An exploratory analysis of the suitability of diets fed to a flightless insectivore, the North Island brown kiwi (Apteryx mantelli), in New Zealand

The ingredients and the macro- and micro-nutrient contents of diets that are fed to captive kiwi at seven New Zealand holding facilities were subject to analysis. The nutrient compositions were compared across facilities and with an estimate of the nutrient composition of the diets of wild kiwi based on the intake of various dietary ingredients reported in the literature. A total of 20 ingredients were used, the number and proportion of these ingredients varied greatly between facilities. Six of the diets were based primarily on meat and three comprised a mixture of meat and cat biscuits. Just one included a proprietary insectivore mix. Nutrient content varied greatly between the seven diets, organic matter ranging from 91.8 to 95.6%, crude protein from 41.9 to 62.9%, and crude fat from 9.0 to 28.7% of dry matter content. Large variations were found in the total content and profile of amino acids and of fatty acids of the diets. The nutrient content of all seven diets differed from that of the natural diet of wild kiwi. Hence, the presence of nutrient deficiencies in the current formulations cannot be exclude

Gastrointestinal tract of the brown kiwi (Apteryx mantelli)

The caeca of the brown kiwi Apteryx mantelli increased in length isometrically with body mass, but wall mass and thus mucosal thickness increased allometrically. Kiwi caeca are sacculate, with greater thickness of mucosa in the proximal portions. The caecal mucosa is similar to the small intestinal mucosa, with well-developed mucosal folds, villi, and crypts of Lieberkühn or intestinal glands. The solid matter in caecal digesta contained disproportionately large quantities of material that was not retained by a 75 ¿m sieve. The per cent of incombustible material (total ash) within the caeca digesta did not differ significantly from those within adjacent small intestinal or rectal segments. The fine particles within the caeca were not composed of fine crystalline uric acid; chemical analyses showed only low levels of uric acid in caecal digesta. These findings indicate that the caeca of this flightless insectivorous ratite are a site for the sequestration and fermentative digestion of fine particulate material, such as plant fibre, fragmented chitin or uric acid crystals