Alexandro Pereira Andrade

Avaliação bioeconômica de estratégias de suplementação de novilhos zebuínos mantidos em pastagens diferidas de capim-marandu no período seco

The objective of this work was to evaluate different supplementation strategies on supplement intake, behavior, and performance of beef steers grazing stockpiled palisade grass (Urochloa brizantha cv. Marandu) pastures. There was used a completely randomized design trial to test five supplementation strategies: commercial mineral (SM), mineral plus25% of urea (SP), and three multimixtures (45.5% TDN) with 10% (MM10), 15% (MM 15), or 20% (MM20) of urea. Twenty zebuine steers weighting 300±24.9 kg of initial body weight, being four animals per treatment, were raised on five paddocks of 3.4 hectares under weekly rotation, from July to October of 2010. Data were submitted to ANOVA, using Tukey′s test to compare average values (P≤0.05); however, economic analysis determined the best strategy. Supplementation did not affect the grazing or rumination/resting time (P>0.05). The intake of supplements was affected (P<0.05) by supplementation strategy, being 106, 196, 852, 666, and 400 g/day for SM, SP, MM10, MM15, and MM20, respectively. SM resulted in losing weight (-137 g/animal/day). Using SP practically maintained the cattle weight. However, if gains are desired, multimixtures should be used (P<0.05). In those cases, daily weight gain reached 324 g/animal (MM10). Based on economic analysis, the best strategy was MM20, followed by MM10.

Chemical-nutritional composition of maniçoba ( Manihot sp.) and its relationship with soil chemical characteristics

The objective of this study was to evaluate the chemical composition of leaves of manicoba (Manihot sp.) according to their development stage and their relationship with the soil characteristics. For this purpose, plants in their natural growth areas in the semiarid region of Paraiba State, Brazil, were sampled. Leaves of manicoba collected in five different locations at four different development stages were harvested and characterized: expanding leaf, completely expanded leaf, leaf at the beginning of senescence and a pool (mixture of all leaves). The evaluated traits were: dry matter, crude protein, neutral detergent fiber, acid detergent fiber, neutral detergent insoluble protein, acid detergent insoluble protein, ash, lignin, cellulose, hemicellulose, nitrogen, potassium, phosphorus, sulfur and sodium. The experimental design adopted was completely randomized, in a 4 × 5 factorial arrangement: four leaf development stages and five locations, respectively; each plot had 10 replications. There was interaction effect between leaf development stage and locations on dry matter, crude protein, neutral detergent insoluble protein and acid detergent insoluble protein. The results for neutral detergent fiber of leaves at the beginning of senescence were higher than other treatments and similar to the pool, while the acid detergent fiber content of the leaves in early senescence was higher than those of other treatments, averaging 34.8%. Crude protein content had its highest percentage in expanding leaves, averaging 23.0%. Nitrogen, potassium and sodium data showed interaction between the leaf types and locations of harvest, while phosphorus and sulfur did not show interaction. The chemical and mineral composition of manicoba leaves range according to their development phase and according to their soil and climatic conditions in places of natural occurrence, with a tendency towards reduction of nitrogen and phosphorus as they approach senescence.

Estudo comparativo de metodologias para a determinação do pH em silagens de capim com aditivos seco e nutritivo

O objetivo deste trabalho foi comparar metodologias para a determinacao do pH de silagem de capim-elefante (Pennisetum purpureum) segundo procedimentos descritos na literatura cientifica. Foi utilizada silagem de capim-elefante exclusivo e aditivado com casquinha de soja (5% e 10%) e fuba de milho (5%e 10%) de forma isolada ou conjunta nas mesmas proporcoes totalizando 5% e 10%. Utilizou-se o delineamento em esquema de parcela subsubdividida para verificar o efeito das metodologias em relacao aos tratamentos e ao tempo de abertura. Foram utilizados silos experimentais constituidos de baldes plasticos de 20 L com tampa. Apos 7, 14 e 28 dias de ensilagem, os silos foram abertos, a silagem foi homogeneizada,retirando-se uma aliquota para a leitura do pH. Houve interacao entre os tratamentos e as metodologias sobre os tempos de abertura. A adicao 5% e 10% de casquinha de soja resultou em valores maiores de pH nos diferentes tempos de abertura. Nao houve efeito da interacao entre os tratamentos e as metodologias utilizadas. A metodologia empregada para a determinacao de pH de silagem alterou os resultados, evidenciando que e necessario constante aperfeicoamento das metodologias.