Abstract
New highly productive guineagrass (Megathyrsus maximus syn. Panicum maximum) cultivars have been released in Brazil and grazing trials are necessary to evaluate their carrying capacity and forage quality. The objective of this study was to evaluate the liveweight gains of young Nellore bulls grazing 3 guineagrass cultivars under rotational stocking. The experiment was carried out in Planaltina (Federal District, Brazil) during a single rainy (November‒April) and dry (May‒August) season. Treatments were Massai (control), BRS Tamani and BRS Zuri cultivars. Zuri and Tamani pastures provided greater average daily liveweight gains (ADG) (0.38 and 0.42 kg/head, respectively) over the experimental period than Massai (0.28 kg/head). For all cultivars liveweight gains decreased markedly from May onwards at the beginning of the dry season. Nevertheless, bulls grazing Tamani and Zuri pastures still gained 0.20 kg/hd/d until late August, while those on Massai pastures gained only 0.08 kg/hd/d. The differences in ADGs can be explained to some extent by differences in quality of available forage. In vitro dry matter digestibility of plucked samples of Massai was 555 g/kg, compared with 621 g/kg for Tamani and 590 g/kg for Zuri. Crude protein concentration in plucked samples was also greater for Tamani and Zuri (71.9 and 74.2 g/kg, respectively) than for Massai (62.2 g/kg). As feed wastage was particularly high in Massai, further studies are needed to verify if higher stocking rates during the wet season could result in greater production of live weight per ha on this cultivar, assuming that ADG does not decrease further with the increased stocking rate.
Highlights
There is an increasing demand for highly productive forage species for the Brazilian savannas (‘Cerrados’), owing to the growing intensification of livestock and agricultural systems
Panicum maximum) is recommended for regions with annual rainfall of 800‒1,800 mm on well-drained soils with medium-high fertility (Muir and Jank 2004). This species produces around 21 t DM/ha of forage per year in the Cerrados (Fernandes et al 2014), almost all during the rainy season
Massai and Tamani are small leafy guineagrass cultivars released by Embrapa (Brazilian Agricultural Research Corporation)
Summary
There is an increasing demand for highly productive forage species for the Brazilian savannas (‘Cerrados’), owing to the growing intensification of livestock and agricultural systems. Panicum maximum) is recommended for regions with annual rainfall of 800‒1,800 mm on well-drained soils with medium-high fertility (Muir and Jank 2004). This species produces around 21 t DM/ha of forage per year in the Cerrados (Fernandes et al 2014), almost all during the rainy season. Massai and Tamani are small leafy guineagrass cultivars released by Embrapa (Brazilian Agricultural Research Corporation). The cultivar Zuri was released by Embrapa in 2014, and in contrast with Massai and Tamani, is a tall tufted guineagrass, and is resistant to leaf spot disease (Bipolaris maydis). Zuri and Massai were developed from accessions collected by ORSTOM (Office de la recherche scientifique et technique outre-mer, France) in East African savannas during the 1960s, and designated at the time as T65 and T21, respectively
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