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Author: KRIESE PubID: ANR-0883 |
Title: | GUIDELINES FOR DEVELOPING & TESTING BEEF BULLS |
Pages: 8
Status: OUT OF STOCK |
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| Guidelines For Developing And Testing Beef Bulls On-Farm |
Many producers have used central bull tests to develop herd sire prospects. Most central test stations have limited each producer to testing one bull per year because of space limitations and to allow as many producers to participate as possible. However, testing only one bull per producer per year eliminates estimation of yearling weight EPDS, including individual performance for bulls in central tests, because bulls are in a contemporary group size of one. Thus, to produce bulls with yearling weight EPDs including individual performance, producers should develop and test bulls on-farm.
With each live calf produced on-farm, the value of that calf as a parent comes into question. If the calf is superior to its parents, the calf becomes a candidate as a replacement animal. Not all bull calves should be considered herd sire prospects. At weaning, bull calves should be evaluated for soundness, adequate muscling and growth, and testicular development. Any bulls with unsoundness, especially feet and legs, should be removed as herd sire prospects. Bull calves with inadequate muscling and growth should also be eliminated. Bulls with testicular abnormalities, such as having only one testicle, testicles not descended into the scrotum, or abnormally small testicles, should also be eliminated as herd sire prospects. Inferior soundness, muscling, growth, or testicular development will decrease the productive life of a bull in a herd. These traits can also be passed on to offspring.
Nutritional Management For Bull Development
A good feeding program is essential for growth and development of future herd sires. Failure to supply proper nutrition during the growth and development stage of a bull can result in permanent damage to the bull's digestive tract. This may render the bull useless as a herd sire or shorten his productive life from many years down to several months. A sound feeding program in developing bulls will aid a producer in establishing and maintaining a reputation as a reliable breeder.
Providing Properly Formulated Rations
There are numerous feedstuffs suitable for ration formulation
in Alabama. Producers should feed rations that provide nutrients
in ample quantities for the bull's stage of development. Nutrients
consist of protein, energy, minerals, vitamins, and water. Nutrient
requirements for bulls are listed in Table
1 and Table 2. Contact your county
Extension agent for help in formulating diets with feed ingredients
available in your area.
Protein. Natural protein should be provided for developing
bulls. Natural protein is protein found in feedstuffs such as
hay, corn, and oilseed meals. Nonprotein nitrogen sources, such
as urea, are not natural proteins and are of questionable value
for developing animals. Non-protein nitrogen is best utilized
in finishing cattle rations. Developing bulls should be maintained
on a 12 percent protein diet.
Energy. Energy is measured as total digestible nutrients
(TDN) or net energy for maintenance or gain (NE-M or NE-G). Energy
is important for growth, maintenance, and reproduction. Energy
is supplied by forages, hay, grain, feed by-products, and oilseeds
but will vary depending upon the stage of maturity and type of
feed. Table 3 ranks feedstuffs in descending order, according
to the amount of energy they contain. The values listed are average
energy values. Energy levels in feedstuffs will vary with individual
samples. Developing bulls should be fed diets which contain between
62 and 69 percent TDN.
| Feedstuff | Energy (% TDN(a)) |
| Corn | 90 |
| Grain sorghum | 85 |
| Oats | 78 |
| Silage | 65 |
| Hay | 50 |
| Peanut hulls | 23 |
| (a)TDN = Total Digestible Nutrients | |
Minerals. Major or macrominerals are minerals needed
in relatively large amounts in the diet. Trace or microminerals
are minerals needed in relatively small amounts. Macro or micro
do not denote importance but rather the amounts of a mineral required
by livestock. Table 4 lists the minimum
mineral requirements for growing beef cattle.
Minerals can be supplied in the diet or provided free choice in
a mineral feeder. If calcium and phosphorus are included in the
diet, calcium should be about 0.45 percent of the diet, and phosphorus
should be about 0.35 percent of the diet. These levels of calcium
and phosphorus will provide adequate levels of both minerals at
the correct ratio (1.3 to 1.5:1). Calcium-phosphorus ratios may
be as high as 2 to 1 in diets with some forages. This is acceptable,
and no additional phosphorus needs to be added to the ration.
Phosphorus is the most expensive mineral fed to cattle because
of cost and amount fed.
In a complete feed, calcium, phosphorus, and magnesium should
be added based on the amount in the feed ingredients. A good source
of calcium is steamed bone meal or feed grade limestone (calcium
carbonate). A good source of phosphorus is Dynophos (dicalcium
phosphate).
A good free-choice mineral mix for cattle is 50 pounds of dicalcium
phosphate thoroughly blended with 50 pounds of trace mineral salt.
This mixture contains about 40 percent salt and 9 percent phosphorus.
Cattle will consume about 2 ounces of this mixture per day. Commercial
mixtures contain about 20 percent salt and 4 to 6 percent phosphorus.
Cattle will consume about 4 ounces per day of this mixture. Cattle
consume about the same amount of phosphorus per day in both mixtures.
The amount of minerals consumed is determined by the salt level
in the mineral mix.
Ten pounds of trace mineral salt per ton of mixed feed will provide
an adequate amount of trace minerals.
Vitamins. Developing cattle need vitamins. Beef cattle
are not normally supplemented with B vitamins since they are synthesized
in the digestive tract. The fat-soluble vitamins (A, D, E, and
K) are usually adequate in all green forages. The only vitamin
which may be limited in dry forages is vitamin A. Dry forages
and feeds which include brofler litter are low in vitamin A. Even
though vitamin A is stored in the liver for long periods of time,
liver stores should not be relied upon for vitamin A supplementation
during periods when cattle are on dry forages. The vitamin A requirement
for growing and breeding bulls is 2000 lUs per pound of feed.
Since vitamin A is relatively inexpensive, cattle on dry forages
can be supplemented with 2000 lUs of vitamin A per pound of diet
or 4 million IUs per ton of feed.
Water. Water should never be a limiting nutrient for bulls.
Clean, fresh water should be provided at all times.
Starting Calves on Mixed Feeds
The most stressful time in a bull's life is at weaning and
during the following 3 to 4 weeks. Weaning stress can aggravate
existing nutritional deficiencies. Many weaned calves do not know
how to eat mixed feeds and must be taught to eat a mixed ration
gradually. Starting calves gradually on mixed feeds will help
them maintain weight at weaning and diminish the likelihood of
their getting sick.
Hay is the first feed of choice when calves are weaned. High quality
legume or grass hay should be fed to the calves. Good hay should
be about 9 percent protein, 50 percent TDN, relatively low in
acid detergent fiber, and mold free. Hay alone does not provide
the energy and protein necessary to maintain adequate growth in
bulls. Bulls must be supplemented with grain (energy) and a natural
protein source such as cottonseed, cottonseed meal, or soybean
meal.
Because weaned cattle eat sporadically, bloat, acidosis, and sudden
death can occur when cattle are fed a mixed ration if proper precautions
are not taken. Never provide weaned cattle a high energy mixed
feed free choice. Start with a small amount of feed and gradually
increase the amount fed.
The following are steps for getting bulls on feed:
- Creep feed calves the last 2 months prior to weaning. Calves which have been creep fed are easier to get on feed after weaning because they already know how to eat from a feed bunk.
- Get bulls on limited feed as quickly and safely as possible. Wean calves into an area where they can be observed closely for at least 4 weeks. Check at least twice a day to see if they are consuming their feed. Failure to come up for feed is often an early sign of sickness.
- Have circular weaning pens if possible. After weaning, calves will walk the fence. Place feed bunks and water troughs perpendicular to the fence to entice cattle to eat because they are forced to walk around the water troughs and feed bunks.
- Place hay in the feed bunks rather than free choice in hay rings. This will encourage calves to eat out of feed bunks. Do not place round bales of hay in the center of the weaning pen.
- Provide Bovatec or Rumensin in the feed following manufacturer's recommended amount per head per day. Bovatec or Rumensin will help to control feedlot bloat.
- Vitamins are inexpensive. Formulate mixed feed to supply vitamin A (at 2000 IUs), D (at 125 milligrams), and E (at 20 milligrams) per pound of feed.
- Formulate feed to contain at least 20 percent fiber, 12 percent protein, and 62 to 69 percent TDN. Fiber can be provided by hay or cottonseed hulls. Peanut hull pellets are not a good source of fiber for young cattle. The protein source should be all natural protein such as cottonseed meal or soybean meal and should contain no non-protein nitrogen, such as urea.
- Calcium, phosphorus, salt, and trace minerals can be provided free choice or mixed into the ration. If minerals are to be fed in the mixed ration, the ration should contain a minimum of 0.45 percent calcium, 0.35 percent phosphorus, 0.35 percent trace mineral salt, and 1.0 percent potassium.
- To start calves eating feed, sprinkle a mixed feed over hay in feed bunks. This will entice calves to consume some grain to get hay. Start feeding a mixed feed 2 to 3 days after weaning at the rate of 2 pounds per animal.
- Increase mixed feed 0.75 pound per day. Calves should consume about 1.5 pounds of feed per 100 pounds of body weight in 10 to 12 days.
- Keep only fresh feed available. Do not feed more than calves will clean up. Reduce the amount of hay as the mixed feed is increased.
Pre-Weaning Health Program for Bull Development
Bulls which are to remain on the farm for a postweaning performance
test should undergo a pre-weaning health program (See Table
5). Weaned calves remaining on-farm are at risk for several
types of disease, the most common being respiratory disease, or
"shipping fever pneumonia." A pre-weaning health program
will insure that these potentially valuable animals are prepared
for the stress of weaning and that their subsequent performance
during the test is not affected by health problems.
The health program for a bull calf includes vaccinations and dewormings.
Never implant a bull calf to be used for breeding. Implants can
cause serious infertility problems and will not significantly
increase the bull calf's gain performance while on test.
In all cases, consult with your herd veterinarian to construct
a program which best fits your herd. Everyherd is different. Some
herds and some locations may require additional health management
procedures. Your veterinarian can also recommend particular products
to use.
Performance Guidelines
All performance recommendations found within this section are based on Beef Improvement Federation (BIF) guidelines.
Contemporary Groups
Performance measurements and procedures are dependent upon
the correct formation of contemporary groups. A contemporary group
is defined as a group of animals that is from the same herd, sex,
and birth season and that is similarly managed. Contemporary groups
account for management and environmental differences among groups
of animals. This allows for determination of genetic differences
among individuals once contemporary groups are properly formed.
The producer is the only one who knows the proper designation
of contemporary groups.
Contemporary groups are largest at birth and generally become
smaller at weaning and yearling ages due to death loss and sale
of cattle. Most beef breed associations use 3-month intervals
to define initial birth contemporary groups within herds and sexes.
These are December to February, March to May, June to August,
and September to November. These definitions encourage distinct
calving seasons.
For cattle to remain in one contemporary group at weaning, cattle
must be 160 to 250 days of age and must be measured on the same
day. Similarly at yearling, cattle must be 330 to 430 days of
age and must be measured on the same day so that contemporary
groups will not be split. No other cattle can be added to weaning
or yearling contemporary groups because prior management and environmental
differences cannot be properly accounted for and, thus, genetic
differences will be incorrectly estimated. However, initial birth
contemporary groups can be split at weaning and/or yearling when
inferior bull calves are removed from the herd or are castrated.
Steer calves are not considered to be the same sex as bull calves.
Weaning Measurements
Two primary measurements that should be taken at weaning are
weaning weight and height. An additional measurement of scrotal
circumference can also be beneficial. Cattle need to be measured
between 160 and 250 days of age to adjust measurements to 205
days.
Weaning Weight. Once weaning weight measurements are submitted
to the appropriate beef breed association, adjusted weaning weights
can be calculated. Weaning weight records are adjusted for age
of calf and age of dam. The adjusted weaning weight formula most
breed associations use is:
| Adjusted Weaning Weight | = |
WW - BW |
X 205 + BW + Age of dam adjustment |
|
Age of Calf |
where WW is weaning weight and BW is birth weight. Age of dam adjustment factors are breed dependent. However, magnitude of age of dam adjustment factors are dependent on cow age, sex of calf, and whether the calf received creep feed.
Weaning Height. Figure 1 depicts the correct measurement of hip height, which can be converted into a frame score. Hip height or frame score can be used as an indication of mature size. Measurement needs to be at a point directly over the hooks. To adjust weaning heights for age and sex of calf and age of dam, follow these steps:
| 1. | Determine the number of days above or below 205 the bull is in age. | |
| 2. | Multiply the answer in step 1 by 0.033 inches (which is the height growth an average bull will undergo each day). | |
| 3. | Find adjusted 205-day hip height by taking the actual hip height and adding or subtracting the adjustment found in step 2. | |
| 4. | Adjust the answer in step 3 for age of dam using the adjustment factors found in Table 6. Multiply the answer in step 3 by the adjustment factor in the table. |
 |
Figure 1. Height measurement |
Example:
Bull calf born January 1, 1994. Weaned July 31, 1994.
Dam is 4 years old. Height is 45 inches.
1. 205 days - 211 days = -6 days
2. -6 days x 0.033 inches = -0. 198 inches
3. 45 inches + (-0. 198 inches) = 44.802 inches
4. Adjusted weaning hip height = 44.802 inches X 1.01 = 45.25002
inches
To convert the adjusted weaning hip height into a frame score,
use Table 7. Find the age in months
in the first column and follow the row across until you find the
approximate height. The number above that column is the frame
score.
To find an exact frame score, use the following formula:
Frame Score = -11.548 + (0.4878 X height) - (0.0289 X days of
age) + (0.00001947 X days of age squared) + (0.0000334 X height
X days of age)
This formula can be used only for cattle less than 742 days of
age (approximately 24 months). Frame scores will be incorrect
after 742 days of age. Using figures from the above example, the
exact frame score would be 5.49.
Scrotal Circumference. Scrotal circumference measurements are taken with a scrotal circumference tape at the widest point of the scrotum with both testicles descended. Pull testicles firmly into the lower portion of the scrotum by encircling the top of the scrotum with thumb and fingers and pulling down on the testicles. Put the scrotal tape around the widest portion of the testicles. Make sure fingers are on the side of the scrotum, rather than between testicles. The tape must be adjusted so it fits snugly when taking the measurement. Measurements are taken in centimeters (cm). Bulls with abnormally small scrotal circumferences at weaning (less than 20 cm), should be eliminated as herd bull prospects. Bulls with testicular abnormalities, such as having only one testicle, testicles not descended into the scrotum, or abnormally small testicles, should also be eliminated as herd sire prospects. Bulls with small scrotal circumferences will reach sexual maturity at a later age and pass this trait on to both male and female progeny.
Post-Weaning Test Procedures
In the Southeast, two types of post-weaning tests are used
to develop bulls: full feed tests and forage tests. However, the
best program for bull development usually combines the two. By
combining full feed tests and forage tests, producers can take
advantage of forages when available and supplemental feed when
forages are in short supply or are of low quality. Usually, bulls
which are sold as yearlings need to be grain fed from weaning
to sale, and bulls which are sold as 18-month bulls or older can
be developed using a combination feeding program of complete feed
and forages. All bulls should be fed to gain at least 2.25 pounds
per day.
No matter which format is chosen to test bulls on farm, the following
procedures should be strictly adhered to:
- All bulls should be 180 to 270 days of age when the test is begun.
- Bulls on test should not exceed a 90-day spread in age.
- Initial and final test weights can either be full or shrunk weights. If full weights are taken, weights should be taken on 2 consecutive days and averaged. If shrunk weights are taken, food and water should be removed 12 hours prior to weighing.
- Nutritional programs need to provide adequate protein and energy requirements to express genetic differences among bulls.
- All bulls sold should be structurally sound and pass a complete Breed Soundness Exam (BSE). The BSE should be performed by a qualified veterinarian or reproductive physiologist.
Full Feed Tests. Full feed tests allow bulls to eat
ad libitum amounts of feed that are 62 to 69 percent of TDN for
a minimum of 112 days. These types of tests allow for maximum
gains. Table 8 is an example of the
ration fed at the Auburn University Bull Test facility.
In addition to the above recommendations, the following guidelines
should be followed during the full feed test:
- Bulls should have a 21-day warm-up period prior to beginning the test. This will allow bulls to become accustomed to feed and water and to eliminate compensatory gain. Compensatory gain occurs in animals whose nutritional level is not adequate prior to test. These animals are able to gain at a more rapid rate compared to bulls that received a normal or high level of nutrition prior to test.
- Never let bulls run out of feed since this can cause severe digestive problems.
- Monitor bull feed intake closely and increase the amount of mixed feed fed when needed.
- Do not put more feed than the bulls will consume in 1 day into open feed bunks. This wastes feed and will lead to feed spoilage.
- Maintain the maximum recommended level of energy of 69 percent TDN for growing bulls. This level of energy is adequate for evaluating genetic differences among bulls. Greater levels of gain bring higher risk levels of acidosis founder and bloat.
- Supply hay in limited quantities to bulls. Approximately 2 pounds per head per day is adequate. Hay is needed to keep the rumen properly functioning. However, limit hay intake during the 112-day test period to make sure bulls are eating as much mixed feed as possible and maximizing gains.
- At the end of the test period, decrease the amount of grain in the feed over a 3- to 4-week period until the ration contains about 60 percent TDN. As the amount of grain is decreased, increase the amount of forage or hay supplied to the bulls.
- After completion of the 112-day test period, bulls should undergo a 4- to 6-week period of reduced concentrate intake and increased exercise prior to herd exposure. This will increase reproductive and performance efficiency in the field.
- Bulls should have yearling measurements (weight, height, and scrotal circumference) taken when bulls are between 330 and 430 days of age.
Forage Tests. Forage tests allow bulls to be developed
at a moderate rate with a moderate level of nutrition. These tests
do not put nutritional stresses on the bull as full feed tests
do. The length of a forage test is at least 168 days to compensate
for the moderate level of nutrition and to ensure that genetic
differences between bulls are expressed. However, forage tests
can be shortened in years when weather conditions are extreme
or when both forage and supplemental feed are unavailable or are
cost prohibitive.
Success of developing bulls on a forage test takes careful planning
and good management throughout the period bulls are on test. The
same rules for getting bulls on feed apply to bulls going on a
forage test. In addition to general guidelines, these guidelines
should be followed during a forage test:
- The warm-up period is optional.
- Forage test feasibility is dependent on year-round high quality forage availability.
- The season when bulls are born will affect farm forage testing programs. In Alabama, a good forage program will use winter annuals such as oats, rye, ryegrass, and wheat with clover mixes to extend grazing late into spring. Summer forages should consist of permanent pastures and millet. No high quality forages are available for fall grazing; thus, fall testing should be avoided unless supplemented with a high quality mixed feed.
- Supplemental mixed feed and hay should also be available for periods of forage shortages as well as extended periods of cold weather or drought. Periods of forage shortages should be anticipated so producers can incorporate feed at 1 percent of the calf's body weight prior to the shortage period. Feed can be increased by about 0.5 pound per day until bulls are on full feed. Feed should contain about the same levels of protein and energy as the forage.
- Sudden or rapid changes in the bulls' diet will decrease performance and could upset their digestive tracts.
- Bulls should have yearling measurements (weight, height, and scrotal circumference) taken between 330 and 430 days of age.
Test Measurements. Average daily gain (ADG) and ADG ratios can be calculated for either full feed or forage tests. ADG should be calculated at the end of the test period. Intermediate ADG measurements can be calculated at regular intervals throughout either the full feed or forage test. To find ADG:
| ADG | = | Final weight - Initial weight |
|
Length of test period |
To calculate an ADG ratio within a contemporary group:
| ADG Ratio | = |
Bull's ADG |
X 100 |
|
Average ADG for |
The average ratio within a contemporary group for ADG is always 100. A ratio of 100 indicates the bull was average for that contemporary group. A ratio above 100 indicates performance above average in the contemporary group. A ratio below 100 indicates below average performance. Thus, an ADG ratio of 112 indicates that the bull was 12 percent above average for ADG, compared to other bulls in his contemporary group. Ratios are only valid within a contemporary group and cannot be compared across groups.
Yearling Measurements
Like weaning measurements, yearling measurements include weight,
height, and scrotal circumference. Cattle must be 330 to 430 days
of age and must be measured on the same day so that contemporary
groups will not be split.
After yearling measurements are taken, they should be submitted
to the appropriate beef breed association before the announced
cutoff date for submission of data to be included in the next
analysis. EPDs which incorporate the individual's own record can
then be estimated for yearling traits.
Yearling Weight. Yearling measurements for weight should
also be adjusted for age of calf and age of dam. Age of dam is
still included in these measurements because yearling weight is
a function of weaning weight. Adjusted yearling weight is calculated
as:
| Adjusted Yearling Weight | = |
YW - Adjusted WW |
X 160 + Adjusted WW |
|
Age of bull at yearling |
where YW is yearling weight and WW is weaning weight.
Yearling Height. Adjusted yearling hip height is calculated similarly to adjusted weaning hip heights. No age of dam adjustments are made to this measurement. Maternal influences are negligible at this point for hip height. To calculate adjusted yearling hip height:
- 1. Determine the number of days above or below 365 the bull
is in age.
2. Multiply the answer in step 1 by 0.033 inches.
3. Adjust the actual hip height by the answer found in step 2.
The adjusted yearling hip height can be converted to a frame
score using Table 7. To calculate an exact frame score, use the
frame score formula discussed previously in the section on weaning
height.
Scrotal Circumference. The suggested minimum scrotal circumference
at yearling is 32 cm. If scrotal circumference is below 32 cm
at yearling, the bull should not be retained as a herd bull prospect.
Bulls with a 32 cm or larger scrotal circumference are sexually
mature. Research has shown that yearling bulls with larger scrotal
circumferences sire progeny reaching puberty at earlier ages.
Early puberty can have many benefits in the cowherd.
Summary
There are many advantages to growing and developing herd bull
prospects on-farm rather than consigning them to a central test
station. However, proper nutrition and health programs are essential
to successfully raising bulls on-farm. Testing and developing
bulls puts tremendous stress on their digestive tracts. Improper
nutrition or health practices can reduce a bull's productive and
reproductive life significantly.
To accurately detect genetic differences between yearling bulls,
contemporary groups need to be tested and developed together.
Information should be submitted to the appropriate beef breed
association for yearling weight EPD estimates to include individual
performance. Selecting young bulls on EPDs is a much better indicator
of what the animal will do as a sire than any other available
information, such as weights or ratios.
For more information, contact your county Extension office. Look in your telephone directory under your county's name to find the number.
For more information, contact your county Extension office. Visit http://www.aces.edu/counties or look in your telephone directory under your county's name to find contact information.
Published by the Alabama Cooperative Extension System (Alabama A&M University and Auburn University), an equal opportunity educator and employer.
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