Pinto peanut is a good forage supplement for ruminants fed on low quality tropical grasses due to its high protein content. Pinto peanut is widely used in tropical grazing systems for ruminants in South and Central America, in mixed swards in association with grass species such as Pennisetum purpureum (Olivo et al., 2009; Olivo et al., 2012; Crestani et al., 2013), Cynodon dactylon (Paris et al., 2009), Brachiaria sp. (Cab Jiménez et al., 2008; Hernandez et al., 1995); and sometimes with white clover (Trifolium repens) as an additional legume (Olivo et al., 2012; Diehl et al., 2013).
Digestibility and degradability
The in vitro DM digestibility of fresh pinto peanut forage is high, within the range of 62-72% (Carulla et al., 1991; Hess et al., 2002; Ferreira et al., 2012b; Fernandes et al., 2013). The in vitro DM digestibility of Arachis pintoi hay is also high, between 71 and 79%, from regrowth ages of 30, 60 and 75 days (Fernandes et al., 2011; Fernandes et al., 2013). In vivo DM, OM and NDF digestibilities of hay determined in sheep were 64%, 68% and 54%, respectively. These values were higher than those obtained with Medicago sativa hay (60% and 51% for DM and NDF digestibilities, respectively) (Ladeira et al., 2002). Based on in vitro measurements, the potential DM degradation at 48 h ranges from 54 to 61% depending on the genotype (Ferreira et al., 2012b). In vitro studies show a high ability of pinto peanut to improve conditions in the rumen, including ammonia levels, microbial populations (protozoa and bacteria), production of volatile fatty acids and nutrient degradation when added to protein-deficient forages (Hess et al., 2003).
In situ NDF degradability in bulls has been found to be 58% at 72h, which was the highest value in a study comparing six tropical legumes at the vegetative stage (Delgado et al., 2007). In Malaysia, in a trial with indigenous cattle (173 kg BW), both soluble and potentially degradable fractions of DM and CP were high, particularly when compared to Leucaena leucocephala cultivars. Intestinal degradation of DM and CP was also much greater than that of Leucaena leucocephala, and close to that of Gliricidia sepium (Khamseekhiew et al., 2001).
Pure pinto peanut pastures may be used as an additional feed to supplement animals grazing mainly tropical grasses pastures, by giving access to the legume pastures for a few hours daily. In Brazil, even when the grass pasture is of good quality (Pennisetum purpureum, 17% protein and 53% NDF), grazing 5 h/d in an adjacent pinto peanut pasture enabled steers to increase their daily DM intake by 16% and daily weight gain from 0.70 to 0.97 kg/d. Enteric methane production per kg DM intake was not affected by grazing or not grazing pinto peanut pastures (Andrade et al., 2014).
Like other forage legumes, pinto peanut may be used in mixed swards in order to reduce mineral N fertilizer requirements. In Brazil, in Charolais steers, a mixture of Pennisetum purpureum and Arachis pintoi (85:15) receiving no N fertilizer provided a similar stocking rate, daily DM intake (2.4% of BW), average daily gain (0.76 kg/d) and performance on a per ha basis as pure Pennisetum purpureum receiving 200 kg N/ha/year (Crestani et al., 2013).
In Costa Rica, including pinto peanut in bread grass (Brachiaria brizantha) pastures increased live weight gain/ha by 30% at a high stocking rate and by 11% at a low stocking rate (Hernandez et al., 1995). In Brazil, however, with a high level of nitrogen fertilisation (200 kg N/ha/year), including pinto peanut with Bermuda grass (Cynodon dactylon) did not support an increased stocking rate and did not increase the daily weight gain of heifers. In the same experiment, where no N fertilizer was added, including pinto peanut into Bermuda grass pastures allowed heifers to produce more than 1000 kg LWG/ha/year with a daily LWG of 0.38 kg/d (Paris et al., 2009).
In Brazil, voluntary intake of Santa Inês sheep (40 kg) increased with the replacement of Cynodon dactylon hay (protein 11% DM) by pinto peanut hay (protein 21% DM), up to 60% inclusion (Fernandes et al., 2013). Likewise, voluntary intake of Texel × Suffolk wethers increased by 12% by replacing 30% of Pennisetum purpureum (protein 10% DM) by pinto peanut hay (protein 17% DM), without affecting in vivo OM and NDF digestibilities of the diet (Schnaider et al., 2014). Given as the sole feed, Arachis pintoi hay was fed at 1.32 kg DM/day to sheep (33 kg), equivalent to 4.0% of BW or 90 g/kg BW0.75 (Ladeira et al., 2002).
No information found (2014).