RESUMO
ABSTRACT: The effects of energetic supplementation and mixture vetch (Vica sativa L.) were studied to evaluate the intramuscular fatty acid profile of steers finished on oat (Avena sativa L.) pastures. Eighteen 21-month-old crossbred steers were evaluated. The experiment was carried out in three treatments and six repetitions: oat pasture (OA), oat pasture + vetch (OA + VET), and oat pasture + supplementation (OA + SUP). Supplementation comprised the addition of corn meal at a daily dose of 1% of the animals' body weight. Steers receiving supplementation had higher lipid content in Longissimus lumborum than did those fed with OA + VET (1.25 vs 1.02%), whereas those fed with OA (1.15%) showed intermediate values. Conjugated linoleic acid levels were higher in steers fed OA (0.57%) and OA + SUP (0.59%), whereas the highest amount of omega-3 fatty acids was observed in animals fed OA + VET (3.32%). Pasture-finishing without supplementation resulted in a lower ratio of n-6:n-3 (3.14). Steers finished in oat mixture with vetch showed healthier intramuscular fat than did those finished with cornmeal supplementation; importantly, the higher the amount of PUFAs, the better n-6:n-3 ratio.
RESUMO: Os efeitos da suplementação energética e da ervilhaca (Vica sativa L.) foram estudados para avaliar o perfil de ácidos graxos intramusculares de novilhos terminados em pastagens de aveia (Avena sativa L.). Foram avaliados 18 novilhos mestiços com 21 meses de idade. O experimento foi realizado em três tratamentos e seis repetições: pastagem de aveia (OA), pastagem de aveia + ervilhaca (OA + VET) e pastagem de aveia + suplementação (OA + SUP). A suplementação compreendeu a adição de fubá na dose diária de 1% do peso corporal dos animais. Os novilhos que receberam suplementação apresentaram maior teor lipídico no Longissimus lombar do que aqueles alimentados com OA + VET (1,25 contra 1,02%), enquanto aqueles alimentados com AO (1,15%) apresentaram valores intermediários. Os níveis de ácido linoléico conjugado foram maiores em novilhos alimentados com AO (0,57%) e OA + SUP (0,59%), enquanto a maior quantidade de ácidos graxos ômega-3 foi observada em animais alimentados com OA + VET (3,32%). Animais terminados em pastagens sem suplementação apresentaram menor proporção de n-6: n-3 (3,14). Novilhos terminados em pastagem de aveia com ervilhaca apresentaram gordura intramuscular mais saudável do que aqueles terminados com suplementação de milho moído, uma vez que apresentaram maior quantidade de PUFAs e melhor a relação n-6: n-3.
RESUMO
OBJECTIVE: The aim was to evaluate backgrounding beef steers on oat + ryegrass pastures mixed with vetch and/or using energy supplementation. METHODS: A randomized block design with three treatments and three replications was used. The treatments were: grass + supplement (oat + ryegrass + supplementation), legume + supplement (oat + ryegrass + vetch + supplementation) and grass + legume (oat + ryegrass + vetch). A continuous grazing system with a variable stocking rate was used. Twenty-seven intact crossbred steers (1/4 Marchigiana, 1/4 Aberdeen Angus and 2/4 Nellore) aged 7 months old and average weight of 190 kg were used. Steers were supplemented at 1% of the body weight of ground corn. The experiment lasted 84 days, between May and August 2014. Behavioral assessments were performed two times per experimental period, for 24 hours. RESULTS: The forage mass was different between treatments, being greater for steers fed without legume. The accumulation rate, forage allowance, and stocking rate did not differ between treatments due to the adequate adjustment of forage allowance. The final weight of animals, as well as the dry matter intake (kg/d), did not differ between treatments. However, forage intake was higher for non-supplemented animals in relation to supplemented steers. Supplement intake did not alter the total digestible nutrient intake due to pasture quality. Animals fed grass + supplement had higher live weight gain per area than those fed grass + legume. Animals without supplementation spent more time in grazing. CONCLUSION: Feeding behavior was not altered by mixing with vetch or supplementation. Non-supplemented animals started the grazing peak earlier and spent more time in grazing than those supplemented; however, the average daily gain was similar between treatments. The live weight gain per hectare was 47% higher in pastures in which the animals received supplementation compared with those mixed with vetch, a consequence of the substitutive effect.
