Feed conversion, livestock

Carboxylic lonophores and Efficiency of Feed Conversion by Livestock. A strong note of relevance to studies of the chemical and pharmacological properties of carboxylic lonophores derives from the large scale use of monensin as a livestock feed additive. The rationale is that carboxylic lonophores control endemic coccidiosis in the poultry gut (30) and promote a more favorable fermentation of cellulose in the bovine rumen (31). In either case, the net result is the economically important Increased efficiency of conversion of feed into meat. 

Pharmacokinetics of lonophore Absorption. We have developed a sensitive chemical assay for carboxylic lonophores (which will be published elsewhere) based on their ability to form lipid soluble complexes with cations. We can detect as little as 1 part per billion (ppb) monensin in 2 ml of blood plasma or tissue. For a comparison yardstick, current feeding regimens call for ca. 30 parts per million (ppm) in cattle feed (32) and as much as 100 ppm in poultry feed (33). 

ACS Symposium Series American Chemical Society Washington, DC, 1980. 

The Need for Increased Surveillance of the Exposure of Man to lonophores. From the lipid soluhllity of monensln and other lonophores, we would predict they should have no trouble equilibrating across biological membrane systems including the gut. This Is certainly the case for the two diverse species observed, the dog, a carnivore, and the rabbit, a herbivore. Accordingly, we infer that there Is ample opportunity for monensln and other carboxylic lonophores administered orally to livestock to distribute systemically and exert a pharmacological effect on the recipient animal. Furthermore, the resultant physiological effects may be part of the mechanism by which lonophores produce their Improved feed conversion efficiency. 

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The prompt identification of bacteria that are animal pathogens is important to veterinarians maintaining the health of pets, livestock, and poultry.14 It is also important to physicians if the animal pathogens are transmissible to humans. In animal husbandry, information on the species found in specialized microbial habitats, such as the bovine rumen, can even be used to improve the efficiency of feed conversion.15... 

More than 97% of the available soybean meal is used for feed where extensive heat treatment is necessary to maximize feed conversion efficiency by livestock. Toasting inactivates protease inhibitors (especially trypsin and chymotrypsin inhibitors) and the enzyme urease, and improves protein digestibility. None of these objectives can be obtained without protein being denatured and loss in water solubility however, depending on the method used, meals with great differences in protein solubilities or dispersibilities can be produced. The optimum amount of heat treatment in toasting soybean meal is still debated among animal nutritionists. 

Its effect of reducing tissue rejection in grafts on animals has been mentioned. The converse is, of course, that it must also reduce immunity to disease. -Vail (388b) reported that powdered hydrated Na20 3SiO, has been added to cattle feed for many years to make up for natural deficiencies which affect the growth of livestock and to limber the Joints of older cattle. ... 

On a feed, calorie, or protein conversion basis, it is not efficient to feed grain to animals and then to consume the livestock products. This fact is pointed up in Figs. W-29 through W-31. 

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