Regenerative Grazing System Boosts Weight Gains in Livestock

Grazing on such crops brings direct advantages to agroecosystems without compromising yield. Preliminary results from trials conducted at INTA Oliveros’ experimental farm showed that this crop combination provided a diverse, highly digestible, and balanced diet for cattle, leading to average daily weight gains of 1.2 kg per animal. Additionally, weed populations were reduced by 50%. These findings will be presented at the Argentine Congress of Animal Production in Reconquista, Santa Fe, from September 25 to 27.

Integrating Livestock and Agriculture

Aranza Rodríguez, a researcher at Conicet and INTA Oliveros, emphasized that “grazing multi-species cover crops allows for the integration of livestock and agriculture by providing high-quality forage while maintaining plant diversity without affecting subsequent crop yields.”

As agriculture expands, livestock farming has been pushed to marginal areas. A study in Monje, Santa Fe, revealed that only 28% of producers engage in both cattle farming and agriculture, with limited integration between the two activities.

Typically, breeding systems are found in natural grassland areas, while rearing and fattening occur in confined or semi-confined systems using alfalfa-based pastures. Among these, 25% use winter cover crops, primarily oats. “As an alternative to this system, we propose incorporating multi-species cover crops to integrate agriculture and livestock in cattle rearing and fattening,” Rodríguez added.

Botanical Families of the Cover Crops

The cover crops studied include species from three botanical families: Grasses (such as oats, wheat, rye, and triticale), Legumes (Vicia villosa and Vicia sativa), and Brassicas (canola and radish). These species were chosen for their unique benefits to the system:

1. Grasses produce large amounts of biomass and have fibrous roots that enhance soil structure and support the cycling of phosphorus through associations with mycorrhizal fungi. They also have a high carbon-to-nitrogen (C/N) ratio, which slows down decomposition, providing long-term soil benefits. Grasses are often the preferred choice for cattle grazing.
2. Legumes fix atmospheric nitrogen through symbiotic relationships with bacteria, increasing the protein content in herbivores’ diets. Their lower C/N ratio promotes faster decomposition, which provides nutrients for subsequent crops.
3. Brassicas suppress weeds and reduce soil compaction, earning them the nickname “biological subsoilers.” Their properties fall between those of grasses and legumes, offering balanced benefits.

Promising Results from the Trial

During the evaluated season, grazing on multi-species cover crops allowed for the integration of livestock and agriculture in mixed systems. The forage produced was highly digestible (62% to 68% dry matter digestibility), resulting in weight gains of 1.2 kg per animal per day and a production rate of 150 kg of live weight per hectare. The system also increased biodiversity, as measured by the Shannon index, ranging from 1.3 to 1.6.

Additionally, the trial demonstrated a 30% to 50% reduction in weeds and improved nutrient cycling, as carbon, nitrogen, and phosphorus were returned to the soil through manure. Organic carbon in the soil increased by 10% within the first three years of the trial, highlighting the regenerative benefits of the system.

Key Ecological Advantages

This regenerative grazing approach not only enhances livestock performance but also creates greater competition for resources and produces allelopathic substances that help control weed populations. The cover crops provide a more stable and consistent supply of dry matter under stress conditions, create habitats for beneficial insects that control pests, and improve soil health by increasing resilience to potential environmental and biological adversities.

Furthermore, the diverse root structures of the plants improve soil aeration and support the development of a healthy soil microbiome. A diverse, balanced diet for herbivores, such as finishing cattle, also contributes to better nutrient cycling within the system.

Lastly, the varied C/N ratios and decomposition rates of the cover crops provide nutrients to subsequent crops as they grow, improving overall crop yield and sustainability. Rodríguez emphasized that “the results show that these species allow for staggered flowering periods, offering extended food and shelter sources for pollinators and beneficial arthropods.”

This approach to regenerative grazing, focusing on multi-species cover crops, shows immense potential for creating resilient, sustainable agricultural systems while simultaneously improving livestock productivity and ecosystem health.

Source: INTA