280 steaks from 56 beef carcasses were evaluated to determine the effects of different mechanical and physical methods for increasing the tenderness of the longissimus muscle. Changes in method of suspension, carcass integrity or chilling procedures resulted in increases in tenderness of approximately 47.5% for shear force and 53.6% for taste panel ratings. Experiment 2 (suspension from the achilles tendon, severonce between vertebrae in 5 locations, severance of the ligamentum nuchae and the attachment of 68 kg weights) resulted in a 15% increase in tenderness as evaluated by both shear force values and the taste panel ratings. Experiment 3 (suspension via the obturator foromen, severance of the vertebrae in 5 different locations, severonce of the ligamenturn nuchae and the attachment of 68 kg weights to the neck) gave the grootost positive response in taste panel tenderness ratings (53.6%).Experiments 3, 4. 5 and 6 had the disadvcmtage of resulting in irregularly shaped carcasses, which could present problems in fabrication.The assumption that increases in ccmass length are necessary to achieve o positive response in the tenderness of the longissimus appears unjustified, since post-mortem chilling at elevated tempemtures (16°C) increased tenderness 47% with no appreciable change in carcass length. It was conclude&from this study that the degree of post-mortem muscle contraction which occurs during the development of rigor mortis is a primary factor influencing the ultimate tenderness of beef. The degree of such contraction is related to the temperature at which the carcass is stored during the initial period of cooling. Chilling the corcoss in o 16°C cooler during the first 16 hr post-mortem resulted in a 40.2% increase (P < .OS) in ratings of longissimus tenderness and (I 47.5% decrease (P < .01) in shear force requirement, yet involved no additional labor expense nor any irregularity in carcass form. Of the methods studied, the procedure invdved in experiments 8 and 9 (chilling the CQ~COSSS for the first 16-20 hr in a cooler at 16°C) appears to be the most practical for industrial ulilixalion.
Ammonia (NH3) concentration has seldom been used for environmental control of weaner buildings despite its impact on environment, animal welfare, and workers’ health. This paper aims to determine the effects of setpoint temperature (ST) on the daily evolution of NH3 concentration in the animal-occupied zone. An experimental test was conducted on a conventional farm, with ST between 23 °C and 26 °C. NH3 concentrations in the animal-occupied zone were dependent on ST insofar as ST controlled the operation of the ventilation system, which effectively removed NH3 from the building. The highest NH3 concentrations occurred at night and the lowest concentrations occurred during the daytime. Data were fitted to a sinusoidal model using the least squares setting (LSS) and fast Fourier transform (FFT), which provided R2 values between 0.71 and 0.93. FFT provided a better fit than LSS, with root mean square errors (RMSEs) between 0.09 ppm for an ST of 23 °C and 0.55 ppm for an ST of 25 °C. A decrease in ST caused a delay in the wave and a decrease in wave amplitude. The proposed equations can be used for modeling NH3 concentrations and implemented in conventional controllers for real-time environmental control of livestock buildings to improve animal welfare and productivity.
An AutoRegressive Integrated Moving Average model was validated for the prediction of temperatures in the animal zone of conventional weaned piglet barn. The validation period covered seven cycles and recorded values at 10-min intervals for 292 days. Average weight was 5.75±0.86 kg at the beginning of the production cycle and 18.41±2.12 kg at the end of the cycle. Mean outdoor air temperatures ranged 6.14 to 17.85ºC with deviations in the range 2.49ºC to 5.24ºC, which involved marked differences in the operation of the ventilation system. The Mean Average Percentage Error was below 4%, with a mean error of 1ºC. The Root Mean Square Error was in the range 0.77ºC to 1.19ºC, whereas the coefficient of determination ranged between 0.52 and 0.81. Despite the changes in environmental conditions and in animal weight and management, the accuracy of the model remained stable with low dispersion of values. Tao outdoor air temperature, ºC Taz animal zone temperature, ºC Vao volume of extracted air by the fan, m 3
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