As degradabilidades in situ da matéria seca (MS), matéria orgânica (MO), proteína bruta (PB), fibra em detergente ácido (FDA) e da fibra em detergente neutro (FDN) do caroço de algodão integral (CAI), farelo de soja (FS), grão de girassol (GG), torta de nabo forrageiro (TN) e do milho triturado (MT) foram determinadas com a incubação de sacos de náilon no rúmen de cinco bovinos ½ sangue Simental-Zebu. As degradabilidades efetivas (DE) da matéria seca (MS) e da proteína bruta (PB) a taxa de passagem de

ResumoEste trabalho teve como objetivo avaliar o desempenho e estimar a viabilidade da produção leiteira para vacas em pastejo, suplementadas com rações concentradas contendo teores crescentes de torta de girassol (0; 24; 48 e 72% na MS). Neste estudo foram utilizadas 20 vacas multíparas e primíparas após o pico de lactação distribuídas em quadrado latino tipo 4x4. Os dados da produção leiteira corrigida para 3,5% de gordura demonstraram não haver diferença entre os tratamentos. A produção de leite apresentou efeito linear, verificou-se maior produção para os animais alimentados com rações contendo teores de 24% de torta de girassol e menor produção com 72%. Houve efeito quadrático para o teor de gordura, o tratamento contendo 72% de torta de girassol apresentou ponto de mínimo; entretanto, este último obteve acréscimo no teor de gordura apresentando resultado de 3,98%, em comparação ao controle 3,63%. A estimativa da viabilidade econômica por litro de leite não apresentou diferença (P>0,05), entre os tratamentos, indicando que a torta de girassol é uma boa alternativa à suplementação de vacas lactantes sem acarretar ônus econômico. Neste sentido, verifica-se que a torta de girassol pode ser empregada na suplementação de vacas lactantes até o nível de 72%. Palavras-chave: Agronegócio, biodiesel, co-produtos, leite AbstractThis study aimed to evaluate the performance and estimate the viability of milk production for grazing cows supplemented with concentrate rations containing increasing levels of sunflower cake (0, 24, 48 and 72% DM). In this study were used 20 multiparous and primiparous cows after peak lactation distributed 4x4 Latin Square type. The data corrected milk yield to 3.5% fat showed no difference (P> 0.05) among treatments. Milk production presented linear effect; there was increased production for animals fed rations containing concentrated levels of 24% of sunflower cake and lower production with 72%. The fat content had a quadratic effect, the treatment containing 72% sunflower cake had minimum point; however, the latter had increase in fat presenting result of 3.98% compared to the control, 3.63%. The estimate of the economic viability per liter of milk did not differ (P> 0.05) among treatments, indicating that sunflower cake is a good alternative to lactating cows without causing additional economic burden. In this sense, it is found that the sunflower cake can be employed in supplementing lactating cows until the level of 72%.

The objective of this work was to study the effect of different zinc content (ZnSO 4 ) in the mineral supplementation for Nellore steers grazing Brachiaria brizantha (cv) MG-4, on productive performance and carcass traits. Twenty-eight castrated animals with average body weight of 355 kg, were used. The animals were randomly divided into four groups and housed in paddocks of 6.25 ha each one, equipped with covered feeders and waterers, and grazed alternately each 28 days. The experimental design was completely randomized, with four zinc (Zn) content and seven repetitions. Different zinc content were: Zn-0, without Zn; Zn-2, with 2,000 mg Zn kg -1 ; Zn-4, with 4,000 mg Zn kg -1 ; and Zn-6, with 6,000 mg Zn kg -1 ; in the inorganic form (Zinc Sulphate) in mineral supplement. Mineral supplements were given ad libitum in covered troughs and previously weighed, with leftovers control for determining intake. The experimental period was 370 days. Organs, viscera, carcass and non-carcass components were weighed from each slaughtered animal. Loin eye area (LEA) and subcutaneous fat thickness (SFAT), as well as, color, pH and lipid oxidation, were evaluated. The increasing inclusion of zinc content in the diet of steers do not affected (P>0.05) final body weight (FBW) and average daily weight gain (ADWG). Difference (P < 0.05) was observed in the Zn intake (ZnI) (Ŷ = -2.09386 + 146.9616x; R 2 = 0.99) and hot carcass weight (Ŷ= 299.92662 + 3.33362x; R 2 = 0.24), as well as, in meat lipid oxidation (Ŷ = 0.15170 + 0.02539x; R 2 = 0.31). There was an increasing linear effect for meat color, evaluated by values of L* (luminosity) (Ŷ = 32.23309 + 0.41445x, R 2 = 0.14), a* (red-green intensity) (Ŷ = 0.88592 + 18.16225x, R 2 = 0.25) and b* (yellow-blue intensity) (Ŷ = 9.35295 + 0.45030x, R 2 = 0.20), but remained within normal values for meat. It can be concluded that beef cattle grazing Brachiaria brizantha MG-4, and supplemented with different zinc contents in mineral supplements, supplied ad libitum, do not show changes in weight gain, carcass yield, physical carcass composition, as well as, in non-carcass components, but the Zn content has a positive linear influence on hot carcass weight, without causing changes in absolute and relative weights of organs and viscera. Key words: Intake. Non-carcass component. Organs and viscera. Ruminants. Weight gain. ResumoObjetivou-se estudar o efeito de diferentes teores de Zinco na suplementação mineral de novilhos Nelore em pastagem de Brachiaria brizantha cultivar (cv) MG-4, sobre o desempenho produtivo e características de carcaça. Foram utilizados 28 animais, castrados, com peso vivo médio inicial de 355 kg. Os animais foram divididos ao acaso em quatro grupos e alojados em piquetes de 6,25 hectares cada, equipados com comedouro coberto e bebedouros, sendo pastejados alternadamente a cada pesagem (28 dias). O delineamento experimental foi inteiramente casualizado, com quatro dosagens de zinco (Zn) no suplemento mineral e sete repetições. As doses de zinco avaliadas foram: Zn-...