Effect of Feeding Barley, Corn, and a Barley/Corn Blend on Beef Composition and End-Product Palatability.

This study evaluated the relationship among palatability attributes, volatile compounds, and fatty acid (FA) profiles in meat from barley, corn, and blended (50:50, barley and corn) grain-fed steers. Multiple correspondence analysis with three dimensions (Dim) explained 62.2% of the total variability among samples. The Dim 1 and 2 (53.3%) separated pure from blended grain-fed beef samples. Blended grain beef was linked to a number of volatiles including (E,E)-2,4-decadienal, hexanal, 1-octen-3-ol, and 2,3-octanedione. In addition, blended grain-fed beef was linked to fat-like and rancid flavors, stale-cardboard, metallic, cruciferous, and fat-like aroma descriptors, and negative categories for flavor intensity (FI), off-flavor, and tenderness. A possible combination of linoleic and linolenic acids in the blended diet, lower rumen pH, and incomplete biohydrogenation of blended grain-fed polyunsaturates could have increased (p ≤ 0.05) long-chain n-6 fatty acids (LCFA) in blended grain-fed beef, leading to more accumulation of FA oxidation products in the blended than in barley and corn grain-fed meat samples. The Dim 3 (8.9%) allowed corn separation from barley grain beef. Barley grain-fed beef was mainly linked to alkanes and beef positive FI, whereas corn grain-fed beef was associated with pyrazines, in addition to aldehydes related to n-6 LCFA oxidation.

Using near-infrared spectroscopy to determine intramuscular fat and fatty acids of beef applying different prediction approaches.

This study aimed to predict fat and fatty acids (FA) contents in beef using near-infrared spectroscopy and prediction models based on partial least squares (PLS) and support vector machine regression in radial kernel (R-SVR). Fat and FA were assessed in 200 longissimus thoracis samples, and spectra were collected in reflectance mode from ground meat. The analyses were performed for PLS and R-SVR with and without wavelength selection based on genetic algorithms (GAs). The GA application improved the error prediction by 15% and 68% for PLS and R-SVR, respectively. Models based on GA plus R-SMV showed a prediction ability for fat and FA with an average coefficient of determination of 0.92 and ratio performance deviation of 4.8.

Near-Infrared Spectroscopy as a Beef Quality Tool to Predict Consumer Acceptance.

This study was conducted to evaluate the feasibility of using near-infrared spectroscopy (NIRS) to predict beef consumers' perceptions. Photographs of 200 raw steaks were taken, and NIRS data were collected (transmittance and reflectance). The steak photographs were used to conduct a face-to-face survey of 400 beef consumers. Consumers rated beef color, visible fat, and overall appearance, using a 5-point Likert scale (where 1 indicated "Dislike very much" and 5 indicated "Like very much"), which later was simplified in a 3-point Likert scale. Factor analysis and structural equation modeling (SEM) were used to generate a beef consumer index. A partial least square discriminant analysis (PLS-DA) was used to predict beef consumers' perceptions using NIRS data. SEM was used to validate the index, with root mean square errors of approximation ≤0.1 and comparative fit and Tucker-Lewis index values <0.9. PLS-DA results for the 5-point Likert scale showed low prediction (accuracy < 42%). A simplified 3-point Likert scale improved discrimination (accuracy between 52% and 55%). The PLS-DA model for purchasing decisions showed acceptable prediction results, particularly for transmittance NIRS (accuracy of 76%). Anticipating beef consumers' willingness to purchase could allow the beef industry to improve products so that they meet consumers' preferences.

Interrupción temporal de la lactancia (ITA) y presentación de estro en vacas cebú posparto / Effect of suckling restriction on heat presentation in postpartum zebu cows

Este estudio se llevó a cabo en vacas cebú amamantando bajo condiciones de trópico bajo, pastoreando brachiaria en condiciones semintensivas y con días abiertos mayores a 150. Con el fin de determinar si la interrupción temporal del amamantamiento (ITA) disminuye los días abiertos, se escogieron 34 vacas con 80 a 120 días abiertos y ciclando. Se dividieron en dos grupos al azar, uno de 19, a las que se les retiró el ternero durante 72 horas y otro de 15 controles. Todas las vacas pastorearon juntas. La semana previa al experimento, durante la restricción y hasta dos semanas después, se realizaron ecografías y detección de calor. Las variables consideradas fueron la tasa de crecimiento folicular durante el ITA y la tasa de crecimiento del folículo dominante, así como la presentación de calor. El 94.7 por ciento de las vacas con ITA presentaron calor durante el tratamiento, o en la semana siguiente,aparentemente ejercieron un efecto social sobre las compañeras sin tratamiento, ya que en estas se presentaron 46.7 por ciento de calores simultáneamente. El tratamiento afectó positivamente el diámetrofolicular de las vacas tratadas.