Fermentation quality and nutrient content of browse silage and its acceptance by captive ungulate and nonhuman primates in Japan

Abstract

Feeding browse silage to captive zoo animals is becoming increasingly common in European countries. However, only few studies have evaluated changes in nutrient content and/or fermentation property of browse silage during ensiling. In addition, studies on the acceptance of browse silage by zoo animals are also limited. In this study, we ensiled two evergreen species (bamboo-leaf oak: Quercus myrsinifolia and Japanese chinquapin: Castanopsis sieboldii) and one deciduous species (Yoshino cherry: Cerasus×yedoensis) for eight weeks, and compared 18 nutrient contents and six fermentation properties in each browse species during ensiling. Then, we evaluated the acceptance (amount of leftover, feeding time, feeding order, and number of putting in the mouth) of fresh and ensiled browses in two ungulates (Giraffe, Giraffa camelopardalis and Malayan tapir, Tapirus indicus), and four nonhuman primates (Abyssinian colobus, Colobus guereza; Lion-tailed macaque, Macaca Silenus; Japanese macaque, Macaca fuscata; and De Brazza’s guenon, Cercopithecus neglectus). To determine the content of nutrients and fermentation quality, the browse sample before and after one, two, four, six, and eight weeks were collected. In all browse species, lactic acid was slightly produced; accordingly, the pH did not decrease during ensiling. However, spoilage and putrid odor of the browse silage were not observed. The contents of nonfibrous carbohydrate (NFC) and organic cell contents (OCC) decreased significantly during ensiling, whereas the contents of neutral detergent fiber insoluble crude protein (NDICP) and acid detergent fiber insoluble crude protein (ADICP) in the three browse species did not change during ensiling, suggesting that the plant cell wall did not decompose during the ensiling process. The four nonhuman primates left both fresh and ensiled browses, and the amount of leftover remained constant for all browse species before and after ensiling. The feeding time of the two ungulate species and the number of putting in the mouth of the four nonhuman primates remained constant before and after ensiling. Browse species affected the acceptance of silage in each animal species. In Abyssinian colobus and De Brazza’s guenon, which fed on browses in a group, the number of putting in the mouth increased in inferior individuals when feeding on ensiled browses, implying that browse silage is an effective feed for group-housing nonhuman primates. In conclusion, browse silage can be used as a feed for zoo animals in terms of feed quality and acceptance.