Forage intake processes by goats on a massai grass pasture with different sward heights

Abstract

The objective of this study was to evaluate the forage-intake process of goats feeding on Massai grass pastures with different heights (40, 50, 60, and 70 cm). The experimental design was completely randomized, with treatments corresponding to four sward heights with two replicates over time and space. Collected data were related to the forage-intake process and the chemical and morphological composition of the pasture. Grazing trials (45 min) were performed with four Anglo-Nubian crossbred goats. Total forage mass intake, bite mass, and intake rate were expressed in relation to animal weight. Pasture density, forage mass, and leaf blade increased as forage height increased. The chemical composition of forage at the evaluated heights was similar, except for reduced crude protein content at 70-cm height. Bite rate, intake rate, and time per bite had a quadratic relationship with increasing sward height. The greatest intake rate was observed at 54.7 cm of height, with 0.136 g DM min -1 kg -1 LW. Bite rate exhibited a linear and positive correlation with increase in intake. At the 50-cm height, goats harvested a mass of 3.65 g DM bite -1 kg -1 LW, when they performed 34.5 bites per minute. Adult goats had a greater forage intake on 50-cm high Massai grass pastures because they could obtain a greater bite mass in a shorter time per bite. Key words: Bite mass. Bite rate. Intake rate. Intake. ResumoObjetivou-se avaliar os processos de ingestão de forragem por caprinos em pastagem com capimMassai manejado sob diferentes alturas (40, 50, 60 casualizado. Os tratamentos corresponderam a quatro alturas do dossel com duas repetições no tempo e no espaço. Os dados coletados foram relacionados aos processos de ingestão de forragem e composição química e morfológica do pasto. Foram realizados testes de pastejo de 45 minutos com quatro cabras mestiças da raça Anglonubiana. A massa de forragem total consumida, massa de bocados e a taxa de ingestão foram expressos em relação ao peso dos animais. Com o incremento da altura da forragem houve aumento na densidade do pasto, massa de forragem e lâmina foliar. A composição química da forragem nas alturas avaliadas foi semelhante, com exceção da redução do teor de proteína bruta aos 70 cm. A taxa de bocado, taxa de ingestão e tempo por bocado apresentou relação quadrática com o aumento da altura. A maior taxa de ingestão foi observada aos 54,7 cm de altura, com 0,136 g MS min -1 kg -1 de PC. A massa de bocado apresentou relação linear e positiva com o aumento da altura. Aos 50 cm as cabras colheram uma massa de 3,65 g MS bocado -1 kg -1 PC, quando realizavam 34,5 bocados por minuto. No pasto de capim-massai aos 50 cm ocorre maior consumo de forragem por cabras adultas, pois os animais conseguem obter uma massa maior do bocado em menor tempo por bocado. Palavras-chave: Consumo. Massa do bocado. Taxa de ingestão. Taxa de bocado.

Effect of stocking rate on grazing behaviour and diet selection of goats on cultivated pasture

“…Rodrigues et al . (2016) reported that bite rate exhibited a linear and positive correlation with intake. However, the increase of eating time and number of bites could not compensate completely.…”

“…Goats could adjust eating time, bites/step and bite rate to obtain the require intake after the reduction in bite weight. Rodrigues et al (2016) reported that bite rate exhibited a linear and positive correlation with intake. However, the increase of eating time and number of bites could not compensate completely.…”