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Features of psittacine birds in captivity: focus on diet selection and digestive characteristics

Isabelle Kalmar UGent (2011)
abstract
Parrots have been kept in captivity for at least 2500 years, their popularity as highly intelligent pet animals that are admired for their vocal abilities and exotic appearance, increasing continuously. Partly as a result of their popularity, they have become the most endangered order of birds in the world. Therefore, optimisation of their husbandry is of utmost importance. This not only improves the health and well-being of our companion birds, but also enhances fertility and extends lifespan and thus reproductive period of rare specimens kept in ornithological collections for conservation purposes. A major area that unquestionably requires improvement is the nutrition of captive parrots, as the inadequacy of captive diets leads to malnutrition and contributes to obesity, which comprise the primary cause of the majority of clinical problems in these species. Therefore, the objectives of this work were to identify and alleviate constraints with regard to the nutritional value of common so-called complete seed diets for parrots. Second, feeding strategies to reduce overweight by diminishing voluntary energy intake were evaluated in nectarivorous and granivorous parrots. Finally, attributes affecting owner perception towards pelleted parrot diets are considered, as provision of a more nutritionally balanced diet is more feasible through a mono-component diet. Lorikeets are usually fed dilutions of commercially available powdered nectar as the principal source of nutrition. The first trial aimed to investigate the effect of the degree of dilution of an artificial nectar powder and availability of supplemental fruit (apple) on energy and nutrient intake in two lorikeet subspecies, green-naped lorikeets (Trichoglossus haematodus haematodus) and red-breasted lorikeets (Trichoglossus haematodus mitchellii). Diluting nectar to a higher degree resulted in both subspecies in a significant decrease in dry matter intake of nectar, but intake of apple increased when offered next to higher diluted nectar. Besides a higher degree of dilution of nectar, availability of apple also resulted in lower intake of nectar. Neither degree of dilution, nor availability of fruit had a clear-cut effect on total energy intake, but significant interactions between dilution degree and subspecies, and between dilution degree and availability of fruit were present. In green-naped lorikeets fed solely nectar, daily intake of energy showed a noticeable numerical decrease when the nectar was diluted to a higher degree. An opposite effect of the degree of dilution on voluntary energy intake was noted in red-breasted lorikeets when fed nectar added with fruit. A second trial investigated the effect of management and animal factors on the nutritive value of multi-component seed-based diets, and the effect of additional fruit when fed to yellow-shouldered amazons (Amazona barbadensis). Besides nutritional deficiencies and imbalances inherent to seed diets, three interfering factors further deteriorated adequate nutrient supply: segregation, seed dehusking and selective feeding. Segregation of ingredients when temporarily stored in a food container vastly decreased the proportion of mineral, amino acid and vitamin supplements in the top-layer. As such containers are usually replenished before they completely emptied and daily portions are scooped from the top-layer, this inappropriate storage method negates the effect of nutritional supplements that are necessary to counter-balance nutrient deficiencies and imbalances inherent to seeds. Next, seed-dehusking and profound selective feeding behaviour substantially increased the fat content and energetic density of the fraction actually ingested compared to the offered diet. Furthermore, consumption of only the seed kernels and low ingestion of supplements additionally deteriorated the Ca:P ratio. However, with the prerequisite of the opportunity of ad libitum feeding from all ingredients, neither the availability of fruit nor increasing the daily amount of offered seed mixture altered the ingredient profile of the consumed fraction of the seed diet. Nonetheless, availability of fruit effectively lowered voluntary energy intake, although this also tended to decrease the Ca:P ratio. Pelleted diets offer the advantage that they can be formulated according to available guidelines, whilst their nutritive content is not altered through segregation or feeding behaviour. However, several constraints remain with regard to this type of diet, which include less desirable excreta characteristics. Therefore, the aims of a third trial were to assess daily excreta output and its consistency and pH-value in African grey parrots (Psittacus erithacus erithacus) fed extruded pellets differing in particle size. Food and water intake, and apparent nutrient digestibility coefficients were not influenced by particle size of the pellets. A coarser grinding of ingredients prior to extrusion resulted in more firm droppings, whereas particle size did not affect daily excreta output or pH-value. The change in excreta consistency was not due to altered moisture content and therefore this must have originated from an effect on water binding capacity. Possibly, a decrease in availability of non-starch polysaccharides, resulting from lower particle size reduction, contributed to improved firmness of droppings when fed the coarse pellets compared to the fine particle size pellets. In conclusion, provision of fruit effectively reduced voluntary energy intake in granivorous parrots without adverse effects on consumption of essential nutrients. This way, obesity can be safely abated even in group-housed parrots. In nectarivorous parrots, however, highly diluted nectar food can be lower in energetic density compared to fruit. Hence, ad libitum provision of fruit beside nectar does not necessarily lower the energy content of the ingested ration in nectar feeders. In green-naped and red-breasted lorikeets, lowest voluntary energy intake was attained when fed high dilution-nectar and low-dilution nectar added with fruit, respectively. Seed-based diets intended for granivorous parrots do not entail a possibility to contain less energy compared to supposedly energy-diluting supplements such as fruit. Yet, in order not to adversely affect essential nutrient supply, the contents of the latter in the principal diet should always be evaluated prior to implementation of feeding strategies that try to abate obesity. Next, seed-based diets inherently entail a number of nutritional inadequacies that are not overcome through supplements. In contrast, segregation due to inappropriate storage negates supplementation efforts in the form of, for instance, oyster shells or extruded pellets enriched with vitamins, amino acids and minerals. Although not specifically studied in this thesis, incorporation of larger-sized supplements and regular turning of storage containers might reduce the adverse effects of segregation in multi-component diets. Another aspect that deteriorates the nutritional adequacy of supplemented seed-based diets includes the typical feeding behaviour of parrots. The most effective means to oppose both these management and animal factors is to offer mono-component pelleted diets, which precludes segregation as well as selective feeding and hereby ascertains ingestion of the intended formulation. Finally, increasing the particle size in pelleted diets improved the appearance of parrot droppings without affecting food or water intake, apparent nutrient digestibility coefficients or other excreta characteristics. This may enhance the perception of parrot caretakers towards pelleted diets and contribute to persuade them to provide their birds with this nutritionally more adequate type of diet.
Please use this url to cite or link to this publication:
author
promoter
UGent
organization
year
type
dissertation (monograph)
subject
keyword
parrot, nutrition, psittacine, particle size, dietary dilution, behaviour
pages
163 pages
publisher
Ghent University. Faculty of Veterinary Medicine
place of publication
Merelbeke, Belgium
defense location
Merelbeke : Faculteit Diergeneeskunde (auditorium D)
defense date
2011-02-18 17:00
ISBN
9789058642509
language
English
UGent publication?
yes
classification
D1
additional info
dissertation consists of copyrighted material
copyright statement
I have transferred the copyright for this publication to the publisher
id
1919305
handle
http://hdl.handle.net/1854/LU-1919305
date created
2011-09-30 14:59:26
date last changed
2011-10-03 09:30:25
@phdthesis{1919305,
  abstract     = {Parrots have been kept in captivity for at least 2500 years, their popularity as highly intelligent pet animals that are admired for their vocal abilities and exotic appearance, increasing continuously. Partly as a result of their popularity, they have become the most endangered order of birds in the world. Therefore, optimisation of their husbandry is of utmost importance. This not only improves the health and well-being of our companion birds, but also enhances fertility and extends lifespan and thus reproductive period of rare specimens kept in ornithological collections for conservation purposes. 
A major area that unquestionably requires improvement is the nutrition of captive parrots, as the inadequacy of captive diets leads to malnutrition and contributes to obesity, which comprise the primary cause of the majority of clinical problems in these species. Therefore, the objectives of this work were to identify and alleviate constraints with regard to the nutritional value of common so-called complete seed diets for parrots. Second, feeding strategies to reduce overweight by diminishing voluntary energy intake were evaluated in nectarivorous and granivorous parrots. Finally, attributes affecting owner perception towards pelleted parrot diets are considered, as provision of a more nutritionally balanced diet is more feasible through a mono-component diet.
Lorikeets are usually fed dilutions of commercially available powdered nectar as the principal source of nutrition. The first trial aimed to investigate the effect of the degree of dilution of an artificial nectar powder and availability of supplemental fruit (apple) on energy and nutrient intake in two lorikeet subspecies, green-naped lorikeets (Trichoglossus haematodus haematodus) and red-breasted lorikeets (Trichoglossus haematodus mitchellii). Diluting nectar to a higher degree resulted in both subspecies in a significant decrease in dry matter intake of nectar, but intake of apple increased when offered next to higher diluted nectar. Besides a higher degree of dilution of nectar, availability of apple also resulted in lower intake of nectar. Neither degree of dilution, nor availability of fruit had a clear-cut effect on total energy intake, but signi\unmatched{fb01}cant interactions between dilution degree and subspecies, and between dilution degree and availability of fruit were present. In green-naped lorikeets fed solely nectar, daily intake of energy showed a noticeable numerical decrease when the nectar was diluted to a higher degree. An opposite effect of the degree of dilution on voluntary energy intake was noted in red-breasted lorikeets when fed nectar added with fruit. 
A second trial investigated the effect of management and animal factors on the nutritive value of multi-component seed-based diets, and the effect of additional fruit when fed to 
yellow-shouldered amazons (Amazona barbadensis). Besides nutritional deficiencies and imbalances inherent to seed diets, three interfering factors further deteriorated adequate nutrient supply: segregation, seed dehusking and selective feeding. Segregation of ingredients when temporarily stored in a food container vastly decreased the proportion of mineral, amino acid and vitamin supplements in the top-layer. As such containers are usually replenished before they completely emptied and daily portions are scooped from the top-layer, this inappropriate storage method negates the effect of nutritional supplements that are necessary to counter-balance nutrient deficiencies and imbalances inherent to seeds. Next, 
seed-dehusking and profound selective feeding behaviour substantially increased the fat content and energetic density of the fraction actually ingested compared to the offered diet. Furthermore, consumption of only the seed kernels and low ingestion of supplements additionally deteriorated the Ca:P ratio. However, with the prerequisite of the opportunity of ad libitum feeding from all ingredients, neither the availability of fruit nor increasing the daily amount of offered seed mixture altered the ingredient profile of the consumed fraction of the seed diet. Nonetheless, availability of fruit effectively lowered voluntary energy intake, although this also tended to decrease the Ca:P ratio.
Pelleted diets offer the advantage that they can be formulated according to available guidelines, whilst their nutritive content is not altered through segregation or feeding behaviour. However, several constraints remain with regard to this type of diet, which include less desirable excreta characteristics. Therefore, the aims of a third trial were to assess daily excreta output and its consistency and pH-value in African grey parrots (Psittacus erithacus erithacus) fed extruded pellets differing in particle size. Food and water intake, and apparent nutrient digestibility coefficients were not influenced by particle size of the pellets. A coarser grinding of ingredients prior to extrusion resulted in more firm droppings, whereas particle size did not affect daily excreta output or pH-value. The change in excreta consistency was not due to altered moisture content and therefore this must have originated from an effect on water binding capacity. Possibly, a decrease in availability of non-starch polysaccharides, resulting from lower particle size reduction, contributed to improved firmness of droppings when fed the coarse pellets compared to the fine particle size pellets.
In conclusion, provision of fruit effectively reduced voluntary energy intake in granivorous parrots without adverse effects on consumption of essential nutrients. This way, obesity can be safely abated even in group-housed parrots. In nectarivorous parrots, however, highly diluted nectar food can be lower in energetic density compared to fruit. Hence, ad libitum provision of fruit beside nectar does not necessarily lower the energy content of the ingested ration in nectar feeders. In green-naped and red-breasted lorikeets, lowest voluntary energy intake was attained when fed high dilution-nectar and low-dilution nectar added with fruit, respectively. Seed-based diets intended for granivorous parrots do not entail a possibility to contain less energy compared to supposedly energy-diluting supplements such as fruit. Yet, in order not to adversely affect essential nutrient supply, the contents of the latter in the principal diet should always be evaluated prior to implementation of feeding strategies that try to abate obesity.
Next, seed-based diets inherently entail a number of nutritional inadequacies that are not overcome through supplements. In contrast, segregation due to inappropriate storage negates supplementation efforts in the form of, for instance, oyster shells or extruded pellets enriched with vitamins, amino acids and minerals. Although not specifically studied in this thesis, incorporation of larger-sized supplements and regular turning of storage containers might reduce the adverse effects of segregation in multi-component diets. Another aspect that deteriorates the nutritional adequacy of supplemented seed-based diets includes the typical feeding behaviour of parrots. The most effective means to oppose both these management and animal factors is to offer mono-component pelleted diets, which precludes segregation as well as selective feeding and hereby ascertains ingestion of the intended formulation.
Finally, increasing the particle size in pelleted diets improved the appearance of parrot droppings without affecting food or water intake, apparent nutrient digestibility coefficients or other excreta characteristics. This may enhance the perception of parrot caretakers towards pelleted diets and contribute to persuade them to provide their birds with this nutritionally more adequate type of diet.},
  author       = {Kalmar, Isabelle},
  isbn         = {9789058642509},
  keyword      = {parrot,nutrition,psittacine,particle size,dietary dilution,behaviour},
  language     = {eng},
  pages        = {163},
  publisher    = {Ghent University. Faculty of Veterinary Medicine},
  school       = {Ghent University},
  title        = {Features of psittacine birds in captivity: focus on diet selection and digestive characteristics},
  year         = {2011},
}

Chicago
Kalmar, Isabelle. 2011. “Features of Psittacine Birds in Captivity: Focus on Diet Selection and Digestive Characteristics”. Merelbeke, Belgium: Ghent University. Faculty of Veterinary Medicine.
APA
Kalmar, I. (2011). Features of psittacine birds in captivity: focus on diet selection and digestive characteristics. Ghent University. Faculty of Veterinary Medicine, Merelbeke, Belgium.
Vancouver
1.
Kalmar I. Features of psittacine birds in captivity: focus on diet selection and digestive characteristics. [Merelbeke, Belgium]: Ghent University. Faculty of Veterinary Medicine; 2011.
MLA
Kalmar, Isabelle. “Features of Psittacine Birds in Captivity: Focus on Diet Selection and Digestive Characteristics.” 2011 : n. pag. Print.