Beef Cattle Nutrition Planning Part I: Managing Nutrition for Cattle Grazing on Rangeland

Rangeland grazing is a cornerstone of livestock production, offering a cost-effective way to feed cattle. However, ensuring your cattle herd receives the right nutrition from rangeland forage throughout the year can be complicated. This post explores the considerations that come with managing nutrition for cattle grazing on rangeland, focusing on the evaluation of essential nutrients present in your rangeland’s forage, classification of forage quality, and the potential need for supplementation of specific nutrients.

Nutrient Evaluation for Rangeland Forage

The nutrient value of forage on rangeland is the limiting factor in meeting your cattle herd's nutritional requirements. Understanding four key nutrients – protein, phosphorus, energy, and carotene (Vitamin A) – is essential for building your herd’s nutrition plan.

Protein Content:

Digestible protein content is adversely correlated to your forage’s maturity. Grasses typically decline in digestible protein as they mature, while shrubs better retain their protein content. Forbs, however, fall in between, offering moderate protein levels. If your rangeland has an overabundance of mature grasses and is lacking shrubs, then it may be necessary to consider protein supplementation. 

Phosphorous:

Phosphorous content varies depending on soil conditions. Grasses have lower phosphorous levels soon after seed formation. Shrubs consistently provide good phosphorous content. Forbs also offer decent phosphorous levels. However, it’s important to keep in mind that soil on your grazing land may contain an over or underabundance of phosphorus, which will be reflected in the phosphorous content of your forages, regardless of the type of forage that you’re working with. 

*Note: When considering phosphorus (P) content in the diet, calcium (Ca) must be considered as well. Research shows that the optimal Ca:P ratio for beef cattle is 1.5:1 to 2:1, with variations depending on the age and physiological state of your cattle. 

Energy Values:

Energy values are often expressed as Total Digestible Nutrients (TDN) or Digestible Energy (DE). Grasses are energy-rich due to their cellulose content. However, mature grasses have lower digestibility, reducing energy intake. Shrubs become less valuable for energy as they mature, while forbs provide intermediate energy levels. 

Carotene (Vitamin A) Values:

Vitamin A precursors, carotenoids such as beta carotene, are found in leafy green grasses. Some rangeland forage contains enough carotenoids to more than meet your herd’s requirement. However, rangeland that has suffered drought conditions or lower-than-average precipitation will often be deficient. In this case, supplementation should be considered, especially if there are pregnant or lactating cows in your herd.

Classifying Your Rangeland Forage

To effectively manage nutrition, you need to classify your rangeland forage into three categories: high, medium, and low (or poor) quality.

High-Quality Forage:

High-quality forage is both nutritious and palatable, producing abundant forage to meet your herd's needs.

Medium-Quality Forage:

Medium-quality forage contains adequate nutrients but may not be preferred by animals or produce enough forage.

Low or Poor-Quality Forage:

Low-quality forage lacks adequate nutrients and may contain anti-quality compounds, toxins, or harmful elements.

Supplementing Feed for Livestock on Rangeland

In certain conditions, cattle grazing on rangeland may struggle to obtain sufficient nutrients from forage alone. Supplementary feeding becomes necessary to maintain production, albeit at an additional cost. Here's how to determine when and how to supplement your cattle herd:

Understand Nutritional Requirements:

Familiarize yourself with your cattle herd's nutritional needs at different times of the year and during various physiological states. Compare their nutritional needs with the forage quality classification on your rangeland, and supplement as needed. 

Assess Forage Nutrient Content and Classification:

Regularly evaluate your rangeland forage to determine its nutrient content and classify its quality. Quality and classification will vary depending on the time of year, forage maturity level, and the nutritional requirements of your herd. Supplementation may be necessary at some points in the year, but not in others. 

Consider Cost-Benefit Analysis:

Evaluate the cost of supplementation compared to the expected benefits in terms of cattle performance and health. For example, the cost of supplementing digestible energy in the form of hay may not be totally necessary outside of lactation and pregnancy, depending on the forage classification on your rangeland. 

Base Decisions on Forage Supply, Protein Content, and Animal Condition:

Decisions to supplement should consider forage supply, protein content, and the body condition score (BCS) of your cattle. Healthy cattle typically maintain a BCS of 4, with variations depending on physiological state. If your herd’s average BCS is 2 or lower, the forage on your rangeland is likely not meeting their nutritional requirements and you may need to consider supplementation. 

Conclusion

Managing nutrition for cattle grazing on rangeland requires at least a basic understanding of forage quality, nutrient content, and the timely provision of supplements. By following the guidelines outlined in this blog post, ranchers can optimize their cattle herd's health, productivity, and overall sustainability of rangeland grazing operations. Effective nutrition management not only benefits cattle but also contributes to the long-term success of livestock production on the open range.