Grape pomace in rabbit diets: Effects on Growth, health & meat quality

Introduction

The wine industry produces a significant amount of solid residue known as grape pomace (GP), consisting primarily of skins, seeds, and stems of grapes fruits (Rockenbach et al., 2011; Garcia-Cabezon et al., 2020). This byproduct represents approximately 25% of the initial grape weight (Yu & Ahmedna, 2013), and its large volume poses environmental and economic challenges (Salami et al., 2019). Utilizing agro-industrial byproducts like GP in animal feed offers a sustainable approach to waste management while potentially reducing feeding costs (Chikwanha et al., 2018). Grape pomace is not only a source of fiber but is also rich in valuable bioactive compounds, such as polyphenols and tannins, recognized for their antioxidant, antimicrobial, and anti-inflammatory properties (Kafantaris et al., 2017; Hassan et al., 2019).

Use of grape pomace in rabbit nutrition

Rabbits are important livestock, and managing feed costs is crucial for profitability (Guemour et al., 2010). Research into incorporating GP into rabbit diets has explored its effects on nutrient digestibility, growth performance, and meat quality (Bouzaida et al., 2021; Carta et al., 2025). Studies have shown varied results; some indicate that while GP can improve antioxidant status and meat shelf life (Derbali et al., 2024), it may negatively impact feed conversion or carcass yield depending on the inclusion level and processing method (Ferreira et al., 1996; Nicodemus et al., 2007). Additionally, benefits on reproduction (Eid, 2008) and pathogen mitigation (Hassan et al., 2019) have been explored. This article provides a comprehensive overview of the current scientific literature on feeding grape pomace to rabbits, aiming to synthesize diverse findings and offer practical insights for rabbit producers interested in sustainable feeding strategies.

Impact of Grape Pomace on Rabbit Growth Performance and Feed Efficiency

The impact of grape pomace on the growth performance of rabbits varies by dosage and breed. Ferreira et al. (1996) observed that substituting alfalfa hay with 100–300 g/kg grape pomace linearly reduced feed conversion efficiency in Californian × New Zealand White rabbits, likely due to lower crude protein and energy digestibility. Conversely, Derbali et al. (2024) found that 2% dehydrated grape pomace improved growth performance in California rabbits, suggesting breed-specific responses or benefits from lower inclusion levels. These contrasting results underscore the need for tailored formulations. While moderate doses (1–2%) may enhance growth, higher concentrations (>5%) could impair nutrient digestibility and absorption in rabbits, emphasizing the importance of precision in feed formulation. Eid (2008) found no adverse effects on growth parameters in rabbits fed up to 20% grape pomace, suggesting efficient utilization of its fiber and nutrients. However, optimal inclusion levels may vary by breed and production goals. Derbali et al. (2024) identified 1–2% as effective for reproductive benefits without compromising feed intake, whereas higher doses (10–20%) may suit meat-production systems seeking cost-effective fiber sources.

Antioxidant and Immune Support

The polyphenols in grape pomace, such as flavonoids and tannins, play a critical role in reducing oxidative stress. Chedea et al. (2019) demonstrated in pigs that grape pomace increased antioxidant enzyme activity (e.g., catalase and glutathione peroxidase) in key organs, a mechanism likely applicable to rabbits. In rabbits, reduced oxidative stress can improve overall health, immune function, and disease resistance. Brenes et al. (2016) reported that polyphenols in grape pomace bind to free radicals, protecting cellular structures and enhancing metabolic efficiency. Farmers may benefit from reduced veterinary costs and improved herd vitality.

Enhancing Meat Quality and Oxidative Stability

Grape pomace is rich in polyphenols, compounds known for their antioxidant activity. Carta et al. (2025) demonstrated that supplementing rabbit diets with 5–10 g/day of dried grape pomace significantly reduced lipid oxidation in meat, as measured by thiobarbituric acid reactive substances (TBARS). Similarly, Bouzaida et al. (2021) found that 20% grape pomace inclusion improved the fatty acid profile of rabbit meat, increasing polyunsaturated fatty acids (PUFAs) and reducing atherogenicity and thrombogenicity indexes. These changes are attributed to polyphenols like resveratrol and flavonoids, which scavenge free radicals and inhibit oxidative damage (Carta et al., 2025). However, higher inclusion levels may not always yield benefits. Guemour et al. (2010) reported that 6% sun-dried grape pomace reduced organic matter digestibility, indirectly affecting meat yield. Balancing pomace dosage with basal diet composition is critical to maximizing antioxidant benefits without compromising growth.

Reproductive Health and Digestibility

Grape pomace supplementation has shown promising effects on rabbit reproductive performance. Derbali et al. (2024) reported that 1–2% supplementation improved sperm motility and concentration in male California rabbits, likely due to its high polyphenol content, which reduces oxidative damage to sperm cells. However, higher doses (2%) reduced crude protein digestibility, highlighting a trade-off between reproductive benefits and nutrient utilization. Eid (2008) observed that rabbits receiving 10–20% grape pomace in their diets had higher ejaculate volume and improved plasma membrane integrity in sperm. These findings suggest that grape pomace enhances semen quality by mitigating oxidative stress, a key factor in reproductive efficiency.

Economic and Environmental Considerations

Incorporating grape pomace can lower feed costs by utilizing agro-industrial waste. Bouzaida et al. (2021) noted that 20% pomace inclusion reduced reliance on medicated feeds while maintaining meat quality. However, Guemour et al. (2010) cautioned that high pomace levels (6%) lengthened growth periods in Algerian rabbits, potentially offsetting cost savings. Farmers must weigh reduced feed expenses against potential delays in production cycles.

Conclusion

Grape pomace offers a dual advantage for rabbit production by enhancing meat quality through antioxidant activity and reducing feed costs. However, its efficacy depends on careful dosage management and breed considerations. Farmers are encouraged to start with low inclusion levels (1–5%) and monitor growth and health metrics closely. 

Future Research Directions

Future research directions should focus on identifying breed-specific dosage thresholds for maximal benefits without growth trade-offs, assessing the long-term impacts on reproductive health and meat quality, evaluating cost-benefit ratios across farming systems, and exploring how polyphenols interact with gut microbiota to enhance nutrient absorption.

References

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