.60 m²) had similar growth (P &gt;0.05); these groups, in turn, were the ones that obtained the highest DWG and P60 compared to smaller AL (0.56 m²). Higher growth of the female lambs was observed in the year 2012 compared to 2013. EA had no significant effect (P &gt;0.05). <strong>Implications.</strong> The availability of the space allowance implies the quantity and quality, including the area occupied by the feeder and drinker. <strong>Conclusion.</strong> Under the conditions of the present study, AL should be adjusted between 0.69 and 0.60 m²/female lambs and that A and A × EA interaction can play an important role in animal growth.<strong></strong></p>