The Impact of Saccharomyces cerevisiae on Growth Performance of Rabbit: A Meta-Analysis

Bilal Ahmed1, Nuruliarizki Shinta Pandupuspitasari1,2, Faheem Ahmed Khan3, Mohammad Miftakhus Sholikin4, Muhammad Rizwan Yousaf1, Muhammad Asif Raza1,5, Sugiharto Sugiharto1, Asep Setiaji1*

1Department of Animal Science, Faculty of Animal and Agricultural Sciences, Universitas Diponegoro. Jl. Prof. Jacub Rais, Tembalang, Semarang 50275, Central Java, Indonesia; 2Food Research for Safety, Security, and Sustainability (FORC3S), Semarang, 50275, Indonesia; 3Stem Cell and Cancer Research Indonesia. Jl. Kol. R.W Sugiarto, Gunung Pati, Semarang 50223, Central Java, Indonesia; 4Research Center for Animal Husbandry, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Bogor, Indonesia; 5Department of Pathobiology, Faculty of Veterinary and Animal Sciences, Muhammad Nawaz Shareef University of Agriculture. Old Shujaabad Rd, Chungi No. 21, Sui Gas Rd, Multan 66000, Pakistan.

Received | May 25, 2025; Accepted | June 24, 2025; Published | September 09, 2025

*Correspondence | Asep Setiaji, Department of Animal Science, Faculty of Animal and Agricultural Sciences, Universitas Diponegoro, Tembalang Campus, Semarang, 50275 Central Java, Indonesia; Email: [email protected]

Citation | Ahmed B, Pandupuspitasari NS, Khan FA, Sholikin MM, Yousaf MR, Raza MA, Sugiharto S, Setiaji A (2025). The impact of saccharomyces cerevisiae on growth performance of rabbit: A meta-analysis. J. Anim. Health Prod. 13(3): 812-818.

DOI | https://dx.doi.org/10.17582/journal.jahp/2025/13.3.812.818

ISSN (Online) | 2308-2801

Copyright: 2025 by the authors. Licensee ResearchersLinks Ltd, England, UK.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Introduction

The rising demand for meat and protein in resource-constrained regions is on the watch for alternative hopeful solutions and rapid sources of supply, one of which is rabbit farming (Abdel-Rahman and Ashour, 2023; Johnson et al., 2024; Ayeni et al., 2023). Rabbit prolific reproduction ability, lower input dependency, efficient feed consumption, adaptability to environmental extremes, and the ability to cope with high-fiber diets make them an economical and sustainable approach to provide protein supply, particularly in underdeveloped and heat-stressed regions (Peixoto-Gonçalves et al., 2023; Nicula–Neagu et al., 2023; Liu et al., 2023; Abdelsalam et al., 2023). However, maximizing feed and nutrition is critical to effectively maximizing rabbit production, feed conversion, and ultimately economic benefits (Ayoola et al., 2024; Bashar et al., 2023; Setiaji et al., 2022). In this context, supplementing diets with Saccharomyces cerevisiae (S. cerevisiae), a kind of yeast that enhances nutrient availability and absorption, is an exciting approach to boost rabbit performance, economic turnover, and welfare (Al-Sagheer et al., 2023; Elbaz et al., 2023).

The inclusion of S. cerevisiae in rabbit diets has great potential owing to its numerous health benefits, feed utilization, nutrition digestibility, and capacity to improve animal production (Kalma et al., 2016; Mancini and Paci, 2021). The use of growth promoters and antibiotics, and their drawbacks, have prompted researchers to seek effective and environmentally sustainable alternatives. One of the alternatives is S. cerevisiae as a promising candidate (Elghandour et al., 2020; Falcão-e-Cunha et al., 2010). The level of effectiveness of S. cerevisiae, however, has been in doubt as a result of substantial disparities across studies, many of which have a significant positive influence on body weight gain (532 g difference between control and experimental groups) and improved feed conversion ratio, while others disclose minimal to no significance on weight gain (176 g loss between control and treatment groups) and feed conversion ratio (Shehu et al., 2014; Emmanuel et al., 2019; Ahmed et al., 2019). One likely reason for the disparity in conclusions is the dose of S. cerevisiae administered and the duration of treatments; however, not a single study has been able to address this correlation so far.

Meta-analysis provides a systematic approach to characterize the cumulative effect of dose-dependent and age-related yeast supplementation on key rabbit outcomes, such as body weight gain (BWG), feed conversion ratio (FCR), and weight increase, providing useful insights for informed choices in rabbit farming. Meta-analysis can offer helpful information on the overall efficacy of S. cerevisiae supplementation across various research studies, with a focus on age- and dose-sensitive performance, promoting evidence-based decision-making, and steering future research directions in rabbit farming. This study aimed to systematically evaluate the effects of S. cerevisiae supplementation on rabbit growth performance using a meta-analytical approach. By identifying consistent patterns and dose-age interactions across published studies, this meta-analysis seeks to provide evidence-based recommendations for optimizing rabbit nutrition and enhancing farming efficiency.

Materials and Methods

Literature search and inclusion criteria

The literature search was conducted in National Center for National Center for Biotechnology Information, and Google Scholar by using the keywords “Saccharomyces cerevisiae” “rabbit” “body weight” “performance,” the literature was then screened/reviewed by all the authors. In order to qualify the research manuscripts had to be (1) original research (not a review or conference abstract), (2) Written in English, (3) full-text publications, (4) rabbit animal trials, (5) must have control reports, (6) direct use of S. cerevisiae without enzyme or carbohydrate addition, and (7) reports of body weight and feed conversion ratio in control and experimental trials. A total of 159 results were obtained initially from NCBI and after screening and removing the double, reviews, and non-animal trials, 7 papers were finalized for analysis along with 8 from Google Scholar, and the data extraction was performed as follows (Figure 1).

 

Data extraction

The dataset was prepared in Microsoft Excel, with means of first author, publication year, breed, control, and experimental trials for the BWG and FCR parameters of experimental and control animal groups (Figure 2). The measure of variability in the literature was in the form of standard deviation, standard error of the mean, confidence interval, or mean square error, but was all homogenized in the form of standard deviation.

 

Meta analysis

The meta-analysis was conducted using OpenMEE build date 2016-07-26 software by utilizing a continuous random-effects model with the DerSimonian-Laird method. The effect size was calculated by using Hedges’ d as follows:

Where XE represents pooled observations from experimental groups (with S. cerevisiae supplementation), and XC represents pooled observations from control groups with SJ as a small sample size correction factor.

Results and Discussion

The meta-analysis assessed the effect of S. cerevisiae supplementation on rabbit body weight gain using a continuous random-effects model with the DerSimonian-Laird method. The pooled standardized mean difference (SMD) was 0.591, with a 95% confidence interval (CI) of -0.024 to 1.206 and a p-value of 0.060. This indicated a potential positive effect of yeast supplementation on BWG, although the results were statistically significant. Heterogeneity among the studies was substantial, with an I² value of 93.08%, suggesting considerable variability across the included trials. The forest plot (Figure 3) shows the individual study effects, their confidence intervals, and the overall pooled estimate, with larger squares representing studies with a greater statistical weight. For FCR, the pooled SMD was -0.126 (95% CI: -0.580–0.328), with a p-value of 0.586, indicating that S. cerevisiae supplementation had no statistically significant effect. Heterogeneity remained high (I² = 88%), reflecting notable variability among studies. The forest plot (Figure 4) illustrates individual and pooled effects. The diamond representing the overall estimate lies slightly left of the null line, suggesting a trend toward improved FCR but without statistical support.

 

 

The findings of this meta-analysis suggest that dietary supplementation with S. cerevisiae may positively influence BWG in rabbits. Although the pooled effect size was moderate (SMD= 0.591), the p-value (0.060) indicated a borderline statistical significance. This suggests a promising yet cautious optimism toward the efficacy of yeast supplementation in improving growth performance in rabbits. This effect is likely attributable to the role of yeast in enhancing gut health, stabilizing intestinal microflora, and improving nutrient digestibility and absorption factors that directly contribute to BWG (Henderickx et al., 2019). In contrast, S. cerevisiae supplementation did not produce a statistically significant effect on the feed conversion ratio (SMD= -0.126, p = 0.586). Despite a slight trend toward improved FCR, evidence does not robustly support its influence on feed efficiency. This contrasts with several earlier studies that reported improvements in FCR with yeast inclusion, pointing to inconsistencies in outcomes across the literature (Abd El-Aziz et al., 2021; Belhassen et al., 2016; Rotolo et al., 2014). One possible explanation for these inconsistencies is the substantial heterogeneity observed across both analyses (93.08% for BWG and 88% for FCR). These factors likely interact in complex ways, influencing the metabolic and physiological responses of rabbits to dietary supplementation.

Body weight gain

The alluvial diagram provides a visual synthesis of the interplay between experimental factors, namely, age, dosage of S. cerevisiae, and their cumulative effect on rabbit performance (Figure 5). This complements the meta-analysis findings by offering a more detailed view of variability and conditional responses in the literature. Overall, the trend in the plot supports the meta-analytical results, suggesting a positive influence of S. cerevisiae supplementation on rabbit BWG. Several treatment groups demonstrated a clear improvement in total body weight compared with their control counterparts. This aligns with the known mechanisms by which S. cerevisiae improves nutrient utilization, stabilizes gut flora, and boosts the immune response, thereby supporting growth performance. The most notable trend in the plot is the dose-dependent nature of the response. Rabbits supplemented with 0.5 g to 1.5 g of S. cerevisiae per day exhibited the most consistent and pronounced increases in body weight, as indicated by thicker, uninterrupted flow lines toward higher BW values (e.g., 2040 g, 2177 g). In contrast, extremely low or high doses resulted in mixed outcomes, with some studies reporting little to no gain or even lower final weights than the control groups. This suggests a threshold beyond which additional yeast does not translate to further benefits, likely due to the saturation of microbial or metabolic responses (Hackett et al., 2016).

Another visible pattern is the effect of rabbit age on the effectiveness of yeast supplementation. The age groups between 6-10 weeks appear more responsive to supplementation, as indicated by denser lines, leading to improved BWG outcomes. This supports previous findings that mid-growth phases may offer an optimal physiological window for benefiting from functional feed additives owing to rapid gut development and high nutrient demand (Aftab et al., 2018). Despite the positive trend, the figure also illustrates inter-study variability, with similar doses and age groups yielding different results in the different experiments. This reflects the heterogeneity quantified in the meta-analysis (I²= 93.08%). Potential reasons for this include breed differences, environmental stress, baseline diet composition, health status, and experimental design. Even at identical doses (e.g.,1g/day), final body weights ranged from below 1,900g to above 2,100g, indicating a significant influence of external or unreported factors. Importantly, this visual evidence helps reconcile previous contradictory findings, such as those of Shehu et al. (2014), who reported lower weight gain under yeast supplementation. By aggregating multiple datasets, the plot highlights that despite some variability, the overall trend indicates improved body weight, reinforcing the general efficacy of S. cerevisiae supplementation when used under optimized conditions.

 

Feed convertion ratio

The alluvial plot illustrates the intricate relationships between various experimental factors, including age, breed, and dosage of S. cerevisiae, and their influence on rabbit FCR (Figure 6). This visualization complements the meta-analysis by revealing nonlinear, context-dependent trends that may explain the high heterogeneity observed among studies. The diagram shows that different breeds, such as New Zealand White, New Zealand × Local crosses, and other heterogeneous lines, responded differently to yeast supplementation. New Zealand White rabbits appeared frequently across studies; however, their FCR outcomes varied depending on age and dosage. Notably, younger rabbits (4-6 weeks) tended to show more variable responses than older ones (8-12 weeks), suggesting that age may mediate digestive efficiency and microbial adaptation to yeast-based diets. These findings are in line with previous reports by Zheng et al. (2021), which suggested that the gut microbiota stabilizes with age, potentially influencing the efficacy of prebiotic additives.

 

A central trend revealed by the plot is that moderate yeast doses (e.g., 0.5 g to 1.0 g per rabbit/day) were more consistently associated with improved or neutral FCR values, while very low or high doses produced more scattered and inconsistent results. with 1.0 g was frequently correlated with better FCRs (3.86-3.97), particularly in standardized breeds. This highlights the potential of an optimal dose window beyond which no further benefits or even negative effects may be observed. This dose-dependent effect aligns with earlier research in ruminants and poultry, where excessive yeast supplementation disrupted microbial equilibrium rather than enhancing it (Chae et al., 2024). Some studies using the same breed and similar age groups have shown divergent FCR outcomes, further reinforcing the role of unaccounted environmental or methodological differences. Factors such as ambient temperature, baseline feed composition, and stress levels might confound the results (Kierman et al., 2023), thereby contributing to the high heterogeneity (I²= 88%) found in the meta-analysis. While the meta-analysis statistically confirmed no significant effect of S. cerevisiae on FCR, the alluvial plot confirms this conclusion by revealing patterns that suggest conditional improvements, particularly at optimal dosages and in specific breed-age combinations. This underlines the importance of moving beyond simple effect size reporting toward multifactorial interpretations of performance data.

Conclusion

This meta-analysis provides evidence that S. cerevisiae supplementation in rabbit diets has a positive effect on body weight gain, although its effect on the feed conversion ratio remains inconclusive. These findings support its use as a potential natural growth enhancer for rabbit production. Future studies should focus on it’s influence on health, well-being of rabbits, and other performance and efficacy optimizations.

Acknowledgement

The authors thank Universitas Diponegoro for supporting the international collaboration through the Diponegoro International Student Program.

Novelty Statement

This is the first of it’s kind meta-analysis of Saccharomyces cerevisiae’s influence over the rabbit growth performance. It focuses on age and breed-specific trends in rabbit performance under Saccharomyces cerevisiae’s supplementation.

Author’s Contribution

Conceptualization: Asep Setiaji, Faheem Ahmed Khan; Methodology: Mohammad Miftakhus Sholikin; Data Analysis: Bilal Ahmed, Muhammad Rizwan Yousaf; Validation: Nuruliarizki Shinta Pandupuspitasari; Writing manuscript-original: Bilal Ahmed, Muhammad Rizwan Yousaf; Writing manuscript-review/revision: Bilal Ahmed, Mohammad Asif Raza, Sugiharto Sugiharto; others: Asep Setiaji.

Funding statement

This research has no funding.

Generative AI or AI-assisted Technology Statement

The authors declare that no Genrative AI was used in the creation of this manuscript.

Conflict of interest

The authors have declared no conflict of interest.

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