Estimate of milk and curd yield loss of sheep and goats with intrammamary infection and its relation to somatic cell count

Equations for predicting milk and curd loss due to intramammary infection in sheep and goat herds were derived. The empirical equations were derived from previously published studies conducted by this team with Assaf sheep and crossbreeds of goats in Israel. From these equations, it appears that infection of 25, 50 and 75% of the udders in a given herd was associated with loss of 4.1–12.2.5% milk in sheep and 0.8–2.3% in goats; whereas curd loss was 5.2–15.5% in sheep and 3.3–9.8.9% in goats. Based on percent of udder infection and projected SCC, the following categories are suggested for classification of sheep and goat milk: i. High-quality milk <800,000 SCC/mL, associated with infection of ∼25%; ii. Medium quality milk <1,500,000 SCC/mL, associated with infection rate between 25 and 50%; iii. Low-quality milk >1,500,000 SCC/mL, associated with infection rate above 50%; iv. Milk containing >3,500,000 SCC/mL should not be accepted for human consumption.