RESUMO Objetivou-se avaliar três tipos de silagem de grão úmido de sorgo (alto tanino, baixo tanino e branco), na forma de silagem de grão úmido, combinados com duas formas de fornecimento da ração (volumoso e concentrado fornecidos de forma separada ou misturada), sobre o consumo de matéria seca, evolução do peso vivo, ganho de peso médio diário, conversão alimentar e principais características de carcaça (área de olho de lombo, espessura de gordura subcutânea e marmorização in vivo e post mortem) e carne (cor, maciez e pH) de novilhos cruzados Hereford-Angus. Foram utilizados 48 bovinos machos, castrados, cruzados Hereford-Angus, com idade média de 20 meses, divididos em blocos casualizados, em fatorial 3 × 2. A regressão do ganho de peso de cada tratamento foi comparada utilizando-se contrastes ortogonais. Para consumo de matéria seca relativo, houve efeito do tipo de sorgo (P=0,002) e forma de fornecimento da ração (P=0,0005). A forma de fornecimento da ração pode interferir sobre o consumo de matéria seca absoluto e peso vivo médio (P=0,0001). Para a conversão alimentar foi observado efeito do tipo de sorgo (P=0,04. Observou-se efeito da forma de fornecimento da ração para a marmorização (P=0,04) post mortem. Não houve efeito do tipo de sorgo e da forma de fornecimento da ração sobre as características de carcaça e pesos dos cortes cárneos. O fornecimento do volumoso separado do concentrado na alimentação de bovinos confinados é viável do ponto de vista operacional e nutricional.

SUMMARY This work aimed to evaluate three varieties of sorghum as wet grain silage (high, low and white tannin), combined with two form of food supply (concentrated with roughage separated or mixed) on dry matter intake, body weight evolution, average daily growth, feed conversion, main meat and carcass traits (rib eye area, fat thickness and marbling in vivo and post mortem) in Hereford-Angus crossbred steers. Forty eight males castrated with 20 months of age were used, divided into randomized blocks, arranged in a 3 × 2 factorial. The regression coefficients for the weight gain of each treatment was compared using orthogonal contrasts. Dry matter intake was affected by the type of sorghum (P=0.002) and the form of food supply (P=0.0005). The form of food supply can interfere with the dry matter intake (P=0.0001) and weight (P=0.0001). Feed conversion and marbling, was affected by the type of sorghum (P=0.04). Meat marbling measured at deboning was affected by the form of food supply (P=0.04). The type of sorghum and form of food supply did not influence carcass characteristics and weights of meat cuts. The concentrated with roughage separated supply is nutritionally and operationally preferable.

Con el objetivo de evaluar el efecto de la ingesta de deoxinivalenol (DON) y de un adsorbente de micotoxinas en la producción de vacas lecheras, 32 vacas fueron asignadas a los siguientes tratamientos en un diseño de bloques completos al azar durante nueve semanas: oferta de 6 kg/día de concentrado/vaca con a) 0, b) 2,5, c) 5,0 o d) 5,0 ppm de DON más 0,1 % de un adsorbente de micotoxinas, equivalente a una oferta de 0, 15, 30 y 30 mg de DON/día, respectivamente. Los concentrados fueron formulados para ser isoenergéticos e isoproteicos, y se ofreció a todas las vacas la misma cantidad de pradera y ensilaje de maíz. El consumo de concentrado y la producción de leche no difirió entre tratamientos, pero la oferta de 30 mg/día de DON sin adsorbente disminuyó el porcentaje, el rendimiento de grasa y la producción de leche corregida a 4 % de grasa (LCG), e incrementó el recuento de células somáticas (RCS). La inclusión de un adsorbente en el concentrado con 5,0 ppm de DON evitó el aumento del RCS y la disminución de la producción de LCG. No hubo efecto del DON sobre la variación de peso o condición corporal, o la concentración plasmática de las enzimas aspartato aminotransferasa y gamma glutamiltransferasa. En condiciones pastoriles, una ingesta diaria mayor a 14 mg/vaca de DON redujo la productividad de vacas lecheras en lactancia temprana, lo que fue evitado mediante la inclusión de un adsorbente comercial

To evaluate the effect of deoxynivalenol (DON) intake and a mycotoxin adsorbent on dairy cow performance, 32 cows were assigned to the following treatments in a randomized complete block design for nine weeks: daily allowance of 6 kg/cow of a concentrate with a) 0, b) 2.5, c) 5.0 and d) 5.0 ppm of DON plus 0.1% of a mycotoxin adsorbent, which delivered 0, 15, 30 and 30 mg of DON/day, respectively. Every cow was daily offered with the same quantity of pastures and corn silage, and concentrates were designed to be isoenergetic and isoproteic. Concentrate intake and milk yield did not differ among treatments, but a daily allowance of 30 mg of DON without adsorbent reduced milk fat,yield, and 4 % fat-corrected milk (FCM) yield, and increased milk somatic cell count (SCC). The inclusion of an adsorbent in the concentrate with 5.0 ppm of DON avoided the increase in SCC and the reduction in FCM yield. There was no effect of DON on body weight, condition score change, or plasma concentration of aspartate aminotransferase and gamma glutamyl transferase. Under grazing conditions, a daily intake of DON higher than 14 mg/cow reduced dairy cow performance, which was avoided through the inclusion of a commercial mycotoxin adsorbent.

Este trabalho foi desenvolvido com o objetivo de estudar a evolução das características de crescimento e carcaça em função da idade em bovinos da raça Hereford, utilizando modelos não-lineares. Foram utilizados dados de 240 bovinos machos (castrados) da raça Hereford, pertencentes à fazenda Experimental "La Estanzuela" do INIA, Colonia, Uruguai. As características começaram a ser mensuradas a partir da desmama de animais com aproximadamente seis meses de idade, até o abate (dois anos de idade). As medições de peso foram realizadas a cada 15±3 dias durante todo o período e sem jejum prévio. As mensurações de área de olho de lombo, obtidas por ultrassom, e altura dos animais foram obtidas a cada 90 dias, sendo que as medidas de ultrassom foram tomadas entre a 12ª e 13ª costelas. Os modelos não-lineares utilizados foram os modelos de Brody, Gompertz, Logístico e Von Bertalanffy. Para as características peso, altura e área de olho de lombo, todos os modelos avaliados atingiram a convergência. Para descrever a evolução dos dados de peso e área de olho de lombo em função da idade, o modelo de Von Bertalanffy foi o mais indicado, e os modelos de Brody e Logístico mostraram o pior ajuste, respectivamente. A evolução da altura dos animais desde o desmame até os dois anos de idade pode ser modelada através de qualquer um dos modelos não-lineares considerados neste estudo.

The objective of this research was to study the evolution of growth and carcass traits as a function of age in Hereford cattle using nonlinear models. Records from 240 Hereford steers (castrated), belonging to the experimental station "La Estanzuela" of INIA Uruguay, were utilized. The animals were measured from weaning, approximately at 6 months of age, to slaughter (two years of age). The animals were weighed, without fasting, every 15±3 days throughout the period. The measurements of ribeye loin area (between the 12th and 13th rib) were obtained by ultrasound every 90 days. The height of the animals was obtained every 90 days. The Brody, Gompertz, Logistic and Von Bertalanffy nonlinear models were applied to describe the trajectory of weight, height and ribeye loin area along the age. For height, weight and ribeye loin area, all the models reached the convergence. To describe the evolution of weight and ribeye loin area, the Von Bertalanffy nonlinear model was the most suitable. For weight and ribeye loin area, the Brody and Logistic nonlinear models have shown the worst fit, respectively. The height trajectory from weaning until two years of age can be modeled by any of the nonlinear models considered in this research.

The aim of this study was to investigate the use of near infrared reflectance (NIRS) spectroscopy to predict the nutritive value of silages from pastures and to assess the effect of silage structure type (e.g. bunker and bag silos) on the NIRS predictions. Samples (n = 120) were sourced from commercial farms and analyzed in a NIRS monochromator instrument (NIR Systems, Silver Spring, Maryland, USA) using wavelengths between 400 and 2500 nm in reflectance. Calibration models were developed between chemical and NIRS spectral data using partial least squares (PLS) regression. The coefficients of determination in calibration (R²) and the standard error in cross validation (SECV) were 0.73 (SECV: 1.2%), 0.81 (SECV: 2.0%), 0.75 (SECV: 6.6%), 0.80 (SECV: 6.7%), 0.80 (SECV: 4.0%), 0.60 (SECV: 3.6%) and 0.70 (SECV: 0.34) for ash, crude protein (CP), neutral detergent fiber (NDF), dry matter (DM), acid detergent fiber (ADF), in vitro dry matter digestibility (IVDMD) and pH, respectively. The results showed the potential of NIRS to analyze DM, ADF and CP in silage samples from pastures.

El objetivo de este trabajo fue investigar el uso de la espectrofotometría de reflectancia en el infrarrojo cercano (NIRS) para predecir el valor nutritivo en ensilaje de pasturas y evaluar el tipo de estructura de silo (silo bolsa y trinchera) en las predicciones NIRS. Muestras (n = 120) provenientes de granjas comerciales fueron leídas en un equipo monocromador NIRS (NIR Systems, Silver Spring, Maryland, USA) en el rango de longitudes de onda de 400 a 2500 nm, en reflectancia. Modelos de calibración entre los datos químicos y los espectros NIRS fueron desarrollados usando el método de los cuadrados mínimos parciales. Los coeficientes de determinación en calibración (R²) y el error estándar de la validación cruzada (SEVC) fueron 0,73 (SECV: 1,2%), 0,81 (SECV: 2,0%), 0,75 (SECV: 6,6%), 0,80 (SECV: 6,7%), 0,80 (SECV: 4,0%), 0,60 (SECV: 3,6%) and 0,70 (SECV: 0,34) para cenizas, proteína cruda (PC), fibra detergente neutro (FDN), materia seca (MS), fibra detergente ácido (FDA), digestibilidad in vitro de la materia seca (DIVMS) y pH, respectivamente. Los resultados demuestran el potencial de la técnica NIRS para el análisis de rutina en ensilaje de pasturas para MS, FDA, y PC.

Near infrared reflectance (NIR) spectroscopy was used in combination with chemometrics to discriminate between fishmeal, meat meal and soya meal samples. Samples were obtained from commercial feed miles and scanned in the NIR region (1100 - 2500 nm) in a monochromatic instrument in reflectance mode. Principal component analysis (PCA) and linear discriminant analysis were used to classify samples based on their NIR spectra. Full cross-validation was used in the development of classification models. Partial least squares-discriminant analysis (PLS-DA) correctly classified 85.7% of the fishmeal samples and 100% of the meat meal and soya meal samples. These results demonstrate the usefulness of NIR spectra combined with chemometrics as an objective and rapid method to classify fishmeal, meat meal and soya meal samples. NIR spectroscopic methods can be easily implemented in food miles and may be most useful for initial screening at early stages in the food production chain, enabling more costly methods to be used selectively for suspected specimens.

El objetivo de este trabajo fue investigar el uso de la espectrofotometría de reflectancia en el infrarrojo cercano (NIR) en combinación con la quimiometría para discriminar muestras de harinas de pescado, carne y soja. Muestras provenientes de molinos racioneros comerciales fueron leídas en un equipo monocromador NIRS (NIRSy stems, Silver Spring, USA) en el rango de longitudes de onda de 400 a 2500 nm, en reflectancia. Análisis de componentes principales (APC) y de discriminantes utilizando la técnica de los cuadrados mínimos parciales (PLS-DA) fueron usados para clasificar las muestras de acuerdo a su origen. El método de la validación cruzada fue utilizado para validar los modelos. El 85,7% de las muestras de harina de pescado y el 100 % de las muestras de carne y soja fueron correctamente clasificados usando el método PLS-DA. Los resultados obtenidos en este estudio demuestran el potencial uso de la reflectancia en el infrarrojo cercano combinada con la quimiometría como un método rápido y de bajo costo para clasificar muestras de harina de pescado, carne y soja.