Influence of nitrogen sources and cutting interval on the digestibility of four (4) grass species in the southern guinea savanna of Nigeria

摘要

The study on the influence of nitrogen sources and cutting intervals on the digestibility of four (4)grass species was carried out during the 2002/2003 cropping season at the Teaching andResearch Farms of the University of Agriculture, Makurdi. The objectives of the study werefocused on feed supply as major constraints to ruminant livestock production by evaluatingAndropogon gayanus, and three (3) other grass species to identify promising genotypes suitablefor exploitation and acceptability to livestock. There were twenty four (24) treatment combinationsreplicated three times, in a split-split design. The grass genotypes (Andropogon gayanus,Panicum maximum, Cynodon nlemfuensis and Pennisetum purpureum). Nitrogen sources(Mineral fertilizer, legume and zero-nitrogen) and cutting intervals (6 and 9 weeks) constituted themain plot, sub-plot and sub-sub plots, respectively. Among the grass genotypes tested, thehighest amount of organic matter (OM) was produced by A. gayanus (899.90g/kg), which wassignificantly different from other grass genotypes. The highest values of Invitro-organic matterdigestibility (IVOMD), Invitro-D and D-values were obtained with P. maximum (64.53, 56.84 and59.60% respectively), while the lowest were obtained with C. nlemfuensis (52.7, 47.00 and47.75% respectively). The effect of nitrogen source revealed that the legume inter-crop sourcesproduced the highest and significantly values of OM, IVOMD, INVITRO-D and D-Value(881.00g/kg, 60.81, 53.69 and 55.79% respectively), while lowest values were obtained theirzero-N (871.60g/kg, 57.95, 50.43 and 52.02% respectively). The effect of cutting interval showedthat, cutting the grass at 6 weeks produced significantly higher concentrations of OM, IVOMD,INVITRO-D and D-values (878.50g/kg, 60.27, 52.90 and 55.01% respectively) than the 9 weekscutting (873.50g/kg, 58.64, 51.28 and 53.01% respectively). The interaction effects resultrevealed that A. gayanus recorded similar (non-significant) OM value at all nitrogen sources whencompared to other grass genotypes.