Alfalfa and Orchardgrass Silages Treated with Formaldehyde and Formic Acid or Anhydrous Ammonia for Heifers

Alfalfa and orchardgrass were harvested in October 1980, ensiled either untreated or treated with either formaldehyde-formic acid or with anhydrous ammonia, and offered to four Holstein heifers to measure intake, digestibility, and nitrogen balance. Alfalfa had lower cell wall and hemicellulose and higher total nitrogen and insoluble nitrogen than orchardgrass. These differences in composition increased apparent digestibility of dry matter, gross energy, and nitrogen for alfalfa compared with orchardgrass at similar dry matter intakes. Digested dry matter contained less cell wall and hemicellulose for alfalfa than orchardgrass. Formaldehyde-formic acid and ammonia treatments increased insoluble nitrogen in alfalfa. Ammonia treatment increased ammonia nitrogen in alfalfa and orchardgrass. Treatments increased dry matter intake but reduced dry matter, cell solubles, and hemicellulose digestibilities. Ammonia treatment of orchardgrass increased nutrient digestibilities compared with formaldehyde-formic acid, but formaldehyde-formic acid treatment of alfalfa increased digestibilities compared with ammonia. Nevertheless, ammonia treatment increased retained nitrogen by heifers fed alfalfa, indicating improved nitrogen status. Effect of ammonia treatment of high quality forage on nitrogen and carbohydrate economy in the gut of dairy cattle needs further attention.