Relationships among slurry characteristics and gaseous emissions at different types of commercial Spanish pig farms

This study aimed to analyse several factors of variation of slurry composition and to establish prediction equations for potential methane (CH 4 ) and ammonia (NH 3 ) emissions. Seventy-nine feed and slurry samples were collected at two seasons (summer and winter) from commercial pig farms sited at two Spanish regions (Centre and Mediterranean). Nursery, growing-fattening, gestating and lactating facilities were sampled. Feed and slurry composition were determined, and potential CH 4 and NH 3 emissions measured at laboratory. Feed nutrient contents were used as covariates in the analysis. Near infrared reflectance spectroscopy (NIRS) was evaluated as a predicting tool for slurry composition and potential gaseous emissions. A wide variability was found both in feed and slurry composition. Mediterranean farms had a higher pH ( p 0.90) and similar accuracy of prediction of potential NH 3 and CH 4 emissions ( R 2 =0.84 and 0.68, respectively) to models using slurry characteristics, which can be of interest to estimate emissions from commercial farms and establish mitigation strategies or optimize biogas production.