How Weather Impacts Forages

March 14, 2025Health, Members Only, Ownership

Reading Time: 5 minutes

Feed can be the most significant expense in raising goats, often exceeding other costs. There’s plenty of pressure to strike a balance between cost and nutrition, but this isn’t the place to scrimp because feed plays a large role in health.

As a key component of ruminant diets, forages present some unique challenges. Their nutrient density can vary widely depending on the region, climate, and weather-related events in which they were grown and harvested, and this, in turn, impacts the overall health and productivity of your animals.

This variability can be critical in the winter when hay is often the primary forage. The quality of hay depends heavily on the growing season. For example, forages can suffer in years of challenging weather patterns, leading to potential health issues in the herd. Nutritional deficiencies or toxicities may arise, setting back performance and growth.

Weather and Climate Impact on Forage Quality

Weather and climate conditions contribute to the quality and availability of forage, and fluctuations can have a cascading effect on livestock operations.

Drought is one of the most significant threats to forage quality and quantity, impacting pastures and harvested hay. Prolonged dry periods stress plants, reducing growth, nutrient content, and digestibility. Protein levels in forage crops decline during drought because plant metabolism slows, leading to less nitrogen uptake. At the same time, fiber content increases, making the forage less palatable and harder to digest. Persistent drought conditions can also lead to long-term pasture degradation, reducing productivity for years.

Victor Shelton, a retired Natural Resources Conservation Service agronomist and grazing specialist, highlights this challenge in his 2024 bulletin, “Normal” vs. “Average” Weather: The Impact on Forages. Shelton notes the difficulty of defining “normal” weather patterns given the variations experienced over decades.

“Over the past six decades, I’ve witnessed both extremely cold, snowy winters and warm, dry ones, often without a discernible pattern,” Shelton writes.

He explains that the water cycle, more than air temperatures, most directly affects forage productivity. Its impacts include precipitation patterns, soil moisture, drought, and floods.

Excessive rainfall can also be detrimental to forages. Saturated soils limit oxygen availability to plant roots, inhibiting growth and leading to die-offs. Extended wet conditions can delay harvesting and damage standing crops, resulting in mold, spoilage, and reduced nutritional content. Frequent rains during haymaking prevent proper drying, which decreases quality and storage life.

Abrupt temperature shifts, particularly unseasonable frosts, can also harm forage. Frost events can inhibit pasture regrowth and delay maturity in annual forage crops like alfalfa or winter rye. Some forage species may accumulate potentially toxic compounds such as prussic acid (cyanogenic glycosides, more commonly known as cyanide) under cold stress, posing a risk to livestock.

Beware of Toxicities

Drought and flooding can also cause toxic concentrations in some plants, particularly Johnson grass and Sudan grasses (Sorghum spp.), depending on soil maintenance and composition and in your region.

The concentration of hydrogen cyanide, or prussic acid, is higher in plants where nitrogen is in abundant supply or when the conditions inhibit optimal growth. Both drought and frost can contribute to this. While cyanogenic glycosides are present in many plants and seeds, stress from drought or other factors can cause the plant cells to rupture, which releases the cyanogenic compounds and allows them to combine with enzymes in the plant that together create prussic acid. Hydrogen cyanide is released when the animal chews or digests the plant material.

According to the University of Kentucky Veterinary Diagnostic Laboratory’s Beware of Prussic Acid, “Once consumed, the toxin goes immediately to the bloodstream and blocks a necessary step in the release of oxygen from hemoglobin in the blood to the cells. The animal essentially suffocates from lack of oxygen. Ruminants are much more susceptible to prussic acid poisoning because they have enzymes in the rumen capable of converting the cyanogenic compounds in the plant into hydrogen cyanide.”

According to the Arkansas State University bulletin Preventing Prussic Acid and Nitrate Toxicity in Small Ruminants, “When animals ingest forage with elevated levels of prussic acid, it can interfere with normal cellular respiration, which damages how the body can use oxygen. If cell respiratory mechanisms are blocked, it can cause cyanide toxicosis, and signs of toxicity can appear in minutes.”

Nitrate toxicity is a different but similar-appearing issue that occurs when plants accumulate excessively high levels of nitrates in their tissues. This condition commonly results from disruptions in normal plant metabolism triggered by environmental stresses or management practices, including environmental stressors (drought, frost, or lack of sunlight), excessive fertilization, rapid growth after a stressful period, and poor soil and drainage conditions.

When ruminants eat forages high in nitrates, their rumen microbes convert nitrates into nitrites. Excessive nitrite levels interfere with the blood’s ability to carry oxygen. Symptoms of nitrate toxicity may take hours to appear and include reduced performance, respiratory distress, or even death in severe cases. For those that grow their own hay, regular soil tests can help identify potential issues in the pasture. However, for those who buy hay, the only way to be certain of forage quality is to collect a sample and have it tested. Avoid buying hay from a heavily drought-impacted region whenever possible.

Managing Forage

When buying hay, it’s best to know as much as possible about the conditions where it was grown, baled, and stored. If possible, try to purchase hay analyzed by a lab and ask to see the reports. Alternatively, you can also send in samples for a reasonable fee.

weather-impacts-forages — Adobe Stock/Sergei

Unfortunately, after harvest, nothing can be done about the hay quality. However, you can prevent further degradation by storing it away from excessive moisture and sunlight to prevent spoilage.

If your goats graze as a primary forage source, you’ll want to take practical steps to preserve your pasture. Temporary fencing options are a great way to rotate grazing areas throughout the seasons and weather to ensure your grasses get time to rest and regrow.

You can have more grazing pressure when there’s adequate rainfall and new growth is appearing and decrease the pressure when it’s dry and more stressful on the plants. Overgrazing in drought-like conditions can stress your forages even more than they already are and will slow their recovery process.

Growing a diversity of plants that includes grasses and legumes can help improve your soil with natural nitrogen fixation and better fertility and longevity. Your state extension service likely has some good resources to help you determine what is best for your specific region. Remember, if you graze your animals mindfully and carefully, you’ll enhance the environment and soil health.

Because forage is often the primary staple of the goat’s natural diet, it’s essential to get it right — when growing it in the field and feeding it in the bunk. Fortunately, resources and tools are available to help you manage healthy soils that grow nutrient-dense forages for your goats.

JACLYN DE CANDIO is a professional agriculture writer, communications specialist, and farmer. A member of the Ohio Farm Bureau and the Agriculture Communicators Network, she lives in southwest Ohio with her husband and children where they operate Latria Livestock Co., feeding out market kids and lambs.

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Originally published in the March/April digital issue of Goat Journal