Fat Tolerance in Laying Hens

THE TOLERANCE of growing chicks for dietary fat is high. Donaldson et al. (1957) showed that fat levels of up to 33.8 percent could be used without depressing growth if amino acid, vitamin, and mineral levels of the diet were adequate for the higher energy content. In laying hens the effect of dietary fat is not quite as clear. Numerous workers (including Lillie et al., 1951; Hill et al., 1956; Lillie et al., 1957; and Turk et al., 1958) have shown that added fat levels of up to 8 percent had no effect on egg production. In contrast, Millar (1960) observed significantly lower egg production and increased weight gains when 30.4 percent added animal fat was used in a balanced diet. Weiss and Fisher (1957) found that 10 percent added animal fat resulted in reduced egg production, increased body size, obesity, and a generally deranged fat metabolism. It has …