Small Ruminant Research 141 (2016) 11–16 Contents lists available at ScienceDirect Small Ruminant Research journal h om epa ge: www.elsevier.com/locate/smallrumres Quantitative expression of hepatic toll-like receptors 1–10 mRNA in Osmanabadi goats during different climatic stresses I. Sophia a , V. Sejian b,∗ , M. Bagath b , Raghavendra Bhatta b a ICAR—Central Island Agricultural Research Institute, Portblair, Andaman and Nicobar Islands 744101, India b ICAR—National Institute of Animal Nutrition and Physiology, Adugodi, Bangalore 560 030, India a r t i c l e i n f o Article history: Received 11 November 2015 Received in revised form 25 May 2016 Accepted 9 June 2016 Available online 11 June 2016 Keywords: Climate change Combined stress Goats Heat stress Immune response Nutritional stress TLR a b s t r a c t A study was conducted to establish the impact of heat stress, nutritional stress and the combined effect of both stresses (heat and nutrition) on the expression of toll-like receptors (TLRs) genes in liver samples of Osmanabadi goats. Twenty-four adult male Osmanabadi goats (average body weight 16.0 kg) were divided into four equal groups of six each: control (C), heat stress (HS), nutritional stress (NS) and com- bined stress (CS). The study was conducted over a 45 day period. The C and HS goats had ad libitum access to their feed while NS and CS goats were restricted feed (30% intake of C) to induce nutritional stress. The HS and CS goats were exposed to solar radiation for six hours a day between 10:00 h–16:00 h to induce heat stress. The animals were slaughtered at the end of the study and their livers were sampled for dif- ferent TLRs gene expression assay. Among the different TLRs studied, TLR1, TLR3, TLR6, TLR7, TLR8 and TLR10 mRNA expressions were significantly (P < 0.05) higher in HS group as compared to other groups (C, NS and CS). The significantly higher levels of TLR1, TLR3, TLR6, TLR7, TLR8 and TLR10 mRNA expres- sion in HS groups indicated that, when nutrition is not compromised, heat stressed animals were able to maintain their immune functions against heat shock proteins. This suggests that improving nutrition during heat stress condition may be highly beneficial to maintaining the immune status against heat shock proteins of the goats. The higher expression of TLR8 and TLR10 in the HS group indicates that these two genes may act as the immunological markers of heat stress in goats. © 2016 Elsevier B.V. All rights reserved. 1. Introduction The Livestock sector is the source of livelihood for about 1.3 bil- lion world population (FAO, 2009) contributing about 53% of world agricultural GDP (World Bank, 2009). Among livestock, small rumi- nants are mainly reared by small, marginal and landless farmers of developing countries (Mengesha and Tsega, 2012). The native goat species are hardy animals with disease resistance mechanisms that allow them to survive in the harsh climatic conditions in tropical and sub-tropical regions. Small ruminants especially sheep and goats have an impor- tant role in the socio-economic well-being of people in developing countries in the tropics in terms of providing nutrition, income and savings, insurance against emergencies, cultural and ceremonial purposes (Kosgey et al., 2008). Goats play a vital role in securing the livelihood of poor and marginal farmers (Escareno et al., 2013). ∗ Corresponding author at: Animal Physiology Division, National Institute of Ani- mal Nutrition and Physiology, Adugodi, Bangalore−560030, India. E-mail addresses: drsejian@gmail.com, drsejian@rediffmail.com (V. Sejian). They play a crucial role in the economy and provide a valuable contribution for stable households in developing nations. Animals reared in the tropical environments are frequently sub- jected to multiple stressors due to high temperature combined with high relative humidity (Abi-Saab and Saleiman, 1995), inade- quate feed and fodder with low-quality nutrients and unavailability of drinking water (Sejian, 2013). These stressors impair produc- tion, reproduction (Martin et al., 2004; Sejian et al., 2011) and also compromise the immune system, thus increasing the animal’s sus- ceptibility to diseases (Deng et al., 2012; Meng et al., 2013). The bottom line is that these stresses don’t occur individually rather cumulatively in the changing climate scenario. Simulation of such stressors cumulatively under controlled conditions is quite difficult (Blanc et al., 2001) but such studies are required as the livestock sector is currently facing the threat of climatic change and global warming. Innate immunity is one of the preliminary, evolutionary con- served mechanisms that enable the differentiation between self and non-self components through Pattern Recognition Receptors (PRRs). Toll-like Receptors are one among them and widely been studied which recognize specific signature molecules in microbes. http://dx.doi.org/10.1016/j.smallrumres.2016.06.005 0921-4488/© 2016 Elsevier B.V. All rights reserved.