The effects of stem density of tropical swards and age of grazing cattle on their foraging behaviour

Abstract

The effects of stem density of tropical swards and age of cattle on their foraging behaviour were evaluated using artificial microswards, consisting of leaves of 20 cm in height and high tensile-resisting stems of 25 cm in height of Panicum maximum. The treatments consisted of a factorial combination of four stem densities of swards (0, 100, 200 and 400 stems m )2 ) and two ages of cattle (1-and 3-year-old steers). There was a significant interaction between stem density of sward and age of cattle for bite area (BA), bite mass (BM) and instantaneous intake rate (IIR). Stem density had a significant negative effect on these variables describing ingestive behaviour which was particularly strong for older steers. In leaf-only swards, mature cattle achieved a much greater BA (106AE5 vs. 57AE9 cm 2 ), BM (0AE88 vs. 0AE47 g DM) and IIR (46AE9 vs. 17AE2 g DM min )1 ) than did young cattle. However, these variables were very similar across ages of cattle at the highest stem density of sward. These results show the importance of the high tensile-resisting stems as deterrents of the grazing process in tropical pastures, particularly in older cattle.

Forage mass and morphological composition of Marandu palisade grass pasture under rest periods

“…Thus, a significant increase in the mass of the residual forage between the third and fourth grazing cycles of the RP30 treatment was observed, thereby revealing the damage that was caused by stems in the use of forage. Benvenutti, Gordon and Poppi (2008) observed that with increasing stem densities, there is a restriction in the bite size and a consequent reduction in the instantaneous intake by 1 and 3-year-old steers.…”

“…This finding confirms the hypothesis that the increase in forage mass in response to the grazing interval is primarily a result of the increased stem biomass (Alexandrino et al, 2005). A high proportion of stem and dead forage in the forage mass hinders the forage apprehension capacity and hence the grazing efficiency, thereby decreasing the voluntary intake of grazing animals (Difante et al, 2011;Benvenutti et al, 2008;Brancio et al, 2003).…”

“…However, the evaluation of the productive potential is not the only factor that can be used to determine the grazing management efficiency, given that it is also necessary to know the structural characteristics of the canopy, which affects the feeding behavior (Benvenutti;Gordon;Poppi, 2008) and the efficiency with which forage is used (Pereira et al, 2015).…”

Effect of planting pattern of forage sorghum on forage productivity and heifer performance during finishing phase

“…The decreased participation of leaf blade of forage sorghum in the total forage mass reflects the preferential consumption of leaves by the animals when compared to other plant parts (FONSECA et al, 2013) due to the lower bromatological quality of the stems in relation to leaves (BENVENUTTI et al, 2008). As the cycle advances and the photoperiod decreases, the plants tend to flower differentiation, decreasing the leaf appearance rate, which is lower compared to the consumption of leaves, reflecting the decrease in mass and leaf supply.…”

Características do pasto e eficiência agronômica de nitrogênio em capim-tanzânia sob pastejo contínuo, adubado com doses de nitrogênio

“…BURNS et al (1989) destacam que, sob pastejo, as massas de forragem e folha verde podem alterar o desempenho individual dos animais e a taxa de crescimento do pasto. Em pastos artifi ciais de Panicum maximum, o comportamento seletivo de pastejo de bovinos variou de acordo com a resistência à preensão dos colmos (BENVENUTTI et al, 2008). Estudos mostram que, em pastagens de capimtanzânia sob pastejo contínuo, durante a estação do inverno, a altura do pasto pode alterar características do pasto (CANTO et al, 2001) e, em consequência, o desempenho de novilhos de corte (CANTO et al, 2002).…”