Maize green forage as a partial replacement for lettuce in the diet of West Indian manatee Trichechus manatus

Abstract

In zoos, West Indian manatees Trichechus manatus are fed mostly with different varieties of lettuce. It is a relatively expensive product and highly sensitive to improper storage conditions. In the wild, manatees feed on aquatic vegetation, whose content of dry matter, fibre and ash is usually higher than in zoo diets. However, manatees willingly ingest lettuce and reproduce on such a diet, so it is commonly used in zoos. The large amount of lettuce being fed and its high price make zoos look for alternative feeds. Maize green forage was proposed as a lettuce replacement and was introduced as a part of the diet at Wroc?aw Zoo (Poland) for the first time in 2019. Based on scientific literature and data from the zoo, the nutritional values of plants consumed by West Indian manatees in the natural environment and zoos were compared. The costs related to the feeding of butterhead lettuce and maize green forage were also calculated. The introduction of maize green forage increased the concentration of dry matter and fibre in the diet, and reduced concentration of the crude protein, which may have a positive influence on the functioning of the digestive system. Furthermore, the addition of maize green forage into the diet reduced the cost of feeding by 17% (€60,000) within 3 years.