**1. Introduction**

Lot of commonalities in chemical signaling have been observed between vertebrates (mammals) and invertebrates (insects), phylogenetically two distant taxa sharing common ancestors 550 million years back. Despite the fact, different taxa among vertebrates and invertebrates comprise of thousands of species, this commonality has been maintained, mainly due to selective constraints imposed by a terrestrial lifestyle that resulted in dominance of fewer animal phyla in terrestrial habitats. The dominance of Mammaliaformes has been attributed to nocturnal lifestyle that reduces the risk of getting predated from dominant archosaurs [1]. Similar trend has been seen in night active insects that were observed to be having larger body sizes than day active insects sharing the same communities [2]. The nocturnal behavior may have resulted in decreased reliance on visual signals, and full reliance on chemical signals mediated by various mechanisms such as acquisition of hairs in mammals and insects that helped in dispersing chemical signals such as, tail hair tufts in Asian elephants [3], and hair pencils in male noctuid moths [4]. Also certain behavioral aspects are common in mammals and insects that are mediated by chemical signals, such as territory marking, or living in families, and recognition of individuals or group members [5]. Similarities have also been observed in signal processing pathways mediated by chemosensory proteins, olfaction and gustation that have evolved independently. In both the groups membranes of chemosensory cells are modified to increase surface area positioned in proximity to a number of accessory cells and these cells are bathed in liquid through which odorants travel to reach receptors [6]. Also neurons of booth the groups express same protein, synapsing in the same glomerulus, and olfactory cells project directly to the brain. However, olfactory receptor gene families and regulatory process of protein expression by neurons differ between mammals and insects [7]. Despite the organizational similarity in mammals and insects, differences have been observed in olfactory receptors and gustatory receptor proteins. In terms of taste, similarities have been observed in the organization of gustatory systems, recognizing nutritionally important dietary constituents such as bitter, carbon dioxide, water and sweet in insects, and bitter, salty, sour, sweet and umami in mammals [8]. In both mammals and insects chemicals involved in communication are secondary metabolites, derived from primary metabolic processes that show tremendous structural diversity due to differences in selective forces arising from different ecologies. Chemical signals involve primary metabolites such as amino acids, nucleotide bases, sugars, fatty acids and glycerol as starting materials that are utilized to produce secondary metabolites having conservative elemental composition mostly composed of carbon, oxygen, hydrogen, and nitrogen [9]. Chemical signals in terrestrial and aquatic environments differ significantly, and this structural variation has been attributed to the medium through which chemical signals travel. Diffusion in air is a function of molecular weight, that means lighter weight compounds will diffuse faster, such as most insect sex pheromones (MW 200–300) [10]. In contrast, diffusion of chemical signals in aqueous environment depends on water solubility (independent on molecular weight), conducive for signal transmission of biologically important large polar molecules such as proteins [10].

The term Pheromone was coined by karlson and Luscher in 1959 and the name of first pheromone extracted from Honey Bee was proposed as *Bombykal* [11]. Pheromone is a biologically active substance like hormone, a chemical substance secreted externally in urine, feces, or by sub-cutaneous glands or other biological secretions that cause specific reaction in a receiving animal. Exteroceptive cues playing a role in male and female interaction include olfactory, visual, auditory and tactic stimuli, that trigger a specific behavior or physiological change in recipient's endocrine or reproductive system [12]. Extensive studies in insects, rodents, swine, sheep, goats and cattle have established the strong influence exerted by the pheromones secreted by the male on reproductive activity in the female. It has been demonstrated that the urine of male mice, rats, feral species and other wild rodents contains a priming pheromone that is responsible for hastening puberty in the females. Pheromones in the wool, wax and urine of a ram are sufficient to stimulate ewes to ovulate, while the buck has a strong characteristic seasonal odor. The mere presence of the boar at the time of insemination of the sow improves sperm transport and ovulation, while the presence of the vasectomized bull has been reported to hasten the onset of puberty in heifers and also early resumption of ovarian activity in cattle following parturition [13].

*Chemical Signaling in Bovines: Understanding the Behavior and Way of Communication DOI: http://dx.doi.org/10.5772/intechopen.99834*
