Livestock producers across North Dakota are facing forage quality and quantity issues this grazing season because of the continuing drought.

Some producers already have reduced their forage needs by culling or relocating cattle. Other options include feeding cattle in a drylot or trying to find a supplemental feed to offset nutrient deficiencies in the forage or replace a portion of forage intake. 

In a typical growing season, nutrient requirements of grazing beef cattle are met by native range and/or tame pasture species. However, drought can cause reductions in forage quality and quantity, which may impact cattle performance if supplemental feed is not provided in adequate amounts.

“The main objective of supplementation programs is to meet nutrient requirements as efficiently and economically as possible,” says Janna Block, livestock systems specialist based at North Dakota State University’s Hettinger Research Extension Center. “In order to do that, it is important to understand which primary nutrient (protein or energy) is found in the shortest supply relative to requirements. Factors that should be considered when making decisions about supplement include forage supply, protein content, cow body condition, and cost and availability of supplements.”

An important first step is measuring forage availability so producers can calculate the appropriate number of animals and grazing days for their pasture resources.

During the growing season, drought-affected forage actually may be higher quality because nutrients are not as diluted by moisture as in normal years. However, drought also can lead to early plant dormancy and reduced quality earlier in the grazing season.

Protein Supplementation

Pastures that have reached early dormancy due to drought conditions are usually deficient in crude protein. Ensuring that protein requirements are met is important to optimize animal performance and reproduction. A minimum of 7% of dietary crude protein is necessary to ensure adequate digestion and nutrient utilization by microbes in the cow’s rumen.

At this stage of the production cycle, mature cows weighing 1,300 pounds that calved in March and April require approximately 2.5 pounds of crude protein (CP) per day. If we assume that most cool-season dormant grass species contain around 5% CP and that cows can eat approximately 2% of their body weight in low-quality dormant forage, cows would be consuming about 1.3 pounds of CP per day from forage. In this example, they would need an additional 1.2 pounds of supplemental CP to meet requirements.

Examples of protein supplements include oilseed meals (sunflower, soybean and canola), peas, coproducts such as distillers grains, or commercial protein blocks, liquids or tubs.  

Protein supplement does not need to be delivered on a daily basis. Feeding every third day or even as infrequently as once every six days can result in similar performance. If producers were planning to feed 2 pounds per head per day, they simply would multiply the daily feeding rate by the number of days between feedings. Therefore, if feeding every three days, cows would receive 6 pounds of supplement at each feeding.

Interval feeding can result in significant savings of labor and supplement delivery costs. Interval feeding is not as effective if large quantities of supplement are necessary. The maximum recommended amount to provide at any one feeding is 1% of body weight.

Determining forage quality simply by visual evaluation of the forage is difficult, so nutrient analysis of standing forage is beneficial in cases where supplementation decisions are being made. Understanding that protein supplementation has positive effects on forage intake and digestibility also is important. Therefore, if forage quantity is limited, protein supplement is not an ideal choice. Feeding larger quantities of a low-protein, high-energy supplement would work better in this situation.

“If forage production is limited, producers may wish to replace a portion of pasture intake with supplemental feed,” says Karl Hoppe, livestock systems specialist based at NDSU’s Carrington Research Extension Center. “Feeding harvested forages such as alfalfa or annual forages on pasture is one option; however, forage supplies are already short in many situations.

“It is also challenging to get cattle to consume harvested forage while on pasture,” he notes. “Consideration should be given to possible negative impacts on rangeland or pasture health by leaving cattle grazing in drought-affected areas.”

Energy Supplementation

Cereal grain such as corn often is used as an energy supplement; however, starchy feeds have been shown to have a negative impact on forage digestibility and intake when fed at levels greater than 0.4% of body weight. Typically, this “substitution effect” would be considered a negative consequence of feeding grain with a forage-based diet.

However, this response actually may be beneficial during drought, provided that the energy lost through the reduction in forage intake is made up by the supplement. High-energy, fiber-based supplements such as wheat midds, soyhulls, beet pulp and corn gluten feed also can be used to substitute for forage without negative impacts on fiber digestibility. Research conducted at the University of Nebraska indicated that a mix of 30% wet distillers grains and 70% wheat straw stored in bunkers or silage bags replaced forage on nearly a 1-to-1 basis.  

Unlike protein supplements, energy supplements should be delivered daily for optimal performance to avoid excess energy intake and maintain optimum conditions in the rumen.

Cow body condition should be 5 or greater at breeding to optimize conception rates. Now may be too late for some producers to increase condition in time for breeding, but providing a moderate protein (less than or about 20%), high-energy supplement at 0.3% to 0.5% of body weight should help prevent further body condition losses and reduced performance.

In addition to protein and energy, mineral supplementation is an important consideration for any nutrition program. Producers must recognize that feeding wheat midds, distillers grains and corn gluten feed will provide substantial levels of phosphorous in addition to protein and energy. These feeds also may be high in sulfur, which can have negative impacts on absorption of other minerals such as copper. The best way to determine the optimum mineral formulation for a particular operation is to test forages, supplemental feeds and water sources for mineral content.

Evaluating Supplement Costs

Supplement costs should be evaluated on a cost per pound of nutrient basis when comparing potential options. If a 20% protein supplement costs $300 per ton, the cost per pound of protein is $0.75 (2,000 times 0.2 = 400 pounds of protein and $300 divided by 400 pounds of protein = $0.75).

Overall supplement costs also should be evaluated based on unit cost of nutrient and amount of supplement delivered per head per day. If supplement costs are excessive, another option that will improve cow condition consistently and result in forage savings is to wean calves early.

“Because supplemental feeding accounts for a large percentage of total production costs, producers must understand the benefits and goals of utilizing a certain type of feed in a specific production environment,” Block says.

For more information about forage sampling and analysis or choosing a supplement, contact your county Extension agent.

NDSU Agriculture Communication - July 12, 2021

Source: Janna Block, 701-567-4323, janna.block@ndsu.edu

Source: Karl Hoppe, 701-652-2951, karl.hoppe@ndsu.edu

Editor: Ellen Crawford, 701-231-5391, ellen.crawford@ndsu.edu