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Bull Raising



Bulls take stronger facilities to raise and hold, which is why we do not commercially feed out bulls for slaughter in this country.  If one has less than 20 head of cattle it is more cost effective to use artificial insemination (AI) than keeping a bull around.  Bulls can be dangerous, and should never be trusted, especially dairy bulls.  If you are taking a bull to the veterinarian, bringing along a second herd mate will greatly reduce the stress in working and handling him.  One bull alone may become very wild at time, yet if there are 1-3 others with him he is easier to work.  You need well-built facilities to house and work a bull.  If a bull gets out because of poor fencing, then it is the bull owner’s responsibility to pay for any damages, dystocia, etc if the bull is found within another herd.  The open range livestock laws are not protection if any animal gets out because of a poor fence and cause misbreedings and/or an auto accident.

            Too fat of a bull will result in excess testicular fat.  Excess fat in the testicles and scrotum can cause infertility if the bull becomes too hot.  .  The average yearling bull should weigh 1100# before he is used for breeding; this weight can vary with each species.  The bull test sales rely also on average daily gain (ADG) where gain is a desired trait.  These bull tests us a rate of gain on feeding concentrates and that on pasture has probably a close correlation.  Some of the bull test sales in the future may go to a pasture test, which is what the yearling offspring will be raised on.   A body temperature of 104 degrees may produce a sterile bull for up to 2 months.  Thus if a bull has an infection within a couple of months of the breeding season, a collection of the sperm before he is turned in with the cows is indicated.  The testicles should be at 96 degrees; a process the bull‘s body regulates itself.  If a bull was sick a few months before the breeding season and he had a body temperature over 106+ degrees he may be temporarily sterile for 2-3 months!  For a similar reason we do not recommend using MLV vaccines in bulls within a few months of breeding and/or some long acting pyrethroids fly control products and pour-on and/or premise spray (i.e. bifenthrin) within a month of breeding.

            When raising bulls the yearlings should be kept separate from the older bulls, to allow for proper growth and feeding.  A diet high in fiber and low in concentrates is the best for a growing bull.  We recommend feeding a growing bull 1.5% of his body weight a day in alfalfa hay for a 1.5-2# per day gain.  Other feeds such as silage, supplements, grains and other concentrates can also be fed to a bull to achieve the 1.5-2% ratio of body weight diet fed daily.  The ration should be 12%+ CP and 65+% TDN.  All bulls should be given a magnet after 4-6 months of age, and a ring placed in their nose as soon as possible.  Dehorning should be performed on all breeds, expect those breeds which desire horns.  We prefer you notify sellers if the bull being sold is polled, which should be a premium for the breeds that need dehorning.  Vaccines are inexpensive and thus we recommend the routine IBR/BVD/PI3/BRSV/Lepto 5, the 7-way Clostridial, Haemophilus, and maybe even Moraxella bovis (Pinkeye), anthrax, tetanus, Trichomoniasis, rabies and/or Campylobacter (Vibrio).  Some vaccines are not indicated in some areas and/or some breeds.  We recommend that the first BVD vaccine be a killed vaccine, then there be two other such vaccines which are modified live vaccines with the BVD vaccine be cytopathic to prevent persistently-infected testicles; the vaccine we recommend has both type 1 and type 2 BVD plus the cytopathic and non-cytopathic strains.  We recommend the ear notch test for PI-BVD for all breeding animals, especially those being sold.  Young bulls should not be allowed to become overweight, or this may increase the fat in their testicles.   At the start of the breeding season a bull should be at a body score of around 2.5-3 (of 5, or at 6 of a 9 scale system). 

            The ratio of a bull to cows is typically 1:25.  A new 2-year-old bull should start with preferably 10-15 cows, with 20x being maximum if he is with other bulls.  ( A very high fertility bull can be placed with 40-60 cows, and expect this bull to loose 15% of his weight).  For the average bull a ration of 1 bull to 25 cows is recommended; missing a few breedings can be costly.  A clean-up bull can be place with 60 cows.  We recommend placing the cows and heifers with a bull for 45-60 days.  A rotation of the bulls may be needed in some situations, and especially if the bull is a 2 year old.

            If possible, young bulls should be allowed 2 acres per bull, to allow for proper exercise before the breeding season.  If the herd has only one group of bulls, it is best to house them together 1-2 months before turning them out.  The bulls will need to form a social hierarchy first.  If there are enough bulls, keep the young bulls in one pasture and the mature bulls in another.  Turn out the mature bulls first for 1/3 of the breeding season, then only the young bulls, then again the mature bulls for the last 1/3 of the season.  A 15 month old bull can cover 10-12 cows, at 18 months he can cover 12-18 cows, 24 months he can cover 18-25 cows, and after 2+ years of age a bull to cow ratio should be approximately 1:35 maximum, and maybe less if only one bull.  Some bulls are better than others are (libido).    

            Studies have shown that a cow will breed back sooner if their calf is a steer instead of a bull.  Although this is true, consider that this delayed timing is only a 6-7 day advantage.  This one-week period is not a major concern to castrate all bulls less than 4 months of age if they are on the range.  It is better to castrate the bull calves early than to have dystocia problems in the yearling heifers they could breed.

            When purchasing or selling a bull, expect a bull test to be performed.  In our state any bull sold over 18 months old and/or is not a virgin bull must be tested for Tritrichomoniasis; a 12+ month old bull has to also be tested if he was with the herd recently/within 4-6 months ago and may not be a virgin.  If you loan out or rent a bull, yearly trichomoniasis testing should be done.  Any livestock species sold in Colorado will need a bill of sale and a brand inspection.   All premises where livestock are kept are to be registered with the USDA;   Since 2012 the use of brands and tattoos for official identification is no longer recognized for official identification such as a health certificate, some blood tests, etc.  When we work cattle we attempt to place one of the veterinary USDA tags in all animals, or you can obtain the USDA RFID microchip ear tag yourself; we recommend the large flap tag so you can use it as a farm tag.  A blood test for Brucellosis and tuberculosis is also routinely performed.  We also recommend you consider bovine leukemia, Johne’s, a fecal float test for internal parasites, a fecal Bauerman test for lungworms if a high cost bulls (and those you purchase yourself).  There is also a fertility-associated antigen test (FAA) which tells you if the bull has a higher percentage of sperm able to easily penetrate the cow’s egg.  Although the FAA bulls may settle 15% more cows, there are many other factors to consider with purchasing a bull, such as the expected progeny difference (EPD), stocking rates, etc.


The Staff at the Nelson Road Veterinary Clinic