Spreading fresh manure on pastures being grazed by horses (or any type of livestock) is not a recommended practice. However, manure of any species that has been properly composted for a period of 30 days (specific environmental conditins will alter this guideline) may be spread on pastures. The heat generated during composting kills internal parasite eggs/larvae and potentially harmful bacteria, such as Salmonella. It is important to compost properly. Ruminant manure spread on horse pastures should create few parasite problems as there is only one species of internal parasite (Trichostronglus axei) that horses and ruminants can share. Poultry litter is routinely spread on horse pastures as they share no parasites with horses. The biggest problem with poultry litter is the weed infestation that occurs due to weed seed found in poultry manure. Also, salmonella may a concern with non-composted manure from both poultry and ruminants. An additional concern is if atypical substances such as trash are inadvertently included in composted products.