Effect of supplementation of organic acids on gut health in broilers

Introduction

Poultry farming is one of the fastest-growing sectors in Indian agriculture, contributing significantly to food security, rural livelihoods, and the national economy. According to the 20 th Livestock Census (2019), India's poultry population rose by 17% to 851.81 million, while poultry meat and egg production reached 10.25 million tonnes and 142.77 billion, respectively, in 2023-24. Despite this growth, per capita availability of poultry products still falls short of ICMR recommendations, highlighting the need to further enhance productivity. The rapid expansion of poultry production has been achieved through advances in genetics, nutrition, and scientific management. However, intensive rearing systems expose birds to stress and disease, historically managed by including antibiotic growth promoters (AGPs) in feed. AGPs improved performance by reducing microbial competition and enhancing nutrient utilization. Yet, their long-term use raised concerns about antibiotic resistance and residues in poultry products, leading to regulatory bans such as the European Union's prohibition in 2006. This created a need for safe and effective alternatives. Organic acids and their salts have emerged as promising substitutes for AGPs. By lowering gut pH, they suppress pathogens like E. coli, Salmonella, and Campylobacter while promoting beneficial microbes and improving enzymatic activity. Their antimicrobial action results from disrupting bacterial enzymes and transport systems, leading to better nutrient absorption and gut health. Additionally, organic acids improve feed hygiene and act as natural preservatives (Manvatkar et al., 2022) [7] . A wide range of organic acids such as formic, acetic, propionic, butyric, lactic, citric, and fumaric acids are used in poultry diets, often in salt form for improved stability and safety. These acids, naturally present in fruits, vegetables, and dairy products, are effective in improving feed conversion, mineral absorption, and intestinal morphology. Considering that feed accounts for up to 75% of poultry production costs, organic acids play a vital role in enhancing productivity under antibiotic-free broiler production systems.

Materials and Methods

A total of 120-day-old commercial broiler chicks were sourced from Venkateshwara Hatcheries Pvt. Ltd. Bengaluru for the research project. Organic acids (Acidac gold) used in the study was procured from Bionnar Health Care Pvt. Ltd. Kannur, Andhra Pradesh. Chicks were randomly distributed into four treatment groups in a completely randomized design. Each group had three replicates, with 10 chicks in each replicate. Following the Bureau of Indian Standards (BIS) 2007 [6] guidelines, the control group (T1) was fed a basal diet, the treatment group T2 was fed with 0.05% organic acids, treatment group T3 was supplemented with 0.075% organic acids and treatment group T4 fed with 0.1% organic acids. The chicks were reared in a deep litter system until six weeks of age with free access to feed and water throughout the experiment. Standard management practices were followed to maintain optimal conditions and ensure the welfare of the birds. Standard management practices were followed to maintain optimal conditions and ensure the welfare of the birds. The study was approved by the KVAFSU Institutional Animal Ethics Committee in Bidar, Karnataka. At the end of the experiment, two birds from each replicate within the T1 to T4 treatment groups were selected for slaughter, tissue samples from the duodenum, jejunum, and ileocaecocolic junction were collected from the sacrificed birds, rinsed with buffered saline, and then preserved in a 10% neutral buffered formalin solution. This preparation was for histomorphological analysis, enabled the assessment of villus height and crypt depth. Additionally microbial enumeration were assessed by quantifying Lactobacillus spp. and E. coli counts from the intestinal contents the data were statistically analysed.

Results

 Gross morphology

The results of supplementation of organic acids on intestinal villi height and crypt depth in broilers presented in Table 1. Across the six-week study, the statistical analysis revealed a significant differences (p≤0.05) were observed on intestinal villi height and crypt depth in broilers at 42 nd day from different dietary treatment groups of the experiment of chicks among the different treatment groups. The treatment groups T2, T3 and T4 were showed significantly higher intestinal villi heights and crypt depths in all the sections of intestine such as duodenal, jejunal and ileocaecocolic junction compared to T1 with no significant difference among T2, T3 and T4 treatment groups. These results indicate that treatments T2, T3 and T4 were the most effective in enhancing the gut health of chicks.

 Gut microbial count

The results of supplementation of organic acids on gut microbial load in broilers presented in Table 2. The intestinal E. coli counts (log10 CFU/g) in groups T1, T2, T3 and T4 were 7.82, 6.70, 6.71 and 6.69, respectively. The statistical analysis revealed significant (p>0.05) difference in the E coli counts of birds among treatment groups. The treatment groups T2, T3 and T4 showed significantly (p≤0.05) lesser E coli counts than the group T1. There was no significant difference (p˃0.05) in E coli counts among treatment groups T2, T3 and T4. The intestinal Lactobacillus counts (log10CFU/g) in groups T1, T2, T3 and T4 were 6.65, 6.99, 6.99 and 7.06, respectively. The statistical analysis revealed significant (p≤0.05) difference in the Lactobacillus counts of birds among treatment groups at the end of sixth week. The treatment groups T2, T3 and T4 showed significantly (p≤0.05) better Lactobacillus counts than the group T1. There was no significant difference (p˃0.05) in Lactobacillus counts among treatment groups T2, T3 and T4.

Discussion

There was significant difference (p≤0.05) in intestinal villi height and crypt depth in the groups fed with organic acids compared to the control group at the end of the experiment. The present study findings were in agreement with Yang et al. (2018) [9] who investigated in broilers on organic acids and noted significant increase (p<0.05) in villus height and deeper crypts in the jejunum and ileum in dietary blend of essential organic acids supplemented groups compared to control group. This can be due to changes resulted from altered gut micro flora, improving epithelial proliferation and overall intestinal absorptive capacity.

In contrast Dong et al. (2024) [5] who investigated the impact of acidifiers and essential oils added on broiler intestinal morphology and the results noted no significant (p>0.05) difference on villus height, crypt depth, or villus height to crypt depth ratios in the duodenum, jejunum, and ileum among all groups. There was significant difference (p≤0.05) in gut microbial load of birds in the groups fed with organic acids compared to the control group at the end of the experiment. The current study findings were in agreement with Dai et al. (2021) [4] who studied the effects of organic acids on gut microbiota of broilers and the results revealed significantly modified the gut micro biota composition (p<0.05) in gut health and performance improvement in organic acids supplemented group compared to control group. This may be due to organic acids reduce gut pH which reduced pathogenic bacterial population through bacteriostatic and bactericidal property. The present study was in disagreement with Agboola et al. (2015) [1] who investigated the effects of organic acid, probiotic, and combination on gut health in broiler chickens and noticed no effects on lactic acid bacteria, coliform bacteria or total bacterial counts in the gut in organic acid alone fed groups than organic acid and probiotic combined group.

Conclusion

Based on the above results it was concluded that the gut morphology of different groups fed with 0.05, 0.075 and 0.1% organic acids diet showed significant difference (p≤0.05) in comparison to the control group at the end of the experiment (42 nd day). The gut microbial count of E. coli and Lactobacillus spp. in different groups supplemented with 0.05, 0.075 and 0.1% organic acids diet showed significant difference (p≤0.05) in comparison to control group at the end of the experiment (42 nd day). There was no significant difference among 0.05, 0.075 and 0.1% organic acids on gut health. Hence it was concluded that addition of 0.05% organic acids is more beneficial in improving gut morphology, gut microbial count of E. coli and Lactobacillus spp. in broilers.

Acknowledgement

AcknowledgmentsAuthors gratefully acknowledge the facilities provided by Department of Poultry Science, Veterinary College, Hebbal, and Bengaluru.

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