Nutritional analysis of forages for horses

The horse industry in Ireland is renowned globally and is estimated to be worth approximately €2 billion per annum to the Irish economy. While Ireland excels in horse production the quality of forages fed to horses over the winter and throughout the grazing season is largely unknown. Forages are an essential component of the horse’s diet and the NRC guidelines recommend a minimum forage intake of 1% of body weight for a healthy equine digestive system. From an owner’s perspective it is critical that the nutritive quality of these forages are optimised to ensure continued health and well-being for their horses. An understanding of the nutritional variation that is naturally occurring in forages will help owners strive to ensure a quality product for their horses. Forage samples of hay and haylage, representing the harvest period 2009 to 2014 were collected. The majority of the samples were produced in Ireland (73%) with the remaining samples produced in the UK (18%) and Canada (9%). Nutritional analysis was conducted on all samples in accordance with AOAC procedures and included: DM, moisture, ash, crude protein, NDF, ADF, ADL, GE and estimated DE. The distribution of moisture content in forages varied significantly according to country of production: Hay; Ireland 13.6% (10.9%, 16.4%), UK 12.3% (10.6%, 14.4%), Canada 10.0 (9.0%, 11.2%) (P<0.001), Haylage; Ireland 32.7% (25.4%, 42.7%), UK 26.0% (22.6%, 29.5%) (P<0.05). Year of production for Irish hay had a significant effect on the all of the nutrient parameters with the exception of crude protein; moisture P<0.001, ash P<0.001, NDF P<0.001, ADF P<0.001, ADL P<0.001, GE P<0.001, DE P<0.001. The moisture, ash and crude protein content of Irish haylage was not affected by year of production. However, the content of NDF (P<0.001), ADF (P<0.001), ADL (P<0.001), GE (P<0.05), DE (P<0.001) and pH (P<0.01) in Irish haylage was significantly affected by year of production. Presence of pathogenic fungi was measured by culture on Sabouraud dextrose agar and mycotoxin presence was determined using Neogen Veratox ELISAs. A total of 77% of the samples were analysed for the presence of pathogenic fungi. Country of production had a significant effect on the presence of pathogenic fungi in hay (P<0.01) but not in haylage. Twenty-six percent of Irish hay samples were positive for the presence of pathogenic fungi, whilst only 10.8% of UK hay and 2.5% of Canadian hay were positive for the presence of pathogenic fungi. Aspergillus sp. was the most common pathogenic fungi isolated (98%) from the samples, however, Fusarium was isolated in 1 sample of hay. There was no significant effect of the moisture content categorisation of hay and the presence of Aspergillus sp. There was a similar distribution of samples positive for Aspergillus sp. in the three moisture categories (low <10%, moderate 10-15%, high >15%). The data generated has been used to monitor nutrient variations and to help establish normal and ranging values.