On Feed - March 22, 2018
– By #Roxanne Knock, PhD
Focus on Bulls
Right now is the heart of bull sale season. If you want your latest purchase to have maximum impact on your herd, then there are steps you can
take to make sure that is possible. Not providing your bull with the nutrition he needs devalues the investment you made.
In a Nutshell:
- A Breeding Soundness Exam for bulls is worth the time
- Protein should be approximately 13% for yearling bulls
- Fat supplements improve feed efficiency but do not improve fertility
- Bulls should be in a BCS 5 or 6 for maximum fertility
- Availa-4 trace minerals improve semen quality
- Watch the quality of feed going to the bulls
A Breeding Soundness Exam (BSE) on the bulls prior to breeding is worth your time. A BSE will include physical examination of the bull, examination of the
reproductive tract of the bull, measurement of scrotal circumference, and semen collection and evaluation. Bulls that fail to pass a BSE are sub-fertile and will likely have an impact on the percentage of open cows that you get at pregnancy testing. Factors like body condition, previous nutrition, weather stress, disease status, and libido impact fertility. Bulls that fail a semen test may breed some cows, but chances of him settling cows is simply not as high as those that pass.
Remember that yearling bulls are still growing. They will continue to grow and develop even after they are delivered. How will you make sure that you can keep him on a solid plane of nutrition? Just like feeding your calves for backgrounding, we need to know the nutrients available in your feed base and then fill any gaps. Protein and energy are critical for bulls to continue to develop and put on muscle mass. If you short the bulls on protein, you could end up with bulls lacking the muscle development they will need to get across the cows during breeding season. Protein of 13% in the ration for yearling bulls should be adequate to meet their needs for growth. Mature bulls require roughly 10%.
Questions sometimes come up regarding fat supplements and fat sources for bulls and what impact they have on fertility. The data would say that there is essentially no effect on semen quality parameters with varying fat supplementation. Research from Kansas State indicated that supplementing with flax did not improve any measure of fertility. Additional fat typically improves feed conversion and gains. So, if you have some bulls in poor condition, increasing energy density of the ration would likely be helpful.
There is a balance to strike when it comes to energy because too much energy means the bulls start accumulating fat in the scrotum, compromising semen quality. Bulls that lack adequate body condition can also have reduced semen quality. Dropping a substantial amount of weight in the 60 days prior to breeding also has a significant
negative impact on breeding soundness exam scores (Magee, 2005). Another study found that bulls with poorer body condition scores had reduced semen quality, as did bulls that were overconditioned (Barth and Waldner, 2002). Bulls in a BCS of 5 and 6 tend to have the best chance of passing breeding soundness exams. The energy level we need in the ration is going to be dependent upon the age and current condition of the bulls. For your mature bulls, it may not take much to get them into shape. Some coming 2-year-old bulls that got used heavily as yearlings and then spent some time on stalks may need a little more energy and grain. Your feeding program also depends on when you plan to turn the bulls out and how much time you have to get them in shape. No matter what the case is, we can help you figure out a ration to help get the bulls in breeding condition.
Trace minerals like zinc and copper are also important to fertility. Because zinc is necessary for any growth and new cell development, it has particular significance for bulls and reproduction. The Availa-4 trace mineral program has been shown to positively impact fertility when supplied to the bulls at least 60 days prior to evaluation (see chart at right). The Availa-4 trace mineral product includes zinc, copper, manganese, and cobalt. It also helps maintain better semen quality in the face of heat stress event. Keep in mind, a solid nutrition program needs to be in place at least 60 days prior to bull turnout to help optimize fertility. Zinc and copper are also important for hoof integrity and foot health which are another critical part of making sure the bulls can cover all of the cows.
If you have questionable feed in terms of mold, toxins or nitrates, or even poor quality, now is no longer the time to be feeding it to the bulls just because it isn’t good enough for anything else. Molds can be associated with increased toxin risks. And, zearalenone is a potential silage toxin that can have a very negative impact on semen quality and fertility.
The bitter cold many of us faced earlier this winter could also have had a lasting negative impact on the fertility of your bull battery. Frost bite and scabs on the scrotums of your mature bulls and young bulls may have caused permanent damage. Bedding the bulls can help provide the protection your bulls need to ensure fertility.
Even though Mother Nature seems to be bipolar lately, spring will be here soon. With its’ arrival, we need to watch our bull nutrition program and make sure we take care of our investment in genetics. The bulls you buy are going to be a significant part of your total calf crop next year. They are too large of an investment to kick in the back forty and forget about until you haul them to pasture. Stress Tubs, Ultimate Breeder minerals, and other Availa-4 products can help you take care of the mineral side of your bulls nutrition requirements. Talk with your local Dakotaland Feeds consultant if you need a ration to help get the bulls in the right condition for breeding. Protect your investment by feeding them right.
What do you need to be thinking about this time of year?
- Get prepared for calving- get chains, OB sleeves, lube, and calf puller in place and colostrum replacement on hand
- Make sure mineral is in place for pre- and post-calving cows to promote re-breeding
- Scrape pens when possible to help avoid foot problems
- Set up an implanting protocol for calves to finish
- Feed Rumensin to the cows to improve feed efficiency and to limit environmental coccidia prior to calving
- Remember to get MGA if you are planning to use a synchronization protocol for your heifers to calve early
- Consider getting BQA certified if you are selling fat cattle
- Talk with your veterinarian about newborn calf products
- Get the bulls in good body condition- they should be a BCS 5 or 6 at 60 d prior to breeding