A nutritional evaluation of buckwheat (Fagopyrum esculentum)

Experiments were conducted with rats, pigs, chickens and laying hens. Buckwheat had a high neutral detergent fibre content of 20%; digestible energy measured with pigs was 11.5 MJ/kg, and a mean metabolizable energy value of 11.0 MJ/kg with poultry. Growth studies with rats and chicks showed that buckwheat in mono-grain diets was superior to cereal grains. However, it was not possible to identify limiting amino acids in buckwheat, and supplementation with fat and protein sources did not promote the growth responses anticipated. Removal of the fibrous hulls from buckwheat by sifting did not increase growth rate, but food conversion was improved.Although chemical analysis indicated that amino acids were adequate to maintain egg production, this was not confirmed in laying trials even when additions of lysine and methionine were made to buckwheat. The most favourable response to buckwheat was achieved in pig-growth studies. Growth rate on an all-buckwheat diet was not different from that on an all-wheat (12% CP) diet but addition of lysine improved growth rate and feed conversion. Addition of 10% meat meal or sunflower meal to buckwheat gave similar growth and feed conversion to those of a commercial grower diet. Amino acid disappearance, measured at the terminal ileum of pigs prepared with re-entrant cannulas, gave values ranging from 90% for methionine to 65% for leucine, although there was substantial variation among pigs.It was apparent that buckwheat as the sole grain source was not suitable for the species examined. Differences in performance between individual animals may be attributed to their capacity to degrade the buckwheat fibre. This may in part explain the variation in the response of individuals to the experimental diets and therefore a tendency to mask responses to the various supplements. It can be concluded from this study that buckwheat as the sole source of energy is unsuitable for pigs and poultry even though in the diets of pigs it gave acceptable growth rate and feed conversion. Some pigs, however, did not take readily to this grain and often took several hours to consume their rations. Poor acceptability, perhaps due to the presence of a toxin or other chemical compounds, appears to be associated with this grain.