Pheromones are found throughout the living world and are a primal form of communication. These chemical messengers are transported outside the body and have a direct developmental effect on hormone levels and/or behaviour. The pheromones play an important role in animal behavior and reproductive processes. This review article aims to highlight the role of pheromones of farm animals. The pheromone signals are known to have a potential role in animal reproduction and management. The sources of chemosignals are urine, feces, vaginal secretions, saliva, and specialized scent glands including the odor produced from hair and wool. Pheromones can act as a marker to detect estrus where its detection is a problem and for diagnosing early pregnancy in farm animals. The potential implication of pheromones on improving sexual desire in male is also important. There is huge scope of application of pheromones once it is characterized and synthesized chemically.

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At present, broilers reach slaughter weight at a physiologically younger age and the embryonic developmental period as well as the first week after hatching represents a larger proportion (45%) of the whole life span. Thus, pre-hatch as well as the transitional post-hatch period must be achieved efficiently. It is known that body weight is increased three to four fold during the first week and considerable changes in gut, and muscle weight and morphology are observed. The post-hatch period is critical for the digestive tract because the system is switching itself from off to on. The first day after hatch is critical for the development of body systems in the chicken and certain types of manipulation must occur during the first days after hatch in order to achieve long-term effects. Meat-type broilers are capable of achieving 70 g/day until 40 days. This achievement requires emphasis on early phase nutrition (i.e. pre-starter diets). The use of pre-starter diets assumes that starter diets are somewhat inefficient in providing balanced nutrients. Early nutritional strategies offer the promise of sustaining progress in production efficiency and welfare of commercial poultry. In order to achieve broiler potential several unconventional changes must be made: supplying nutrients to the developing embryo before hatch, supplying feed within hatchery, developing highly digestible pre-starter diets. Integrate all of the above to create a continuous feeding process from several days prior to hatch, during hatch and till farm placement where first feed is provided.

The present study was undertaken to evaluate the effect of bypass fat supplementation on weight gain, feed intake and efficiency of feed utilization growing crossbred calves. Eighteen growing crossbred calves 6-7 months of age and 134 kg average body weight were randomly divided into three equal groups viz, Group-T0 (control), T1 and T2 on the basis of age, weight and sex with three male and three female in each group. All the groups received standard concentrate mixture for 13 weeks. The animals in treatment T1 and T2 fed on concentrate mixture supplemented with bypass fat @ 30 and 60 g per calf per day, respectively. The average body weight gain, DM intake, TDN and DCP intake by calves from group T2 was significantly (P less than 0.01) higher than group T0 and T1. The efficiency of feed utilization in terms of DM, TDN and DCP intake per kg gain was non significant. The nutrient digestibility was higher for treatment groups supplemented with bypass fat. Thus it was concluded that supplementation of bypass fat @60 g per calf per day was beneficial for improving the overall growth performance of calves.