Beef Business

Grazing Forage Brassicas

by Mike Trammell, Oklahoma State University

Extension

Forage brassicas have been used in the US for more than 100 years. The biggest factor affecting the popularity for brassicas as forages in the US may be their suitability as cover crops as well. Many producers are attracted to the idea of improving their soil health while also feeding their livestock. This has led to an increase in brassica seed availability and new varieties. Brassica crops were developed by selective breeding and crossbreeding of a few species into many forms designed for different uses as forages, vegetables, oilseeds, and cover crops. In the US, turnips, rape, and kale are old standby forages. Newer additions to this group include swedes (rutabagas), forage collards, mustards, radishes, and a few interspecies hybrids selected for various traits like the production of high levels of secondary compounds to combat soil pests in crop rotations as cover crops. However, if the primary reason for growing them is for grazing, be sure the variety purchased was developed for that purpose.

The strength of brassicas as a forage crop is their cold tolerance, allowing them to provide high-quality pasture well into the fall and winter when most other forages are dry and brown. Little new growth will occur after temperatures fall below freezing at night, but existing forage remains and holds its nutritional value very well. Brassica’s extremely high moisture content makes preservation as a hay crop impractical. Brassicas that form big bulbs, such as turnips, swedes, and radishes, can be grazed but are less suitable for multiple grazing than varieties that do not elevate their crowns on top of bulbs. However, there are turnip and radish varieties selected for grazing that have an increased proportion of top growth relative to the bulb and livestock readily learn to dig up brassica forage bulbs. Another strong point is a fast growth rate that, under good growing conditions, can provide emergency forage in as little as 45 days. Forage brassica yields are quite variable, ranging from two to five tons of dry matter per acre depending on species, variety, and environmental conditions.

Nutritionally, forage brassicas behave like a high-moisture concentrate feed. Crude protein is typically sufficient to meet the needs of livestock on pasture. Brassicas are naturally low in fiber compared to grass and legume pasture. Brassica neutral detergent fiber (NDF) can range from 11–44% and has NDF digestibility up to 70%. Brassicas that form stems (rape and kales) will be at the higher end of the range, and leafy brassicas like turnips and radish will be at the lower end. Due to their high nutritive value, brassicas can produce excellent animal performance but require adjustments to grazing management. Animals should be introduced to brassica-based pastures slowly to allow the rumen time to adapt and should never be grazed on pure brassica pastures. Effective fiber can be provided by planting brassicas in mixtures with small grains (oats, cereal rye, triticale, or wheat) or other forages, supplementing pastures with hay, or providing access to a separate grass pasture. A good rule of thumb is to limit brassicas to no more than 70% of the diet.

Forage brassicas do best on productive, fertile, well-drained soils and do not tolerate waterlogging. They are responsive to nitrogen (N) fertilizer up to 100 pounds per acre, which should be applied in split applications before planting and about three weeks post-planting. Phosphorus and potassium should be applied according to a soil test. Seeding rates are two to four pounds per acre for turnips, four to five pounds per acre for swedes, five to six pounds per acre for rape and kale, and four to 20 pounds per acre for radish.

Although infrequent, brassica crops can cause animal health disorders if grazing is managed improperly. Most brassica-related disorders in cattle tend to occur during the first two weeks of grazing while adjusting to the forage. The primary potential disorders are polioencephalomalacia or PEM, hemolytic anemia (mainly with kale), nitrate poisoning, and pulmonary emphysema. In general, potential problems can be minimized by feeding brassicas as no more than 70% of the dietary dry matter intake, introducing animals to brassica pasture slowly, never turning hungry animals onto a brassica pasture, providing a trace mineral supplement that includes iodine, not grazing immature rape (safe maturity is indicated by a reddish/bronze tint to leaves), and avoiding excessive N and sulfur fertility.

Is it Time to Wean?

by Mark Johnson, Bovine Veterinarian

As of August 1, 2024, the Mesonet Oklahoma Drought indicates over 69% of Oklahoma is abnormally dry. Of that percentage over 25% of our state is rated in moderate to severe drought. One potential management solution to dwindling forage resources in cow-calf operations is weaning calves.

The average age of beef calves weaned in the US is a little over seven months of age. While calves can be weaned as early as 60 days of age, this comes with quite a bit of added management. Simply weaning calves one to two months early is a cost effective management strategy that saves body condition score (BCS) and allows thinner cows (falling below BCS of 4) to more easily recapture flesh before having their next calf. When the nutritional demands of lactation are removed by weaning there is significant reduction (15–20%) in the dietary energy needed by cows. Saving BCS on cows now comes with the potential benefit of improved cow productivity in the years that follow. Weaning earlier than normal is most beneficial in years when pasture forage is inadequate to support herd nutritional requirements. From the standpoint of range management, it reduces the risk of overgrazing and accordingly adds to the long-term health of the grazing system.

If you plan to wean earlier than normal to alleviate stress on cows and pastures, keep the following management practices in mind:

• The first two weeks post weaning are a critical time for calves to overcome weaning stress, maintain health, and become nutritionally independent by learning to consume feed.

• Lower the risk of health problems and promote calf growth by giving proper vaccinations prior to weaning. Castrate and dehorn calves when giving pre-weaning vaccinations. This permits calves to deal with the stress of these management practices while still nursing.

• Get calves accustomed to a feed bunk and water trough as quickly as possible (if not prior to weaning). Creep feeding calves for a few weeks prior to weaning will ease the transition and get calves accustomed to concentrate feed. Maintain access to good quality, clean water at all times.

• Fence line wean if possible. This eliminates stress by permitting calves to remain in the same pasture where they are familiar with feed, water, shade, etc.

• The feed ration is critical because feed intake is initially low after weaning. It needs to be highly palatable, nutrient dense, dust free, and include a complete vitamin and mineral supplement.

• After calves are over the stress of weaning they should begin to consume approximately 3% of their body weight in high-quality feed each day. Feed intake variation or depressed appetite can indicate health problems.

• Shade is important if weaning during summer heat. .

2024 Creep Grazing Options

by Mark Z. Johnson, Oklahoma State University Extension

As opposed to creep feeding a traditional grain-based diet, creep grazing has potential to be a more cost-effective solution. There are many ways to adapt this system to each individual situation, but the bottom line is that it must be profitable.

Most forages can be used for successful creep grazing as long as they are high in nutrient quality and readily available. Time of year will affect which forage is used for creep grazing. During the cool-season months, annual grasses like rye, oats, wheat, or ryegrass will be used. During the warm-season months, most producers will use legumes, Bermuda grass, pearl millet, or sorghum-sudan grass. With the potential of high-nitrate millet or sorghum-sudan grass due to heat stress and spotty rainfall during the Oklahoma summer of 2024, calves are a safer bet to utilize those standing forages than cows. If you have done a forage analysis on millet or sorghum-sudan, you have likely seen the following information regarding the safest way to utilize these forages based on nitrate levels.

Generalized interpretation for Nitrate test (ppm-dry matter basis):

• 0–3,000 = generally safe for all cattle.

• 3,000–5,000 = generally safe for non-pregnant cattle. Low risk of reduced breeding performance and early term abortion.

• 5,000–10,000 = some risk for cattle. May cause mid- to lateterm abortions and weak newborn calves. May decrease growth and milk production.

• 10,000 = potentially toxic for all cattle. Can cause abortions, acute toxicity symptoms, and death.

Similar to grain creep feeds, the added weight gain from creep grazing depends on pasture quality. Regardless of forage quality, if forage quantity is a problem, creep grazing should have a positive effect on calf performance. Daily gains tend to be less than the full-fed-energy creep systems, but are usually increased by 10 to 20 percent with creep grazing. This underscores the effects that pasture quality and quantity exert on gains of creep-grazed calves.

Creep grazing has a few other indirect benefits. One is that calves do not get as fat as when they are fed a grain-based creep feed and may not receive price discounts often applied to calves fed an unlimited high-energy creep feed. Replacement heifers may get too fat if fed a grain-based creep feed, and have reduced milk production. This problem is less likely to occur when using forage as a creep feed.

Remember, most experiments that track cow weight change and calf milk intake show that calves consume all the milk available whether they are creep fed or not. Creep feeding simply does not change or improve cow weights or body condition. Calves prefer milk first, palatable creep feed second, then forage. Accordingly, the primary benefit of creep grazing is cost-effectively putting pay weight on calves.

COW SENSE

Ten questions designed to test your beef industry knowledge:

1. Define “shrinkage.”

3. At what level of Simmental breeding is a bull considered a purebred?

4. With regard to per capita beef consumption, what would you expect as a population becomes more affluent with more disposable income?

5. In general, how many pounds of feed are needed to produce a pound of gain for a beef animal?

6. What is the term that describes the fluid part of unclotted blood?

7. Animals that have backbones and are symmetrical on both sides are known by what general classification?

8. What is the major influencing factor on cattle disposition?

9. Proteins are composed of nitrogenous compounds known by what common name?

10. Approximately what percentage of US land is unsuitable for cultivated crops? .

Answers:

1. Weight loss at shipping or handling; 2. Ten percent; 3. 15/16ths; 4. Beef consumption increases; 5. Six to seven pounds; 6. Plasma; 7. Vertebrates; 8. How they are handled; 9. Amino acids; 10. 45%.