This study aimed to evaluate levels of yerba mate (Ilex paraguariensis) extract (YME), as a feed additive in the diets of growing lambs on serum biochemical parameters and hematological indices, animal performance, body metrics and carcass traits. Thirty-six entire (nine per treatment), male growing lambs, weighing 23.8 ± 3.7 kg, were fed the experimental diets which were treatments consisting of increasing levels of YME (0, 1, 2, and 4% inclusion on a dry matter [DM] basis) during an experimental period of 53 days. The experiment was carried out in a randomized block design, which initial body weight was used as blocking factor and the results were analyzed by orthogonal contrasts (linear, quadratic, and cubic). Yerba mate extract did not change the general health status of the animals; however, inclusions of up to 2% of the extract increased globulins (p = 0.05) and white blood cell count, as segmented neutrophils (p = 0.02) and lymphocytes (p = 0.04). Additionally, inclusion of up to 2% YME increased dry matter intake, final weight gain, total and daily gain (p < 0.05), also tended to increase ribeye area and reduce fat thickness (p < 0.10); however, YME above 2% of inclusion reduced animal productive parameters (p < 0.05). In conclusion, levels up to 2% of YME were beneficial to the health and productive parameters of growing lambs.

This study aimed to assess the influence of lamb finishing systems on zootechnical performance, as well as on carcass and meat quality. The experiment was conducted at the APTA’s experimental farm. Thirty-three lambs were used – both sexes, initial age of 90 ± 3 days, Texel with Santa Inês, each animal being one experimental unit, with 6 males and 5 females per treatment. Treatments consisted of: lambs finished on pasture, in semi-feedlot or in feedlot. The lambs were slaughtered with average live weight of 35 kg. Weight gain and carcass measures were taken by ultrasound. After slaughter, carcass conformation and yield, pH, temperature, color, water retention capacity and tenderness were measured. Animals finished on pasture had lower weight gain, were slaughtered at an older age, with lighter carcass weight, smaller loin area, lower shank compactness index, besides lighter shoulder and shank weights, compared to the other production systems (p < 0.05). There was no difference between the semi-feedlot and the feedlot systems for the assessed characteristics. In conclusion, production systems affect animal performance, as well as carcass and meat quality, especially when it comes to important production aspects, such as slaughter age and yield of premium cuts.

Functional oils are known for their compounds with antioxidant, antimicrobial and anti-inflammatory properties, and are used in ruminant nutrition as alternatives to chemicals in order to improve performance. This study aimed to compare the influence of castor and cashew nut shell oils with pure organic selenium (hydroxy-selenomethionine) plus vitamin E, which are known and well-stablished antioxidants, on the performance traits, shelf life and microbial quality of the meat, physiological functions and oxidative stress control of lambs. Thirty-two Dorper x Santa Ines lambs (initial bodyweight of 22.42 ± 3.9 kg and 60 days of age) were submitted to a diet consisting of Cynodon dactylon hay (6%) and concentrate (94%). The animals were divided into four treatments: control, without additives; functional oils (FO), 0.50 g/kg DM of castor and cashew nut shell oils; hydroxy-selenomethionine and vitamin E (SeE), 0.50 mg/kg of organic selenium and 100 IU/kg DM of vitamin E; FO plus SeE, at the same doses as the other groups. Blood samples were collected after 1, 30 and 53 days on feed. After 54 days, the lambs were slaughtered and rumen health, carcass and meat traits, shelf life, and microbiological quality were evaluated. There were no differences in performance or carcass traits. A higher muscle and serum Se concentration (p < 0.0001), lower lipid peroxidation in meat during display (p < 0.0001), and a lower count of psychrotrophic microorganisms on day 5 were observed in the SeE and FO plus SeE groups. The treatments reduced the counts of Enterobacteriaceae, and Staphylococcus spp. FO animals showed higher GSH-Px activity on day 30, while the peroxidase activity was higher in FO plus SeE animals (p = 0.035). SeE and FO plus SeE animals had lower serum ALT and AST levels. Functional oils improved the microbiological quality of meat. Hydroxy-selenomethionine and vitamin E prevented oxidative stress, lipid peroxidation, and microbial spoilage.