Hydrogen sulfide emissions from a swine building affected by dietary crude protein

Abstract

Hydrogen sulfide (H2S) is a toxic air pollutant at animal facilities; but the understanding of its generation and emission processes has been limited. This paper studied H2S emissions during a complete cycle of wean–finish pigs from a research building, where 12 pig rooms were divided into three groups that were fed with standard feed (control), and 2.1–3.8% (T1) and 4.4–7.8% (T2) reduced dietary crude protein (CP) feed. The group cycle mean H2S emission rates were 4.0 ± 2.9, 4.3 ± 3.2, and 5.4 ± 4.0 g d−1 AU−1 (Animal Unit = 500 kg live mass), respectively, for the control, T1, and T2 groups. Emissions of H2S were promoted by 10.0 and 36.7%, respectively, for the T1 and T2 groups (p < 0.001), although large variabilities existed in the emissions from different rooms within the same groups. The enhanced H2S emissions from the T1 and T2 groups were related to the reduced manure pH and were possibly affected through a number of pathways, which could involve volatile fatty acids and nitrogen concentrations, and microbial activities in manure.