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Providing evidence to improve practice

Action: Carnivores: Feed a plant-derived protein diet Management of Captive Animals

Key messages

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Supporting evidence from individual studies


 A replicated, randomized, controlled study in 2006 of maned wolves Chrysocyon brachyurus and domestic dogs Canis lupus in a research centre in the USA found that feeding maned wolves a plant-derived protein diet resulted in higher energy digestibility and dry matter digestibility but lower mineral retention compared to an animal-based protein diet. When maned wolves were fed a plant-derived protein diet, apparent digestible energy (3,510 kcal/kg) and apparent dry matter digestibility (67%) were higher compared to an animal-based protein diet (apparent digestible energy: 3,331 kcal/kg; apparent dry matter digestibility: 65%). Apparent retention was lower on the plant-derived protein diet for copper (7% vs 12%), iron (9% vs 12%), magnesium (26% vs 32%) and sodium (42% vs 53%). The plant-derived protein diet had previously been shown to raise the low urine pH associated with the renal disorder cystinuria in maned wolves. Diet did not affect transit time. Six wolves and six dogs were randomly assigned to be fed a diet containing plant-derived protein (soybean meal) or animal-based protein (meat meal and low ash poultry meat meal) for a period of 16 days. After 16 days, the animals were switched to the alternative diet. Faecal samples were collected on two consecutive days immediately after 12 days of being fed the diets. Dry matter, energy, protein, and minerals contained in the faeces were measured and chromic oxide was used as a marker to detect digestibility.


   A replicated, controlled study in 2001 of maned wolves Chrysocyon brachyurus in a research centre in the USA, found that when fed a plant-derived protein diet, plasma taurine levels were lower compared to a supplemented animal-protein based diet. When fed a plant-derived protein diet or animal-based protein diet (4.03 nmol/ml), average plasma taurine was lower compared with a supplemented animal-based protein diet (66.68 nmol/ml). The plant-derived protein diet was not within target domestic canine reference ranges (60–120 nmol/ml). Deficient concentrations of plasma taurine levels responded within four months of supplementation. In the original experiment, four wolves were maintained on the commercial diet (animal-based protein) and two were maintained on an experimental diet (plant-derived protein). Four weeks prior and at the end of the diet trial, animals were restrained and sedated to collect a 12 ml blood sample. Due to clinical signs including weight loss and decreased appetite, the trial was terminated early and taurine supplementation (0.3% concentration) was deemed necessary. Taurine concentrations were monitored over a four-month period.

Referenced papers

Please cite as:

Jonas, C.S., Timbrell, L.L., Young, F., Petrovan, S.O., Bowkett, A.E. & Smith, R.K. (2019) Management of Captive Animals. Pages 539-567 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.