A comparison of different legume seeds as protein supplement to optimise the use of low quality forages by ruminants

Abstract

The potential of different legume seeds species, including recently new developed varieties (Vicia faba: a commercial variety and varieties Alameda, Palacio and Baraka; Lupinus angustifolius; Pisum sativum and Cicer arietinum: varieties Fardon and Zegrí) as protein supplements to low quality forages was evaluated. First, the chemical composition, in vitro digestibility, in situ degradability and in vitro/in situ intestinal digestibility of legume seeds were determined. The chemical composition was rather similar within genus. Vicia faba beans contained more condensed tannins (35.8–56.4 g/kg DM) and less ether extract (12.8–9.5 g/kg DM) than the other legumes. The rumen degradability and intestinal digestibility of the undegraded protein in the rumen was very similar among the seeds, with exception of lupins, having a much higher degradation rate than the rest. Second, the fermentation characteristics of diets, which were based on two low quality forages (olive leaves and barley straw) and feed blocks without or with supplementation of legume seeds or soybean meal, were investigated by using single-flow continuous culture fermenters. In this trial, the fermentation parameters (ammonia, pH and volatile fatty acids), the microbial protein synthesis and the degradation of olive leaves and barley straw promoted by the different diets were studied. Compared to soybean meal, beans and peas showed similar suitability as protein supplements for sustaining in vitro fermentation of low-quality forages. However, our results suggest a significant interaction between the type of legume used as supplement and the type of forage used, which need to be further studied in vivo.

Keywords:

• ruminants
• legume seeds
• forages
• nutritive quality
• feed blocks
• fermentation
• in vitro digestibility

Acknowledgements

This research was supported by CICYT (Project AGL2001-0941-CO2-01). Thanks to Dr M^a Teresa Moreno from Centro de Investigación y Desarrollo Agrario (Córdoba, Spain), for providing legume seeds and L. del Boz, E. Serup and E. Olsen for technical assistance.