Investigations in pet birds (Agapornis spp.) fed different vitamin K3 contents in the diet
In the past many discussions about possible toxic effects of vitamin K3 fed to pet birds arose frequently, and were published also in magazines for pet bird fanciers, in the internet as well as in veterinary journals.
Therefore, the aim of this study was an evaluation of effects of different dosages of vitamin K3 on birds' health when given orally for a longer period. These investigations were carried out with adult lovebirds (Agapornis spp.) fed a pelleted diet with different levels of vitamin K3 (menadionesodiumbisulphite): control group 0 mg, group V1 20 mg and group V2 200 mg/kg diet dry matter. General condition and well being of the lovebirds were checked daily. Body weight gains as well as feed and water intakes were examined once a week. Every 2-month blood samples of each lovebird were collected and analysed. After a period of 6 and 10 months, respectively, four birds of each group were necropsied in order to carry out a pathological and histological examination. In general, the behaviour, feed and water intakes as well as quality of excreta were not influenced by ingestion of diets with different levels of vitamin K3. All variations were in physiological ranges. Individuals of all groups showed positive body weight gains and an active reproduction status. However, the best body mass (BM) development and egg laying activity could be observed in lovebirds of group V2 with the highest vitamin K3 supplementation. In the haemotogram some time-depending variations could be observed; however, a systematic influence of vitamin K3 could not be determined in any group or at any time. All analysed biochemical values in plasma and the activities of enzymes were within normal ranges. Only few birds of every group showed aberrant histological findings, but none of these could be related to the vitamin K3 intake. Moreover, no forced accumulation of vitamin K3 in the liver depending on vitamin K3 intake was found. This result suggests a rapid metabolism of the absorbed vitamin K3. All in all, the application of pelleted diets with addition of 20 or 200 mg vitamin K3/kg diet over a period of several months did not affect pet birds' health. Given these results, any doubts about the compatibility of usual doses of vitamin K3 in diets for lovebirds must be considered as absolutely groundless.