Sward structure and ingestive behavior of cows in tropical pastures managed under different forage allowances

Abstract

This study evaluated how changing the structure of Brachiaria brizantha cv. Marandu pasture under different forage allowances (FA) of 4, 7, 10 and 13kg DM/100kg BW (body weight) affected animal behavior over a two-year evaluation period. The experiment was conducted as a randomized block design with three replications (paddock). Sward height, total forage, and stem mass were lower for pastures managed with lower FA. Lower leaf mass was observed for lower FA in the second year. In hand-plucked samples, leaf and stem percentages remained unchanged in the morning but leaf percentage increased while stems decreased in the afternoon. Permanence time decreased linearly with increasing FA. In turn, a quadratic effect was observed for displacement rate. The bite rate was similar among different FAs. The results demonstrate that FA varying between 7 and 10kg DM/100kg BW are more suitable to balance the amounts of leaves and stems in the sward. The studied FA levels do not limit forage availability. Permanence time decreases and displacement rate increases as FA increases.Keywords: bite rate, displacement, forage mass, sward height RESUMOO objetivo foi avaliar como mudanças na estrutura de pastos de Brachiaria brizantha cv. Marandu, sob diferentes ofertas de forragem (OF) de 4, 7, 10 e 13kg MS/100kg PC, afetam o comportamento animal durante um período de avaliação de dois anos. O delineamento utilizado foi em blocos ao acaso, com três repetições (piquetes). A altura do dossel, a massa de forragem total e de colmos foram menores em pastos manejados com menores OF. A menor massa de folhas foi observada na menor OF no segundo ano. Nas amostras de pastejo simulado, as porcentagens de folhas e colmos não diferiram pela manhã, mas a porcentagem de folhas aumentou, enquanto a de colmos diminuiu à tarde. O tempo de permanência dos animais diminuiu linearmente com o aumento das OF. Efeito quadrático foi observado para taxa de deslocamento. A taxa de bocados foi similar entre as OF. Os resultados demonstram que variar as OF entre 7 e 10kg MS/100kg PC é mais adequado para balancear as quantidades de folhas e colmos no dossel forrageiro. Os níveis de OF estudados não limitam a forragem disponível. O tempo de permanência diminuí e a taxa de deslocamento aumenta com o aumento das OF.Palavras-chave: altura, deslocamento, massa de forragem, taxa de bocados

Forage availability and weight gain of goats on caatinga enriched with Urochloa trichopus (Hochst.) Stapf subjected to fallowing and fertilized with phosphate

“…Santos et al (7) argued that the fallowing leads to the accumulation of mature stems and dead material and a decrease in the availability of leaves, with a consequent reduction in animal consumption and performance. Pastures managed at different heights provide different forage masses, interfering with the availability and accessibility of pastures to animals, affecting intake by grazing animals and the animal (30,31) . On the other hand, the botanical composition of the diet for goats, sheep and cattle in the caatinga tends to adjust to the frequency, availability and supply of dry matter (35) , with emphasis on species with better nutritional value (36,37) , especially in protein (38) .…”