The Effect of Unidentified Growth Factor Sources and Restricted Feeding on the Performance of Egg Strain Chickens

Abstract

A GOOD deal of evidence has accumulated in the literature to indicate the need by growing chicks of unidentified growth factors (UGF) found in certain natural feedingstuffs including fish meals, meat meals and dried whey. In previous studies conducted in our laboratory (Summers et al., 1959a, b) it was found that fish meals and meat meals are not reliable sources of UGF for the chick. Dried whey gave a fairly consistent UGF response but did not supply UGF activity not present in fish solubles.Variable results have been reported concerning the need for UGF by mature hens. Couch et al. (1950) reported that liver fraction “L” contained an unidentified factor necessary for maximum hatchability. Dieckert and Couch (1951) found a hatchability response using whole liver, various fractions of liver “L” and Difco yeast as inclusions in a purified diet. Stephenson and Clower (1952) and Arscott and Combs (1953) presented evidence…