Small Ruminant Research 74 (2008) 221–225 Available online at www.sciencedirect.com Short communication Estimate of milk and curd yield loss of sheep and goats with intrammamary infection and its relation to somatic cell count Gabriel Leitner a,∗ , Nissim Silanikove b , Uzi Merin c a National Mastitis Reference Center, Kimron Veterinary Institute, P.O. Box 12, Bet Dagan 50250, Israel b Department of Ruminant Physiology, Institute of Animal Science A.R.O., The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel c Department of Food Science, Institute of Technology and Storage of Agricultural Products, A.R.O., The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel Received 5 September 2006; received in revised form 8 February 2007; accepted 12 February 2007 Available online 26 March 2007 Abstract 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 >1,500,000SCC/mL, associated with infection rate above 50%; iv. Milk containing >3,500,000 SCC/mL should not be accepted for human consumption. © 2007 Elsevier B.V. All rights reserved. Keywords: Sheep; Goat; Udder infection; Milk yield; Curd yield 1. Introduction The major income from dairy animals is derived from their milk; therefore, factors that reduce milk quantity and quality can cause high economic losses to the farm- ers. In the case of dairy goats and especially sheep, most, if not all of the milk is processed into fermented prod- ucts and cheese; therefore, any reduction in the content of the dry matter, mainly casein, will have a detrimental influence on the industrial value of the milk. In recent years there is an effort in industrialized countries to implement payment schemes for goats and sheep milk ∗ Corresponding author. Tel.: +972 3 9681745; fax: +972 3 9681692. E-mail address: leitnerg@moag.gov.il (G. Leitner). based on somatic cell count (SCC) and protein content, similar to those practiced for bovine milk (Gonzalo et al., 1994). Consequently, factors influencing milk qual- ity that were ignored hitherto are now proving to be more crucial to the farmers than ever before. Goat and sheep farming encompass a greater variety of breeds and more different management systems than the farming of dairy cows. To date, variations between countries in the acceptable levels of SCC in healthy udders exist (Maisi et al., 1987; Fthenakis et al., 1991; Fthenakis, 1994; Gonzalez-Rodriguez et al., 1995). Moreover, the effect of the number of somatic cells in the milk on the final product (quality and yield) is unclear. In Israel, clinically infected glands of goats and sheep are not always treated, and even if treated, it saves the animal but leads in most cases to irreversible loss of 0921-4488/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.smallrumres.2007.02.009