Effect of organic acid supplementation through drinking water on growth performance and feed efficiency of broiler Chickens

Introduction

High levels of production and efficient feed conversion are the need of the modern poultry industry, which to a certain extent could be achieved by the use of specific feed additives. Antibiotic feed additives as growth promoters have long been supplemented to poultry feed to stabilize the intestinal microbial flora, improve the general performances and prevent some specific intestinal pathology (Hassan et al. 2010) [7] . The poultry sector is continuously in look for new feed additives in order to improve the feed efficiency and health of poultry birds. Alternative strategies comprising of organic acids and their salts, probiotics, prebiotics and enzymes were developed to cope up with antibiotic residual problem in meat which can ultimately give rise to antibiotic resistance issue. One such substitute was the use of organic acids as a feed additive in the animal production. Organic acids stimulate the epithelial growth of the intestinal wall (Langhout and Sus, 2005) [18] . India's poultry sector is one of the most dynamic segments of its agricultural economy. From the humble backyard flock to large-scale commercial integrations, the country has built a significant poultry industry that places it among the top producers globally. According to the Department of Animal Husbandry and Dairying (DAHD), the 20th Livestock Census recorded India's total poultry population at approximately 851.81 million birds with increase in 16.81 per cent during 2019. Over 45.78 per cent increase in backyard poultry and total backyard poultry is 317.07 million in 2019. The commercial poultry has increased by 4.5 per cent and the total commercial poultry is 534.74 million (DAHD, 2019). The total Egg production in the country is estimated as 149.11 billion nos. during 2024-25 and registered a growth of 4.44% the production has increased annually by 3.18% during 2023-24. The per capita availability of eggs increased from 62 nos/annum in 2014-15 to 106 nos/annum in 2024-25. The total Meat production in the country is estimated as 10.50 million tonnesduring 2024-25 and registered a growth of 2.46% the production was increased over 2023-24. The meat production from poultry is 5.18 million tonnes, contributing about half of total meat production. (BAHS 2025). Feed additives are now considered essential for the optimum performance and productivity in modern poultry production (Shahid et al. 2015) [15] . Antibiotic growth promoters have been used in livestock production systems for several years (Haulisah et al., 2021) [1] . However, in 2006, the European Union prohibited the administration of these growth promoters due to the continuous development of antibiotic resistance. The hazardous use of leads to the destruction of beneficial intestinal flora and the emergence of resistant bacteria, which are transmitted to humans through the food chain (Robinson et al., 2019, Khan et al., 2022) [5,6] . Therefore, the search for suitable alternatives has become an urgent issue, especially for the poultry production system (Dai et al., 2021, Hafeez et al., 2021, Scicutella et al., 2021) [8,9,10] . The European Union permitted the use of acidifiers or organic acids (OAs) and their salts in poultry production due to their safety [Adil et al., 2010] [11] . They also have many advantages, such as the absence of pollution, drug resistance, and residues, as well as beneficial effects on health. Dietary OAs promote the production of prebiotics and probiotic lactic acid bacteria.

Organic acids were originally added in the food animal industry as an antifungal agent, however, in the past, there is evidence that the different acids such as formic acid and propionic acids have been used for their antibacterial activities against contaminated food-borne pathogens especially Salmonella species. The improved performance of broilers in response to the supplementation of organic acid is due to enhanced digestibility of energy and protein contents of the feed and reduction of microbial pathogens, improving the immunity, lowering the infectious level, and reducing the ammonia and other harmful metabolites. The present study will be highly useful for researchers, scientists, veterinary professionals, poultry and pharmaceutical industry to enrich their knowledge in promoting organic acid usage in poultry industry helping to draw a line for anti biotics as feed additive.

Materials and Methods

The present investigation was carried out at the Poultry Unit, Department of Poultry Science, College of Veterinary and Animal Science, Rajasthan University of Veterinary and Animal Sciences, Bikaner, Rajasthan. The experimental trial was conducted for a duration of 28 days. A total of one hundred twenty (120) unsexed, clinically healthy, day-old commercial broiler chicks were utilized for the study. The experimental birds were assigned to different treatments, and organic acids were supplemented through drinking water as per the following treatment schedule:

Result and Discussion

At the end of the four-week experimental period, three birds from each replicate (i.e., nine birds per treatment), with body weights approximating the mean body weight of their respective groups, were selected for the assessment of carcass characteristics.

Carcass Characteristic

The data pertaining to carcass characteristics of broiler birds subjected to organic acid treatments are presented in Table 1.1. Overall, supplementation of citric acid, acetic acid, or their combination via drinking water did not exert a significant influence on the dressing percentage or eviscerated yield of broilers. The mean eviscerated yield (%) for groups T1, T2, T3, and T4 was 66.81 ± 0.32, 67.30 ± 0.22, 67.21 ± 0.22, and 66.69 ± 0.36, respectively. Although relatively higher numerical values were observed in T2 and T3, statistical analysis revealed that the differences among treatments were not significant (p >0.05). The highest eviscerated yield was recorded in group T2, followed by T3, whereas the lowest value was observed in T4.

The mean dressed weight (%) for T1, T2, T3, and T4 was 74.53 ± 0.34, 74.74 ± 0.20, 74.85 ± 0.18, and 74.02 ± 0.32, respectively. The highest value was noted in T3, followed closely by T2 and T1, while T4 exhibited a comparatively lower percentage. Despite these numerical differences, the variations among treatments were also statistically nonsignificant (p >0.05). The results obtained for dressed weight percentage and eviscerated yield are in agreement with the findings of Nezhad et al. and Thokwane, who reported no significant effect of citric acid supplementation on dressed weight and eviscerated yield in broilers.

The mean weight (%) of different carcass cuts is summarized in Table 1.1. The head weight (%) recorded for groups T1, T2, T3, and T4 was 2.74 ± 0.04, 2.67 ± 0.04, 2.66 ± 0.01, and 2.81 ± 0.07, respectively, with no statistically significant variation among the treatments. Likewise, the mean weight (%) of neck, wing, back, thigh, and breast did not differ significantly across the experimental groups.

A marginal numerical increase in drumstick weight (%) was observed in groups T3 and T4. The corresponding values for T1, T2, T3, and T4 were 8.75 ± 0.11, 8.95 ± 0.09, 9.24 ± 0.14, and 9.20 ± 0.18, respectively. Overall, supplementation of organic acids did not significantly influence the weight (%) of back, thigh, breast, wing, neck, and head. However, Mohammed reported a significant enhancement in the weight (%) of back and head, which was not evident in the present investigation. The observations related to head and neck weight (%) are in agreement with Sohail et al. (2015) [21] . Furthermore, the slight numerical improvement in drumstick weight (%) in organic acid-supplemented groups corroborates the findings of Islam et al. (2008) [19] .

The weight (%) of giblets, including liver, heart, gizzard, and total giblets across different treatment groups, is summarized in Table 1.1. The total giblet yield ranged from 5.04 ± 0.25% in T4 to 5.50 ± 0.08% in T2, with no statistically significant differences observed among the treatments. Similarly, the individual organ weights-heart (0.54-0.58%), liver (2.37-2.45%), and gizzard (2.08-2.46%)-remained statistically comparable across all groups. Although a slightly higher gizzard weight was recorded in T3, the variation was not significant. Giblet yield, comprising the liver, heart, and gizzard, is an important parameter reflecting internal organ development and the physiological response of broilers to dietary interventions. The present findings indicate that supplementation of citric acid, acetic acid, or their combination through drinking water did not significantly influence giblet yield. These results are consistent with previous reports suggesting that organic acid supplementation at moderate levels does not affect the development of internal organs in broilers. Sohail et al. (2015) [21] , Mahmoud et al. (2020) [23] , and Saleem et al. (2020) [24] similarly reported no significant effect of organic acid supplementation via drinking water on the weight percentages of gizzard, liver, and giblets. The present observations are also in agreement with the findings of Haq et al. (2017) [22] .

The weight (%) of visceral inedible components, including intestines, lungs, pancreas, proventriculus, kidneys, spleen, and crop of broiler birds under different treatments, is presented in Table 4.1. A statistically significant difference (p<0.05) was observed in intestinal weight (%), with T4 (4.57 ± 0.00) exhibiting the lowest value. The corresponding values for T1 (5.00 ± 0.03), T2 (4.90 ± 0.05), and T3 (4.85 ± 0.09) were statistically similar but significantly higher than T4, indicating a possible improvement in gut efficiency with combined acid supplementation. In contrast, the mean weight (%) of lungs, spleen, and crop did not differ significantly among the treatment groups.

The highest mean weight (%) of pancreas was recorded in T3 (0.87 ± 0.45); however, the large standard error suggests considerable variability, and the differences among treatments were statistically non-significant (p >0.05). The values for T1 (0.42 ± 0.01), T2 (0.35 ± 0.02), and T4 (0.43 ± 0.01) were relatively similar, indicating comparable treatment effects on pancreatic weight. For the proventriculus, the highest values were observed in T1 (0.47 ± 0.01) and T3 (0.47 ± 0.01), followed by T2 (0.45 ± 0.02), while the lowest value was recorded in T4 (0.44 ± 0.01). Although T1 and T3 exhibited comparatively higher values than T4, the differences were not statistically significant (p >0.05). Regarding kidney weight (%), T2 (0.46 ± 0.02) and T3 (0.49 ± 0.01), as well as T1 (0.51 ± 0.01) and T4 (0.51 ± 0.02), showed statistically comparable values across treatments.

Overall, the significant reduction in intestinal weight in T4 may indicate improved digestive efficiency due to the synergistic effect of citric and acetic acid supplementation. Other visceral inedible organ weights remained unaffected, suggesting that organic acid supplementation did not adversely influence internal organ development. The observations for weight (%) of intestines, blood, lungs, spleen, pancreas, and proventriculus are in agreement with the findings of Bozkurt et al. (2009) [2] , Sohail et al. (2015) [21] , and Adil et al. (2020) [4] .

The weight (%) of external offal components, including feathers, blood, and shanks of broiler birds under organic acid treatments, is presented in Table 1.1. The mean shank weight (%) showed only minor numerical variations among the groups, and statistical analysis indicated no significant differences (p >0.05). Feather weight (%) was numerically highest in T4 (15.77 ± 0.16), followed by T3 (15.40 ± 0.08), T1 (15.28 ± 0.18), and T2 (15.27 ± 0.06); however, these

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