RESUMENSe caracterizaron 1,000 canales ovinas producidas en México. Los datos se procesaron a través de estadística descriptiva y mediante un diseño totalmente al azar. Del total de canales evaluadas 82.2 % correspondieron a machos y 17.8 % hembras. Se identificaron 53 genotipos (11 razas puras y 42 cruzamientos diversos). El peso al faenado promedió 43.2 ± 7.2 kg (20.4 a 85.7), el peso medio de la canal fría fue 22.0 ± 4.1 kg (11.3 a 50.0) y tuvo un rendimiento medio de 50.0 ± 5.1 % (34.7 a 73.5), el área del ojo de chuleta promedió 14.8 ± 3.8 cm 2 (2.7 a 29.7), el espesor de la grasa subcutánea promedió 3.1 ± 1.6 mm (1.0 a 10.0) y el pH 5.5 ± 0.2 (5.0 a 6.5). El sistema de producción intensiva mostró mayores valores en peso a la matanza, peso de la canal fría y área del ojo de chuleta (44.4 ± 5.9 kg, 22.8 ± 3.3 kg y 15.5 ± 3.6 cm 2 , respectivamente) que el semiintensivo (43.6 ± 5.3 kg, 19.9 ± 3.1 kg y 13.8 ± 2.5 cm 2 ) y el extensivo (36.4 ± 9.7, 19.6 ± 2.6 kg y 9.6 ± 2.6 cm 2 ). Los machos presentaron mayores valores que las hembras en peso al sacrificio (44.3 ± 6.7 vs 40.1 ± 6.1 kg), peso de la canal fría (22.2 ± 3.8 vs 21.2 ± 4.4 kg) y área del ojo de chuleta (15.2 ± 3.7 vs 12.7 ± 3.7 cm 2 ). La gran diversidad en el fenotipo y condición de los ovinos para abasto originó una amplia variabilidad en las propiedades de la canal, que limita el mercado formal de la carne ovina, por lo que convendría reordenar la producción ovina nacional dirigiéndola hacia una condición de calidad más uniforme.PALABRAS CLAVE: Caracterización, Ovinos, Calidad, Canal. ABSTRACTOne thousand (1,000) sheep carcasses produced in Mexico were characterized. Data were processed through descriptive statistics and using a totally random design. From total carcasses, 82.2 % were males and 17.8 % females. Fifty three (53) genotypes (11 pure breeds and 42 different crosses) were identified. Slaughter weight averaged 43.2 ± 7.2 kg (20.4 to 85.7), cold carcass weight averaged 22.0 ± 4.1 kg (11.3 to 50.0) carcass yield was 50.0 ± 5.1 % (34.7 to 73.5), rib eye area averaged 14.8 ± 3.8 cm 2 (2.7 to 29.7), subcutaneous fat thickness had a mean of 3.1 ± 1.6 mm (1.0 to 10.0) and pH averaged 5.5 ± 0.2 (5.0 to 6.5). The intensive production system showed higher values in slaughter weight, cold carcass weight and rib eye area (44.4 ± 5.9 kg, 22.8 ± 3.3 kg and 15.5 ± 3.6 cm 2 , respectively) than the semi-intensive system (43.6 ± 5.3 kg, 19.9 ± 3.1 kg and 13.8 ± 2.5 cm 2 ) and extensive system (36.4 ± 9.7, 19.6 ± 2.6 kg and 9.6 ± 2.6 cm 2 ). Males had higher values than females in slaughter weight (44.3 ± 6.7 vs 40.1 ± 6.1 kg), cold carcass weight (22.2 ± 3.8 vs 21.2 ± 4.4 kg) and rib eye area (15.2 ± 3.7 vs 12.7 ± 3.7 cm 2 ). The great diversity in phenotypes and different lamb conditions caused considerable variability in carcass traits, which limits the formal lamb market, so sheep domestic production should be reordered towards a more uniform quality condition.

The present study constitutes a meta-analysis of the use of zilpaterol hydrochloride (ZH) in sheep production (18 studies, n = 724 animals were evaluated), focused in its effects on productive performance and carcass characteristics in sheep who were given ZH in different doses (control 0, ≤0.50 and ≥0.54 mg/kg raised to the power 0.75 body weight (BW)). The analysis of the data assembled in the database was conducted by a statistical meta-analysis based on mixed model methodology. Results on weight gain were higher (P < 0.03) for the group supplemented with ≥0.54 mg vs. control treatment, feed conversion improved (P < 0.01) with the inclusion of ZH compared with the control group. Carcass yield and Longissimus dorsi area showed no differences (P > 0.05) between treatments, fat content in the carcass diminished in a linear effect (P = 0.02) with the inclusion of ZH. The results show a positive effect on improving animal performance, mainly in the characteristics on the fat deposition. The optimal dose varies depending on the variable to improve, ranged in 0.24 up to 1.21 mg ZH/kg BW 0.75 to reduce fat and carcass get leaner or increase average daily gain, respectively.

Zilpaterol hydrochloride (ZH) supplementation (0 vs. 0.15 mg/kg live weight) was evaluated based on the carcass characteristics of Katahdin x Charollais (32 KCh) and Katahdin x Dorper (28 KD) crosses. Lambs were fed a mixed ration with 14% crude protein (CP) and 2.9 Mcal EM/kg DM. Data were analyzed using a completely randomized 2 x 2 factorial design: 2 genotypes (KCh and KD) and 2 ZH levels (0 and 0.15 mg/kg live weight). No interaction was found between ZH and the genotypes. Zilpaterol hydrochloride increased dressing percentage from 52.1 ± 0.3 to 53.7 ± 0.4% (P < 0.001). Animals that received ZH supplementation increased (P < 0.001) the area of their Longissimus dorsi (Ld) by 18.5% and had 7.5% more muscle, 6.0% less bone and 22.4% less fat compared with control lambs (P < 0.05). The breed of the sire had no effect on any of the variables studied. Final pH, fat thickness, conformation and linear carcass measurements did not change with ZH supplementation.

The objective of the study was to evaluate the effects of sire breed (Charollais, Dorset and Texel), utilizing Hampshire ewes, lamb sex and birth type, on carcass traits of the lambs. After weaning (74±8 d), 45 lambs from these crosses were fattened during 63 d, consuming a balanced diet with 14% CP and 2.82 Mcal of ME/kg of DM. Lambs were weighed and slaughtered at 137 d of age; later, measures on slaughter weight and yield of hot and cold carcass, rib eye area, subcutaneous fat, carcass length, leg length, and rump perimeter were taken and the carcass compactness index was calculated. In addition, the carcass regional composition (shoulder, chest-belly, anterior-loin, leg, neck, and rear-loin) was determined. Data were analyzed utilizing a mixed model. Charollais-sired lambs had the highest (P<0.05) rib eye area (20.1±0.5 cm 2 ), while Dorset-sired lambs were superior (P<0.05) in carcass length (66.3±0.9 cm) and leg length (34.8±0.3 cm). Ram lambs surpassed ewe lambs (P<0.05) in most traits analyzed. Lambs born as singles had higher means than twin lambs (P<0.05) in subcutaneous fat and leg length. In general, crosses with Charollais and Dorset showed superiority in carcass traits.

ResumenSe evaluó el efecto de la administración de clorhidrato de zilpaterol (CZ) sobre las características de la canal en los cruzamientos Katahdin x Charollais (32 KCh) y Katahdin x Dorper (28 KD). Los corderos se alimentaron con una dieta integral con 14% de proteína cruda (PC) y 2.9 Mcal EM/kg MS. Los datos se analizaron mediante un diseño al azar con arreglo factorial 2 x 2 con dos genotipos (KCh y KD) y 2 niveles de CZ (0 y 0.15 mg/kg de peso vivo). No se presentó interacción entre el genotipo y el CZ. El clorhidrato de zilpaterol incrementó el rendimiento en canal de 52.1 ± 0.3 a 53.7 ± 0.4% (P < 0.001). Los animales que recibieron CZ incrementaron (P < 0.001) el área del músculo Longissimus dorsi (Ld) en 18.5% y tuvieron 7.5% más músculo, 6.0% menos hueso y 22.4% menos grasa que los corderos del tratamiento testigo (P < 0.05). La raza del padre no afectó ninguna de las variables estudiadas. El pH final, el espesor de la grasa subcutánea, la conformación y las mediciones morfológicas de la canal no se modificaron con el uso de CZ.Palabras clave: Cordero; Zilpaterol; Calidad de canal; Cruzamiento; Katahdin; Charollais; Dorper. IntroducciónDurante la última década la ovinocultura mexicana se ha enfocado, principalmente, en la producción de carne y ha mantenido una tasa de crecimiento anual del 5.11% en promedio, al pasar de 38,196 t en 2002 a 57,692 t en 2012 (SIAP, 2012). En consecuencia, la importación de carne ha disminuido casi en 75% (SIAP, 2012; SAGARPA, 2013). Aunque este crecimiento ha sido muy importante, aún se requieren 32,500 t de carne anualmente para tener una disponibilidad de tan sólo 750 g de carne/persona/año. Esta tendencia en el crecimiento motivó el interés de los criadores de ovinos para introducir a México animales de distintas razas con alto potencial de producción, que permitieran aprovechar la oportunidad de satisfacer la demanda del mercado interno a través del empleo de razas puras o mediante distintos esquemas de cruzamiento en sistemas intensivos. Estudios recientes evaluaron algunos de los modelos de cruzamiento y determinaron un Efecto del clorhidrato de zilpaterol sobre las características de la canal en cruzas terminales de corderos Kathadin