Abstract
Common marmoset monkeys (Callithrix jacchus) belong to the family Callithrichidae. They are native to the outskirts of the rainforest in Northern Brazil. The animals have been housed and bred under laboratory conditions for about 30 years and are used mainly for biomedical research. Apart from the low body weight of 300-500 g, their high reproductive rate (they bear twins two times a year) commends their use as laboratory animal. Even though Common marmoset monkeys are relatively stress-resistant compared to other non-human primates, they still require an optimal husbandry. This includes, apart from aligning the room temperature and humidity to their natural habitat, a corresponding light-program and high hygiene-status. Optimal feeding is of particular importance for the well-being of the common marmoset monkey. The influence of nutrition on the results of biomedical research should also not be underestimated. Under standardized experimental conditions, the feeding has to be standardized too, so as to prevent an influence on the results of the research. In many laboratory colonies the animals are being fed a mixture of commercial pellets, fruits, vegetables, insects and other amending ingredients (e.g. gummi arabicum). These diets are difficult to standardize. Especially their compliance with hygienic standards is next to impossible, because e.g. the contamination of fruit with pathogenic germ cannot be controlled or foreseen. Housing and breeding in the German Primate Center showed that the standardization of the diet is possible with the exclusive feeding of commercial pellets. However, under these conditions, the animals tend to develope overweight. The aim of our research was the development of a diet suited to the species, based on verified requirements and adapted to laboratory conditions. Following an extensive literature inquiry regarding the validity of requirement-data for Common marmoset monkeys, the first experiment was conducted. The aim for this experiment was the development of a basal ingredient composition of a complete diet. Therefore, 24 non-reproducing male and female animals were available (2 animals per cage n=12). Based on the protein sources plant, fish and egg protein, two diets per feed protein were developed . These diets were compared with a commercial diet in a 9-week trial considering their acceptance by the animals. The egg-protein based feeds were generally rejected by the animals and thus excluded from the remaining experiment. The analysis of the data showed that the animals feed intake was highest with the commercial diet. Among the tested diets the plant-protein-based feeds resulted in the highest feed intake. The second experiment was based on the plant-protein-diet of the first experiment. The aim of this trial was to achieve a feed intake comparable to the commercial diet. Adding aroma-components is known to increase the feed intake in farm animals and was of interest for Common marmoset monkeys also. In the second experiment the plant-based diet was therefore compared to 5 aroma added diets and the commercial diet. The addition of aroma did not yield a significant increase of feed intake. To achieve an increase of feed intake the addition of gummi arabicum-powder was tested in a third trial. Tree saps belong to the native diet of Common marmoset monkeys and are also well accepted in human care. In the experiment a basal mixture with 0% gummi arabaicum was compared to a mixture with 2.5%, 5% and 7.5% gummi arabicum, respectively, all of them were then compared to a commercial diet. The feed intake of the 5%-gummi arabcium-diet was comparable to the commercial one and, additionally, diarrhea decreased. Furthermore the body mass decreased slowly and stable and reached a constant level in the end. It can be concluded that the development of a new standardized complete diet, based on the requirements of Common marmoset monkeys held under laboratory conditions is progressing well. Further research is e.g. necessary in the methodology. In addition to the animals body mass, the changes of body composition should be the benchmark for the evaluation of the animals individual development. As the breeding of Common marmoset monkeys in captivity is an important factor, further research is necessary to develop new complete diets based on the requirements of juveniles and reproducing adult animals.
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