The Value of Soluble and Insoluble Grit in All-Mash and Mash-Grain Rations for Caged Layers

Observations on the Inter-relationships of Egg Quality Traits and Their Association with Season, Age, and Strain of Bird

“…While Jenkins and Taylor (1960) and Walter and Aitken (1961), as well as others, have shown that the calcium level of the feed affects shell thickness, early work by Morgan and Mitchell (1938) has shown that a high production rate does not necessarily lead to a loss of calcium within the birds system. While Jenkins and Taylor (1960) and Walter and Aitken (1961), as well as others, have shown that the calcium level of the feed affects shell thickness, early work by Morgan and Mitchell (1938) has shown that a high production rate does not necessarily lead to a loss of calcium within the birds system.…”

“…Shell quality remained high through the fall and early spring and then declined (Jull, 1924;Miller and Bearse, 1934;Wilhelm, 1940;Warren et al, 1950;O'Niel and Rae, 1952;Johnson and Merritt, 1955;Brant et al, 1953;Strain and Johnson, 1957;Froning and Funk, 1958;Funk et al, 1958;Huston, 1958;Mueller et al, 1960;and Pfost, 1960;Pope et al, 1960;Tyler and Geake, 1960;Huston and Carmon, 1961;Redman and Shoffner, 1961;Walter and Aitken, 1961;Hurwitz and Griminger, 1962;and Fry et al, 1963). Under these conditions shell quality during the fall as measured by percent shell, shell thickness or specific gravity, was relatively high.…”

Effects of insoluble grit on the productive performance of ten white leghorn strains1

“…Walters and Aitken (1961) found that insoluble grit had no beneficial effects when offered to caged layers which had been reared on range with free access to granite grit. Proudfoot (1973) confirmed that hens housed in cages do not benefit from the offering of insoluble grit; the birds were reared under confinement, in floor pens, with no access to grit.…”

Bird response to grit and pesticide granule characteristics: Implications for risk assessment and risk reduction

“…Birds can retain grit in their gizzards for extended periods [51,52], and although the mechanisms are largely unknown, several factors seem to influence retention time, including grit availability, size, and diet. When grit is readily available, birds ingest and eliminate considerable amounts of grit daily [35,41,42], whereas birds without ready access to grit tend to reduce grit elimination [51]. When larger grit is consumed, fewer particles are ingested and retained [35,40,41].…”