Effect of citric acid, avilamycin, and their combination on the performance, tibia ash, and immune status of broilers

Efficacy of supplementing Aspergillus awamori in enhancing growth performance, gut microbiota, digestibility, immunity, and antioxidant activity of heat-stressed broiler chickens fed diets containing olive pulp

BACKGROUND

Gut microbes play a significant role in digestion, developing immunity, and intestinal health. Therefore, direct-fed microbials are used to modify gut microbiota, maintain a healthy digestive system, enhance immunity, and promote the broilers' performance. In addition, it has a role in improving the utilization of unconventional feed ingredients (olive pulp, OP). This study provides the potential role of Aspergillus awamori in enhancing gut microbial content, nutrient utilization, growth performance, and antioxidative status in heat-stressed broiler chickens fed diets containing olive pulp.

METHODS

Three hundred chicks (Ross 308; one day old) were divided into four treatment groups (75 chick/ group) randomly, as follows; CON: chicks fed a basal diet based on corn and soybean meal, OP10: chicks fed a diet containing 10% OP, OA1: chicks fed a diet containing OP with A. awamori at 100 mg per kg, OA2: chicks fed a diet containing OP with A. awamori at 200 mg per kg.

RESULTS

Adding A. awamori to the broiler diet that contains OP had a positive effect on productive performance via enhancing nutrition digestibility, body weight gain, feed conversion ratio, and carcass characteristics. A. awamori supplementation had a positive impact on immune responses by increasing serum immunoglobulin G and the relative weight of bursa of Fabricius (P < 0.05) compared to the other groups. Chickens fed A. awamori showed a noticeable improvement in the oxidative status through the increase in the level of serum superoxide dismutase, and glutathione peroxidase, and the decrease in the level of malondialdehyde. Feeding A. awamori also modified the intestinal microbial content by increasing the population of Lactobacillus (P < 0.05).

CONCLUSIONS

Our study indicated that adding 200 mg A. awamori reduced the negative effect of heat stress by modifying the microbial content of the intestine, immune response, and enhancing feed utilization, thus improving broiler performance, as well as, improving the nutritional value of the olive pulp. Therefore, adding A. awamori to the OP diet can be effectively used in heat-stressed broiler diets.

Modulation of Performance, Plasma Constituents, Small Intestinal Morphology, and Cecum Microbiota in Growing Geese by Dietary Citric Acid Supplementation

To investigate the efficiency and optimum inclusion level of CA in growing geese diets on performance, plasma constituents, and intestinal health, 240 healthy female geese at the age of 28d were randomly allotted six treatment diets incorporated with 0, 0.8, 1.6, 2.4, 3.2, and 4% CA. Each treatment group consisted of five replicates and eight birds per replicate. The findings demonstrated that 3.2% CA supplementation resulted in improved growth performance (ADG, ADFI, and FBW) (p = 0.001), and geese who received CA also showed lower body fat contents (p < 0.05) than the control group. Moreover, geese from the 2.4% and 3.2% CA group had the highest plasma glutathione peroxidase and insulin-like growth factor 1 levels compared to the other groups (p < 0.05). A microbial diversity analysis of the cecum conducted by 16S rDNA sequencing revealed that 3.2% CA supplementation showed a significantly higher abundance of beneficial bacteria (Muribaculaceae, CHKCI001, Erysipelotricha-ceae_UCG_003, and UCG_009) (p < 0.05) and a lower abundance of harmful bacteria (Atopobiaceae, Streptococcus, Acinetobacter, Pseudomonas, and Alistipes) (p < 0.10). Collectively, our results revealed that dietary supplementation with 3.2% CA had several benefits on the performance and physiological health of growing geese by promoting nutrients metabolism, improving antioxidant capacity, and modulating cecum microbiota.

Impact of buffered sodium butyrate as a partial or total dietary alternative to lincomycin on performance, IGF-1 and TLR4 genes expression, serum indices, intestinal histomorphometry, Clostridia, and litter hygiene of broiler chickens

BACKGROUND

Sodium butyrate (SB) is a short-chain fatty acid and a safe antibiotic alternative. During 35 days, this study compared the impact of coated SB (Butirex C4) and lincomycin (Lincomix) on broiler growth, gut health, and litter hygiene in 1200 one-day-old Ross-308 broiler chicks that were randomly assigned into 5-dietary groups with 5-replications each. Groups divided as follows: T1: Basal diet (control), T2: Basal diet with buffered SB (1 kg/ton starter feed, 0.5 kg/ton grower-finisher feeds), T3: Basal diet with 100 g/ton lincomycin, T4: Basal diet with buffered SB (0.5 kg/ton starter feed, 0.25 kg/ton grower-finisher feeds) + 50 g/ton lincomycin, and T5: Basal diet with buffered SB (1 kg/ton starter feed, 0.5 kg/ton grower-finisher feeds) + 50 g/ton lincomycin. Birds were housed in a semi-closed deep litter house, where feed and water were available ad libitum. Results were statistically analyzed using ANOVA and Tukey's post hoc tests.

RESULTS

Combined dietary supplementation with SB and lincomycin (T4 and T5) significantly enhanced body weights, weight gains, feed conversion ratio, and profitability index. Also, carcasses in T4 and T5 exhibited the highest dressing, breast, thigh, and liver yields. T5 revealed the best blood biochemical indices, while T3 showed significantly elevated liver and kidney function indices. T4 and T5 exhibited the highest expression levels of IGF-1 and TLR4 genes, the greatest villi length of the intestinal mucosa, and the lowest levels of litter moisture and nitrogen. Clostridia perfringens type A alpha-toxin gene was confirmed in birds' caeca, with the lowest clostridial counts defined in T4.

CONCLUSIONS

Replacing half the dose of lincomycin (50 g/ton) with 0.5 or 1 kg/ton coated SB as a dietary supplement mixture showed the most efficient privileges concerning birds' performance and health.

Effects of dietary organic acid and pure botanical supplementation on growth performance and circulating measures of metabolic health in Holstein calves challenged by heat stress

To evaluate the effects of heat stress environmental conditioning and dietary supplementation with organic acid and pure botanicals (OA/PB) on growth in dairy calves, we enrolled 62 bull (noncastrated) and heifer calves in a study with a completely randomized design. Calves were assigned to 1 of 5 groups (n = 11 to 14/group): (1) thermoneutral conditions (TN-Con), (2) HS conditions (HS-Con), (3) thermoneutral conditions and pair-fed to match nutrient intake with HS-Con (TN-PF), (4) HS with low-dose OA/PB [75 mg/kg of body weight (BW); 25% citric acid, 16.7% sorbic acid, 1.7% thymol, 1.0% vanillin, and 55.6% triglyceride; HS-Low], or (5) HS with high-dose OA/PB (150 mg/kg of BW; HS-High). Supplements were delivered as a twice-daily bolus via the esophagus from wk 1 through 13 of life; all calves, including those on the control treatments, received an equivalent amount of triglyceride used for microencapsulation. Calves were raised in TN conditions from birth until weaning. After weaning, calves (62 ± 2 d; 91 ± 10.9 kg of BW) were transported to a new facility and remained in TN conditions [temperature-humidity index (THI): 60 to 69] for a 7-d covariate period. Thereafter, calves remained in TN or were moved to HS conditions (THI: diurnal change 75 to 83 during night and day, respectively) for 19 d. Clinical assessments were performed thrice daily, BW was recorded weekly, and blood was sampled on d 1, 2, 3, 8, 15, and 19. Upon experiment completion, calves from HS-Con and TN-Con were euthanized, and hot carcass and visceral organ weights were recorded. The mixed model included calf as a random effect; treatment, day, hour (when appropriate) as fixed effects, and the interactions of treatment × day and treatment × hour (when appropriate). Rectal and skin temperatures and respiration rates were greater in HS-Con than in TN-Con. During heat stress exposure, dry matter intake (DMI), average daily gain (ADG), and gain to feed (G:F) were lower in HS-Con relative to TN-Con. Comparing HS-Con and TN-PF, ADG and G:F were similar. Plasma fatty acid concentrations were elevated in TN-PF compared with HS-Con and TN-Con. Despite tendencies for increased aspartate aminotransferase, HS conditions did not overtly influence liver and inflammation markers. Liver weights were lower in HS-Con relative to TN-Con. During the first week of heat exposure, DMI was greater for HS-Low relative to HS-Con. Supplementation of OA/PB at low and high levels had a similar G:F to HS-Con. We conclude that reductions in DMI accounted for production losses during HS conditioning and that dietary OA/PB supplementation was not able to improve growth performance in heat-stressed calves.

Growth studies in commercial broiler birds offered citric acid in formulated feed with low mineral density

Study of 35 days was conducted to evaluate citric acid (CA) as an additive in poultry broiler feed with lower mineral content of calcium (Ca) and total phosphorus (TP) in commercial broiler poultry birds for its effect on growth, nutrient utilization, carcass characteristics, and economics. Vancobb-400 strain day old broiler chicks were divided into four main treatment groups T_0, T₁, T₂, and T_3. Treatment groups were further divided into eight replicates with ten chicks in each. T₀ served as control, given standard corn-soy flakes-based ration (Pre-starter %: Crude protein (CP)-23, Ca-1.00, TP-0.70; Starter %: CP-22, Ca-1.10, TP-0.72, and Finisher %: CP-20, Ca-0.99, TP-0.70). Treatment T₁ served as positive control with added 0.5% CA (Pre-starter %: CP-23, Ca-1.00, TP-0.70; Starter %: CP-22, Ca-1.10, TP-0.72 and Finisher %: CP-20, Ca-0.99, TP-0.70). Treatment T₂ was given feed containing 0.5% CA with low Ca and TP content (Pre-starter %: CP-23, Ca-0.90, TP-0.66; Starter %: CP-22, Ca-0.99, TP-0.71 and Finisher %: CP-20, Ca-0.90, TP-0.69), whereas treatment T₃ was given feed containing 0.5% CA with moderately low Ca and TP content (Pre-starter %: CP-23, Ca-0.80, TP-0.65; Starter %: CP-22, Ca-0.88, TP-0.70 and Finisher %: CP-20, Ca-0.79, TP-0.68). Birds offered moderately low Ca and TP with 0.5% CA addition, exhibited higher growth rate (P < 0.05), better nutrient utilization with positive influence on dressing percentage and forequarters weight. Economics of broiler feeding revealed that 0.5% CA supplementation fetched highest gross return above feed cost in broiler birds offered feed with moderately low Ca and TP content whereas lowest profit was recorded in feed with low content of Ca and TP. In conclusion, supplementation of 0.5% CA in feed with low and moderately low Ca and TP content positively influenced overall growth, and carcass characteristics. Economics of broiler feeding with moderately low Ca and TP content revealed highest profit with CA (0.5%) supplementation.

Potential Feed Additives as Antibiotic Alternatives in Broiler Production

This article aimed to describe the current use scenario, alternative feed additives, modes of action and ameliorative effects in broiler production. Alternative feed additives have promising importance in broiler production due to the ban on the use of certain antibiotics. The most used antibiotic alternatives in broiler production are phytogenics, organic acids, prebiotics, probiotics, enzymes, and their derivatives. Antibiotic alternatives have been reported to increase feed intake, stimulate digestion, improve feed efficiency, increase growth performance, and reduce the incidence of diseases by modulating the intestinal microbiota and immune system, inhibiting pathogens, and improving intestinal integrity. Simply, the gut microbiota is the target to raise the health benefits and growth-promoting effects of feed additives on broilers. Therefore, naturally available feed additives are promising antibiotic alternatives for broilers. Then, summarizing the category, mode of action, and ameliorative effects of potential antibiotic alternatives on broiler production may provide more informed decisions for broiler nutritionists, researchers, feed manufacturers, and producers.

Prospects of organic acids as safe alternative to antibiotics in broiler chickens diet

Genetically, modern broilers are fast-growing birds which attain the market age at the age of 5 weeks. To maintain optimum production, antibiotics have been commonly included in the diets as growth promoters. However, due to the increase in antimicrobial resistance, their uses have been banned worldwide. To keep the optimum level of production and health in broiler industry, the use of alternative growth promoters such as probiotics, prebiotics, enzymes, and organic acids has been proposed. Chemically, organic acids are weak acids and only partially dissociate. They are considered safe and have been used for preservation of food for centuries. Nowadays, organic acids have been reported for antibacterial, immune potentiating, and growth promoters in broilers. In this review, the effects of dietary inclusion of organic acids on growth, nutrient digestibility, intestinal integrity, immune system, and antibacterial activity in broilers are discussed.

A Pilot Study on the Effect of Thyme Microemulsion Compared with Antibiotic as Treatment of Salmonella Enteritidis in Broiler

Multidrug resistance poses a global threat to the poultry industry and public health, so the direction towards eliminating the use of antibiotics and finding alternatives is a vital step to solve this problem. Thyme microemulsion (10% oil/water) had nanodrop size 28.65 ± 0.89 nm, with a polydispersity index (PDI) of 0.28 with greater homogeneity. It showed IC₅₀ > 100 ug/ml on cytotoxicity assay and 14 active components by GC-Mass. The study was carried out using 210 Cobb chicks divided into fourteen groups. The infected groups were challenged using two Salmonella Enteritidis multidrug resistance (MDR) and Salmonella Enteritidis sensitive strains to the sulpha-trimethoprim antibiotic. The challenged inoculum was 1 × 10⁹ CFU of Salmonella Enteritidis by oral route. The MIC treatments doses were 1 ml/liter water for thyme oil and thyme microemulsion and 33.34 mg/kg b.wt sulfadiazine for 5 days. The results showed that both thymol oil (0.1%) and microemulsion (0.01%) are able to decrease the count of Salmonella Enteritidis in cecal content and fecal dropping and the mortality rates after five days of treatment. In addition, thyme oil and microemulsion had no pathological alteration on chickens' tissues that were collected two weeks after giving the treatment. By the robust HPLC method, the SDZ and TMP residues in tissues of infected groups treated with Cotrimazine® + thyme oil microemulsion had a slight significant economic impact (P < 0.05) compared to Cotrimazine® alone. In conclusion, thymol oil and microemulsion could be an alternative economic choice for multidrug resistance Salmonella Enteritidis treatment in poultry farms.

Regulatory Effects of Combined Dietary Supplementation With Essential Oils and Organic Acids on Microbial Communities of Cobb Broilers

The emergence and spread of antibiotic resistance genes in pathogenic microorganisms have resulted in many countries restricting the use of antibiotics as growth promoters in animal feed. The combined use of essential oils and organic acids can help maintain intestinal health, improve animal growth performance, and alleviate the negative effects of banned antibiotics for certain economically important animals. Although the modes of action for the combined dietary supplementation of essential oils and organic acids such as thymol-citric acid (EOA1) and thymol-butyric acid (EOA2) remain unclear, it is speculated that their activities are achieved through beneficial modulation of gastrointestinal microbial communities and inhibition of pathogen growth. In this study, 16S rDNA amplicon sequencing was used to analyze the effects of treatment with EOA1 and EOA2 on the jejunal, cecal, and fecal microbial communities of Cobb broilers while also evaluating effects over different broiler ages. The intestinal microbial communities of broilers developed with increasing age, and Lactobacillus gradually came to dominate the intestinal communities of treated broilers. Further, the microbial communities of feces were more complex than those of the jejuna and ceca. We systematically elucidate that the longitudinal changes in the intestinal microbial communities of Cobb broiler chickens at different ages. Meanwhile, we found that the addition of EOA1 or EOA2 to the diet: (1) inhibited the proliferation of Ralstonia pickettii and Alcaligenaceae in the jejuna on day 28, (2) promoted the colonization and growth of beneficial bacteria such as Lactobacillus, Clostridia, and Bacteroidia at various growth stages, and (3) enriched the abundance of certain microbiota functions, including biological pathways related to metabolism (e.g., enzyme families). Taken together, the results of this study demonstrate that EOA1 and EOA2 dietary supplementation can affect various microbial metabolic pathways related to the metabolism and absorption of nutrients via regulation of the intestinal microbial community structures of Cobb broilers.

Acidification of drinking water improvement tibia mass of broilers associated with the alterations in intestinal barrier and microbiota

Objective

Diet acidification supplementation is known to influence intestinal morphology, gut microbiota, and on phosphorus (P) utilization of broilers. Alterations in intestinal barrier and microbiota have been associated with systemic inflammation and thus regulating bone turnover. Hence the effect of acidifier addition to drinking water on tibia mass and the linkages between intestinal integrity and bone were studied.

Methods

One-d-old male broilers were randomly assigned to normal water (control) or continuous supply of acidified water (2% the blend of 2-hydroxy-4-methylthiobutyric acid, lactic, and phosphoric acid) group with 5 replicates of 10 chicks per replicate for 42 d.

Results

Acidification of drinking water improved the ash percentage and calcium content of tibia at 42 d. Broilers receiving acidified water had increased serum P concentration compared to control birds. The acidified group showed improved intestinal barrier, evidenced by increased wall thickness, villus height, the villus height to crypt depth ratio, and upregulated mucin-2 expression in ileum. Broilers receiving drinking water containing mixed organic acids had a higher proportion of Firmicutes and the ratio of Firmicutes and Bacteroidetes, as well as a lower population of Proteobacteria. Meanwhile, the addition of acidifier to drinking water resulted in declined ileal and serum proinflammatory factors level and increased immunoglobulin concentrations in serum. Concerning bone remodeling, acidifier addition was linked to a decrease in serum C-terminal cross-linked telopeptide of type I collagen and tartrate-resistant acid phosphatase reflecting bone resorption, whereas it did not apparently change serum alkaline phosphatase activity that is a bone formation marker.

Conclusion

Acidified drinking water increased tibia mineral deposition of broilers, which was probably linked with higher P utilization and decreased bone resorption through improved intestinal integrity and gut microbiota and through decreased systemic inflammation.

Does the use of lactic acid as an antibiotic substitute in broiler diets affect growth, carcass traits, blood indices and intestinal microbiota?

The objective of the current study was to determine the impact of lactic acid (LAC) as an antibiotic alternative in broiler diets on growth performance, carcass traits, blood indices and intestinal microbial load. A total of 300 broiler chicks one day old (Ross 208) were allotted to five experimental groups in a complete randomized design experiment. Each group was subdivided into six replicates, each of ten unsexed chicks. The treatments were as follows: NC: negative control (basal diet); PC: positive control (basal diet + 0.5 g Colistin® antibiotic/kg diet); LAC2, LAC4, and LAC6: basal diet + 2, 4, and 6 cm³ lactic acid/kg diet, respectively. Results showed no significant effects of dietary treatments (antibiotic or lactic acid) on growth performance traits (body weight, BW; daily body weight gain, DBWG; feed intake, FI and feed conversion ratio, FCR) and carcass characteristics except for Thigh %. All blood biochemical traits were affected (p > 0.01) by dietary treatments. The highest values of blood total protein and albumin were found in birds of LAC2 group. Adding graded doses of LAC to broiler diets inhibited the activity of liver enzymes and reduced the concentration of blood urea. The positive effect of LAC supplementation excelled that of antibiotics regarding the antioxidant status parameters. The lowest pathogenic bacteria (E. coli and Salmonella) were recorded by LAC4 and LAC6 groups. It could be concluded that dietary supplementation of lactic acid did not significantly affect most growth performance traits. But its use could have beneficial impacts on blood parameters, oxidative status and intestinal microbial counts. Based on our results, the highest level (6 cm³ LAC/kg diet) is the recommended level for the best results.

Protected Organic Acid and Essential Oils for Broilers Raised Under Field Conditions: Intestinal Health Biomarkers and Cecal Microbiota

The objective of the present study was to evaluate the effect of protected organic acids (OA) and essential oils (EO) [P(OA + EO)] on the intestinal health of broiler chickens raised under field conditions. The study was conducted on four commercial farms. Each farm consisted of four barns, two barns under a control diet and two tested barns supplemented with P(OA + EO), totaling 16 barns [8 control and 8 under P(OA + EO)]. The control group was supplemented with antibiotic growth promoters [AGP; Bacitracin Methylene Disalicylate (50 g/ton) during starter, grower and finisher 1, and flavomycin (2 g/ton) during finisher 2]. The tested group was supplemented with 636, 636, 454, and 454 g/ton of P(OA + EO) during starter, grower, finisher 1 and 2, respectively. Eighty birds were necropsied (40/treatment; 20/farm; and 5/barn) to collect blood, jejunal tissue, and cecal contents. The data were submitted to analysis of variance (ANOVA) (P < 0.05) or Kruskal-Wallis' test and the frequency of antimicrobial resistant (AMR) genes was analyzed by Chi-Square test (P < 0.05). It was observed that the supplementation of P(OA + EO) reduced (P < 0.05) the histopathology scores, such as the infiltration of inflammatory cells in the epithelium and lamina propria and tended (P = 0.09) to reduce the serum concentration of calprotectin (CALP). The supplementation of P(OA + EO) reduced the serum concentration of IL-12 (P = 0.0001), IL-16 (P = 0.001), and Pentraxin-3 (P = 0.04). Additionally, P(OA + EO) maintained a cecal microbiota similar to birds receiving AGP. The substitution of AGP by P(OA + EO) reduced (P < 0.05) the frequency of four AMR genes, related to gentamicin (three genes), and aminoglycoside (one gene). Overall, the inclusion of P(OA + EO), and removal of AGP, in the diets of commercially raised broiler chickens beneficially changed the phenotype of the jejunum as shown by the lowered ISI scores which characterizes an improved intestinal health. Furthermore, P(OA + EO) significantly reduced the serum concentration of several inflammatory biomarkers, while maintaining the diversity and composition of the cecal microbiota similar to AGP fed chickens and reducing the prevalence of AMR genes.

Butyric and Citric Acids and Their Salts in Poultry Nutrition: Effects on Gut Health and Intestinal Microbiota

Intestinal dysfunction of farm animals, such as intestinal inflammation and altered gut microbiota, is the critical problem affecting animal welfare, performance and farm profitability. China has prohibited the use of antibiotics to improve feed efficiency and growth performance for farm animals, including poultry, in 2020. With the advantages of maintaining gut homeostasis, enhancing digestion, and absorption and modulating gut microbiota, organic acids are regarded as promising antibiotic alternatives. Butyric and citric acids as presentative organic acids positively impact growth performance, welfare, and intestinal health of livestock mainly by reducing pathogenic bacteria and maintaining the gastrointestinal tract (GIT) pH. This review summarizes the discovery of butyric acid (BA), citric acid (CA) and their salt forms, molecular structure and properties, metabolism, biological functions and their applications in poultry nutrition. The research findings about BA, CA and their salts on rats, pigs and humans are also briefly reviewed. Therefore, this review will fill the knowledge gaps of the scientific community and may be of great interest for poultry nutritionists, researchers and feed manufacturers about these two weak organic acids and their effects on intestinal health and gut microbiota community, with the hope of providing safe, healthy and nutrient-rich poultry products to consumers.

The Effect of Acidifier-Dextrose against Hen Day Production and Feed Conversion Ratio in Laying Hens Infected with Avian Pathogenic Escherichia coli

Colibacillosis in Indonesia until now still appears frequently, so the case of colibacillosis laying hens cannot reach the peak of egg production; the egg production period is delayed and easily infected with other diseases. The purpose of this research is that the acidifier-dextrose combination is expected to be able to suppress the development of Avian Pathogenic Escherichia coli (APEC) bacteria in laying hens so that, in the end, the case of colibacillosis can be controlled in Indonesia. A total of 240 heads of laying hens were divided into 6 treatments and each consisted of 40 replications. The results of this research state that a combination of acidifier-dextrose can increase Hen Day Production (p < 0.05) and decrease Feed Conversion Ratio (p < 0.05) in laying hens infected with APEC. The Hen Day Production results of the treatment group infected with APEC showed the lowest results, amounting to 65.75% whereas the other treatments are still above 90%. Furthermore, the highest Feed Conversion Ratio results were on treatments infected with APEC, which amounted to 2.17 while other treatments of the Feed Conversion Ratio results are still below 1.80. In general, the use of a combination of acidifier and dextrose with the lowest dose, that is, 1 g/3.75 liters of drinking water can still give good results to Hen Day Production and Feed Conversion Ratio for laying hens infected with APEC. Giving combination of acidifier-dextrose can increase Hen Day Production and decrease Feed Conversion Ratio in laying hens infected with APEC. The recommended dosage of acidifier-dextrose combination in laying hens based on this research is 1 g/3.75 liters of drinking water.

Modulations of genes related to gut integrity, apoptosis, and immunity underlie the beneficial effects of Bacillus amyloliquefaciens CECT 5940 in broilers fed diets with different protein levels in a necrotic enteritis challenge model

Background

The ban of in-feed antimicrobial additives has negatively affected the poultry industry by causing necrotic enteritis (NE) to emerge in the flocks. Alternatives such as Bacillus probiotics have shown to be effective on eliminating the negative effects of this disease. Two experiments were conducted to investigate the effect of Bacillus amyloliquefaciens CECT 5940 (BA) in broiler chickens under NE challenge and/or fed diets with different protein levels.

Methods

In both experiments, 480 day-old mix-sexed Ross-308 broilers were arranged in a 2 × 2 factorial arrangement of treatments. In experiment 1, the factors were NE challenge (yes or no) and probiotic (yes or no). In experiment 2, the factors were dietary crude protein levels (standard or reduced) and probiotic (yes or no) and were used under NE challenge condition. Oral administration of Eimeria oocysts (day 9) followed by inoculation with Clostridium perfringens (day 14 and 15) was used to induce NE challenge. On day 16, two birds from each treatment were gavaged with fluorescein isothiocyanate-dextran (FITC-d) and blood samples were collected for gut integrity evaluation, and jejunal samples were collected for gene expression assay.

Results

In experiment 1, BA supplementation decreased caspase-3 (CASP3) (P < 0.001) and caspase-8 (CASP8) (P < 0.05) and increased occludin (OCLD) (P < 0.05) expression regardless of the challenge. Additionally, BA supplementation downregulated interfron-γ (IFN-γ) expression (P < 0.01) and upregulated immunoglobulin-G (IgG) (P < 0.01) and immunoglobulin-M (IgM) (P < 0.05) only in challenged birds. In experiment 2, the expression of genes encoding mucin-2 (MUC2) (P < 0.001), tight junction protein-1 (TJP1) (P < 0.05) and OCLD (P < 0.05) were upregulated by the addition of BA in the diet, regardless of the crude protein level. Further, BA supplementation downregulated INF-γ (P < 0.01) and upregulated immunoglobulin-A (IgA) (P < 0.05), IgM (P < 0.05) and IgG (P < 0.01) regardless of the crude protein level.

Conclusion

These findings suggest that supplementation of BA in broiler diets can improve gut health by modulation of genes related to the mucosal barrier, tight junction, and immunity in broilers challenged by unfavourable conditions such as NE challenge.

Isolated and combined organic acids in diets of broiler chickens challenged with Eimeria acervulina

ABSTRACT This study aimed to evaluate the effect of isolated or combined citric and benzoic acids added to the diets of broiler chickens on performance, allometry of the digestive system organs, intestinal pH and quantity of microorganisms in the jejunum. A total of 840 male Cobb broiler chicks were utilized, distributed in a complete random design in 2 × 2 factorial scheme, supplemented or not with citric acid, and sodium benzoate, with seven replications. At 14 days old, 1mL of a solution containing 1 × 105 sporulated oocysts of Eimeria acervulina per bird was inoculated orally. There was no effect of the acids on the broiler’s performance in the 1 to 21-day period. In the total period (1 to 42 days), the broilers fed with a blend of citric and benzoic acid presented greater feed intake, without increment in weight gain. The data of allometry of the digestive system organs and the jejunal pH values were not influenced by the treatments. The citric acid increased the bacterial quantity of gram-positive coccus and total anaerobes in the jejunum. Under the conditions of the present study, we conclude that the citric and benzoic acids, isolated or combined, do not benefit the nutrition of broilers challenged with E. acervulina.

Feed acidification and steam-conditioning temperature influence nutrient utilization in broiler chickens fed wheat-based diets

Two experiments were conducted to examine the effects of conditioning temperature (CT) and the interactive influence of feed acidification (FA) and CT on the performance, coefficient of apparent ileal digestibility (CAID) of nitrogen (N), starch, fat calcium (Ca) and phosphorus (P), and AME in broilers. In both experiments, each treatment was randomly allocated to 6 cages (8 birds per cage) and fed from 1 to 21 D posthatch. In experiment 1, the effect of CT was evaluated using a wheat-based diet at 3 CT: unconditioned, conditioned at 60°C or 90°C. All the diets by-passed the pellet press and collected in mash form. Birds fed the diet conditioned at 90°C consumed more (P < 0.05) feed and tended (P = 0.087) to have higher feed per gain (F:G) than those fed the unconditioned diet but similar to those fed the diet conditioned at 60°C. A tendency was noted for CT to affect the CAID of N (P = 0.071) and starch (P = 0.093), with reduced digestibility values in the diet conditioned at 90°C. Conditioning at 90°C resulted in lower (P < 0.05) AME. In experiment 2, three inclusions of an acidifier (0.0, 7.0, and 10 g/kg) and 2 CT of 60°C and 90°C were evaluated in a 3 × 2 factorial arrangement of treatments using pelleted diets. Neither the main effects nor the interaction between acidifier addition and CT was significant for weight gain, feed intake, and F:G. The FA increased (P < 0.05) the CAID of N, fat, and P at both inclusion levels and of starch at 10 g/kg. Conditioning at 90°C reduced (P < 0.05) the CAID of starch, fat, and Ca, regardless of FA level. Overall, the present data showed that the application of high CT for broiler feed manufacture can impair nutrient utilization and, consequently the feed efficiency in broilers. Feed acidification imparts some benefits to nutrient digestibility in broilers fed pelleted wheat-based diets.

Protected Organic Acids Improved Growth Performance, Nutrient Digestibility, and Decreased Gas Emission in Broilers

Simple Summary

Recently, the development of antimicrobial resistance of bacteria has become a global health problem. Such a situation has compelled nutritionists and researchers to explore other potential alternatives. Among a variety of candidates for the replacement of antibiotic growth promoters, organic acids (OAs), both individual and as a blend of several acids are the most promising ones as feed additives in animal production. Organic acids maintain cellular integrity of the gut lining and improve the digestive process by maintaining normal gut flora. Addition of OAs to the diet can improve the absorption rate of proteins, amino acids, and minerals. This may contribute not only in improving performance but also reducing nitrogen and phosphorus excretion. Besides, medium-chain fatty acids (MCFAs) constitute another type of acid and have been shown to be potential alternatives for in-feed antibiotics in farm animals as they have strong antibacterial activity against Gram-positive cocci and Escherichia coli. The combination of OAs and MCFAs has been reported to improve the nutrient digestibility, growth performance, proliferation of Lactobacillus, and immunity of the animal. The present study investigated the effect of a blend of dietary protected OAs and MCFAs on broiler chickens. The results of this study showed that the blend of OA and MCFA supplementation positively influenced growth performance, DM digestibility, excreta Lactobacillus counts, as well as NH₃ gas emission in broiler chickens.

Abstract

We investigated the effects of a blend of organic acids (OAs) and medium-chain fatty acids (MCFAs) supplementation in 800 1-d-old male Ross 308 broiler chickens (42 ± 0.90 g) in a 7-week study. Broiler chicks were randomly allocated into one of the five dietary treatments (16 birds per pen with 10 pens per treatment). Dietary treatments consisted of corn-soybean meal based basal diet and the basal diet supplemented with blend of OAs and MCFAs at 0.25, 0.5, 0.75 g, and 1 g per kg of feed. In the current study, during the whole experimental period, the inclusion of the blend of OAs and MCFAs in the basal diet linearly improved (p < 0.05) body weight gain (BWG), feed conversion ratio (FCR), and dry matter digestibility. The increasing inclusion of the blend of OA and MCFA levels in the diets linearly decreased (p = 0.002) feed intake during d 1 to 7. Broilers fed diets containing different levels of the blend of OAs and MCFAs showed a linear increase (p = 0.006) in Lactobacillus concentrations and decrease (p = 0.014) in ammonia (NH₃) at the end of the experiment. However, the blend of OAs and MCFAs did not affect carcass quality, E. coli, and Salmonella counts, as well as hydrogen sulfide and total mercaptans gas emission (p > 0.05). In conclusion, the blend of OA and MCFA supplementation positively influenced growth performance, DM digestibility, excreta Lactobacillus counts, as well as NH₃ gas emission in broiler chickens.

Role of acidifiers in livestock nutrition and health: A review

Ever since the European ban on use of in-feed antibiotics in food animals, the search for alternate antibiotic-free growth promoter is undertaken worldwide. There are few alternatives such as probiotics, pre-biotics, phytochemicals, enzymes and organic acids. Among these alternatives, the organic acids or simply acidifiers play an important role in gut health in animals. The acidifiers could be used to favourably manipulate the intestinal microbial populations and improve the immune response, hence perform an activity similar to antibiotics in food animals in countering pathogenic bacteria. Acidifiers also improve the digestibility of nutrients and increase the absorption of minerals. The incorporation of organic acids also leads to thinning of the intestinal lining which facilitates better absorption of nutrients and its efficient utilization. However, their effect will not be similar among all types of organic acids as their mechanism of activity is based on its pKa value. Moreover, there are claims about the neutralization of acids by the secretion of bicarbonates in the initial part of intestine, reactivity with metallic items in feed mills and reduced palatability due its bitter taste demands non-reactive and targeted delivery for better performance. Currently, coated salts of acidifiers are available commercially for use in food animals especially pigs and poultry. The present review highlights the role of different acidifiers in livestock nutrition with their potent applications in improving nutrient digestibility, mineral utilization, meat quality, enhancing immunity, antimicrobial effects in countering pathogenic bacteria, boosting performance and production, and thus safeguarding health of livestock animals and poultry.

Effects of compound organic acid calcium on growth performance, hepatic antioxidation and intestinal barrier of male broilers under heat stress

Objective

The aim of this study was to evaluate the effects of compound organic acid calcium (COAC) on growth performance, hepatic antioxidant status and intestinal barrier of male broilers under high ambient temperature (32.7°C).

Methods

Nine hundred healthy one-d-old Cobb-500 male broiler chicks were randomly assigned into three groups with six replicates of 50 birds each. A basal diet supplemented with 0% (control), 0.4% and 0.8% COAC, respectively were fed to birds for 6 weeks. All treatments were under high ambient indoor temperature of 32.7°C, and had a constant calcium and available phosphorus ratio.

Results

The results showed that, compared with control, the average daily gain of broilers in 0.4% and 0.8% was significantly increased and the ratio of feed to gain in in 0.4% and 0.8% was significantly decreased at 1 to 21, 22 to 42 and 1 to 42 days of age (p<0.05). Compared with control, 0.8% COAC slightly decreased (p = 0.093) the content of malondialdehyde in liver at 42 days of age while 0.4% COAC significantly decreased (p<0.05) the activity of alkaline phosphatase. Furthermore, 0.4% COAC significantly enhanced the intestinal barrier function via increasing jejunal and ileal ocln transcription, promoting jejunal mucin 2 transcription at 42 days of age (p<0.05), and decreasing jejunal toll-like receptor 2 (TLR-2) and ileal TLR-15, inducible nitric oxide synthase compared with control group (p<0.05). Whereas, no significant differences on the transcription of interleukin-1β in jejunum and ileum were observed among three treatments (p>0.05). Overall, heat stress caused by high natural environment temperature may induce the damage to hepatic antioxidation and intestinal barrier.

Conclusion

Dietary inclusion of COAC can improve the tolerance of broilers to thermal environment through the modification of antioxidative parameters in liver and the mRNA expression of genes in intestinal barrier, resulting in an optimal inclusion level of 0.4%.

Effects of commercial organic acid blends on male broilers challenged with E. coli K88: Performance, microbiology, intestinal morphology, and immune response

This study assessed the effects of 3 commercial organic acid (OA) preparations on growth performance, intestinal morphology, cecal microbiology, and immunity of Escherichia coli K88-challenged (ETEC) broiler chickens. One thousand one-day-old male broiler chickens were divided into 8 treatments of 5 replicate pens: Negative control (NC) birds received a basal diet (BD) and were not challenged with ETEC; positive control (PC) birds fed the BD and challenged with ETEC; BD + 0.2% (S1) or 0.4% (S2) of an OA mixture (Salkil) from one to 35 d; BD + 0.1, 0.075, and 0.05% (O1) of another OA mixture (Optimax) in the starter (one to 10 d), grower (11 to 24 d), and finisher (25 to 35 d) diets, respectively, or 0.1% (O2) from one to 35 d; BD + 0.07, 0.05, and 0.05% (P1) or 0.1, 0.07, and 0.05% (P2) of a further OA mixture (pHorce) in the starter, grower, and finisher diets, respectively. All groups (not NC) were challenged with one mL of ETEC (1 × 108 cfu/mL) at 7 d of age. The 3 OA mixtures are commercial formic and propionic acid preparations. Birds challenged with ETEC (PC) had reduced (P < 0.05) growth performance, ileal morphological parameters (not crypt depth, which was increased), cecal lactobacilli, and immune responses, and increased cecal E. coli compared with unchallenged, NC birds. The addition of OA to the diets of ETEC challenged birds (S1-P2) either numerically or significantly (P < 0.05) improved growth performance, ileal morphology and immune responses, increased cecal lactobacilli, and reduced cecal E. coli. For most OA additions, the assessed parameters were generally enhanced to equivalence to NC birds. The results suggest that dietary OA supplementation can enhance the growth performance, ileal morphology, cecal microbiota, and immunity of ETEC-challenged broilers to an extent that, under such circumstances, the formulations used in this study provided similar performance and assessed parameters as non-challenged birds.

Meta-analytic study of organic acids as an alternative performance-enhancing feed additive to antibiotics for broiler chickens

The effect of organic acids as an alternative to antibiotics on the performance of broiler chickens was evaluated by meta-analysis, identifying and quantifying the main factors that influence results. A total of 51,960 broilers from 121 articles published between 1991 and 2016 were used. Interactions of additives [non-supplemented group (control), organic acids, and growth promoter antibiotics] with microbial challenge (with or without inoculation of pathogenic microorganisms) were studied on performance variables. Moreover, the effects of organic acids, used individually or in blends, were evaluated. Relative values of average daily gain (ADG) and average daily feed intake (ADFI) were obtained in relation to control: ΔADG and ΔADFI, respectively. Analysis of variance-covariance revealed lower ADG with organic acids when compared to antibiotics (P < 0.05). There was a significant interaction between the additives and the challenge on feed conversion ratio (FCR) (P < 0.01) and on viability (P < 0.05). Without challenge, organic acids improved broilers’ FCR (P < 0.01), presenting results similar to antibiotics (P > 0.05). Under challenge, the organic acids were again effective on FCR (−5.67% in relation to control, P < 0.05), but they did not match antibiotics (−13.40% in relation to control, P < 0.01). Viability was improved only under challenge conditions, and only by antibiotics (+4.39% in relation to control, P < 0.05). ADG (P < 0.05) and FCR (P < 0.01) were increased by blends of organic acids, but not by the organic acids used alone (P > 0.05). ADFI and production factor were not influenced by the treatments (P > 0.05). ΔADFI of organic-acid supplemented group showed a linear influence on ΔADG, which increases 0.64% at every 1% increase in ΔADFI. In conclusion, organic acids can be utilized as performance enhancing, but the results are lower than those found with antibiotics, particularly under microbial challenge. The blends of organic acids provide better results than the utilization of one organic acid alone.

Diet supplementation with an organic acids-based formulation affects gut microbiota and expression of gut barrier genes in broilers

This study was designed to study the effect of diet supplementation with an organic acids-based formulation (OABF) on luminal- and mucosa-associated bacteria, concentration of volatile fatty acids (VFA), microbial glycolytic enzyme activity and expression of mucin 2 (MUC2), immunoglobulin A (IgA) and tight junction protein, i.e., zonula occludens-1 (ZO1), zonula occludens-2 (ZO2), claudin-1 (CLDN1), claudin-5 (CLDN5) and occludin (OCLN), genes at the ileal and cecal level. A 2 × 2 factorial design was used having OABF inclusion and avilamycin as main factors. Subsequently, 544 day-old male Cobb broilers were allocated in the following 4 treatments, each with 8 replicates: no additions (CON), 1 g OABF/kg diet (OA), 2.5 mg avilamycin/kg diet (AV) and combination of OA and AV (OAAV). The trial lasted for 42 days. In the ileum, OAAV resulted in lower mucosa-associated total bacteria levels (P_{O × A} = 0.028) compared with AV. In addition, ileal digesta levels of Clostridium perfringens subgroup were decreased by avilamycin (P_A = 0.045). Inclusion of OABF stimulated the activity of microbial glycolytic enzymes, whereas avilamycin resulted in lower acetate (P_A = 0.021) and higher butyrate (P_A = 0.010) molar ratios. Expression of ZO1 and CLDN5 was down-regulated by both OABF (P_O = 0.016 and P_O = 0.003, respectively) and avilamycin (P_A = 0.016 and P_A = 0.001, respectively). In addition, CLDN1 was down-regulated in AV compared with CON (P_{O × A} = 0.012). Furthermore, OABF down-regulated MUC2 (P_O = 0.027), whereas avilamycin down-regulated nuclear factor kappa B subunit 1 (NFKB1) (P_A = 0.024), toll-like receptor 2 family member B (TLR2B) (P_A = 0.011) and toll-like receptor 4 (TLR4) (P_A = 0.014) expression. In the ceca, OABF inclusion increased digesta levels of Clostridium coccoides (P_O = 0.018) and Clostridium leptum (P_O = 0.040) subgroups, while it up-regulated MUC2 expression (P_O = 0.014). Avilamycin (P_A = 0.044) and interaction (P_O × A < 0.001) effects for IgA expression were noted, with CON having higher IgA expression compared with AV. In conclusion, new findings regarding OABF inclusion effects on an array of relevant biomarkers for broiler gut ecology have been reported and discussed in parallel with avilamycin effects used as a positive control. This new knowledge is expected to provide a response baseline for follow up trials under various stress and challenge conditions.

Supplement comprising of laccase and citric acid as an alternative for antibiotics: In vitro triggers of melanin production

An indiscriminate use of antibiotics in humans and animals has led to the widespread selection of antibiotic-resistance, thus constricting the use of antibiotics. A possible solution to counter this problem could be to develop alternatives that can boost the host immunity, thus reducing the quantity and frequency of antibiotic use. In this work, for the first time, citric acid and laccase were used as extracellular inducers of melanin production in yeast cells and human cell lines. It is proposed that the formulation of laccase and citric acid together could further promote melatonin-stimulated, melanocyte-derived melanin production. Melanization as a probe of immunity described in this study, is an easy and a rapid test compared to other immunity tests and it allows performing statistical analyses. The results showed the synergistic effect of citric acid and laccase on melanin production by yeast cells, with significant statistical differences compared to all other tested conditions (p: 0.0005-0.005). Laccase and citric acid together boosted melanin production after 8 days of incubation. An increase in melanin production by two human colon cells lines (Cacao-2/15 and HT-29) was observed on supplementation with both laccase and citric acid in the cell growth medium. Produced melanin showed antimicrobial properties similar to antibiotics. Therefore, a formulation with citric acid and laccase may prove to be an excellent alternative to reduce the antibiotic use in human and animal subjects.

Effect of organic acids or probiotics alone or in combination on growth performance, nutrient digestibility, enzyme activities, intestinal morphology and gut microflora in broiler chickens

A feeding trial was conducted to determine the effect of organic acids or probiotics alone or in combination on growth performance, nutrient digestibility, enzyme activity, intestinal morphology and gut microflora in broiler chickens (Ross308). A completely randomized design was used, with 1,440 broiler chicks across four treatments and five replications of 72 chicks each. The chicks in the control treatment were fed on a control diet (CD), whereas for the other treatment groups, the CD was supplemented with 0.2 g/kg organic acids (CDOA), probiotics (CDP) or a combination of organic acids and probiotics (CDOAP). All the chicks were fed ad libitum during the feeding trial throughout 35 days. A total of 20 chicks were randomly allotted to individual metabolic cages to measure the nutrient digestibility (35-42 days) and the digestive enzyme activities (42 days). The intestinal morphology and gut microflora of 80 chicks were examined at the end of experiment. There were no significant (p > .05) differences in the feed intake, body weight gain or feed conversion ratio of the chicks across the four dietary treatments. The crude fibre digestibility was significantly increased in chicks fed on CDOA or CDOAP relative to CD (p < .05). Nutrient utilization, in terms of digestive enzyme activities and excreta thermal property, was unchanged by any supplementation. The chicks fed on the CDOAP had significantly higher duodenal villi height and crypt depth than the chicks fed on CDOA (p < .05). This dietary treatment dramatically improved gut microflora by decreasing the population of Escherichia coli and increasing the Lactobacillus spp.:E. coli ratio. Based on our investigations, supplementation of organic acids and probiotics in chick diets can increase the ability to digest crude fibre and villus height and decrease intestinal E. coli without impairing growth performance.

Supplementing the feeds of layer pullets, at different ages with two different fiber sources improves immune function

Two experiments were conducted to study the effects of lignocellulose supplementation on immune function in layer pullets at different stages of growth. Four-wk-old pullets (Experiment 1) were fed a control, diet (Diet C); Diet C plus 1% mixed soluble/insoluble fiber (Diet MF), or plus 1% insoluble fiber (Diet IF). At 7.5 wk-of-age, heterophil phagocytosis, and oxidative burst in Groups MF (328.5 beads/100 cells; 4,330.0 ΔRFU; relative fluorescent units) and IF (350.3; 5,264.4) were greater (P < 0.05) than Controls (303.4; 3,509.0). At 8 wk-of-age, Group MF and IF relative weights of bursa of Fabricius (0.57 g/100 g BW; 0.58 g /100 g BW), thymus glands (0.77; 0.78), and areas of Peyer's patches (PP) (2.7 cm2; 2.9 cm2) were higher (P < 0.05) than Controls (bursa, 0.50 g; thymus, 0.70 g; PP area, 1.8 cm2). In Experiment 2, 10-wk-old pullets were fed a control diet or diets containing 1.5% MF or IF for 8 wk. At 14 wk-of-age IF pullets had higher (P < 0.05) heterophil phagocytosis efficiency (447.9 beads/100 cells) than Controls (376.4) and MF and IF had greater (P < 0.05) oxidative burst (1,302.9 and 1,857.7 ΔRFU) than Controls (744.1). At 17 wk-of-age MF and IF had increased (P < 0.05) proliferation of T-lymphocytes (ConcanavalinA-stimulated) (100.4 and 103.1% of unstimulated cells) and B-lymphocytes (lipopolysaccharide-stimulated) (122.4 and 129.0) than Controls (ConA, 79.4; lipopolysaccharide, 106.6). At 18 wk-of-age, IF pullets were heavier (1,607.5 g, P < 0.05) than Controls (1,506.5 g), had heavier (P < 0.05) bursa of Fabricius (1.12 g) than MF and Control groups (0.98 g; 0.92 g) and cecal tonsils of MF (0.38 g) and IF (0.39 g) weighted more (P < 0.05) than Controls (0.33 g). Number of jejunal and ileal PP (10.0) in IF pullets was higher (P < 0.05) than Controls (7.1). These results indicate that both MF and IF can improve development of the immune system of young and grower pullets during periods of maturation and involution of lymphoid organs.

Alternatives to antibiotics for maximizing growth performance and feed efficiency in poultry: a review

With the increase in regulations regarding the use of antibiotic growth promoters and the rise in consumer demand for poultry products from ‘Raised Without Antibiotics’ or ‘No Antibiotics Ever’ flocks, the quest for alternative products or approaches has intensified in recent years. A great deal of research has focused on the development of antibiotic alternatives to maintain or improve poultry health and performance. This review describes the potential for the various alternatives available to increase animal productivity and help poultry perform to their genetic potential under existing commercial conditions. The classes of alternatives described include probiotics, prebiotics, synbiotics, organic acids, enzymes, phytogenics, antimicrobial peptides, hyperimmune egg antibodies, bacteriophages, clay, and metals. A brief description of the mechanism of action, efficacy, and advantages and disadvantages of their uses are also presented. Though the beneficial effects of many of the alternatives developed have been well demonstrated, the general consensus is that these products lack consistency and the results vary greatly from farm to farm. Furthermore, their mode of action needs to be better defined. Optimal combinations of various alternatives coupled with good management and husbandry practices will be the key to maximize performance and maintain animal productivity, while we move forward with the ultimate goal of reducing antibiotic use in the animal industry.

Effect of different doses of coated butyric acid on growth performance and energy utilization in broilers

We recently applied four dietary treatments in experiments I and II to determine the effect of protected calcium butyrate (BP) on growth performance and nutrient digestibility in broiler chickens. A group of one-day-old male Ross 308 broiler chicks (total 960, 480 per trial) were used in the study. In experiment I, the basal diets were fed with protected BP inclusion (0.2, 0.3, or 0.4 g/kg of finished feed) (BP) or without (C). In experiment II, 4 different diets were tested: 1) basal diet with no supplementation (C), 2) basal diet supplemented with protected BP (0.3 g/kg) (BP), 3) basal diet supplemented with avilamycin (6 mg/kg, active substance) a common antibiotic growth promoter (AGP) (Av), and 4) basal diet supplemented with the combination of both avilaymicin and BP. In experiment I, considering the entire study period, the use of BP improved feed conversion ratio (P<0.05) irrespective of the dose. Apparent total tract crude fat digestibility and apparent metabolizable energy corrected for nitrogen (AMEN) were improved after BP supplementation (P<0.05). In experiment II, A or AB diets improved (P<0.05) body weight gain compared to the control treatment. The diets Av, BP, and AvB improved (P<0.05) feed conversion ratio compared to the control treatment. Birds from the treatment diet were characterized by having the thickest mucosa (P<0.05). On days 14, 35, and 42, the use of AB diets improved AMENcontent compared to the control treatment (P<0.05). The apparent ileal digestibility of amino acid data showed that Av or AvB treated birds were characterized by higher Asp, Glu, Cys, Gly, and Ala ileal digestibility than the control animals (P<0.05). The use of Av, BP, or AvB increased ileal digestibility of Thr, Ser, and Pro (P<0.05). There is an indication that BP, alone or in combination with avilamycin, improve the digestion and absorptive processes and consequently birds performance results.

Comparison of the effects of basil (<i>Ocimum basilicum</i>) essential oil, avilamycin and protexin on broiler performance, blood biochemistry and carcass characteristics

Abstract. The effects of a probiotic (protexin), a medicinal plant (basil essential oil) and an antibiotic growth promoter (avilamycin) as broiler feed additives on performance, carcass characteristics and some blood parameters of broilers were studied. A total of 600 Arian broilers were divided into six treatments, with four replicates of 25 birds. Treatments were a plant essential oil in three levels (200, 400 and 600 ppm), the probiotic (150 ppm), the antibiotic (150 ppm) and a control group with no additives. Birds in different treatments received the same diets during the experimental period. Growth performance, blood biochemical parameters and carcass traits were measured. There were no effects of dietary treatment on body weight gain, feed intake and feed conversion ratio of the broilers. Internal organ weights and carcass characteristics were not influenced by treatments; however, 200 ppm basil essential oil supplementation decreased abdominal fat (P < 0.05). Biochemical parameters including serum low-density lipoprotein (LDL), high-density lipoprotein (HDL) and total cholesterol were not statistically influenced. However, addition of 400 ppm basil essential oil into diet increased serum triglyceride as compared to the control (P < 0.05). Results of this experiment demonstrated that the herbal natural feed additives such as basil may be used as alternatives to an antibiotic growth promoter without any adverse effects on broiler production.