Potential nutritive value of various parts of wild sunflower (Tithonia diversifolia) as source of feed for ruminants in Kenya

Abstract

Various parts of the wild sunflower (Tithonia) were analysed for their chemical composition and degradation characteristics. Pyrethrum marc (pymarc), a common agro-industrial by-product was also analysed to compare the potential nutritive value. Leaves and flowers both young and mature were harvested, dried and ground. The crude protein (CP) content ranged from 143.3 g/kg dry matter (DM) in pymarc to 235.6 g/kg DM in mature Tithonia leaves. The neutral detergent fibre (NDF) content was highest in pymarc (421 g/kg DM) and least in mature leaves (264.8 g/kg DM). Concentration of polyphenolic compounds was highest in young leaves and lowest in young flowers. However, the concentrations were far below levels (50.0 g/kg DM) known to have detrimental effects in ruminants. Flowers were more digestible than leaves but overall pymarc recorded the highest value of 60.5% organic matter digestibility (OMD). The same trend was recorded for metabolizable energy (ME). Addition of polyethylene glycol (PEG), a tannin-binding agent did not yield significant increase in gas production values except for mature flowers, which also recorded significant increases in both OMD and ME. Tithonia forages (leaf and flower) at both young and mature vegetative state have high nutritive value compared to pymarc. However, mature leaves and young flowers are slightly higher in CP and low in concentration of phenolic compounds than young and mature leaves and flowers, respectively. This depicts the high potential of Tithonia shrub in feeding of ruminants. Key words: Tithonia diversifolia, pymarc, gas production, rumen fermentation