Rhizoma peanut is readily eaten by all classes of livestock as hay, silage and pasture, and is browsed by wild species such as deers. It can be grazed in rotation, harvested for hay or haylage or ensiled. In Florida, where rhizoma peanut has been extensively studied, it combines and excellent nutritive value, competitive ability with tropical grasses, and high animal performance (Cook et al., 2005).
Palatability
Arachis glabrata hay is reported to be as palatable as alfalfa hay (Cook et al., 2005).
Digestibility and degradability
The in vitro OM digestibility of rhizoma peanut herbage was shown to vary from 45-68% for material cut twice a year up to 77% for material cut more regularly (Valencia et al., 2001; Williams et al., 2004). Rhizoma peanut hay is considered of an equal quality to alfalfa hay with an OM digestibility that is about 60% or more (Hill, 2002; Gelaye et al., 2010). Protein degradability of rhizoma peanut hay was found to be lower than that of alfalfa hay, compensating for a lower protein content (Romero et al., 1987).
Dairy cows
In a trial where rhizoma peanut hay, alfalfa hay or maize silage were mixed with concentrate at two levels (30% and 70%), milk yied obtained with rhizoma peanut hay was similar to that obtained with maize silage, but rhizoma peanut hay produced the highest levels of butterfat (Romero,1985, cited by French et al., 1988). Rhizoma peanut silage could replace 70% of maize silage in diets containing 50% concentrate without affecting dairy cow performance. Intake and digestion of the diet were depressed only when rhizoma silage was the sole source of forage (-2kg of DM intake and -2 to 3% of apparent DM digestibility) consequently affecting milk production (-1kg/cow/day) (Staples et al., 1997).
Based on nutrient content, in vitro DM degradability, and voluntary intake, rhizoma peanut hay showed greater potential for dairy heifers as a forage source than Stylosanthes guinanensis and Cajanus cajan, showing a higher DM digestibility than the control grass and a similar selective intake (Rodriguez et al., 2010). Cows and heifers being wintered on residual Bahia grass (Paspalum notatum) pasture and hay showed similar performances (body weight and body condition score changes, pregnancy rate, calf birth weight) when offered 2.3 kg of the perennial peanut hay than when fed with 0.9 kg of a 20% CP concentrate cube supplement (Hammond et al., 1992).
Growing cattle
In Florida, yearling bulls from temperate and tropical breeds were offered mixed pastures of rhizoma peanut with Bahia grass (Paspalum notatum) , Bermuda grass (Cynodon dactylon), Chenopodium ambrosoides, Imperata cylindrica and blackberry (Rubus cuneifolius), at different stocking rates and N fertilization levels. Summer average daily gain (ADG) averaged about 0.2 kg/d lower than spring ADG, due in part to a seasonal decline in nutritive value. Because herbage allowance was never limiting, full-season ADG was not affected by stocking rate or N fertilization and averaged 0.61 ± 0.03 kg/d (Valencia et al., 2001). Steers finished on rhizoma peanut-tropical grass pasture in Florida experienced lower ADG during the growing and finishing periods (0.49 and 0.94 kg/d, respectively) than concentrate-finished steers (0.78 and 1.33 kg/d, respectively). Steers can be finished on rhizoma peanut-tropical grass pastures, but dark lean color and poor tenderness of carcasses may reduce beef quality produced on this forage (Bennett et al., 1995).
Creep grazing, defined as the utilization of a high quality forage species that only the calves have access to during the preweaning stage, may be another method of efficiently utilizing limited acreage of rhizoma peanut. Creep grazing enabled improvements in calf gains and body weight with greater benefits later in the grazing season as quality of the Bahia grass base pasture and cow milk production declined (Williams et al., 2004; French et al., 1988). However, creep grazing perennial peanut was less effective than creep grazing cowpea (Vigna unguiculata), both leading to lower calf performance than creep feeding with concentrates (Foster et al., 2013). Creep grazing the calves had no effect on cow performance (weight, ADG, or body condition score) (Foster et al., 2013; Williams et al., 2004).
Sheep
Voluntary intake of DM, NDF and CP from ram lamb was higher when fed with rhizoma peanut hay than with grass hay (Digitaria eriantha, 80%, and Urochloa maximum, 20%). Daily supplementation with fish silage for the sheep fed the basal diet of rhizoma peanut hay slightly increased DM and protein digestibility but should be limited to 0.225% of BW (Diaz-Rios et al., 2008). Rhizoma peanut hay (first cut), supplemented at 50% of total diet DM (based on bahiagrass hay), increased DM and N intake and digestibility and improved microbial N synthesis of ram lambs (initial body weight 30.6 ± 5.5 kg) compared with no supplement or annual peanut, cowpea, pigeonpea or soybean hays (Foster et al., 2009).
Goats
Based on nutrient content, in vitro DM degradability, and voluntary intake, rhizoma peanut hay showed greater potential for goats as a forage source than Stylosanthes guinanensis and Cajanus cajan, showing a higher apparent digestibility of DM than the control tropical grass hay and a similar selective intake (Rodriguez et al., 2010). When offered the choice, mature goat bucks showed a strong preference during the autumn grazing (no preference in summer), spending 64.1% of their grazing time on rhizoma peanut plots compared to 35.9% for alfalfa, in relation with higher available rhizoma peanut DM. This preference was not associated with difference in quality of pre- and post-grazed rhizoma peanut forage, which indicates no selective grazing by the goats on these plots.
Growing goats fed peanut hay consumed approximately the same amount of DM but gained more body weight (+11-17 g/day) and were more efficient (-5-7 g DM/g gain) in converting DM intake into gain than those fed alfalfa hay or a combination of both forages (Gelaye et al., 1990). Goats fed rhizoma peanut hay (10% of the diet based on cracked maize, soybean meal and peanut hulls) grew at the same rate and utilized most of the nutrients as well or better than goats fed alfalfa hay (10% of the based diet). In tropical and subtropical parts of the world, goat productivity could be improved by using rhizoma peanut extensively in their rations (Gelaye et al., 1991).
