Production systems and important antimicrobial resistant-pathogenic bacteria in poultry:a review

Economic losses and market constraints caused by bacterial diseases such as colibacillosis due to avian pathogenic Escherichia coli and necrotic enteritis due to Clostridium perfringens remain major problems for poultry producers,despite substantial efforts in prevention and control.Antibiotics have been used not only for the treatment and prevention of such diseases,but also for growth promotion.Consequently,these practices have been linked to the selection and spread of antimicrobial resistant bacteria which constitute a significant global threat to humans,ani-mals,and the environment.To break down the antimicrobial resistance(AMR),poultry producers are restricting the antimicrobial use(AMU)while adopting the antibiotic-free(ABF)and organic production practices to satisfy consum-ers’demands.However,it is not well understood how ABF and organic poultry production practices influence AMR profiles in the poultry gut microbiome.Various Gram-negative(Salmonella enterica serovars,Campylobacter jejuni/coli,E.coli)and Gram-positive(Enterococcus spp.,Staphylococcus spp.and C.perfringens)bacteria harboring multiple AMR determinants have been reported in poultry including organically-and ABF-raised chickens.In this review,we discussed major poultry production systems(conventional,ABF and organic)and their impacts on AMR in some potential pathogenic Gram-negative and Gram-positive bacteria which could allow identifying issues and opportuni-ties to develop efficient and safe production practices in controlling pathogens.

Assessment of different grass species extracts as source of micronutrients in prawn Macrobrachium rosenbergii feeds

The present research is an attempt to screen five perennial indigenous grass species for their biochemical constituents seasonally for one year in order to determine the exact season for the harvest of the target species which will be used as feed ingredient.Among them,Cynodon dactylon has shown better result compared to other grass species and was hence incorporated as micronutrient in the formulated feed.Macrobrachium rosenbergii culture was carried out by feeding conventional and formulated feed(prepared from grass species)in tanks and ponds filled with spring water for 180 days in 2020 in the Eastern Ghats region of Koraput district,Odisha,India.Two treatments namely T_(1)and T_(2)having four replications each were supplied with commercial feed and formulated feed.Feeds were applied as per the body weight of prawns at 20%for the 1st month,15%for the 2nd month,10%for the 3rd and the 4th month,5%for the 5th month and 2%till the end of the experiment.The water temperature,pH,dissolved oxygen,transparency,nitrate,phosphate,silicate,Chl a in the culture tanks and ponds were monitored fortnightly.ANOVA results between all the water parameters for both culture tanks and ponds showed significant variation(P<0.05).The survival rate(77.0%±0.89%),daily growth rate(0.233±0.05)g/day,specific growth rate(4.657%±1.04%)per day and condition index(2.638±0.05)were found to be highest in prawns fed formulated feed.The feed conversion ratio varied from(2.03±0.05)to(2.68±0.04).Benefit cost ratio of field culture were 1.46 with yield of 702 kg/ha in conventional feed and 1.75 with yield of 950 kg/ha in formulated feed respectively.The study proved grass extracts to be efficient micronutrients for prawn feed which can be easily adopted in prawn production.