New PhD thesis: Erythrina foliage as an alternative feed for growing goats
Goats are important animals for farmers in Lao PDR. Since grazing land often is limited, foliages from tropical plants and the legume Erythrina could be used as alternative feedstuffs.
Foliages from some tropical plants and from different species of the legume Erythrina were examined in five studies assessing the characteristics of these foliages as feed for goats. Digestibility and feed preference studies showed that ad libitum feeding of foliage from Erythrina (Erythrina variegata), jackfruit (Artocarpus heterophyllus) and kapok (Ceiba pentandra) resulted in a longer time spent eating and more changes in diet selection, feed intake, crude protein (CP) digestibility and nitrogen (N) retention than foliage from jujube (Ziziphus jujube Mill), fig (Ficus racemosa) and mango (Mangifera indica). Supplementation of low quality foliage with water spinach (Ipomoea aquatica) increased intake and apparent digestibility.
In a survey study, three different Erythrina spp., E. indica, E. subumbrans and E. variegata, were found in the north, centre and south of Lao PDR. These species were in limited use as an animal feed on smallholder farms. Erythrina variegata appeared to be a better option in terms of degradability than E. indica and E. subumbrans according to in vitro gas production and in sacco degradation studies. A cropping study showed that cow manure or mineral fertiliser significantly decreased shoot mortality and increased shoot height and fresh and CP yield of E. variegata foliage compared with no fertiliser. The nutritive value of the foliage did not differ significantly between the fertilised and unfertilised treatments.
Studies on different degrees of processing (fresh or sun-dried) of E. variegata foliage showed similar CP, neutral detergent fibre and acid detergent fibre contents, and no difference in total voluntary intake, when either fresh or dry foliage was fed ad libitum to growing goats. Four levels of replacement (0, 20, 40 and 60%) of dietary CP with CP from E. variegata foliage resulted in similar dry matter intake, apparent CP digestibility, N retention and carcass characteristics, but total CP intake was significantly higher in goats fed the diet with 60% replacement compared with 20%. Thus CP from E. variegata foliage can replace up to 60% of CP in a mixed diet with soybean meal without any negative effects on animal growth performance.
PhD student Daovy Kongmanila will defend her thesis on October 19.