Composição nutricional da inflorescência e índice de seletividade por ovinos em pasto diferido

Abstract

Sheep are very selective animals, in deferred pasture areas these animals are expected to make intense selection for more nutritious parts of the plant, such as live leaves. However, it has been observed in deferred grass grazing by sheep that these animals tend to select the inflorescence of the plants, more preferably by the seeds. However, the chemical composition of these structures is not known, therefore it is necessary to know how the sheep selects the deferred pasture, through the determination of the selectivity index, as well as obtaining the nutritional information of the Brachiaria brizantha cv. Marandu grass inflorescence. Thus, the objective of this study was to determine the selectivity index in sheep, as well as the chemical composition of inflorescence in deferred pastures of grass Brachiaria brizantha cv. Marandu. An experiment will be conducted with twenty-four male, intact sheep, ½ Dorper x ½ Santa Inês, with an average body weight of 17 kg. The animals will be kept in twelve grass paddock Brachiaria brizantha cv. Marandu, which will be submitted to three grazing strategies at the beginning of the deferment period: 1) maintenance of the grass with 15 cm during three months before the start of the deferment period; 2) maintenance of the grass with 25 cm for three months, but at the beginning of the deferment period the grass will be lowered to 15 cm; and 3) maintenance of the grass with 35 cm for three months until the start date of the deferment period, when the grass will be lowered to 15 cm. The parameters evaluated will be: forage mass, apparent selectivity index of dry matter, crude protein and neutral detergent soluble fiber (NDF) and chemical bromatological composition of the whole inflorescence of marandu grass and its fractions (rachis and seeds).