Poultry industry has undergone rapid growth during last three decades. For which even higher usage of antibiotics, both as growth promoters as well as therapeutic agents, has been adopted. However, due to the fear of resistance development in bacterial populations to antibiotics, presence of antibiotic residues in poultry products and increasing consumer demand for products free from antibiotic residues, search for alternatives that could replace antibiotics without causing loss to productivity or product quality has accelerated. Such alternatives in poultry include the use of organic acids, probiotic microorganisms, prebiotic substrates that benefit proliferation of beneficial bacterial populations or synbiotic (combinations of prebiotics and probiotics) ensuring better production and maintaining health of the birds. Others include vitamins and minerals, herbal drugs, plant extracts, phytobiotics and antimicrobial peptides. Probiotic organisms provides competition to pathogenic organisms for intestinal colonizing sites, reduce the diversion of nutrients for harmful microbes and the toxins produced by them and stimulates the immune systems. Similarly, prebiotic offers an alternative, as it alters the intestinal microbes and immune system to reduce colonization by pathogens and allows proliferation of beneficial microflora in the gut. Even using synbiotic is a better strategy for enhancing poultry production, however, more research is needed for selection of probiotic, prebiotics or synbiotics either alone or in combination that can result in the selection of strains capable of performing effectively in the gastrointestinal tract. The contents of this review will be useful for researchers to enrich their knowledge on alternatives of antibiotics in poultry birds without compromising performance of birds and bird welfare.

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Bisphenol A (BPA) acts as an endocrine disruptor, affects animal reproductive success in vivo and affects sperm functions in vitro at environmentally relevant concentrations, leading to reduction in sperm motility and fertilizing ability in fish. The effect of in vitro BPA on avian sperm functions has not been explored. The present study examined the effect of environmentally relevant concentrations of BPA (0 mM, 0.18 mM, 0.37 mM, and 0.74 mM) on sperm functions in chicken in vitro. Sperm were exposed to concentrations of BPA for 30 min and analyzed for motility, fertilizing ability, live sperm percentage, and mitochondrial membrane potential (Δψm). Results showed that BPA at a concentration of 0.74 mM significantly decreased motility, fertilizing ability, live sperm count percentage, and sperm Δψm. Sperm motility was positively correlated with fertility (r = 0.73, p ≤ 0.01), live sperm percentage (r = 0.64, p ≤ 0.01), and high Δψm (r = 0.44, p ≤ 0.01). A dose-dependent and time-dependent effect of BPA was observed on sperm motility at all BPA concentrations. However, sperm's fertilizing ability was unaffected in low BPA concentration (0.18 mM and 0.37 mM). A significantly higher percentage of moribund sperm was observed at 0.37 mM and 0.74 mM BPA compared with at 0.18 mM BPA, in the negative control, and in the vehicle control. The present study confirms that environmentally relevant concentrations of BPA are capable of compromising sperm functions, leading to reduction in fertilizing ability of chicken sperm.

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1. The objective of the experiment was to determine the influence of age, sex and rearing system on Toll-like receptor 7 (TLR7) gene expression in gut, lung and lymphoid tissues and physiological responses to stress in male and female indigenous ducks of Tamil Nadu, India. 2. A total of 36 ducks (12 males and 24 females) were obtained from local farmers and tissue samples of gut tissues (duodenum, jejunum, ileum and caecum), lymphoid organs (spleen and bursa) and lungs were collected in RNAlater solution followed by RNA extraction. 3. After normalisation to β-actin (endogenous control) qPCR analysis identified a significant effect of age, sex and rearing system on TLR7 expression in the ducks. 4. A significant up-regulation of TLR7 expression was observed in lungs, duodenum, jejunum, ileum and caecum of sexually mature (45 wk) compared with that of immature ducks (16 wk). Among sexes, male ducks had significantly higher TLR7 expression than female ducks. 5. Age and sex interactions were significant in lungs, duodenum, jejunum and caecum. Ducks reared in an extensive housing system showed significantly higher TLR7 expression in bursa, lungs, duodenum, ileum and caecum compared to intensively reared ducks. There were no effects of age, sex and rearing systems on TLR7 expression in the spleen. 6. The heterophil-to-lymphocyte ratio and serum corticosterone were higher in ducks reared on an intensive system compared with ducks from an extensive rearing system.

Scientific and technological advancements have led to great expansion of poultry sector in last few decades. The development of genetically superior stocks capable of higher production, even under adverse climatic conditions, has transformed poultry from rural farming to full-fledged industry within 30-35 years. Increase in production volume and productivity per bird may largely be attributed to the combined crossbred and purebred selection (CCPS). The superior purebred lines were evaluated for their nicking ability by specialized cross-breeding program, and the best nicking male and female lines were used for developing four-way commercial crosses. With advancement in molecular techniques, the DNA marker technology emerged as a finer tool for assessing the genetic variability. Genome-wide scan using microsatellites led to identification of quantitative trait loci (QTL) for their use in marker-assisted selection (MAS). Subsequently, the single nucleotide polymorphisms (SNPs) were discovered as third generation of genetic markers. Recent "next-generation sequencing" technique led to the development of highdensity SNP arrays as powerful tool for genetic analysis. Predicting genomic estimate of breeding value (GEBV) of individual using SNPs across the whole genome paved way to conceptualization of "genomic selection" which emerged as the most advanced technology to revolutionize the animal production.