Nutritional Value of Rubber Seed and Its Application in Aquafeed

Rubber tree (Hevea brasiliensis) is an important economic tree in China. It is widely planted in Yunnan and Hainan Province. Rubber seed is an important by-product of rubber tree, and the nutritional values of rubber seed kernel is high. Crude protein content of the rubber seed kernel is about 25%-30%, and the essential amino acid profile is balanced. Crude fat content of rubber seed kernel is about 50%, and the composition of rubber seed oil is similar to that of flaxseed oil which rich in alpha-linolenic acid. The alpha-linolenic acid content of rubber seed oil is more than tens of times than that of peanut oil and sunflower oil. However, rubber seeds contain anti-nutritional factors such as hydrocyanic acid, but most of which will disappear after storage and heating. Thus, rubber seed and its processing products can be used as feed ingredients for farmed animals. Previous studies showed that a certain proportion of rubber seed cake used in aquafeed has no obvious harmful effect on the growth and health of fish, but the high proportion of rubber seed cake will have a negative impact on the digestion and health of fish, which may be attributed to the high crude fiber content. The contents of lysine and methionine in rubber seed cake are relatively low, thus it should be paid attention to the adding of lysine and methionine. Rubber seed oil is rich in alpha-linolenic acid, which is also a high-quality alternative source for fish oil. Rubber seed oil can partially or even completely replace fish oil in aquafeed. The nutritional value of rubber seed and its application in aquafeed were reviewed in this paper, which could provide a theoretical basis for the development and utilization of rubber seed.