Implications of increasing ventilation rates of broiler farms to fulfill European welfare regulations on gasconcentrations

摘要

Ammonia and carbon dioxide concentrations are limited in the EU when rearing density exceeds 33 kg/m~2. Threshold concentrations (20 and 3,000 ppm for ammonia and carbon dioxide respectively), have been reported to be higher in literature. One of thesimplest ways to reduce these concentrations through increasing ventilation rates, although this technique may lead to higher energy consumption due to ventilation and heating needs. The aim of this paper is to evaluate this extra energetic cost in a practical case in a broiler house. To this aim, a broiler house (24,000 places) located in a mild Mediterranean area (Villarreal, Castellon, Spain), was monitored for gas concentrations and ventilation rates during a whole winter cycle. A sensible heat balance was developed to determine heat needs during the cycle. Later, gas concentrations during the cycle were evaluated and when they were higher than the established limits, the extra ventilation rates needed to reduce these concentrations were calculated. The implication on heat consumption of this extra ventilation was also determined using a sensible heat balance. On average, ventilation rated had to be increased 9.87% for the whole rearing cycle. This extra ventilation implied an over energy consumption of 28.61% considering the whole cycle. Ammonia was the main contributor to these extra ventilation needs since carbon dioxide concentrations were found to be high only during the first days of the cycle. It should be considered that the interpretation of some aspects of the regulation may lead to strong modifications of these extra costs.