NL Journal of Veterinary and Animal Nutrition

Introduction

Growing regulatory restrictions on the prophylactic use of antibiotic growth promoters (AGPs) in livestock production, particularly in the European Union, due to concerns over antimicrobial resistance in both animals and humans, have spurred global interest in identifying safe and effective alternatives [1]. Among the proposed substitutes for AGPs are organic acids [2], probiotics [3–5], phytogenic feed additives [6], apiculture products [7], and exogenous enzymes [8]. Organic acids have demonstrated particular promise in poultry nutrition, with studies indicating their ability to enhance nutrient utilization, growth performance, and feed efficiency in broilers [9]. Their mode of action involves lowering gastrointestinal pH (3.5–4.0), creating an environment that promotes beneficial lactobacilli while suppressing pathogenic gram-negative bacteria such as Escherichia coli and Salmonella [10]. Previous research suggests that dietary organic acid supplementation improves body weight gain [11], stimulates feed intake [12], and optimizes feed conversion ratios [13]. Additionally, organic acids have been shown to reduce digesta pH in the crop, gizzard, ceca [14], and intestinal tract [9]. Given these findings, this study aimed to evaluate the effects of acetic and citric acid supplementation on broiler performance, focusing on growth metrics, feed efficiency, and physiological impacts.

Materials and Methods

Experimental Site

The study was conducted under semi-commercial production conditions at a commercial poultry facility in the Kingdom of Saudi Arabia.

Experimental Design and Animal Management

A total of 3,000 one-day-old Ross 308 broiler chicks were randomly allocated into three experimental groups (n = 1,000 birds/group):

• Group A: Received drinking water supplemented with 1% acetic acid (ad libitum) from day 1 to day 28.
• Group B: Received drinking water supplemented with 1% citric acid (ad libitum) from day 1 to day 28.
• Control Group: Received untreated drinking water (no additives).

The trial lasted 28 days, with birds housed in an open-floor system (stocking density: 0.70 ft²/bird) under continuous electric lighting.

Dietary Regimen

Birds were fed ad libitum with a three-phase feeding program:

1. Starter diet (days 1–8)
2. Grower diet (days 9–21)
3. Finisher diet (days 22–28)

All diets were formulated as complete feed mixtures and did not contain anticoccidial additives.

Data Collection

Growth Performance

• Body weight: Recorded weekly.
• Feed intake: Measured cumulatively at the end of the trail.
• Mortality: Tracked daily and recorded as total mortality.

Carcass Characteristics

On day 28, five birds per group (selected based on average group body weight) were euthanized via bronchial vein severing. Carcass, breast, thigh, and abdominal fat weights were individually recorded.

Statistical Analysis

Data were analyzed using one-way ANOVA, and group means were compared using Duncan’s multiple range test (p < 0.05).

Results and Discussion

Growth Performance

Dietary supplementation with acetic acid significantly increased (P < 0.05) average body weight compared to the control group at days 21 and 28 of the trial. By the end of the fattening period, acetic acid yielded higher body weights than both citric acid and the control, though differences between treatments were statistically significant (P < 0.05). These findings contrast with [10], who reported greater body weight gains in broilers supplemented with acetic acid. Notably, citric acid supplementation resulted in lower final body weights (1262 g) compared to acetic acid (1296 g), which contradicts [13], where citric acid improved live weight relative to un supplemented diets as presented in Table 1.

Values shown are mean ± SD (standard deviation)

Table 1: Effect of organic acids on weekly body weight (grams) of broiler chickens.

Feed Efficiency

Total feed consumption varied significantly among groups (Table 2). The reduced feed intake observed with acetic acid aligns with prior studies [11, 13, 14], which attributed this effect to enhanced feed efficiency.

Values shown are mean ± SD (standard deviation)

Table 2: Effect of organic acids on weekly feed consumption (grams) of broiler chickens.

Mortality and Slaughter Traits

Organic acid supplementation positively influenced broiler mortality rates (Table 3). Slaughter weights were significantly higher (P < 0.05) in acid-treated groups (Table 4), consistent with [10, 15]. However, no significant differences
(P > 0.05) were detected in carcass yield, breast or thigh percentages, or abdominal fat weight, corroborating [16].

Values shown are mean ± SD (standard deviation)

Table 3: Effect of organic acids on weekly mortality percentage of broiler chickens.

Values shown are mean ± SD (standard deviation)

Table 4: Effect of organic acids on carcass characteristics of broiler chickens.

Conclusion

This study demonstrated that:

1. Acetic acid (1%) significantly improved final body weight and feed efficiency in broilers.
2. Citric acid (1%) reduced final body weight compared to both acetic acid and the control.
3. Both organic acids lowered mortality but did not alter carcass characteristics.

These results highlight acetic acid’s potential as an alternative to antibiotic growth promoters, though further research is needed to elucidate citric acid’s inconsistent performance effects.

References

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