Brachiara decumbens is widely used as a forage in tropical regions.
Signal grass is palatable during vegetative growth, but coarse and stemmy growth is not well accepted by livestock (Loch, 1977).
Reported values for in vivo and in vitro DM and OM digestibility show huge variations. For instance in vivo DM digestibility ranges from 54 to 82% (the latter for a 14-day old forage) depending on the stage of maturity and other factors (Loch, 1977). Used at pasture in Guyana in a 3 year trial, DM yields, digestibility, OM digestibility and N content of Brachiaria decumbens were higher than those of Digitaria swazilandensis (Xandé et al., 1977). In India, Murah buffalo heifers fed ad libitum with chopped Brachiaria decumbens, had a higher digestibilty of nutrients for Brachiaria decumbens (pre-flowering) compared to Megathyrsus maximus (Sanjiv et al., 1998).
In Brazil, increasing the daily pasture allowance for dairy cows grazing signal grass from 4 or 8% (DM) f the liveweight did not affect milk production and forage intake (Gomide et al., 2001). In Colombia, in Holstein and crossbred dairy cows grazing a Brachiaria decumbens pasture, controlled access during 1 or 2 h after each milking to 2 forage legumes (Centrosema macrocarpum or Centrosema acutifolium) did not increase milk yields, milk fat, nonfat solids and protein levels, but there was a tendency to higher milk production for crossbred cows in the 1st month of lactation, which did not persist (Mosquera et al., 1992).
Most studies on signal grass have been conducted on grazing beef cattle in South America, particularly in Brazil and Colombia.
In grazing conditions, Brachiaria species are an important grass for cattle production in Brazil. And while satisfying performances have been reported for Brachiaria decumbens, different strategies have been studied to improve performance, i.e. the availability of forage, supplementation or legume use.
Supplementation of signal grass pasture is usually favourable. In Holstein-Friesian/zebu heifers grazing signal grass pastures, preliminary supplementation with cottonseed meal had no effect on initial liveweight, final liveweight, average daily gain and pregnancy rate. DM intake was influenced by previous supplementation, but the effect has decreased during the grazing periods (Cavalcanti Filho et al., 2004). In finishing Nellore steers grazing signal grass pastures, supplementation with cottonseed meal mixed with soybean hulls gave better performance (carcass weight and yield) than cottonseed meal mixed with maize grain or citrus pulp (Andrade et al., 2015). In growing steers, supplementation at 0.8% LW with a mixture of maize grain, whole soybeans, soybean hulls and cottonseed meal reduced forage intake and grazing time while increasing daily weight gain (Garcia et al., 2014). In crossbred steers growing on pastures of Brachiaria decumbens in the wet season, supplements such as ground maize grains, maize ears and cobs, ground sorghum all increased performance, though maize ears and cobs was the most efficient (Paulino et al., 2005). In young Limousin-Nelore bulls, supplementation with a mixture of mineral complex, urea and combinations of cracked maize, soybean meal and wheat bran increased DM intake, DM digestibility and average daily gains compared to animals supplemented with a mineral complex only (Santos et al., 2004a). Growing steers supplemented with a mixture of cottonseed meal with either maize and cob with husks, cassava meal or soybean hulls did not show differences in performance, but cassava meal resulted in the best economic efficiency (Garcia et al., 2004) . Some studies about supplementation have been less positive. Santa Gertrudis calves grazing on Brachiaria decumbens supplemented with a mixture based on soybean meal showed a significantly higher average daily gain in the dry season, but not during the wet season (Coutinho Filho et al., 2005).
Supplements may help to compensate specific deficiencies that occurs when grazing Brachiaria decumbens. When crossbred dairy calves reared on a sulfur-deficient pasture of Brachiaria decumbens were fed a basal-supplement mixture containing minerals, urea and maize with or without sulfur, the sulfur-supplemented calves had a higher weight and a better body condition score than unsupplemented calves, which exhibited a loss of weight and body condition, retarded growth,and slight apathy (Ortolani, 2001).
Holstein-Zebu dairy heifers grazing on deferred pastures of signal grass gained weight when the deferral period lasted 95 days and lost weight when the deferral lasted 140 days (Teixeira et al., 2014).
In growing Zebu and Zebu x San Martinero bulls, supplementation with sugarcane and the forage legume Cratylia argentea
gave better weight gains where animals were grazing fertilized signal grass than when they were supplemented in a corral. Grazing animals also gave better results with supplementation than without (Rincon, 2005
). In Romo and Zebu x Romo steers, pastures of mulato grass (Brachiaria ruziziensis
x Brachiaria brizantha
) gave higher DM yields and allowed higher meat yield and weight gains than pastures of Brachiaria decumbens
(Cuadrado et al., 2005
In steers, a comparison of diets containg signal grass hay mixed with soybean meal with diets containing signal grass hay treated with either NH3 or urea concluded that NH3 and urea treatments were not economically viable (Fernandes et al., 2002).
In Brazil, Nelore cows grazing Brachiaria decumbens pastures (on a soil improved with limestone and fertilizer) with free access to a mineral mixture maintained high reproductive (pregnancy, calving and weaning rates) and productivity (weight of calves per ha) performance on during four years (Vieira et al., 2005).
In Brazil, giving whole cottonseeds (up to 49% dietary level) to sheep fed a basic diet of Brachiaria decumbens hay did not affect NDF digestibility (Teixeira et al., 2005).