Geisa Isilda Ferreira Esteves

Infrared Thermography to Evaluate Heat Tolerance in Different Genetic Groups of Lambs

Heat stress is considered a limiting factor for sheep production. We used information from physiological characteristics linked to heat tolerance to determine whether infrared thermography temperatures were able to separate groups of animals and determine the most important variables in this differentiation. Forty-eight four-month-old male lambs from eight genetic groups were used. Physiological (rectal temperature–RT, heart rate–HR, respiratory rate–RR) and blood traits, infrared thermography temperatures, heat tolerance indices, body measurements, weight and carcass traits were measured. Statistical analyses included variance, correlations, factor, discrimination and regression. Observing the correlations between physiological characteristics (RT, RR and HR) with temperatures measured by infrared thermography, regions for further studies should include the mean temperature of flank, nose and rump. Results show that there are strong relationships between thermograph measurements and RR, RT and HR in lambs, which are suggested to be directly correlated with heat tolerance capacity of the different genetic groups evaluated in this study. The assessment of body surface temperature measured by the thermograph could be used as a noninvasive tool to assess heat tolerance of the animals.

Performance and carcass traits of Santa Inês lambs finished with different sources of forage

The objective of this study was to evaluate performance and biometrics of lambs fed different sources of forage. Twenty-four six-month-old Santa Ines female lambs were randomly allocated to four experimental diets and housed in individual stalls. They weighed on average 26.35±0.20 kg. The diets were coast cross hay (HAY), cassava hay (CAS), dehydrated by-product of pea crop (PEA) and saccharin (SAC). The diets were formulated with the same amount of protein and energy with fixed levels of forage (60%) and concentrate (40%). Adaptation to the diet took 7 days, with 45 days on experiment. Weights and biometric measurements were obtained every fortnight and feed intake three times a week. Rights half-carcasses were weighed and sectioned into retail cuts, rib, loin, shoulder, belly, neck and leg, which were weighed individually. Weight gain in lambs was significantly different between diets, with those fed saccharin gaining more. Overall, treatments did not significantly affect biometric measurements. There was a significant difference for feed intake and live weight at the end of the experiment. Animals fed PEA and SAC showed the best results. Average positive correlations were found between biometric measurements and live weight. Treatment PEA had heavier hot (14.36 kg) and cold (14.01 kg) carcass weights than the other groups. Hot carcass kill-out was higher for animals fed PEA as well as ham weight, belly, neck and heart girth. The weight of the abdominal viscera (%) for lambs fed CAS was greater than those fed SAC and PEA. The weights of the thoracic viscera as well as the liver, for lambs fed PEA were higher. The by-product of pea yielded best results, followed by saccharin, and can replace traditional forage sources in the region, providing similar results in terms of cuts and body components. These could be an alternative for feeding sheep in the dry season. The substitution of forages using by-product of pea and saccharin led to improved productivity over the coast-cross hay available in the Federal District - Brazil.

CARCASS CHARACTERISTICS AND MEAT QUALITY IN CULL EWES AT DIFFERENT AGES

The objective of this trial was to evaluate carcass quality in 74 Santa Ines hair ewes aged 6 to 48 months. Slaughter occurred after fasting and electroshock, followed by dissection of the jugular veins and carotid arteries. Hot carcass weight, hot carcass yield, carcass length, skin thickness, shoulder, neck, loin, belly, rib and leg weights and percentages, leg length, and girth were measured. The rib eye area, color (by CIELAB system), shear force, and cooking loss were also measured. The data were analyzed using SAS procedures for analysis of variance, regressions, correlations, and principal components. Hot carcass weight was 15.75 kg and yield was 43.65%. Younger animals had higher leg yield while yields of loin and shoulder increased as age increased. The meat was darker in older animals. As age increased, both the quantity of commercial cuts decreased and the loss of quality traits, such as color, cooking loss, and shear force, increased; therefore, slaughter should be performed before 30 months of age.