ABSTRACT The effect of including partially dehulled sunflower seeds in the diet of grazing chickens in meat quality was evaluated. Two hundred and forty, one-day-old, Ross 308 chickens were used, randomly distributed into four treatments with six replicates of 10 birds each. Seventy-two birds were slaughtered at seven weeks of age, 18 per treatment, extracting the Pectoralis major muscle to analyze meat quality. The treatments were completely randomized in a 2x2 factorial arrangement, where type of rearing (confinement or grazing) and diet (base diet or base diet substituting 10% soybean meal for partially dehulled sunflower seeds) were the independent variables. The grazing chickens spent 8 hours a day in a white clover (Trifolium repens) paddock. Including sunflower seeds improved (p<0.05) the color and crude protein (CP) in breast meat (p<0.05), while grazing increased (p<0.05) CP, dry mater (DM), and shear force (SF), and the percentage of breast fat decreased (p<0.05) by up to 50%. Additionally, grazing increased (p<0.05) saturated fatty acids (SFA) and reduced (p<0.05) lipid oxidation by up to 50%. Partially replacing soybean meal with partially dehulled sunflower seeds in the diet of grazing chickens with white clover improves the physicochemical characteristics and nutritional quality of the breast meat; it also decreases lipid oxidation, extending the shelf life of the meat.

The objective of this study was to evaluate the response, through live-weight change, of steers grazing on African star grass (Cynodon plectostachyus), to supplementation with multi-nutritional block during 90 days, under tropical conditions in Mexico. Thirty steers, with an average initial weight of 360 ± 30 kg, were used. They were placed in three groups of 10 animals and randomly assigned the treatments: 1) grazing+multi-nutritional block, 2) grazing+traditional supplement and 3) only grazing, in a completely random design. The rotational grazing system had three days of occupation and 27 days of rest. The average forage that was provided had 5,312 kg dry matter (MS) ha-¹ with 6.8% of crude protein, FDN 74.0%, FDA 51.9%, and in situ digestibility 38.5%. The total intake of dry matter was greater (p < 0.01) in treatment three (14.4 kg MS animal-¹ d-¹) compared with treatments one and two (10.7 kg and 13.4 kg MS animal-¹ d -1 respectively). Against what was expected, the daily live-weight gain was similar (p > 0.05) among treatments, averaging 0.43 kg animal-¹ d-¹. This response was mainly due to the fact that the multi-nutritional block did not increase the decomposition rate of the forage or the production of volatile fatty acids in the rumen. Under the conditions of this study, supplementing grazing steers with multi-nutritional block did not represent any benefit.

El objetivo de este estudio fue evaluar la respuesta en cambio de peso vivo de toretes pastoreando estrella africana (Cynodon plectostachyus) y suplementados con bloque multinutricional en condiciones tropicales mexicanas, durante 90 d. Se utilizaron 30 toretes con peso inicial promedio de 360 ± 30 kg, alojados en tres grupos de 10, asignados aleatoriamente a los tratamientos: 1) pastoreo+bloque multinutricional, 2) pastoreo+suplemento tradicional y 3) pastoreo solo, en un diseño completamente al azar. El pastoreo rotacional tuvo tres días de ocupación y 27 d de descanso. El forraje ofrecido promedio fue 5 312 kg materia seca (MS) ha-¹; proteína cruda (PC), 6.8%; fibra detergente neutro (FDN), 74.0%; fibra detergente acido (FDA), 51.9%; y digestibilidad in situ 38.5%. El consumo total de materia seca fue mayor (p < 0.01) en tratamiento tres (14.4 kg MS animal-¹ d-¹) comparado con los tratamientos uno y dos (10.7 kg y 13.4 kg MS animal-¹ d-¹, respectivamente). Contrario a lo esperado, la ganancia diaria de peso fue similar (p > 0.05) entre tratamientos, promediando 0.43 kg animal-¹ d-¹. Este comportamiento fue debido principalmente a que el bloque multinutricional no incrementó la tasa de degradación del forraje ni la producción de ácidos grasos volátiles (AGVs) en el rumen. Bajo las condiciones del presente estudio, suplementar con bloque multinutricional a toretes en pastoreo, no representó ningún beneficio.

Dry matter (DM) and total carotenoids disappearane in the rumen and intestinal passage of African stargrass (AS) were measured in 4 Holstein steers using rumen In situ and a mobile nylon bag technique in duodenum, respectively. A higher proportion of DM and total carotenoids (P<0.05) in the AS disappeared in the rumen during first 12 h. Correlation value between the disappearance of DM and total carotenoids in the rumen was 0.997 (P < 0.001). 53.0% of the carotenoids disappeared from the duodenal bags in the lower digestive tract when samples were not incubated in the rumen. Carotenoids disappearance in small intestine was lower in the samples incubated in rumen. These results show an availability of 70.0% in carotenoids into the total digestive tract. In conclusion, the AS has a high availability in the degradation of total carotenoids in the digestive tract of ruminants.

La material seca (MS) y la desaparición total de carotenoides del pasto estrella (PE) en el rumen e intestino del pasto estrella (PE) fueron medidas en 4 becerros Holstein, utilizando las técnicas In situ en rumen y la de bolsas de nylon móviles en duodeno, respectivamente. Una alta proporción de MS y carotenoides totales (P<0.05) de PE desaparecieron en rumen durante las primeras 12 h. El valor de correlación entre la desaparición de MS y los carotenoides totales en el rumen fue de 0.997 (P < 0.001). El 53.0% de los carotenoides desapareció de las bolsas duodenales introducidas en el intestino delgado cuando éstas no se incubaron en rumen, mientras que el porcentaje para la desaparición de los carotenoides fue mas baja en las muestras previamente incubadas en rumen. Los resultados muestran una disponibilidad de 70.0% de desaparición de carotenoides en todo el tracto gastrointestinal. En conclusión, PE tiene una alta disponibilidad en la degradación de los carotenoides totales en el tracto digestivo de los rumiantes.

Vinte cordeiros deslanados (Pelibuey x Katadin x BlackBelly) e 20 cordeiros lanados (Rambouillet x Criollo) foram mantidos em um sistema intensivo de alimentação até atingirem 40kg, aos 10 meses de idade. O rendimento de carcaça e a espessura da gordura foram maiores nos cordeiros lanados (51,9%, 2,5mm vs. 47,0%, 2,3mm). Não houve diferenças entre os dois grupos de cordeiros para pH, mas a temperatura da carne foi mais alta durante as primeiras horas pós-morte, nas meias-carcaças dos cordeiros lanados (27, 23, 20 vs. 24, 20, 17°C). O conteúdo proteico da carne do pescoço (músculos braquicefálico e esternocefálico) e do lombo (músculo Longissimus lumborum) foi maior nos cordeiros deslanados (21,1 e 20,4 vs. 19,7 e 19,3%) enquanto o teor de umidade foi maior nas lanados (75,6 e 75,9 vs 73,6 e 74,3%). O conteúdo de cinzas não diferiu entre os dois grupos de cordeiros, mas o ácido palmitoleico foi maior nos cordeiros deslanados (2,9 e 2,7 vs 2,7 e 2,5%). Na carne fresca, o pH, a maciez da carne e a atividade da água (Wa) do lombo não diferiram entre os grupos, mas a capacidade de retenção de água (WHc) foi maior nos cordeiros deslanados, e a mesma resposta foi observada para a maciez da carne cozida do pescoço e do lombo fresco e cozido. Houve diferenças para cor da carne do pescoço com valores de L*, b* e maior tonalidade entre os cordeiros lanados, e maior a* para os deslanados. Os parâmetros sensoriais foram semelhantes nos dois grupos.

Twenty hair (Pelibuey x Katadin x BlackBelly) and 20 wool (Rambouillet x Criollo) lambs were fattened in an intensive feeding system to reach 40kg body weight at ten months of age. The yield of lamb sides and back fat (51.9%, 2.5mm vs. 47.0%, 2.3mm) were greater in wool lambs. Meat pH was not different between phenotypes but meat temperature was higher during the first hours postmortem in wool lamb sides (27, 23, and 20, vs. 24, 20, and 17ºC). Protein content in meat from the neck (braquicephalic and esternocephalic muscles) and loin (Longissimus lumborum muscle) were higher in hair lambs (21.1 and 20.4 vs. 19.7 and 19.3 %), while moisture of the same muscles was higher in wool lambs (75.6 and 75.9 vs. 73.6 and 74.3%). Ash content was similar in both phenotypes, but palmitoleic acid was greater in hair lambs (2.9 and 2.7 vs. 2.7 and 2.5%). In fresh meat, pH, meat toughness, and water activity (Wa) of loin did not differ; but water holding capacity (WHC) was higher in hair lambs, and the same response was observed for cooked meat toughness from the neck, and in raw and cooked meat from loin. There were differences in the colour of meat from the neck, having values for L*, b* and tonalities greater in wool lambs, and a* greater for hair lambs. Sensorial parameters were similar in both phenotypes.