Leather meal, hydrolyzed leather meal, tannery by-product meal

Description: 

Leather is composed primarily of collagen, which has a poor amino acid profile. The digestibility of unhydrolyzed leather meal is very low so it has little value as a feed. Leather scraps associated with the production of various leather products can be collected and hydrolyzed in a similar manner (see feather meal for processing conditions) to poultry feathers and used as a supplemental protein source for livestock. Normally CP content ranges from 70 to 75 %. Primarily used as a supplemental protein source for ruminant applications, since its amino acid profile is of quite low quality. Because of the poor amino acid profile care needs to be used when formulating diets to assure that the amino acid requirements of the animal that is being fed are being satisfied. Therefore, normally only low levels of leather meal are normally incorporated into diets, because of the poor balance of amino acids that it contains. Chromium (Cr) is commonly added during the leather tanning process, therefore Cr poisoning is a potential problem when leather meal is fed. The Cr level in the leather meals should not exceed approximately 2.75 %. Chromium can exist in several different forms and the form present in leather meal seems not to be absorbed really by animals and does not seem to accumulate in the meat or fat of animals consuming it (Ref #498).

Caution: 

Chromium (Cr) in leather meal can sometimes reach toxic levels, so care should be when formulating rations. 

Source: 

Leather trimmings associated with various manufacturing processes are collected and steam hydrolyzed and the resultant leather meal can be used as a supplemental protein source for livestock.

Feeding Experiments: 

Limited research has been conducted evaluating the feeding characteristics of leather meal. Hydrolyzed leather meal has been shown to be an acceptable source of CP for ruminants for levels up to 6 % (Knowlton, 1976). Vegetable-tanned leather trimmings were ground and added to broiler diets replacing 25 and 50 % of the fish meal and meat and bone meal, it was found that gain and feed conversion were less for the leather meal supplemented groups (2) (CAB N919347) (Kalous, 1986). As the level of unhydrolyzed leather meal was increased (0, 3, 6, or 9%) in broiler diets gain and feed intake was reduced (3) (CAB N250145) (Pinheiro, 1989). When leather meal replaced soybean meal in young (28 to 30 day old) growing swine diets, gains and feed conversion were improved and the incidence of scouring decreased (2) (CAB N919347) (Kalous, 1986). Trout were fed leather meal up to 6-7 % without any depression in performance being observed (1) (CAB N032660) (Eleraky, 1985).

Nutrient Characteristics: