Management Practices and Quality of First-Cut Alfalfa-Grass Silage on Canadian Dairy Farms

Abstract

Fungal contamination of forages can cause decreased nutritive value, mycotoxin production and animal health issues. Ninety-three first-cut alfalfa-grass silage samples were collected from various storage types (wrapped round bales, conventional tower silos, horizontal bunker silos) on Canadian dairy farms. Quality analyses (near infrared reflectance [NIR], wet chemistry, digestibility analyses) and metagenomic sequencing were performed and effects of management factors on these parameters were evaluated. Pichia spp. yeasts capable of aerobic deterioration and mycotoxin-associated moulds of the genera Monascus and Pencillium were most abundant. Mycotoxin contamination was low with zearalenone (ZEA) present in 1% and mycophenolic acid (MPA) in 11% of samples. Higher yeast abundance in tower silos indicate they are not airtight and do not preserve quality well. Bales had lower heat damaged protein (ADF-CP) than other storage types despite a less complete fermentation. Findings will contribute to developing management plans to assist dairy producers in producing high quality silage.