Impact of increasing levels of spineless-cactus meal on the ingestive behaviour of grazing steers

Abstract

The objective of this study was to evaluate the effect of different levels of spineless-cactus meal substituting for maize in diets for supplemented steers grazing on Urochoa brizantha during the postweaning phase. The experiment was conducted on Princesa do Mateiro farm, located in Ribeirão do Largo-BA, Brazil. Forty crossbred steers with an average body weight of 261 ± 7.46 kg were distributed into four groups for evaluation of the following four levels of substitution of ground maize for spinelesscactus meal: 0.00, 30.00, 60.00, and 90.00%. The results were analysed statistically by variance and regression analyses at a 5% error probability. Increasing the amount of spineless-cactus meal in the diet had a quadratic effect on the grazing time and on the time spent on other activities. The diet had a quadratic effect on the number of grazing periods, the number of periods at the trough, and the total feeding and chewing times. In contrast, the number of periods spent on other activities and on rumination was not influenced by the level of spineless-cactus meal. The bite rate, number of bites per swallow, and number of bites per day increased linearly, whereas the swallowing time and number of cuds ruminated per day decreased as the level of spineless-cactus meal added to the diet wasincreased. The feed and rumination efficiencies of dry matter, neutral detergent fibre, crude protein, and non-fibre carbohydrates were not influenced by the level of substitution of spineless-cactus meal for ground maize. Spinelesscactus meal levels close to 60% probably provided greater fibre degradation, leading the animals to spend more time on social interactions with the group, use the feed better, and possibly have a better feed conversion.