Effect of sugar and starch supplementation on feed intake and nutrient digestibility in addax (Addax nasomaculatus) and Reeves's muntjac (Muntiacus reevesi)

Two studies were conducted to determine the effect of the supplementation of sugar, starch or both on feed, nutrient and energy intake and total tract digestibility in four adult female addax (Addax nasomaculatus) and four adult male Reeves's muntjac (Muntiacus reevesi) - representatives of grazing and browsing ruminants, respectively. Studies in both species were conducted according to 4 x 4 Latin Square Design. Animals had free access to meadow hay (addax) or dehydrated chopped lucerne (muntjac), and were fed a restricted amount of a 'basal diet' consisting of: (1) wheat bran; (2) wheat bran and sucrose (source of sugar); (3) wheat bran and wheat (source of starch); or (4) wheat bran, sucrose and wheat. The amounts of supplemental sucrose and wheat were set to account for 2% and 15%, respectively, of dry matter (DM) consumed. There was no effect of the similar to 2% sugar supplementation on DM intake of hay by addax, while the similar to 10% starch supplementation reduced DM intake of hay by 13% (p < 0.01); total DM intake (of hay and the basal diet) was not affected neither by sugar nor starch supplementation. When the diet for addax included wheat, this resulted in a greater intake of crude protein by 15%, lower intake of ADF by 9%, and greater crude protein digestibility by 10% (p <= 0.05). The similar to 2% sugar supplementation did not affect intake of lucerne and total DM intake by muntjac, but the similar to 10% starch supplementation decreased DM intake of lucerne by 25% (p < 0.01), total DM intake by 7% (p = 0.02) and intake of all nutrients (p <= 0.10). In summary, if high intake of roughages by captive ruminants is fundamental for their gastrointestinal functions and health, then starchy feeds supplementation should be limited, as they have an especially negative impact on roughage intake.

Automated summary

The study showed that supplementing sugar had no effect on intake for addax, while supplementing starch reduced intake by 13%; for muntjac, sugar had no effect on intake but starch decreased intake of lucerne by 25% and all nutrients by 10%. This indicates that starchy feeds supplementation should be limited for captive ruminants to maintain high intake of roughages for gastrointestinal health.