Technical Note: Estimating Goat and Sheep Manure Production and their Nutrient Contribution in the Chesapeake Bay Watershed

Abstract

The objectives of this study were to estimate the: (1) the daily manure (feces + urine) outputs by goats and sheep and characterize the nutrient composition, and (2) potential contribution of goats and sheep to the nutrients in the Chesapeake Bay Watershed (Bay) watershed. Manure (feces+ urine) was collected from four 8-month-old mixed-breed hair sheep rams and four 14-month-old meat goat bucks housed in aluminum metabolism crates with rubber-coated expanded metal floors. The animals were fitted with fecal collection bags. Animals were fed a diet of chopped grass hay (75%) and corn/soybean meal concentrates (25%). The animals' numbers in the Chesapeake Bay watershed were obtained from USDA national agricultural animal census database. The manure nutrients excreted by the goats and sheep were compared to those of dairy cows in the watershed to get a feel for the relative impacts. The nitrogen (N), phosphorus (P), and potassium (K) ratios were 8.8:1:6.5 and 8.3:1:6.9, in goat and sheep manure respectively, and over 50% of N and K were in the urine. The goat population in the Bay watershed increased by over 200% between 1997 and 2007, while the sheep population declined by about 10% over the same period of time. Based on the animal census for 2007 in the Bay watershed, the combined N and P excreted by goats and sheep combined were less than 3% of the nutrients excreted by dairy cows.