There was a time when most commercial cow-calf operations started the calving season in the beginning of February and had it was wrapped up by the end of March. Cows were released onto pasture when the weather got warmer; the cows milked and their calves grew. Cows were rebred before the heat of the summer, and their heavy calves were weaned in the fall. Old and open cows were culled, and young animals not kept back as replacements or growers were sold into October markets. It was a predictable way of life.
Today, the dynamics of the cow-calf year is anything, but predictable.
The high cost and often low availability of winter feed and volatile fall markets of the past decade have forced many producers to re-evaluate calving traditions, starting with choosing a different time to calve out their cows. Subsequently, there is a growing practice amongst western Canadian producers to shift their calving season from late winter to “spring calving” to take advantages of some better opportunities.
It’s no secret that a target date of April 15 as to when your first cow drops her calf takes advantage of warmer weather.
Sub-arctic weather of January into March can easily reverse good body condition of the main herd when it calves out at this time of year. Extremely low temperatures and brutal windchills increase dietary energy requirement by as much as 40 percent, over and above its recent doubling due to the demands of lactation.
The fact that many over-wintering diets may not satisfy both of these major demands at the same time, forces many cows to mobilize some of their own internal fat reserves for metabolizable energy. Problems arise in extreme situations, when so much excessive weight is burned off that several cows are susceptible to certain health problems (re: ketosis, liver dysfunction) and a thin body condition, which may also make it harder to get them rebred, later on in the year. Ironically, it’s better weather conditions in the spring that allow producers with a small window of opportunity to put back some necessary body condition on more promising cows that calved out in a thin body condition during the winter.
Keep in mind that early spring weather is much warmer than those winter days, but not always conducive to good spring calving conditions at all times. Unexpected spring snowstorms, and cold rains chill newborn calves, which are particularly vulnerable to catching pneumonia. Similarly, frequent muddy conditions and thawed manure piles provide a catalyst for contagious intestinal scours that could lead to high calf mortality. Fortunately, the majority of spring calves should remain healthy, if their mothers are able to escape any poor spring weather, by going into a suitable shelter such as a poll barn with lots of clean dry bedding.
Aside from the savings on frozen ears, tails, and producer fingers, the best advocate for early spring calving is a significant saving in over-winter feed costs.
A lactating beef cow during the first 60 days after calving requires about 58 to 60 perent TDN and 10 to 11percent protein in order to produce about seven to10 litres of milk for her new calf and maintain an optimum body condition of 2.5 for the upcoming breeding season. Most post-partum winter diets are usually built on a foundation of good quality forages such as mixed alfalfa-grass hay and supplemented with cereal grains, such as up to two kilograms of barley. Fortunately, there is nothing nutritionally special about these drylot diets that cannot be easily be substituted by green pasture grasses.
Consider potential money savings for a 350-beef cow operation by replacing all the drylot forages and one-half of the supplemented barley grain in a drylot lactation ration with one month of grazed May pasture. One may assume these present fields contain enough forage volume (dry matter basis) to support our herd’s general feed intake and contain early vegetative growth of substantial energy and protein value (note: some barley might still be fed on pasture to assure all energy needs are met). The calculations for potential savings are as follows:
Total feed intake of 15 kg = 600 kg x 2.5 percent of body weight
15 kg = 14 kg of mixed hay @ $90/mt + 1 kg of barley @ $150/mt
One month over-winter feed cost = $1.26 + $0.15 or $ 1.41 x 30 days
Total monthly feed cost savings (350 cows) = $14,805.00
It is highly recommended that anyone who considers a two-to three-month delay in their traditional calving season because of winter feed savings should be aware of the inherent risks associated with spring calving. One adverse consequence of moving your calving season toward spring is that 80 days later your breeding season falls upon the hottest parts of July and August.
Heat stress of both cows and breeding bulls is one of the major reasons behind an extended breeding season (and thus creates extended calving season for the following year) of greater than the most desired and profitable 70 days.
Research has clearly shown that heat-stressed cows are more likely to remain open, because they are less likely to ovulate, have irregular estrus cycles, may have poor conception rates, and suffer from a high rate of early embryonic deaths. Similarly, these “dog days” of summer can literary sterilize otherwise fertile bulls for the next couple of months. Luckily, most episodes of heat-stress amongst the beef herds in western Canada tend to last for only a few weeks during a typical prairie summer and can be largely regional in scope, thereby giving many spring calving cows a good chance for a successful breeding season.
Regardless of how favorable the weather turns out in the spring or summer for spring calving and the subsequent breeding seasons, the ultimate litmus test of whether traditional or spring calving works for any operation is based upon the total incoming revenue generated from the amount of saleable pounds of weaned calves sold in the fall and following months.
On average, weaned calves from a spring calving operation weigh about 100 lbs less than their winter-born counterparts at any one time, and have a direct effect on revenue if both sets of calves are sold at the same time. This means that the total amount of saleable pounds of weaned spring calves is always less than the same number of winter calves. Secondly, a 400-lb spring calf must be valued $1.25 @ lb to generate the same monies as a 500-lb winter calf valued at $1.00 @ lb. If buyers value 400-lb calves at a price of less than $1.25 @ lb, the incoming revenue of the heavier winter calves sold at $1 @ lb will always be greater.
In this way, a great number of light spring calves and heavier winter calves may be sold in the same traditional fall markets, however there are many retained light animals from both seasons that are overwintered and marketed at a much later date. Casein-point; backgrounding calves by putting on a few hundred pounds of weight and selling them during the following months of the new year has become a popular choice amongst people with the drylot facilities.
It is taken for granted that many traditional cowherds have successfully opted for spring calving in order to take advantage of the warmer weather and potential overwinter feed savings. Many of these advocates investigate and pursue the best opportunities for raising and selling their weaned calves in available markets, regardless as to when they were born.
Peter Vitti is an independent livestock nutritionist and consultant based in Winnipeg. To reach him call 204-254-7497 or by email at [email protected]