Evaluation of the potential of extract of seaweed Eucheuma denticulatum as an alternative to antibiotic growth promoter in broiler chickens.

The seaweeds are in focus for their immunity and gut health-stimulating potentials in humans and farm animals, but their potential as a gut health-promoting agent and performance booster to replace antibiotic growth promoters (AGP) in broiler chicken-feed remains to be evaluated. In vivo feeding experiments were conducted on commercial broiler chickens (1-42 days post-hatch) to evaluate dried aqueous exact of red seaweed Eucheuma denticulatum (referred to as PBD 5). Each of the three test diets (basal diet with three dosing regimens of PBD5, 0.25 g kg -1 for 0-6 weeks, 0.25 g kg -1 for 0-4 weeks or 1.0 g kg -1 for 0-2 weeks), along with an AGP supplemented diet (Virginiamycin (V), 20 ppm in basal diet), and a control diet was fed to 13 pen replicates of five chicks in each. PBD5 at 1.0 g kg -1 diet for 0-2 weeks improved (P < 0.05) cumulative feed efficiency (4.65 % improvement at 28 d, and 3.74 % at 35 d) than the control and comparable to the V group and the trend in improvement persisted up to 42 d. The group fed with PBD5 @ 1.0 g kg -1 for 0-2 weeks had significantly (P < 0.05) higher serum IgG level, glutathione peroxidase levels, fat digestibility, and expression of occludin and avian beta-defensin 4 gene in the gut and a trend of increased expression of growth hormone receptor gene in the liver as compared to the control with no significant effect on body weight, phytohemagglutinin response or haemagglutination inhibition titer. At d 25 of age, fecal E. coli count was significantly (P < 0.01) lower in the seaweed extract groups and the V group as compared to the control. It can be concluded that dried aqueous extract of E. denticulatum at 1 g kg -1 diet for 0-2 weeks can be used as an alternative to antibiotic growth promoter in broiler chickens to improve feed efficiency and reduce gut pathogen load, and the improved performance was associated with increased expression of gut immunity and growth hormone receptor genes.

An Immobilized Form of a Blend of Essential Oils Improves the Density of Beneficial Bacteria, in Addition to Suppressing Pathogens in the Gut and Also Improves the Performance of Chicken Breeding.

Antimicrobial growth promoters (AGP) are used in chicken production to suppress pathogens in the gut and improve performance, but such products tend to suppress beneficial bacteria while favoring the development and spread of antimicrobial resistance. A green alternative to AGP with the ability to suppress pathogens, but with an additional ability to spare beneficial gut bacteria and improve breeding performance is urgently required. We investigated the effect of supplementation of a blend of select essential oils (cinnamon oil, carvacrol, and thyme oil, henceforth referred to as EO; at two doses: 200 g/t and 400 g/t feed) exhibiting an ability to spare Lactobacillus while exhibiting strong E. coli inhibition ability under in vitro tests and immobilized in a sunflower oil and calcium alginate matrix, to broiler chickens and compared the effects with those of a probiotic yeast (Y), an AGP virginiamycin (V), and a negative control (C). qPCR analysis of metagenomic DNA from the gut content of experimental chickens indicated a significantly (p < 0.05) lower density of E. coli in the EO groups as compared to other groups. Amplicon sequence data of the gut microbiome indicated that all the additives had specific significant effects (DESeq2) on the gut microbiome, such as enrichment of uncultured Clostridia in the V and Y groups and uncultured Ruminococcaceae in the EO groups, as compared to the control. LEfSe analysis of the sequence data indicated a high abundance of beneficial bacteria Ruminococcaceae in the EO groups, Faecalibacterium in the Y group, and Blautia in the V group. Supplementation of the immobilized EO at the dose rate of 400 g/ton feed improved body weight gain (by 64 g/bird), feed efficiency (by 5 points), and cellular immunity (skin thickness response to phytoheamagglutinin lectin from Phaseolus vulgaris by 58%) significantly (p < 0.05), whereas neither yeast nor virginiamycin showed a significant effect on performance parameters. Expression of genes associated with gut barrier and immunity function such as CLAUDIN1, IL6, IFNG, TLR2A, and NOD1 were significantly higher in the EO groups. This study showed that the encapsulated EO mixture can improve the density of beneficial microbes in the gut significantly, with concomitant suppression of potential pathogens such as E.coli and improved performance and immunity, and hence, has a high potential to be used as an effective alternative to AGP in poultry.

Higher concentrations of folic acid reduced the dietary requirements of supplemental methionine for commercial broilers.

Objective: An experiment was conducted to study the effect of supplementing DL methionine (DL Met) at graded concentrations on performance, carcass variables, immune responses and antioxidant variables in broiler chicken fed folic acid (FA) fortified (4mg/kg) low-methionine diet. Methods: A basal diet (BD) without supplemental DL Met, but with higher level (4 mg/kg) of FA and a control diet (CD) with the recommended concentration of methionine (Met) were prepared. The BD was supplemented with DL Met at graded concentrations (0, 10, 20, 30, 40 and 50% supplemental DL Met of CD). Each diet was fed ad libitum to 10 replicates of 5 broiler male chicks in each from 1 to 42 d of age. Results: Body weight gain (BWG) reduced, and feed conversion ratio (FCR) increased in broilers fed low-Met BD. At 30 and 20% inclusion of DL Met, the BWG and FCR were similar to those fed the CD. Similarly, supplementation of 10% DL Met to the BD significantly increased ready to cook meat yield and breast meat weight, which were similar to those of the CD fed broilers. Lipid peroxidation reduced, the activity of antioxidant enzymes (GSHPx and GSHRx) in serum increased and lymphocyte proliferation increased with increased supplemental DL Met level in the BD. The concentrations of total protein and albumin in serum increased with DL Met supplementation to the BD. Conclusion: Based on the data, it can be concluded that supplemental Met can be reduced to less than 50% in broiler chicken diets (4.40, 3.94 and 3.39g/kg, respectively in pre-starter, starter and finisher phases) containing 4 mg/kg FA.

Effects of Dietary Antimicrobial Growth Promoters on Performance Parameters and Abundance and Diversity of Broiler Chicken Gut Microbiome and Selection of Antibiotic Resistance Genes.

Antimicrobial growth promoters (AGPs) are commonly used in broiler production. There is a huge societal concern around their use and their contribution to the proliferation of antimicrobial resistance (AMR) in food-producing animals and dissemination to humans or the environment. However, there is a paucity of comprehensive experimental data on their impact on poultry production and the AMR resistome. Here, we investigated the effect of five antimicrobial growth promoters (virginiamycin, chlortetracycline, bacitracin methyl disalicylate, lincomycin, and tylosin) used in the commercial broiler production in the Indian subcontinent and in the different parts of the world for three consecutive production cycles on performance variables and also the impact on gut bacteria, bacteriophage, and resistome profile using culture-independent approaches. There was no significant effect of AGPs on the cumulative growth or feed efficiency parameters at the end of the production cycles and cumulative mortality rates were also similar across groups. Many antibiotic resistance genes (ARGs) were ubiquitous in the chicken gut irrespective of AGP supplementation. In total, 62 ARGs from 15 antimicrobial classes were detected. Supplementation of AGPs influenced the selection of several classes of ARGs; however, this was not correlated necessarily with genes relevant to the AGP drug class; some AGPs favored the selection of ARGs related to antimicrobials not structurally related to the AGP. AGPs did not impact the gut bacterial community structure, including alpha or beta diversity significantly, with only 16-20 operational taxonomic units (OTUs) of bacteria being altered significantly. However, several AGPs significantly reduced the population density of some of the potential pathogenic genera of bacteria, such as Escherichia coli. Chlortetracycline increased the abundance of Escherichia phage, whereas other AGPs did not influence the abundance of bacteriophage significantly. Considering the evidence that AGPs used in poultry production can select for resistance to more than one class of antimicrobial resistance, and the fact that their effect on performance is not significant, their use needs to be reduced and there is a need to monitor the spread of ARGs in broiler chicken farms.

Gut Microbial Composition Differs Extensively among Indian Native Chicken Breeds Originated in Different Geographical Locations and a Commercial Broiler Line, but Breed-Specific, as Well as Across-Breed Core Microbiomes, Are Found.

Gut microbiota plays an important role in the health and performance of the host. Characterizations of gut microbiota, core microbiomes, and microbial networks in different chicken breeds are expected to provide clues for pathogen exclusion, improving performance or feed efficiency. Here, we characterized the gut microbiota of "finishing" chickens (at the end of production life) of indigenous Indian Nicobari, Ghagus, and Aseel breeds, originating from the Nicobari island, coastal India, and the Indian mainland, respectively, as well as a global commercial broiler line, VenCobb 400, using 16S rDNA amplicon sequencing. We found that diversity, as well as richness of microbiota, was higher in indigenous breeds than in the broiler line. Beta diversity analysis indicated the highest overlap between Ghagus and Nicobari breeds and a very low overlap between the broiler line and all indigenous breeds. Linear discriminant analysis effect size (LEfSe) revealed 82 breed- or line-specific phylotype operational taxonomic unit (OTU) level biomarkers. We confirm the presence of breed specific and across-breed core microbiomes. Additionally, we show the existence of breed specific complex microbial networks in all groups. This study provides the first (and comprehensive) insight into the gut microbiota of three indigenous breeds and one commercial broiler line of chickens reared without antimicrobials, and underscores the need to study microbial diversity in other indigenous breeds.

Dietary supplementation of extracts of red sea weed (Kappaphycus alvarezii) improves growth, intestinal morphology, expression of intestinal genes and immune responses in broiler chickens.

BACKGROUND: Effects of supplementation of dried alkaline (referred to as MVP1) and aqueous (referred to as PBD1) extracts of Kappaphycus alvarezii, were evaluated in broiler (Vencobb 400) chickens (1-35 days post-hatch). In experiment I, each of the seven diets (basal diet with three levels (0.5, 1.5 or 5.0 g kg-1 diet) of MVP1 or PBD1 and a negative control was fed to 12 pen replicates containing five birds in each. In experiment II, each of three diets [a negative control, and PBD1 at two levels (1.0 or 1.5 g kg-1 diet)] was fed to 16 pen replicates of five chicks in each. RESULTS: Concentrations of total phenolics, phycobillins and free radical scavenging activity were higher (P < 0.01) whereas carrageenan was lower in PBD1 than in MVP1. In the experiment I, PBD1 at 1.5 g kg-1 diet improved (P < 0.05) body weight (BW) (7.11% higher). In the experiment II, both the treatments improved (P < 0.01) BW (9.18% and 8.47%, respectively) compared to the control. The group fed with PBD1@ 1.0 g kg-1 had higher (P < 0.05) haemagglutination inhibition titre, expression of intestinal claudin 2, TLR2A, NOD1, avian beta defensin 4, interleukin 2 and interleukin 6 genes than control. Treatments did not influence feed efficiency or levels of most of the antioxidant enzymes. Villus width and crypt depth were significantly higher in the group fed with 1.5 g kg-1 of PBD1. CONCLUSION: Supplementing dried aqueous extract of K. alvarezii at 1 g kg-1 diet may be an effective strategy to increase growth and immunity in broiler chickens. © 2020 Society of Chemical Industry.

Effect of incremental levels of dietary total sulfur amino acids on performance of white leghorn laying hens fed diets containing guar (Cyamopsis tetragonoloba) meal.

BACKGROUND: The present study evaluated the potential of increasing dietary levels of the most limiting amino acids such as total sulfur amino acids (TSAA) with respect to mitigating the adverse effects of the inclusion of guar meal (GM) in the diet of WL layers on egg production, feed efficiency and egg weight. In total, 4928 WL (Lohmann L) hens (32 week of age) were randomly allotted to eight treatments with seven replicates of 88 birds. The dietary treatments were a set of four maize-soybean meal based diets containing four graded concentrations of TSAA (5.85, 6.18, 6.51 and 6.84 g kg-1 ) and another set of four diets containing 100 g kg-1 guar meal (GM) with similar concentrations of TSAA. RESULTS: The inclusion of 100 g kg-1 GM in the diet caused a 20%, 23%, 35.5% and 6.7% reduction in egg production, daily egg mass, feed efficiency and egg weight, respectively, when the diet contained 5.85 g kg-1 TSAA. Increasing TSAA levels in GM groups reduced the adverse effects on egg production and feed efficiency 50%, with no effect on egg weight. The TSAA requirement of WL birds fed 10% GM was estimated as 6.28-7.39 g kg-1 diet at different ages. CONCLUSION: Increasing dietary TSAA to 7.39, 6.28, 6.53 and 6.37 g kg-1 or dTSAA (digestible TSAA) to 6.53, 5.32, 5.80 and 5.63 g kg-1 during 33-36, 37-40, 41-44 and 45-48 weeks of age, respectively, may be an effective and practical strategy for reducing the adverse effects of inclusion of 100 g kg-1 GM in the diet of WL layers. © 2018 Society of Chemical Industry.

Effect of phytase superdosing, myo-inositol and available phosphorus concentrations on performance and bone mineralisation in broilers.

A total of 2,376 one-day-old Ross broiler chickens were used to investigate the effect of myo-inositol (MYO) and phytase supplementation on performance and bone mineralization variables in broilers fed diets formulated to have varying concentrations of available phosphorus (P). The trial was designed as a 2 × 2 × 3 factorial; with and without phytase superdosing (0 or 1,500 FTU/kg), MYO (0 or 3 g/kg), and dietary P (low, moderate or high). At 21 d, dietary phytase and MYO had no consistent benefit on bone mineralization variables. Bone ash reduced by 4.7% from the medium to low P diet (P < 0.01), with no effect of phytase supplementation. Superdosing improved bone P content by 6% in birds fed the low P diet, signifying an interaction between dietary P concentrations and phytase (P < 0.05). Dietary MYO addition resulted in a numerical reduction in bone ash and a significant reduction in bone strength (P < 0.05). At 42 d, the beneficial effect of phytase superdosing on feed intake and body weight gain was evident in the low P diet. Superdosing reduced feed conversion rate (FCR) at all P levels (P < 0.05), although this effect was more pronounced on the low P diet, suggesting that sufficient P being released from the phytase itself to re-phosphorylate MYO and hence improve FCR. The significant improvement in FCR was greater with superdosing than with MYO alone, and the combination led to no further improvement in FCR compared with superdosing alone, signifying a phytase and MYO interaction (P < 0.05). From these results, it can be estimated that MYO is providing around 30% to 35% of the total response to superdosing.