Effect of hay steaming on forage nutritive values and dry matter intake by horses.

The research examines the effect of steaming hay on its nutritive value and the volume of its intake by horses, mainly focusing on its potential as a management strategy for horses with respiratory issues.

Research Methodology and Tests

• The research employed a 10-day crossover design, utilizing six mature horses to observe the differences in intake and nutritious impacts of steamed vs. unsteamed hay.
• Two types of mixed hays were evaluated – low moldy (NM) and moderately moldy (MM).
• The scientists steamed each type of hay for 90 minutes using a commercial steamer before feeding the horses. Horses were allowed to feed for 2 hours post-steaming, and the dry matter intake (DMI) was calculated.
• The researchers also agitated flakes of unsteamed or steamed hay in an electric cement mixer to evaluate the impact of steaming on the total suspended particulate (TSP) levels.
• The team utilised paired t-tests and PROC MIXED of SAS to compare the nutritive values, mold concentration, TSP, and 2-hour DMI of the steamed and unsteamed hay.

Key Findings

• Steaming the hay increased its moisture content and in consequence reduced the DMI to 77% for NM and 81% for MM.
• In both types of hay, steaming resulted in a reduction of phosphorus content by 16% for NM and 17% for MM.
• Steaming also lessened levels of water-soluble carbohydrates (WSC) and ethanol-soluble carbohydrates (ESC) in MM hay by 13% and 27% respectively but did not have any impact on NM hay.
• A significant reduction was observed in mold concentrations in both types of hay due to steaming, with a reduction rate greater than or equal to 91%.
• Total Suspended Particulate of MM hay was reduced by 55% after steaming; however, steaming did not affect the TSP in NM hay.
• Steaming increased dry matter intake of NM hay leading to intake differences of approximately 0.64 kg for unsteamed hay and 2.02 kg for steamed hay. The intake of MM hay, however, remained unaffected by steaming.

Conclusions and Implications

• The study concluded that steaming hay can be beneficial as it can reduce TSP and mold concentration, which is particularly useful for management of horses with respiratory issues.
• However, it was also noted that steaming could result in the leaching of essential nutrients, thereby reducing the nutritive value of the hay.
• In some hays, steaming also increased the dry matter intake. Nonetheless, further investigations are necessary to discern the implications for horse health and nutrition.