Nutritional problems experienced in captivity
In this section some of the most common health, disease and behavioural problems reported in the feeding of captive okapi are discussed.
Health and disease
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Rumen acidosis: Rumen acidosis occurs in ruminants when the pH of the rumen decreases (Kleen et al. 2003). This decrease in pH usually results when the animal is fed a diet high in highly-digestible carbohydrates and low in fibre, which alters the microflora of the rumen, resulting in an increase in lactic acid production and a subsequent decrease in rumen pH (Cheeke and Dierenfeld 2010a). This is a common health problem found in okapi and other captive browsers, and results from the animals' reluctance to consume traditional roughage offered in zoos - grass hay - meaning that the animals do not consume enough fibre (Clauss et al. 2003). Additionally, rumen acidosis has been linked to the development of other health problems in ruminants such as: laminitis (a painful hoof condition) (Zenker et al. 2009); diarrhoea (Hummel and Clauss 2006); and hoof overgrowth (Clauss and Kiefer 2003). The potential for rumen acidosis to occur is increased should the animal be fed on fast-fermenting feedstuffs such as fruit and vegetables (Hummel et al. 2006b). While fruit has not been reported to be a part of a wild okapi's diet (Crissey et al. 2001), it is still commonly fed to okapi, with a report on 12 European zoos with okapi in their collections by Huisman et al. (2008), finding that 10 of the zoos fed more fruit and vegetables to their okapi than the quantities recommended in okapi feeding guidelines (for more information on the Okapi SSP Feeding Guidelines, click here). Chronic, rather than acute, rumen acidosis is suggested to be the most common form found in captive ruminants, and is believed to be under-reported as it is often only diagnosed during post mortem (Clauss and Kiefer 2003).
Laminitis and other hoof problems: To the best of my knowledge, laminitis in captive okapi has not be reported in the primary literature. However, given the links between rumen acidosis, laminitis and other hoof problems reported in other browsers (Clauss and Kiefer 2003; Zenker et al. 2009), as well as closely related species (giraffe: Hummel et al. 2006b) it is worth mentioning it here. Laminitis is a painful hoof condition, with complex causal factors that are still not fully understood (Wylie et al. 2013). In terms of laminitis found in other browsers, such as giraffe, the amount of highly digestible carbohydrate in the animal's diet, such as is found in fruit, is an important contributing factor to the likelihood of the disease developing (Hummel et al. 2006b). Similarly, a report by Husiman et al. (2008) suggested that zoos that fed their okapi a higher quantity of fruit in their diet were more likely to report hoof problems in their animals than zoos that fed relatively less fruit.
Glucosuria: Glucosuria (glucose in the urine) has been reported in many European captive okapi (Vercammen et al. 2003). Glucosuria has been associated with other health problems such as: chronic weight loss; polydipsia; polyuria; and localised skin necrosis (Vercammen et al. 2003). In one study it was suggested that the captive diet may be to blame for the development of glucosuria (Vercammen et al. 2003). The animal described in this study was initially fed on a typical captive okapi diet, featuring fruits and vegetables (and therefore sugars), quantities of which were slowly reduced (Vercammen et al. 2003). In line with the reduction of dietary fruits and vegetables, a reduction in the level of glucosuria was observed (Vercammen et al. 2003). Tellingly, captive animals at a station in their native country, fed upon ad libitum browse with no additional fruit, vegetables, grass, hay or pellets, were reported to not have glucose in their urine when tested (Vercammen et al. 2003).
Laminitis and other hoof problems: To the best of my knowledge, laminitis in captive okapi has not be reported in the primary literature. However, given the links between rumen acidosis, laminitis and other hoof problems reported in other browsers (Clauss and Kiefer 2003; Zenker et al. 2009), as well as closely related species (giraffe: Hummel et al. 2006b) it is worth mentioning it here. Laminitis is a painful hoof condition, with complex causal factors that are still not fully understood (Wylie et al. 2013). In terms of laminitis found in other browsers, such as giraffe, the amount of highly digestible carbohydrate in the animal's diet, such as is found in fruit, is an important contributing factor to the likelihood of the disease developing (Hummel et al. 2006b). Similarly, a report by Husiman et al. (2008) suggested that zoos that fed their okapi a higher quantity of fruit in their diet were more likely to report hoof problems in their animals than zoos that fed relatively less fruit.
Glucosuria: Glucosuria (glucose in the urine) has been reported in many European captive okapi (Vercammen et al. 2003). Glucosuria has been associated with other health problems such as: chronic weight loss; polydipsia; polyuria; and localised skin necrosis (Vercammen et al. 2003). In one study it was suggested that the captive diet may be to blame for the development of glucosuria (Vercammen et al. 2003). The animal described in this study was initially fed on a typical captive okapi diet, featuring fruits and vegetables (and therefore sugars), quantities of which were slowly reduced (Vercammen et al. 2003). In line with the reduction of dietary fruits and vegetables, a reduction in the level of glucosuria was observed (Vercammen et al. 2003). Tellingly, captive animals at a station in their native country, fed upon ad libitum browse with no additional fruit, vegetables, grass, hay or pellets, were reported to not have glucose in their urine when tested (Vercammen et al. 2003).
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Phytobezoars/abomasal obstructions: As with laminitis, to the best of my knowledge phytobezoars have not been reported in captive okapi, but given that they are reported in other, closely related browsers (giraffe: Hummel and Clauss 2006) it is worth discussion. Phytobezoars, blockage of the abomasum by plant material (see Fig. 1 taken from UoG College of Veterinary Medicine), are frequently reported in giraffe (Hummel and Clauss 2006). The obstruction itself is usually made up of grass hay or lucerne hay (a type of hay commonly fed to giraffe and okapi) (Hummel and Clauss 2006). The causal factors behind the development of phytobezoars are not fully known, though it has been suggested that the teeth of browsers are not adapted to adequately break down hay (Hummel and Clauss 2006).
Behavioural issues
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Nutritional related behavioural issues reported in captive okapi relate to the occurrence of oral stereotypies, such as licking of non-food items and tongue play. The type of diet an animal is fed and the length of time it spends eating on a daily basis have been suggested to influence the likelihood of an animal displaying an oral stereotypy (Bashaw et al. 2001). A study by Bashaw et al. (2001), reported that captive okapi and giraffe that were fed diets low in browse and fed in a manner in which the food is easily and quickly consumed, were more likely to display oral stereotypies (Bashaw et al. 2001). Frustrated natural foraging behaviour, which is not facilitated for in a captive environment has been suggested to be an influencing factor in the development of oral stereotypies in captive ungulates (Bergeron et al. 2006). Similarly, in other ruminants and ungulates, oral stereotypies have been suggested to help the individual alleviate the symptoms of gut acidosis through the production of saliva (Bergeron et al. 2006); something that could possibly be an influencing factor in oral stereotypies in okapi.