Poultry Booster Pack is a blend of vitamins and direct-fed microbials specifically designed to refresh aged or held-over Poultry Nutri-Balancer (PNB). Fertrell guarantees its vitamins for six months of normal storage (out of sunlight and dry). Vitamin potency will naturally decrease by 25% after six months of normal storage. Please note: Poultry Booster Pack does not replace the much needed calcium, phosphorus, kelp meal, salt and other essential micro nutrient that Poultry Nutri-Balancer contains. It is only to be used to refresh expired PNB.