Theme 2-2: Forage Production and Utilization--Poster Sessions
Description
We aimed at evaluating the microclimate, canopy structure, and grazing behaviour of cattle on Brachiaria sp. pastures within continuous pasture (CON), integrated crop-livestock (ICL), and crop-livestock-forestry (ICLF) systems in Brazilian dry season. Forage accumulation was monthly assessed in four paddocks per system from May to August 2019. To characterize the microclimate, air temperature and relative humidity were measured every hour and temperature-humidity index calculated. Grazing behaviour of 12 Nellore heifers per system (mean bodyweight 355 standard deviation±32.6 kg) was recorded by chewing sensors on nine continuous days (1 d adaptation + 8 d measurement) of three 15-d periods. Four animals per system were evaluated per period (n=3 systems x 3 animals x 3 periods x 8 d). Data were analysed by mixed model using SAS v9.4. Statistical significances were tested at P< 0.05. Across the whole dry season, heifers were exposed to 343 hours of moderate heat stress and 76 hours of severe heat stress in CON and ICL. Instead, 342 hours of moderate heat stress but no severe heat stress conditions were observed in ICLF. Forage accumulation rate was greater in CON than ICLF, with no differences between ICLF and ICL. There were no differences between the systems for proportions of green leaf and dead plant material, although dead material accounted for 73% of total forage biomass on dry matter basis. Pasture in ICL was taller and had greater stem proportion than CON and ICLF. Forage canopy structure likely reduced bite mass in CON and ICL. As a compensatory mechanism, heifers in CON and ICL increased their number of grazing bites and prolonged their daily grazing time (in CON) as compared to animals in ICLF. In summary, under conditions of Brazilian dry season, grazing behaviour of Nellore heifers seems to be more influenced by canopy structure than by microclimatic factors.
Included in
Forage Production and Grazing Behaviour of Beef Cattle in Agrosilvopastoral Systems in Brazil during the Dry Season
We aimed at evaluating the microclimate, canopy structure, and grazing behaviour of cattle on Brachiaria sp. pastures within continuous pasture (CON), integrated crop-livestock (ICL), and crop-livestock-forestry (ICLF) systems in Brazilian dry season. Forage accumulation was monthly assessed in four paddocks per system from May to August 2019. To characterize the microclimate, air temperature and relative humidity were measured every hour and temperature-humidity index calculated. Grazing behaviour of 12 Nellore heifers per system (mean bodyweight 355 standard deviation±32.6 kg) was recorded by chewing sensors on nine continuous days (1 d adaptation + 8 d measurement) of three 15-d periods. Four animals per system were evaluated per period (n=3 systems x 3 animals x 3 periods x 8 d). Data were analysed by mixed model using SAS v9.4. Statistical significances were tested at P< 0.05. Across the whole dry season, heifers were exposed to 343 hours of moderate heat stress and 76 hours of severe heat stress in CON and ICL. Instead, 342 hours of moderate heat stress but no severe heat stress conditions were observed in ICLF. Forage accumulation rate was greater in CON than ICLF, with no differences between ICLF and ICL. There were no differences between the systems for proportions of green leaf and dead plant material, although dead material accounted for 73% of total forage biomass on dry matter basis. Pasture in ICL was taller and had greater stem proportion than CON and ICLF. Forage canopy structure likely reduced bite mass in CON and ICL. As a compensatory mechanism, heifers in CON and ICL increased their number of grazing bites and prolonged their daily grazing time (in CON) as compared to animals in ICLF. In summary, under conditions of Brazilian dry season, grazing behaviour of Nellore heifers seems to be more influenced by canopy structure than by microclimatic factors.
