Advice on Feeding Low-quality Forage to Cattle
North Dakota livestock producers are faced with low-quality forage and lack of available forage this year because of poor growing and harvesting conditions.
While some producers have plentiful hay, rain during and after cutting resulted in reduced forage quality due to mold, leaf loss, shatter and nutrient leaching. Characteristics of low-quality forages include high fiber content, low crude protein (CP) and energy (total digestible nutrients or TDN) content, and reduced fiber digestibility.
Low-quality forages also may have tough, coarse stems and reduced leaf-to-stem ratios, which can reduce palatability to livestock. In general, dry-matter intake typically is reduced with low-quality forages and the potential for nutrient deficiencies is increased.
“Although beef cows are able to utilize low-quality forages to some degree, supplementation will likely be necessary to meet nutrient requirements this winter for spring-calving cows,” says Janna Block, North Dakota State University Extension livestock specialist based at the Hettinger Research Extension Center.
“The last trimester of gestation is extremely critical in terms of nutritional management of the cow herd,” she adds. “Protein and energy requirements of the cow will increase by 15% to 20% from midgestation to support rapid fetal and placental growth and prepare for lactation.”
Consequences of feeding low-quality forages to pregnant cattle without appropriate supplementation include weight and body condition losses, lowered immune function, calving difficulty, calf health issues, reduced milk production and decreased conception rates.
The best way to utilize any forage is through proper sampling and laboratory analysis so that the correct supplement can be used.
“Recognizing that forage quality can be affected by a variety of environmental factors during harvest and storage, it is extremely important to determine chemical composition of all available forage through laboratory analysis to develop an effective feeding strategy,” says Miranda Meehan, NDSU Extension livestock environmental stewardship specialist.
For more information on feed sampling and analysis, Meehan recommends the NDSU Extension publication “Sampling Feed for Analysis,” which is available at https://www.ag.ndsu.edu/publications/livestock/sampling-feed-for-analysis.
Supplementing Low-quality Forages
Nutrient intake must be adequate to support microbial fermentation in the rumen to meet production goals. Adequate dietary protein and energy are critical for microbial growth and production of volatile fatty acids that constitute the majority of energy used by the cow.
“Research results have established that microbial fermentation is reduced when the crude protein content of forages is less than 7%,” says Yuri Montanholi, NDSU Extension beef specialist. “This results in lowered digestibility, passage rates and, ultimately, intake.”
Supplemental protein will be necessary with this type of forage to improve forage intake and nutrient utilization. To be considered a true protein supplement, feeds should contain at least 25% to 30% CP.
“Commonly used supplements include high-quality grass or legume hay, oilseed meals (canola, sunflowers and soybeans), or byproduct feeds such as corn gluten feed and distillers grains,” says Karl Hoppe, NDSU Extension livestock systems specialist based at the Carrington Research Extension Center. “Self-fed supplements such as protein tubs and blocks may be used, but producers need to ensure that these products will contribute adequate additional protein to the diet.”
Nonprotein nitrogen (NPN) sources such as urea are an inexpensive and widely available source of protein used in many commercial supplements. Although rumen microbes can utilize NPN, research indicates that natural protein is used more efficiently than NPN with low-quality forages.
Other concerns with NPN include the potential for urea toxicity when included at high levels in supplements, particularly if energy is deficient in the diet. Total urea intake should not exceed 0.05 pound for dry cows or 0.10 pound for lactating cows.
Feed tags on supplements should state the percentage of protein equivalents from NPN. Urea contains 281% of CP equivalents, so if a feed tag states that the protein equivalent from NPN is 10%, the supplement contains 3.6% urea (10% divided by 2.81). If the target intake for the supplement is 2 pounds per head per day, the total amount of urea provided per cow would be 0.07 pound. This would exceed recommendations for dry cows but would be within the acceptable range for lactating cows.
“Protein is often a focus, but forages also may be deficient in energy.” Hoppe says. “If TDN content is less than 50%, it would be inadequate in energy for most classes of livestock.”
Energy supplement options include cereal grains high in starch and sugars (corn, barley, etc.), byproduct feeds high in digestible fiber (soybean hulls, wheat midds beet pulp) or high-quality forage such as alfalfa. Forage intake and digestion are reduced when feeding high levels of starch-containing grain (greater than 0.4% of body weight) due to changes in rumen dynamics that interfere with fiber-digesting microbes.
“However, this ‘substitution effect’ can be beneficial if the forage supply is limited by allowing producers to feed higher amounts of grain and reducing the amount of forage in the diet,” Hoppe notes.
In addition to potential protein and energy deficiencies, weather-damaged forages may be deficient in minerals and vitamins. These components of feeds are very small and often overlooked; however, they are critical for growth, immune function and reproduction.
“Analysis for mineral content of forages is an additional cost, but it can be extremely valuable in helping producers choose an appropriate mineral supplement,” Block says.
Vitamins are classified as water soluble (B complex, vitamin C) or fat soluble (vitamins A, D, E and K). Increased supplementation of vitamins A and E should be considered with low-quality forages, particularly during the last trimester of gestation and the first few months of lactation.
Vitamin A deficiency can reduce feed intake, cause digestive disorders and result in negative impacts on reproduction, including low conception rates, abortion and stillborn or weak calves. Vitamin E is closely tied to immune function.
Beef cattle requirements for vitamin A are 1,273 international units (IU) per pound of dry feed for pregnant cows and heifers and 1,773 IU per pound of dry feed for lactating cows and breeding bulls. Vitamin E requirements are less established but are estimated at 16 IU per pound of dry feed for pregnant or lactating cows.
A vitamin A-D-E premix package often is added to mineral mixtures or commercial supplements. Producers should note that vitamin activity can be reduced through time in vitamin or vitamin-mineral premixes, even when a stabilized form is used.
Research has shown activity losses of up to 25% after three months of storage and up to 50% after more than a year. Check the manufacturing date for these supplements to make sure they are being used in a timely manner.
Another option is to provide a two- to three-month supply of vitamins through injections. Some producers have reported injection site tissue damage, so be sure to read the label and follow beef quality assurance injection guidelines (https://www.ag.ndsu.edu/bqa/documents/injections).
Some additional resources for feed options, feeding guidelines and calculating feed costs are available through NDSU Extension:
- “Alternative Feeds for Ruminants,” available at https://www.ag.ndsu.edu/publications/livestock/alternative-feeds-for-ruminants
- A current listing of prices and availability of byproduct feeds in North Dakota at https://tinyurl.com/CoproductFeedPricesNov2019
- Feed Costs Calculator: https://tinyurl.com/FeedCostsCalculator-NDSU
Source: North Dakota State University