Ranking contrasting genotypes of forage peanut based on nutritive value and fermentation kinetics

Abstract

The objective of this study was to evaluate the nutritional divergence of perennial peanut genotypes through chemical characteristics as well as in vitro fermentation and degradation kinetics. The experiment was conducted at The Brazilian Agricultural Research Corporation (Embrapa Cerrados). The treatments consisted of 10 accessions of Arachis spp., 6 accessions of A. pintoi (Ap 8, Ap 19, Ap 20, Ap 24, Ap 31, Ap 65) and the cultivar Belmonte, 2 accessions of Arachis repens (Ar 5, Ar 26) and an interspecific hybrid (Ap×Ar) 9. The experimental design was a completely randomised block with four replications. Forage evaluations were made at a stubble height of 5cm from the soil surface with fixed cutting intervals of 42 days during the rainy season. Nutritional divergence was assessed using canonical variate analysis and hierarchical agglomerative clustering including the variables crude protein, neutral detergent fibre, lignin(sa), potential DM degradation at 48h, the insoluble but potentially degradable DM fraction and the degradation rate of the insoluble but potentially degradable DM fraction. Variables with higher contribution to discrimination of accessions were: rate of degradation, crude protein and potential DM degradation at 48h. Four distinct nutritional groups were identified: Group I (Ap 8, Ap 19, Ap 31, cv. Belmonte), Group II (Ap 20, Ap 24, Ap 65), Group III (Ar 5. Ar 26) and Ggroup IV (Ap×Ar 9). The nutritional divergence of the Arachis evaluated show great variability relative to the parameters analysed, which may impact genetic improvement programs which focus on chemical composition and in vitro fermentation characteristics. Group IV (hybrid Ap×Ar 9) had the highest nutritional quality as ruminant feeds.