Feeding The Beef Cow Herd--Part II Managing the Feeding Program

Read Part 1

Rick Rasby, Extension Beef Specialist
Ivan G. Rush, Extension Beef Specialist
Don Adams, Extension Beef Specialist

Nutrient requirements for heifers calving as 2-year-olds and cows calving as 3-year-olds and older are shown in Table I . Beef cows are seldom fed complete rations where ingredients are weighed daily. Generally, most of a cow's ration is forages such as: 1) summer and winter range, 2) crop residues, or 3) a full feed of hay. For cattle grazing dry native range or being fed hay, producers must estimate both the quantity and quality of feed consumed.

Estimating intake is the most important criteria for developing a sound nutritional program. It is also one of the most difficult to obtain. Many related factors can influence forage intake, including cow size, milk production level, cow condition, quality and availability of forage, amount and type of supplements, and environmental factors. Consequently, the more accurately that actual intake is determined, the better one can design an appropriate feeding program. Estimated dry matter capacities for different weights of cows and heifers are shown in Table II . These general guidelines are adequate for balanced rations meeting the nutrient requirements in Table I .

If the ration is high in both protein and energy, cows will likely consume more than indicated. If the ration is low in protein and energy, cows will probably not consume as much as indicated. Table II provides guidelines to aid in determining forage intake. It may be more appropriate for use when intake is not actually known. Intake guidelines in Table III are also more appropriate when calculating or budgeting feed needs for a total winter feeding program.

Estimated feed intakes in Tables II and III are the amount of feed consumed by the cattle and do not account for feed wasted during feeding. If hay is fed on the ground or if waste is a factor, consider feeding losses when calculating a balanced ration. (Refer to NebGuide G84-738, Management to Minimize Hay Waste. )

Nutritional composition of harvested forages can be estimated by laboratory analysis from representative feed samples. However, it's difficult to estimate the quality of standing forages. Cattle are selective and tend to consume the most nutritious plants or plant parts. Past experience and careful attention to changes in cow condition are important factors to consider when estimating forage nutrient content. Clipped grass samples are often misleading and offer erroneous information on nutritive quality. Often forage quality analysis of clipped samples is lower in nutrient content than what is selected and consumed by the cow.

Because most cow herds are managed so that strict control of the nutrition program is difficult, general guides can be developed based on an understanding of nutrient requirements, previous experience feeding the beef herd, and research results from similar feeding programs.

The following principles can help you develop feeding programs.

Energy Nutrition

Protein Nutrition

1. Protein requirements should be met to provide adequate rumen nitrogen to maximize forage digestion.
2. Protein can increase the digestibility and intake of low quality forages that are the primary energy sources in the ration.
3. Cows have an internal system to recycle nitrogen as urea back into the rumen that can then be combined with the energy source in the rumen to make microbial protein.
4. It is essential that the rumen degradable protein needs are met to ensure maximum forage digestion. NPN (urea) may be included in beef cow rations to meet the rumen degradable protein needs.
5. NPN (urea) and a portion of the natural (i.e., plant and animal proteins) protein is degraded in the rumen of cattle. If urea or proteins extensively degraded in the rumen are used as a protein source for the rumen microbes to make their own protein, a rumen bypass (proteins that escape microbial degradation in the rumen; e.g., feather meal, fish meal, meat and bone meal) protein should also be included in the supplement.
6. Natural plant protein supplements, including SBM, CSM, and legumes appear to be as effective when fed two or three times a week as when fed daily. When greater amounts are fed less frequently, timid cows may be more likely to eat their fair share.
7. Protein supplements should be evaluated and purchased by nutrient cost and feeding cost. Protein sources, such as alfalfa hay, can be an inexpensive or cost effective supplement.

Mineral Nutrition

1. Most mature forages are low in phosphorus; therefore, phosphorus may be deficient in the cow's diet except when grazing young growing grass from spring until mid-July to early August. Phosphorus deficiencies have been shown to decrease weaning weight.
2. Supplemental phosphorus can be fed in the protein supplement, a commercial mineral supplement, or a home-blended, salt-mineral mix. Salt is used to limit consumption of supplemental phosphorus. Bred cows and heifers grazing winter range, crop residues, or low quality forages need about .01 to .015 pounds of supplemental phosphorus daily during gestation. A 10-15 percent phosphorus mineral mixed equally by weight with salt will provide about the correct phosphorus intake for dry cows, cows in late lactation, or cows during early lactation fed high quality hay. In areas where grass is high in sodium, mixtures of three to four parts phosphorus carrier to one part salt (NaCl) may be needed to get the proper phosphorus intake.
3. Magnesium supplementation is recommended in some areas before and during grazing of early lush pasture. In areas prone to grass tetany or when conditions suggest a likely problem with grass tetany, feed supplemental magnesium oxide (see NebGuide G73-32, Grass Tetany ).
4. Research has not indicated that trace minerals are always needed in Nebraska. Any deficiencies should be dealt with and be supplemented on an individual ranch basis. Copper content of forages, especially mature forages, seems to be the trace element likely deficient especially in the Sandhills. Ranchers should consult with Extension educators for information about deficient areas and trace element analyses of ranch forages. Trace minerals can be included in protein or mineral supplements at low cost if a thorough analysis indicates they are needed.
5. Calcium is usually adequate in most rations because forages are usually high in calcium. However, high grain rations fed to heavy milking heifers or cows may need calcium supplementation because they contain considerable amounts of grain which is low in calcium. When legumes high in calcium are fed, there is little need to feed calcium mineral supplements to improve the calcium phosphorus ratio.

Vitamin Nutrition

1. Vitamin A appears to be the only vitamin supplement routinely needed by the cow herd.
2. Vitamin A supplementation can begin about 60 days before calving. Include Vitamin A in the protein supplement, salt mineral mix, or inject it. Vitamin A should be fed at a rate of about 25,000 IU per head daily before calving and 40,000 IU per head daily after calving. If Vitamin A is mixed with salt, mix about 1,250,000 IU per pound of salt before calving and 2,000,000 IU per pound of salt after calving. It is important to keep minerals fresh and dry to assure a high level of active Vitamin A. If high quality, green leafy alfalfa hay that is less than a year old is fed, it is doubtful if Vitamin A supplementation is needed.

General Nutrition Management

1. Underfeeding the cow herd after calving can lower milk production and reduce the number of cows cycling early in the breeding season. This is especially true for cows and heifers that are thin (body condition score 4 or less) at calving.
2. When dry or cool weather delays grass growth, extending the length of the breeding season will help prevent having a high percentage of open cows.
3. Feed costs can be reduced by extending grazing in the fall and winter on range, meadows or crop residues rather than feeding harvested feeds.
4. If feed costs are extremely high, it may indicate that the cow's nutrient needs are not matched with the nutrient quality of the grass/forage resource. Producers may consider changing when calving occurs and/or when calves are weaned based on the nutrient content of the forage resource to help reduce feed costs.

Example rations for late gestation and lactation are shown in Table IV . Extension educators can help producers "fine tune" their feeding programs using computer least-cost ration programs. Rations can be developed if producers know alternative forages that are available and the forages being considered have been analyzed for nutrient content.

File G1262 under: BEEF
A-46, Feeding & Nutrition
Issued September 1995; 5,000 printed.

Electronic version issued September 1996

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Elbert C. Dickey, Director of Cooperative Extension, University of Nebraska, Institute of Agriculture and Natural Resources.

University of Nebraska Cooperative Extension educational programs abide with the non-discrimination policies of the University of Nebraska-Lincoln and the United States Department of Agriculture