Eurasian Lynx (Lynx lynx)
(Eurasian lynx feeding, Ferrero-Labat, www.arkive.org)
The Eurasian lynx are a part of the Felidae family, which shares very similar nutrient requirements across the whole family (MacDonald and Rogers, 1984). Just like most other mammals, the essential amino acids for a feline include; arginine, histidine, lysine, leucine, isoleucine, valine, methionine, threonine, tryptophan, and valine (MacDonald and Rogers, 1984). Unlike other mammals, felines do not require carbohydrates in their diet (MacDonald and Rogers, 1984). An essential amino acid for only young Eurasian lynx is asparagine, as it is important during the growing stage but is not required for adult felines (MacDonald and Rogers, 1984). The Eurasian lynx at all stages of development require a diet high in fat and protein (MacDonald and Rogers, 1984). Felines have an increased activity of nitrogen catabolic enzymes in their liver which is why they require a lot of protein (MacDonald and Rogers, 1984). Sulfur containing amino acids are considered the first limiting amino acids in a felines diet (MacDonald and Rogers, 1984). Taurine is one of the sulfur containing amino acids that is not present in protein, but it essential in the felines diet (MacDonald and Rogers, 1984). Taurine is synthesized from cysteine in the felines liver, and a deficiency of taurine can lead to central retinal degeneration (CRD) (MacDonald and Rogers, 1984).
When the Eurasian lynx consumes the whole body of it’s prey, it’s diet contains all required minerals for survival (MacDonald and Rogers, 1984). But if the Eurasian lynx only consumes the soft tissues from it’s prey, then their diet is limiting in calcium which is acquired from the skeleton (MacDonald and Rogers, 1984). Essential fatty acids (EFA) such as pre-formed arachidonic acid are also required in the diet for felines (MacDonald and Rogers, 1984).
An essential vitamin for felines that must come from the diet, is preformed vitamin A (MacDonald and Rogers, 1984). Preformed vitamin A is found in animal fat, so this requirement can be easily met by the lynx if they consume the organs of their prey (MacDonald and Rogers, 1984). The list of required B vitamins for a feline include; niacin, thiamin, riboflavin, pantothenic acid, pyridoxine, biotin, folacin, and vitamin B12 (MacDonald and Rogers, 1984). One extremely toxic nutrient for felines is benzoic acid (MacDonald and Rogers, 1984).
Eurasian Otter (Lutra lutra)
(Common otter feeding, David Tipling, www.arkive.org)
The Eurasian otters are a part of the Mustelidae family (Ruff, 2007). Eurasian otters are considered an endangered species, and so most otters are held in captivity and there has not been a lot of research done on nutrient requirements for Eurasian otters (Ruff, 2007). Both the Eurasian lynx and Eurasian otter are considered obligate carnivores, so it is assumed that the otters have similar EFA requirements to the lynx since they both have relatively simple gastro-intestinal tracts (Ruff, 2007).
Ruff (2007) compares in-situ and ex-situ diets in the study, where it was found that Eurasian otters also required a high amount of protein in their diet, due to the protein being used as an energy source. Some fish species such as herring, contain a high amount of thiaminases, which breaks down thiamine and can cause a thiamine deficiency (Ruff, 2007). In the wild, Eurasian otters were found to selectively choose prey that did not contain a high amount of thiaminases (Ruff, 2007).