Relationships among forage aluminum levels, soil contamination on forages, and availability of elements to dairy cows.

Abstract

Analyzing forage from ungrazed areas of intensively managed ryegrass pastures re vealed that aluminum concentrations in the plants normally remained below 100 mg/kg of dry matter. Forage samples from grazed areas contained 100 to 400 mg Al/kg during most of the grazing season, but exceeded 1600 mg/kg during cold, wet weather as a result of increased soil contamination on the surface of the forage. Adding 1000 mg/kg Al as aluminum sulfate in the ration of cows or feeding 1 kg soil per cow per day was consistently associated with greater retention of Mg and Ca but had no measurable influence on P or K retention. Soil addition to the ration also in creased Al retention values. Apparent availability of Ca and Al was consistently higher when the cows received either A12(S04)3 or soil in the ration. Apparent di gestibility of organic matter was uniform throughout the experiment. The studies suggest that the intake of soil or A12(S04)3 did not adversely affect Mg or Ca nutri tion of dairy cows.