Lablab forage is a valuable source of protein for ruminants fed on low quality roughages.
Lablab forage is a good source of metabolizable protein for ruminants. However, its protein is highly degradable in the rumen, resulting in a fairly low contribution to by-pass protein. The overall digestibility and energy values of lablab are good. In a comparison of tropical forages, lablab forage was found to have a lower protein degradability than rye-grass, but higher than the legume forage butterfly pea (Clitoria ternatea) and tropical C4 grasses (Bowen et al., 2008). In another comparison, lablab was found to have a higher in vitro digestibility than the legume forages, butterfly pea (Clitoria ternatea), Centrosema pascuorum and Macroptilium bracteatum. It was concluded that lablab had potential to provide a large amount of highly digestible biomass (Hartutik et al., 2012).
Its high yield and good protein content makes lablab a valuable source of forage for growing cattle during hot and dry periods (Fribourg et al., 1984). Most trials have concentrated on supplementation of forage diets with lablab.
Supplementation of cereal forage with lablab
In the USA, the association of lablab with maize was shown to increase the economic value of forage compared to maize alone without compromising forage yield and milk/ha (Armstrong et al., 2008). In Cuba, lablab and soybean intercropped with maize provided the cheapest DM, could feed a greater number of animals and yielded more milk (Cino et al., 1994). In Ethiopia, optimal milk production in crossbred cows was obtained with a combination of maize and lablab hay, or oats-vetch/lablab hay, where the optimal level of lablab hay in the diet was 0.52% and 0.85% of BW, respectively. Increasing the lablab level resulted in no further improvement of animal performance, probably due to an energy deficit in the diet (Mpairwe et al., 2003a; Mpairwe et al., 2003b). In Nigeria, optimal results using maize/lablab silage for growth performance of crossbred calves were obtained with 70:30 maize:lablab (DM basis), which significantly improved animal performance during the dry season, compared to sole maize silage and natural pasture (Amole et al., 2013a). In the Southern Plains of the USA, in a comparison between lablab and cowpea used to supplement maize in dairy and beef cattle, it was concluded that lablab had greater potential than cowpea for forage production and could be an additional source of forage for dairy or beef cattle (Contreras-Govea et al., 2011). In Indonesia, forage sorghum intercropped with lablab had a better nutritive value than sorghum forage alone and resulted in higher live-weight gain, DM intake and milk yield (Juntanam et al., 2013).
Supplementation of low quality forages with lablab
In Nigeria, a mixed stand of lablab and Guinea grass (Megathyrsus maximus) was grazed or harvested 12 weeks after planting. Conserved as silage, it could be fed to ruminant animals during the dry season when feed availability and quality were low (Ojo et al., 2013). In Ethiopia, teff straw was successfully supplemented with lablab hay in calf diets. Increasing the legume forage level in the diet increased the rumen degradation rate, decreased retention time in the rumen and resulted in a higher DM intake (Abule et al., 1995). In Nigeria, supplementing suckling Bunaji cows grazing natural pasture with lablab forage (2 kg/day) increased performance and farmer income (Eduvie et al., 2002). In Kenya, milk production was increased by supplementing an elephant grass (Pennisetum purpureum)-based diet with mucuna or lablab hay (Nyambati et al., 2009). In Uganda, heifers fed on low-protein elephant grass had a higher growth rate when they were supplemented with lablab (Tibayungwa et al., 2011).
Goats and sheep
Lablab hay is a valuable forage for goats and sheep and can supplement forage-based diets of low quality. In Zimbabwe, lablab forage supplementation of maize stover (50:50) in the diets of pregnant and lactating goats kept in stalls resulted in higher DM, OM and N intakes, and had positive effects on productivity (kid health, kid growth after birth, milk yield and meat production) (Makembe et al., 1996). In growing goats, adding lablab hay to low-quality Rhodes grass hay (Chloris gayana) fed ad libitum with maize grain (100 g/day) increased DM intake (+ 42%), nutrient digestibility (DM, OM and NDF) and live-weight gain, which was multiplied threefold (Mupangwa et al., 2000). Compared with other forage legumes (centro, stylo and Aeschynomene histrix), the mixture of lablab with Guinea grass in diets for West African dwarf goats resulted in higher dietary ME and OM digestibility (Ajayi et al., 2008b). Lablab supplementation gave the highest N utilization and the highest weight gain (Ajayi et al., 2008a; Ajayi et al., 2008b).
In Nigeria and Zimbabwe, adding lablab to maize, sorghum or millet during ensiling had positive effects on feed intake in sheep and Yankasa rams (Ngongoni et al., 2008; Amodu et al., 2008). Silages containing equal amounts of pearl millet (Panicum glaucum) and lablab, or Guinea grass and lablab, resulted in better feed intake and digestibility in sheep and goats (Amodu et al., 2008; Babayemi et al., 2006).
Lablab seeds can be included in sheep and goat diets. In India, lablab beans replaced groundnut meal as a protein source in the concentrate mixture for kids with positive effect on roughage intake, nutrient utilization, rumen fermentation and body growth with better N utilization (Sultan Singh et al., 2010). Comparisons between lablab beans and other legume seeds or protein sources are scarce. In Australia, a comparison of mixtures of lablab beans or lupin seeds with roughage (hay + oat straw) fed to Merinos lambs resulted in comparable dietary intakes but the lablab-based diets gave lower values for digestibility, weight gain and wool growth (the latter at 60% lablab beans inclusion) (Garcia et al., 1990).