by: Stephen B. Blezinger
Ph.D., PAS

One thing that most cow/calf producers can attest to is that in order to be profitable you have to get cows bred and get them bred efficiently. On a typical cow/calf operation everything revolves around this central event because if breeding does not take place, nothing else will either. A good percentage of breeders do a reasonable job getting cows bred in a timely fashion. Unfortunately, however many do not. Good breeding is a factor of genetics, health, nutrition and management. Many producers will try to prioritize these four factors with the thought that, “if I do a good job on health, the others will fall into line.” Each of these are of equal importance because if one component is lacking the whole program will suffer as will performance.

Start at the Beginning

As mentioned, your program needs to be based on sound genetics, health, nutrition and management and your program must be complete in each of these areas. This requires several things. Select cows and bulls that are of genetic stock where reproductive performance has been prioritized. Work with your veterinarian to develop a complete health program that will have a focus on reducing or eliminating reproductive diseases that are common to your area. This will mean a regularly and properly scheduled and implemented vaccination program. It also means closely observing cattle to watch for illness, injuries or other irregularities that must be treated in a timely fashion to prevent more extensive or longer term problems that can effect reproduction.

With all stages of beef production nutrition is critical. ALL nutrients must be balanced, in the correct volumes and in proper proportion to one another. Even one nutrient that is deficient can act as a performance limiter. As we have discussed in the past, systemic performance in cattle is prioritized, meaning the less essential systems will be shut down first when nutrients are in short supply or provided inadequately. Reproduction is generally the first system to shut down since it is not required for survival. Work with a qualified nutritionist to help you streamline this program and insure you are covering all the nutritional bases. Finally, overall management oversees all these components and also brings in other tools such as fertility testing of bulls, heat synchronization (HS), artificial insemination (AI), embryo transfer (ET) and so on.

Under normal operating conditions, if all of a breeding operation's bases are covered it is not uncommon to get breeding efficiencies in the upper 80's to lower 90 percentages. This means that in a given production cycle this is the percentage of cows that will breed or conceive and produce a weaned calf. The remaining percentage does not breed or at least does not breed within the desired time frame. This does not allow for cows that lose a calf during pregnancy (abortions), lose the calf during parturition (dystocia) or lose the calf between calving and weaning for any of a number of reasons. We are talking about cows or heifers that simply fail to breed or fail to breed in a timely fashion.

Putting it into Perspective

Let's say a producer has 100 cows and his conception to weaning efficiency is 85 percent. That means that he has 15 cows that did not produce a calf during a normal production year. For arguments sake we'll say these cows simply did not produce at all. This means that the rest of the herd has to cover their annual expenses. Typical annual carrying expense (this number is highly variable) is about $425 per head per year. This means that the other 85 have to absorb the cost of the 15 that did not produce. In this case this number is $6,375 which means production costs for the 85 that did produce went up $75 per head, a 17.64 percent increase in your production cost. Additionally, since the producer did not have these 15 calves to wean, he also lost these revenues. If the average weaning weight is 500 lbs, on today's markets (average price about $1.90/lb.) his lost revenue per head is $950 or a total of $14,250. Between the added cost and lost revenues, this producer, with an 85 percent calf crop is losing $20,625. Compare this to other performance levels in Table 1 below:

As you can see the losses are reduced dramatically when reproductive efficiency improves. But you can also see in today's economy and production costs along with current cattle markets, even the better performance levels leave a lot of money on the table.

Other Techniques to Improve Reproduction

While many techniques are available that can manipulate reproduction (heat synchronization, A. I., ET) many (not all) of the opportunities to improve reproduction are nutritionally related. Let's take a look at some of these:

1) Ionophore Feeding. Feeding Ionophores such as Rumensin™ Bovatec™ and Cattlyst™ through a feed or mineral supplement has been shown to improve reproductive performance. In a paper given at the Applied Reproductive Strategies in Beef Cattle Conference, it was reported that the use of ionophores have been shown to influence reproductive performance during the postpartum period. Remember that ionophores are feed additive that improve feed efficiency and gains (by changing rumen fermentation patterns), thus they allow for improved energy production and utilization by the animal from feeds and forages. Cows and heifers fed an ionophore exhibit shorter post-partum interval (PPI, shorter time between calving and rebreeding) provided adequate energy is supplied in the diet. This effect appears to be more evident in less intensely managed herds that generally have a moderate (60 to 85 days) or longer postpartum interval. This simply means that if you already have a reasonably short PPI (i.e. 30 to 60 days) you may not see as much of an effect. Researchers have also shown that heifers fed an ionophore reach puberty at an earlier age and a lighter weight.

2) Fat Supplementation. A great deal of work has been conducted over the last few years on the effects of feeding appropriate levels of fat to improve reproductive performance. It is well known that inadequate energy intake and poor body condition can and does negatively effect reproductive function. Supplementation of fats has been used to increase the energy density of the cows diet in general and avoid undesirable, negative associative effects that are sometimes seen when high grain supplements are used in conjunction with a forage or roughage based program.

Supplemental fats may also have positive effects not associated with energy contribution. Dietary fats have been shown to positively affect reproductive function at by roles played at the hypothalamus, pituitary, ovary and uterus, i.e. primary sights of hormone production. This appears to be related to the type of fatty acids making up the dietary fat (remember that overall dietary fats are made up of smaller units called fatty acids just as proteins are made up of smaller units called amino acids).

The use of supplemental fats has been investigated at a variety of production stages and a variety of responses have been noted. Consider the following:

a) Fat supplementation to replacement heifers – Studies in this area are somewhat limited. Fat supplementation appears to have a positive effect on breeding of heifers when they have been nutritionally challenged. Well developed heifers and those on a suitable plane of nutrition have shown limited responses to feeding of fats.

b) Fat supplementation pre-partum (prior to calving) – A study by Hess in 2003 summarized research on supplementing fat during late gestation and concluded that feeding fat to beef cows for about 60 days prior to calving resulted in a 6.4 percent improvement in pregnancy rate for the upcoming breeding season.

c) Fat supplementation post-partum (after calving) – Studies have shown an increase in reproductive response when feeding increased dietary fats to cows post-calving. One particular study conducted in South Texas showed an increase in breeding rates in thin cows (BCS ~ 3.5 to 4) when cows were supplemented with 3 to 4 lbs of whole cottonseed per head per day.

Fat supplementation, however, may not be the answer to cow/calf producers breeding woes. Some research has shown both increases and decreases in the production of PGF2a, an important reproductive hormone. In some situations where higher fat levels are fed for an extended period of time, PGF2a synthesis is increased and this may compromise early embryo survival. As with all production components, moderation and care in use are important.

3) Bull Management – managing bulls on many operations seems to be an afterthought. Many commercial producers seem to think that as long as they have some sort of bull in the pasture with their cows, they have it covered. Remember that your bull is ½ of each calf and that it takes a fully functional bull to get cows bred in an appropriate period of time. Additionally, since one bull can sire 10 to 40 calves this is with a limited breeding season. One bull can handle more if allowed access to the herd for longer periods of time. He has a profound effect on the breeding efficiency and, as importantly, profitability of the herd. For instance, if a commercial producer carefully selects a bull to enhance his calves weaning weights he might realize significant increases in these weights. In this situation, he might increase his weaning weights by 50 lbs per head. Using the $1.90 figure from above this means that each calf is worth $95 per head more than the previous year with a less productive bull. This means if he gets 40 head bred the additional revenues generated would equal $3,800. If this bull is carefully managed his productive life could be five to eight years. With an average productive life of 6.5 years this would meant that this bull could generate an additional $24,700 over his lifetime. Thus selection of genetically superior animals that may cost more ($3,000-$4,000 per head) makes economic sense.

As mentioned, bulls need to be cared for properly, paying attention to their health and nutrition. Body condition is as important in bulls as it is in cows and thus, bulls need to be properly conditioned (but not excessively fat) when they are put with the cows for the breeding season. Aggressive bulls will forgo eating in many cases to pursue breeding activities meaning that nutrient intake is down and that they will loose weight as the breeding season proceeds. They need to be in adequate condition going in so that they can breed as effectively toward the end of the season as they do at the beginning.

Bulls should be fertility tested by your veterinarian prior to the breeding season. There is nothing worse than placing an infertile bull with a group of cows only to wonder why, 2/3 of the way through the breeding season, all the cows in a given group still seem to be cycling. A simple trip to the vet can confirm that the bull(s) are sound. This is very cheap insurance.      


Breeding management is probably one of the cow/calf producer's most important jobs. Adhering to the basics and utilization of enhancement techniques can prove profitable to his operation. While it's seldom feasible or cost effective to have 100 percent breeding efficiency efficiencies in the 90 percent range are doable for many producers.

Dr. Steve Blezinger is a nutritional and management consultant with an office in Sulphur Springs, Texas. He can be reached on e-mail at or by phone at 903-885-7992 or by. For more information please visit Reveille Livestock Concepts on Facebook.

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