Ingestive behavior of Girolando steers supplemented on tropical pastures.

In this study, we evaluated the feeding behavior of Girolando steers on Brachiaria brizantha cultivar Marandu pastures. Twenty-two animals with an average initial weight of 209.09 ± 8.18 kg were distributed in a completely randomized design in a 3 × 2 factorial arrangement (three seasons and two nutritional plans (NP)) with 11 replicates, as follows: rainy season 1 (NP1, mineral mixture ad libitum, and NP2, nitrogen/energy supplement [2 g.kg‒1 body weight [BW]]); dry season (NP1, nitrogen/energy supplement [1 g.kg‒1 BW], and NP2, nitrogen/energy supplement [2 g.kg‒1 BW]); and rainy season 2 (NP1, mineral mixture ad libitum, and NP2, nitrogen/energy supplement ([1 g.kg‒1 BW]). Total chewing time was longer in NP1 (566.44 vs 528.33 min.day‒1 in NP2) (p < 0.05). The grazing, idle, trough, and total chewing times were affected by the interaction between nutritional plans and seasons. The period expended grazing was longer for the NP1. The idle time was affected by the nutritional plans and was lower for the NP1. Feeding at the trough was not affected by the nutritional plans. The animals of the NP2 showed the highest feed efficiencies in DM and NDF (0.91 and 0.52 vs 0.75 and 0.45 in NP1, respectively). Rainy season 2 had the highest efficiencies. The feeding behavior changes according to the supplementation level. Nutritional plan 2 in the second rainy season presented the best results.

Physicochemical characterization and lipid profile of meat from crossbred / Caracterização físico-química e perfil lipídico da carne de novilhos mestiços recebendo diferentes suplementações

ABSTRACT: The aim of this study was to evaluate the carcass characteristics and the physicochemical parameters, centesimal composition, and fatty acid profile of the longissimus lumborum muscle of crossbred steers on a Brachiaria (Syn. Uruchloa) brizantha cv. Marandu pasture during the growing and finishing phases. Twenty-two uncastrated steers ½ Holstein/Zebu, with an average initial weight of 210 kg ± 8.2 kg and eight months of age, were distributed in a completely randomized design, in which the experimental period was fractionated in to three seasons associated with two nutritional plans (NP1 and NP2) and 11 animals by treatment: NP1- mineral mixture ad libitum in rainy seasons + nitrogen/energy supplement at 1 g.kg-1 body weight (BW) in the dry season; and NP2 - nitrogen/energy supplement at 2 g.kg-1 BW in rainy season 1 and in the dry season + nitrogen/energy supplement at 1 g.kg-1 BW in rainy season 2, provided daily at 1000 h. Of the carcass measurements, differences were only observed (p>0.05) between the nutritional plans for loin-eye area corrected for 100 kg of hot carcass weight. Among the physicochemical parameters, only shear force was influenced (p>0.05) by the treatments, with higher values obtained in Nutritional Plan 1. The centesimal composition and fatty acid profile were not influenced (P<0.05) by supplementation. Nutritional plans used in the growing and finishing phases involving low levels of protein-energy supplementation do not lead to changes significant in carcass characteristics and meat. Nutritional Plan 1 is the most appropriate because it presents a lower cost.

RESUMO: Objetivou-se avaliar as características da carcaça, parâmetros físico-químicos, composição centesimal e perfil de ácidos graxos do músculo Longissimus lomborum de novilhos mestiços em pastagem de Brachiaria (Syn. Uruchloa) brizantha cv. Marandu, durante as fases de recria e terminação. Foram utilizados 22 novilhos (½ Holandês e ½ Zebu) não castrados, com peso inicial médio 210 kg ± 8,2 kg e oito meses de idade, distribuídos em delineamento inteiramente casualisado, com período experimental dividido em três estações, associada com 2 planos nutricionais (PN1 e PN2) e 11 animais por tratamento: PN1 (mistura mineral ad libitum nas estações chuvosas (EC) e suplemento nitrogenado/energético na quantidade de 1 g.kg-1 do peso corporal (PC) na estação seca) e PN2 (suplemento nitrogenado/energético de 2 g.kg-1 PC nas EC 1 e na seca, e suplemento nitrogenado/energético na quantidade de 1 g.kg-1 PC na EC 2) fornecidos diariamente às 10:00h. Para as características de carcaça foi observado diferença (p>0,05) entre os planos nutricionais, apenas para área de olho de lombo corrigida para 100 kg de peso de carcaça quente. Para os parâmetros físico-químicos apenas a força de cisalhamento foi influenciada pelos tratamentos (P>0,05) e foi maior para o plano nutricional 1. A composição centesimal e o perfil de ácidos graxos, não foram influenciados (p<0,05) pela suplementação. Planos nutricionais de recria e terminação com baixos níveis de suplementação proteico-energética não promove alterações significativas nas características da carcaça e da carne. O plano nutricional 1 é o mais indicado porque apresenta menor custo.