This review attempts to cover the implication of the toll-like receptors (TLRs) in controlling immune functions with emphasis on their significance, function, regulation and expression patterns. The tripartite TLRs are type I integral transmembrane receptors that are involved in recognition and conveying of pathogens to the immune system. These paralogs are located on cell surfaces or within endosomes. The TLRs are found to be functionally involved in the recognition of self and non-self-antigens, maturation of DCs and initiation of antigen-specific adaptive immune responses as they bridge the innate and adaptive immunity. Interestingly, they also have a significant role in immunotherapy and vaccination. Signals generated by TLRs are transduced through NFκB signaling and MAP kinases pathway to recruit pro-inflammatory cytokines and co-stimulatory molecules, which promote inflammatory responses. The excess production of these cytokines leads to grave systemic disorders like tumor growth and autoimmune disorders. Hence, regulation of the TLR signaling pathway is necessary to keep the host system safe. Many molecules like LPS, SOCS1, IRAK1, NFκB, and TRAF3 are involved in modulating the TLR pathways to induce appropriate response. Though quantification of these TLRs helps in correlating the magnitude of immune response exhibited by the animal, there are several internal, external, genetic and animal factors that affect their expression patterns. So it can be concluded that any identification based on those expression profiles may lead to improper diagnosis during certain conditions.

This review attempted to collate and synthesize information on goat welfare and production constraints during heat stress exposure. Among the farm animals, goats arguably are considered the best-suited animals to survive in tropical climates. Heat stress was found to negatively influence growth, milk and meat production and compromised the immune response, thereby significantly reducing goats’ welfare under extensive conditions and transportation. Although considered extremely adapted to tropical climates, their production can be compromised to cope with heat stress. Therefore, information on goat adaptation and production performance during heat exposure could help assess their welfare. Such information would be valuable as the farming communities are often struggling in their efforts to assess animal welfare, especially in tropical regions. Broadly three aspects must be considered to ensure appropriate welfare in goats, and these include (i) housing and environment; (ii) breeding and genetics and (iii) handling and transport. Apart from these, there are a few other negative welfare factors in goat rearing, which differ across the production system being followed. Such negative practices are predominant in extensive systems and include nutritional stress, limited supply of good quality water, climatic extremes, parasitic infestation and lameness, culminating in low production, reproduction and high mortality rates. Broadly two types of methodologies are available to assess welfare in goats in these systems: (i) animal-based measures include behavioral measurements, health and production records and disease symptoms; (ii) resources based and management-based measures include stocking density, manpower, housing conditions and health plans. Goat welfare could be assessed based on several indicators covering behavioral, physical, physiological and productive responses. The important indicators of goat welfare include agonistic behavior, vocalization, skin temperature, body condition score (BCS), hair coat conditions, rectal temperature, respiration rate, heart rate, sweating, reduced growth, reduced milk production and reduced reproductive efficiency. There are also different approaches available by which the welfare of goats could be assessed, such as naturalistic, functional and subjective approaches. Thus, assessing welfare in goats at every production stage is a prerequisite for ensuring appropriate production in this all-important species to guarantee optimum returns to the marginal and subsistence farmers.

Climate change associated heat stress was established to be the crucial factor, which negatively influences animal production. The animals possess several adaptive mechanisms which are helpful for their survival in harsh environmental conditions, but while doing so their productive performances are compromised. Among the various mechanisms, which helps to maintain homeostasis in animals, Physiological adaptability was considered one of the primary response mechanisms by which the heat stressed animals survive the heat stress. This review is therefore an attempt to provide the audience an updated review on the subject to signify the importance of physiological responses in animals and their role in surviving the stressful environment. Respiration rate (RR), pulse rate (PR), rectal temperature (RT), sweating rate (SR) and skin temperature (ST) are the cardinal physiological variables which helps to maintain the heat balance and homeostasis in the stressed animals. Among the various physiological variables, RR, RT and ST were established to be ideal indicators for quantifying heat stress in several farm animals. Therefore, these variables can be effectively used to assess the severity of heat stress in livestock. Although these variables are considered significant in establishing the heat stress impact in animals, a wide genetic variation was also established in these response mechanisms. Further, variations in physiological adaptability were also established between indigenous, cross bred and pure bred animals. The indigenous livestock breeds were tipped to be exhibiting less physiological variability as compared to their counterparts. These discussions vividly indicate the importance of studying in detail the physiological adaptive mechanisms in different farm animals and these efforts can help the farming community to identify the suitable agro-climatic zone specific livestock breeds which can go in long way to help to ensure climate resilient livestock production.