Interpretive Summary: Beef cattle responses to pre-grazing sward height and low level of energy supplementation on tropical pastures
By: Anne Wallace
Marandu Palasade grass (Brachiaria brizantha Stapf. cv. Marandu) is a tropical grass often used for livestock grazing or fodder. However, the performance of cattle grazing on tropical grasses may be poorer than desired due to an undesired reduced energy intake. Therefore, ways to maximize the energy intake of grazing cattle on tropical pastures is desired.
In this June 2020 Journal of Animal Science research paper, authors studied how pre-grazing sward height of Marandu Palisade grass and energy supplementation affected the behavior, nutrient intake, digestion and metabolism of grazing cattle.
Cattle were fed either no energy supplement or an energy supplement made from ground corn. Two pre-grazing sward heights (25 and 35 cm) were also evaluated. With the 25 cm pre-grazing sward height, energy intake and harvesting efficiency improved. Cattle also appeared less stressed by spending less time grazing and more time resting. Rumen fluid analysis suggested improved nutrient digestion with the 25 cm pre-grazing sward height. Feeding of an energy supplement did not show any benefit to performance.
This study strongly supports a 25 cm pre-grazing sward height of Marandu Palasade grass for cattle in tropical pastures. This pre-grazing sward height improved both cattle nutrient intake and nutrient digestibility, compared to the 35 cm pre-grazing sward height. Although there was no significant benefit of energy supplementation on the energy intake of cattle in this study, the authors suggest future studies with increased energy supplementation. Overall, this study shows that sward pre-grazing height has profound effects on the performance of cattle. Further studies evaluating the effects of increased energy supplementation or enzyme supplements that may help to maximize the performance of cattle grazing on Marandu Palasade grass is justified.