# Nitrogen Excretion, Ammonia, and Greenhouse Gases Emission in Italian Heavy Pigs: The Role of Feed in Environmental Impact Mitigation

## TL;DR

This review explores how dietary changes can reduce nitrogen and greenhouse gas emissions in Italian heavy pig farming while maintaining product quality.

## Contribution

The paper reviews dietary strategies for mitigating environmental impacts in Italian heavy pig production under PDO regulations.

## Key findings

- Dietary interventions can reduce ammonia and nitrogen excretion in heavy pigs.
- Nutritional strategies influence greenhouse gas emissions depending on diet composition and additives.
- Compliance with PDO regulations complicates environmental mitigation in heavy pig supply chains.

## Abstract

The focus of pig breeding in Italy is on producing heavy pigs, which are slaughtered at around 160 kg of live weight to produce Protected Designation of Origin (PDO) dry-cured products. The breeding of pigs is strictly regulated by the official guidelines to produce Parma and San Daniele dry-cured hams. In addition to the differences in nutrition, given the longer time spent on the farm, heavy pig production and PDO supply chains pose significant environmental challenges. Concerns have been raised about environmental issues, such as nitrogen emissions and greenhouse gas emissions. To address these issues, several dietary strategies have been proposed as an alternative to traditional ones. The focus of this review is on dietary interventions for reducing emissions during the fattening phase of Italian heavy pigs.

This review examined the environmental impact of fattening pigs, with particular focus on the Italian heavy fattening pig, affected by dietary interventions aimed at mitigating nitrogen excretion and gases emission into the atmosphere, maintaining product quality and complying with the regulation frameworks. In the Italian heavy pig supply chain, environmental regulations are often difficult to comply with due to the constraints imposed by PDO. The pig sector is increasingly committed to developing strategies that can effectively mitigate its environmental impacts. In intensive pig farming, emissions of ammonia (NH3) and greenhouse gases (GHGs) can occur in every production phase, from animal housing to manure treatment, management, storage, and up to in-field application. All these phases present key actions to limit emissions of NH3 and GHG, according to Best Available Techniques (BAT) for housing and Best Practices (BP) for manure treatments and management. Nitrogen excretion in manure is another important aspect to consider for its negative effects when applied in Vulnerable Zones with considerable additions of animal waste and synthetic fertilisers. Nutritional strategies can contribute a priori to mitigate nitrogen excretion, NH3 emissions, and overall GHG output in heavy pigs, particularly in Italian PDO ham systems. While these interventions effectively mitigate NH3 and influence manure-related emissions, their impact on total GHG varies depending on diet composition, fibre type, additive combination, and post-excretion treatment.