For example, nutritional components on a forage report like protein, carbohydrates, fiber fractions, fat and minerals will highlight how that forage is going to go through the cow and into her production. Nevertheless, these nutritional components will likely fluctuate when transitioning to the new year’s forage. Doing regular diet and ration adjustments can help you avoid negative fluctuations to milk production and reproduction programs.
In addition to nutrient quality and ration formulation, forage reports can help explain whether the growing, harvesting and storing phases for your forages were successful – or if they need some revamping.
Breaking down fermentation
When analyzing forage reports, I always start with the fermentation section. This is where the majority of feedout problems stem from, like poor palatability and digestibility. However, it is also the section of the forage report where best management practices can have the greatest impact.
pH value or index is a measure of forage acidity but is also affected by the buffering capacity of the crop. Each type of forage has a certain pH range that it should be into complete fermentation and to stabilize it. Namely, alfalfa and other spring crops naturally have higher buffering capacities, which means the pH of these crops are higher and need longer ensiling times to drop. Upon completion of fermentation, I like to see spring forages, such as alfalfa and small grains, around a 4.5 pH, while corn silage and other fall crops should reach a 4.0 pH.
- Common reasons for high silage pH: Slow fermentation due to early sampling time relative to harvest, cold weather during harvest, slow or poor packing, legume silages with extremely high ash contents (greater than 15% of dry matter) and/or high protein content (greater than 23% to 24% crude protein), excess ammonia or urea, spoiled or moldy silage, manure in silage
Lactic and acetic acid are next on the list. Typically, the lactic-to-acetic-acid ratio should be 3-to-1. Also, lactic acid should be the primary acid in silage when compared to the others – acetic, propionic and butyric acid – because during fermentation it is responsible for lowering the pH and is the most efficiently produced acid from forage carbohydrates. This reduces dry matter (DM) and nutrient loss.
- Common reasons for low lactic acid: Restricted fermentation from too high DM percentage and/or cold weather (ensiling below 40ºF the silage mass may not ferment, so you will not see as much organic acid production), considerable oxygen exposure to silage, high amount of butyric acid (greater than 0.5% of DM)
Moisture and DM percentage are vital meters on the forage report as well. Both have major influence on forage quality and fermentation. A safe number for the moisture of haylages and forages is around 65%. When moisture teeters around or above 70%, risks of clostridium fermentation and palatability challenges arise. On the other hand, forages that are too dry (45% to 50% DM) also inhibit fermentation and are very hard to pack and slower to reach anaerobic conditions.
Moisture percent is a key point when analyzing forage reports. It is a main indicator for whether a farm’s best management practices for putting up forages, packing, covering and so on are adequate and working.
- Common reasons for high moisture percent: Forage was cut premature or past maturity; if a silage is too wet, it was cut too early
Acid detergent insoluble crude protein (ADICP) is a number that can be easily overlooked. I use ADICP to figure how “hot” the forage became during fermentation. Limited heating of forages is normal and supports good fermentation, but excessive heating will start deteriorating crude protein (CP) and make it indigestible for cattle, thus reducing feeding value of the forage. ADICP is expressed as a percent of CP and is an adequate estimate of heat-damaged protein in forage feeds.
- Common reasons for heat-damaged silage: High moisture in bales and silage that are trying to ensile when too dry; plants are harvested at increasing maturity levels; crops are damaged from hail, insects, frost or drought; crops are ensiled with greater than 1 million colony-forming units (CFUs) of yeast per gram of fresh forage; too much oxygen exposure
Challenges can populate from any number of the above factors and are commonly seen on the forage report through the mold and yeast counts. However, dangerous metabolites of molds, commonly referred to as mycotoxins, most often originate in the field due to weather stress. I always say, “Forage quality is heavily dependent on weather patterns and how we manage when we plant, harvest and store forage in relation to weather.”
If crops are weather-stressed or forage samples show indications of inadequate fermentation, forage inoculants and aerobic stabilizers can be a valuable option for future consideration. Inoculants are viable cultures of lactic acid bacteria that help stimulate the fermentation of forages to make higher-quality silage, while aerobic stabilizers become more relevant when conditions are less than ideal and approaching extreme during chopping and packing forage or hay. It is also important to note that best management practices for silage and bunker management go a long way in ensuring silage stays consistent and nutrient-dense the whole year long.
Since we harvest and store a whole year’s worth of feed only a few times a year, it is important to be successful at it. Consultants, nutritionists and veterinarians are all great resources for analyzing forage reports multiple times a year and can offer up-to-date research on various aspects. Take the time to analyze your forage reports throughout the year and identify what challenges can be addressed for the upcoming year, but also highlight your farm’s successes so they can be duplicated. If there’s ever anything you question on a report or an analysis, reach out for a second opinion.
