Feed efficiency, growth response

Rats were fed various non-nutritive polymers and T-2 toxin in the fourth trial and the addition of T-2 toxin to the control diet again reduced final body weights and feed consumption. Zon-olite Verxite and cation exchange resin had little effect on these responses but the decrease in final body weights and feed consumption was reduced by the feeding of bentonite and anion exchange resin. Since both feed consumption and growth rates were reduced by T-2 toxin, feed efficiencies were relatively unaffected. 

In connection with work on animal protein factors, it was found that chlortetracycline fermentation mash containing some vitamin Bi2 gave growth responses well above those obtained with supraoptimal levels of vitamin Bi2 alone. At the present time, both chlortetracycline and oxytetracycline are used extensively for growth stimulation and improvement of feed efficiency in poultry and hogs, and for the reduction of losses from certain disease conditions. Purified antibiotics as well as dried fermentation residues with the mycelium of Streptomyces aureofaciens are used for these purposes. Tetracyclines, used as animal feed supplements, are selling for about 60/kg. 

A dietary deficiency of tin has been reported to depress growth, response to sound, and feed efficiency, alter the mineral composition of several organs, and cause hair loss in rats. Additionally, tin has been shown to influence heme oxygenase activity and has been associated with thymus immune and homeostatic functions. 

Efficiency of feed use for growth is usually improved with anaboHc steroids, but the magnitude of the response is somewhat variable. 

The enhanced efficiency with which dietary protein is used for growth in the neonate is due to the ability of neonatal muscle to markedly increase protein synthesis in response to feeding (Davis etal, 19%). The stimulation of protein synthesis by feeding in neonatal muscle is independently modulated by the post-prandial rise in insulin and amino acids (Davis et al, 2002 O Connor et al., 2003). These responses decrease with development. 

---