Short communication Energy intake, heat production and energy and nitrogen balances of sheep and goats fed wheat straw as a sole diet S. El-Meccawi a , M. Kam b , A. Brosh c , A.A. Degen b, ⁎ a Research and Development of Negev Bedouin, PO Box 999, Hura 85730, Israel b Desert Animal Adaptations and Husbandry, Wyler Department of Dryland Agriculture, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel c Beef Cattle Section, Agricultural Research Organization, Newe Yaar Research Center, P.O. Box 1021, Ramat Yishay 30095, Israel article info abstract Article history: Received 11 November 2008 Received in revised form 15 January 2009 Accepted 23 February 2009 Large areas of the Negev desert are used for rain-fed winter cereal production. Consequently, cereal straw is an important dietary component of sheep and goats raised by the Bedouin in the Negev Desert under both grazing and pen-fed conditions. Often, it is the sole feed offered, although it is relatively low in crude protein content and metabolizable energy yield. We determined metabolizable energy intake and heat production in desert adapted fat-tailed Awassi sheep (n = 8; 49.5 ± 6.6 kg) and mixed breed goats (n = 8; 42.6 ± 11.7 kg) when offered only wheat straw ad libitum, and calculated their energy and nitrogen balances. We hypothesized that there is a difference between sheep and goats in the ability to use wheat straw and predicted that goats would be better able to use wheat straw as an energy and nitrogen source than would sheep. Dry matter intakes of the wheat straw by sheep and goats were similar, 43.4 and 42.6 g kg -0.75 d -1 , respectively, as were apparent dry matter digestibilities, 44.1% and 43.6%, respectively. Metabolizable energy intakes in sheep and goats were also similar, 308.9 and 302.9 kJ kg -0.75 d -1 , respectively, as were their heat productions, 502.3 and 501.0 kJ kg -0.75 d -1 , respectively. Sheep and goats were in negative energy balance, and both lost similar amounts of body reserves,193.6 and 198.1 kJ kg -0.75 d -1 , respectively. Also, both were in negative nitrogen balances; however, the goats were in a lesser deficit (P b 0.05) than the sheep, 0.161 and 0.196 g kg -0.75 d -1 , respectively. Therefore, our predictions were partially confirmed in that the goats were better able to use the nitrogen but not the energy when consuming low-quality wheat straw. © 2009 Elsevier B.V. All rights reserved. Keywords: Desert adapted sheep and goats Low-quality wheat straw Dry matter intake and digestibility Heat production Energy balance Nitrogen balance 1. Introduction Large areas of the semi-arid to arid Negev Desert are used for dry-land (rain-fed) winter cereal production, mainly for wheat but also for barley. After harvesting the grain, sheep and goats often graze the remaining stubble, generally from June to September. In addition, the straw is baled and used as fodder. Consequently, wheat stubble and wheat straw are important components in the diet of sheep and goats under both grazing and penned conditions in the Negev Desert (Landau et al., 2000; Landau et al., 2006). Sheep and goats raised by Bedouin pastoralists in the Negev Desert are generally low producing in terms of milk and offspring output but are well adapted to the climatic conditions and often subsist only on low-quality forage (Degen, 2007). In this study, we determined metabolizable energy intake and heat production in local fat-tailed Awassi sheep and mixed breed goats when offered only wheat straw ad libitum and calculated their energy and nitrogen balances. These local small ruminants are well adapted to desert conditions and are commonly fed low-quality roughages such as wheat straw. In previous studies, it was reported that Livestock Science 125 (2009) 88–91 ⁎ Corresponding author. Desert Animal Adaptations and Husbandry, Ben-Gurion University, Beer Sheva 84105, Israel. Tel./fax: +972 8 6460515. E-mail address: degen@bgu.ac.il (A.A. Degen). 1871-1413/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2009.02.018 Contents lists available at ScienceDirect Livestock Science journal homepage: www.elsevier.com/locate/livsci