If you talk to any number of cattle producers about their calving season you may receive any number of answers. The reasoning is likewise quite varied and diverse and, unfortunately, is based on things like, “that's how we've always done it,” or “well, that's just how it worked out.” We live in a day and time when producers can no longer rely on history or chance to dictate management conditions. If they do they will ultimately end up in a deep hole or out of business. Let's take a look at some of the factors which have an effect on the decision of when to calve your herd as well as issues that come into play. The season and month of the year to begin the calving season should include economic, management, nutritional and health considerations, all of which are part of well designed cow-calf operation.
Time of Year
In general, we commonly find three calving scenarios used by cattle producers: spring calving, fall calving and year-round calving. Within the spring and fall calving programs there are also differences between early season versus late season. As related to these scenarios, there are three very primary economic considerations which need to be accounted for when making this decision:
a) Differences in value of weaned calves
b) Differences in annual cow costs
c) Differences in facilities cost.
To begin, let's look at the value of weaned calves. On the average, moving from an early spring calving season to a late calving season will decrease the pounds of live calf for sale or pounds produced per exposed cow. Within a 90 day calving season the difference in calf size, if all calves are weaned on a common date can be 100 lb. or more with the difference can be due entirely to age and the time the younger calves have simply been alive and allowed to grow and gain weight. However, the weight per day of age may be improved on later born calves. This is due to lowered maintenance requirements by the cow AND the calf associated with the better weather. The younger calves will not have to endure as long a period of inclement weather which takes a toll on production. A note to make is that the effect of lower weaning weights is not as great of a factor unless calves are marketed at weaning time or on the same subsequent date. Another factor that affects the significance of this weight difference is the prices typically brought by lighter calves (normally higher) when compared to heavier (normally lower). If you look at current markets for Oklahoma City we find that 400 lb. average steers are bringing $1.10/lb (animal value = $440), while 500 lb. average steers are bringing $1.00/lb (animal value = $500). This results in a difference in value of $60 per head. So you can see, this age difference may or may not be a huge factor. In this particular case it is. This pricing is affected by time of the year and the demand for certain types or weight classes of cattle. Subsequently, backgrounding calves or finishing calves that are born later are not generally affected by calving date, unless the seasonality of the markets influences their value. Finished cattle pricing tends to have a greater affect on weaned cattle than vice versa.
For the differences that exist in annual cow cost, feed accounts for 65-70 percent of total annual production costs. Of this, forages are usually the most expensive component of this feed cost. Therefore an increase in the amount of harvested forage fed will increase costs (i.e. more hay or silage that must be fed). That being the case, if calving during the time of year when harvested forages must be used to meet nutrient requirements, these production costs increase which then reduce your profit level.
One Nebraska study indicated summer-calving cows were fed more than 3,000 lb. less hay per cow per year than cows that calved in the spring, though protein supplement costs were similar. Cow feed costs should be no more than 40 percent of the total revenue per cow for long-term profitability. In other words, if total revenue per cow is $500, total feed costs, including pasture, should be no more than $200.
By calving earlier in the year, a greater investment in shelter and weather protection will be required, especially in some parts of the country in order to protect newborn calves, postpartum cows and late gestational cows from the elements and increase calve health and survivability. This is obviously more of a factor in northern states than in the southern regions. Some Ag economists state that facilities cost per cow per year should be around $10 per head.
One management consideration is that early calving allows for labor usage to be entirely focused on the calving process. This means being able to devote more attention to one primary task can be productive. It also makes sense if hired labor is being used because it provides more work at times of the year when there are not as many other tasks at hand.
Monitoring the calving process can be too great of a task on some operations if the producer and his labor force are in the middle of planting or harvesting and if the incidence of calving difficulty and/or health problems is great. An example of this might be fall calving of a group of heifers at the same time you are planting winter pasture.
Another management consideration is having adequate early growth pastures to satisfy the nutrient needs of spring calving cows. This might also be related to the time of year discussion above. In a Finnish study, researchers found that dairy cows that calve after April 29 had the shortest postpartum interval. This was related to nutrient, particularly energy, availability at the appropriate time. In addition, a negative energy balance (resulting in ketosis, a symptom of excessive, rapid weight loss, especially in dairy cows) was an important factor in increasing the calving to conception time. This study indicated that cows that were losing weight at a rate of one percent per week had a conception rate of 16 percent, while cows on a feeding program adequate in energy had a 90 percent conception rate. The workers found that the primary reasons for this effect are the daylight hours and temperatures are increasing during this time of year and nutrition as supplied by emerging spring forages. This same rational can be applied to early spring calving cows as compared to late spring calving beef cows and therefore should be considered. This tells us that the early spring calving females will require greater degrees of supplementation to insure adequate energy levels are available.
During later spring calendar dates, the nutritional content of grass is increasing, as well as the volume of grass, which better meets the needs of the cow at this time versus early calving, when basically no grazing takes place, grass nutrition is poor and harvested forages and supplements must be fed to meet the cow's needs. All factors which considerably increase the cost of feeding the cow. Finally, a study done with beef cows had similar results with cows that calved the earliest having the longest calving interval.
One advantage for calving in late spring or fall is decreased contamination and buildup of infectious agents that contribute to disease in the newborn calf. The reduced chance of bad weather in the late spring and fall enables producers to let cows roam to find comfortable surroundings for calving instead of the grouping that is normal during prolonged adverse weather conditions and the subsequent build-up of old hay and manure in these areas. When allowed to find their own calving areas, cows will likely be a significant distance from other cows and calves. This helps reduce the chances of spreading pathogens than if space is restricted.
Calves born in late spring or fall are also likely to be less stressed due to weather conditions, primarily cold stress and exposure to excessive moisture AND cold temperatures. Under wet, muddy and cold conditions, research has shown that a calf's energy requirements are greater and that the ability of the calf to absorb colostral immunoglobulins is reduced. These antibodies normally received from colostrum are vital to the development of a functional immune system in the new calf. Other stress factors such as heat stress also have an effect on calf performance. Calves born late in the spring and early in the summer, especially in the south are very susceptible to heat stress. The body of the young calf is not capable of effectively dissipating heat. Additionally, these young animals are also very susceptible to dehydration.
Time related factors have also been identified as being associated with an increased rate of scours. These factors include but are not limited to: heifers calving, wet conditions in the calving area, limited shelter and wintering cows and heifers on the same grounds where calving occurs.
A North Dakota study showed that calves born to heifers in herds that calve out heifers before cows were 1.6 times more likely to develop scours. The same research showed, that calves born before March 10 were 3.8 times more likely to develop scours than those starting after March 10.
The same study showed that the odds of the development scours problem in a herd increased three times in herds not fed some alfalfa hay. Researchers find that the reason for this is not clear, but may relate to adequate protein intake in late gestating cows. In other words, herds with lactating cows with an inadequate protein intake appear to have a greater chance of suffering from a calf scouring problem.
Finally, a study done in Sweden indicated that calves born between May and September had higher concentrations of gammaglobulins, a component of a functional immune system than calves born from October to April. Once again, it is unclear as to why this occurs, but it may be related to colder weather and a subsequent negative effect on absorption of the appropriate compounds. As becomes obvious there are numerous components of this system that are not very clearly understood although we know they have an effect on calf health.
As you can see, there are many considerations which must be made when selecting when to calve out a herd of cows. Each factor needs to be weighed carefully and an evaluation done of your resources to make a decision appropriate to your facility and operation.
Dr. Steve Blezinger is and nutrition and management consultant with an office in Sulphur Springs, TX. He can be reached at 667 CR 4711 Sulphur Springs, TX 75482, by phone at (903) 885-7992 or by e-mail at firstname.lastname@example.org.