As producers’ cow herds enter the last third of gestation, it is important not to get lax on management. This is because what is done now will have a direct impact on a successful calving season that produces healthy calves.
First and foremost, it is important to keep the herd on an optimum ration. The goal should be to maintain cows and heifers at a body condition score (BCS) of 5. Making money in the commercial cow-calf business means controlling costs, so it generally doesn’t make economic sense to run cows above 5. Conversely, if they are maintained at a significantly lower BCS than 5, productivity may suffer.
Keeping cows in good condition will result in vigorous calves, enhanced calf passive immunity, and faster rebreeding. A mistake to be avoided is trying to control birth weight through the nutrition of the dam. Birth weight will not start to be lowered until the dams are in a BCS of 4- or below.
However, if cows are kept this thin, their calves will have lower metabolism and depressed vigor, which will result in more calves lost. Also, cows with lower body condition will experience delayed rebreeding and you will have more open cows in the fall.
On the other hand, birth weight will not be significantly increased if cows are kept above BCS 5. The only time calving ease will be significantly impacted because of overfeeding is due to excessive fat deposits in the pelvic canal.
Although the calf size is not significantly bigger, if the hole it must pass through to be born is smaller due to fat, the overall result of this will be more pulled calves. For this to be a problem, generally the cow herd and heifers are above BCS 6. Keeping cows this fat means money has been needlessly spent to put condition on females above what is considered optimum.
Most producers who have been in business for some time have developed over the years a tried-and-true low-cost ration generally built around feed available from their ranch along with possibly using low-cost byproducts or crop residues.
However, it is important to remember that the quality of the feed will vary from year to year, and in a particularly bad year, some sort of low-cost supplement can be considered.
Stress and nutrition
It is during the last third of gestation when most fetal growth occurs, which should result in cows gaining weight. This means a ration that meets base nutritional needs is important, and it is also important to manage cattle in a way to minimize stress. Cattle stressed from heat, cold, parasites, or health problems will all need more nutrition to be productive. Therefore, what may seem like an adequate ration will fall short on stressed cattle.
Cold stress can be a real problem during parts of the winter. In general, cows will adapt their metabolism to be comfortable in whatever environment they are being managed if they have adequate nutrition.
However, cold stress can occur during unusual cold snaps, or when the cattle’s coats are compromised during periods like freezing rain. Cattle’s consumption will naturally increase during these times, and it is important to give them extra feed when cold stress is anticipated.
Other enemies of cattle getting the most out of their rations are things like wind chill, mud, and parasites. Cattle are much more likely to become cold stressed from wind chill than they are from ambient temperature. Cattle should have the ability to get out of the wind using natural windbreaks if possible. Man-made wind breaks can also be a good use of resources especially in high use areas.
Like wind, managing mud is also a concern. Frozen ground is the best tool to keep cattle out of the mud, but there should be plans for getting cattle out of the mud during thaws. This can involve natural high ground, high use pads, bedding, and/or moving feeding locations daily. Some mud problems are inherent in running cows, but it should be managed in a way as to not result in the hair coat developing caked-on mud.
Parasites are also a producers’ cow herds’ enemy that needs to be controlled. Lice can be one of the more obvious problems. They not only feed from the host, but they also cause hair to fall out in patches, which can result in an increased possibility for cold stress.
Calving management
It is also a good time to start feeding cattle at the end of the day to maximize the number of calves born during daylight. This is both easier on man and beast, especially for those who start calving early. Producers who calve early in the season must be able to get a cow and calf in quickly during unfavorable weather. However, by far the easiest calving system is to time it with the grass, but this doesn’t work for many who also farm.
Proper management of the cow herd this time of year will also maximize the initial immunity of the calves. In species like humans, newborns already have some immunity from the trans-placental transfer of antibodies from the mother to the fetus. This doesn’t occur in cattle, so all their initial immunity must come entirely from nursing the dam’s colostrum. When first born, calves can absorb large molecules like antibodies, but this ability steadily shuts down over the first 24 hours.
The value of the colostrum in terms of quality and quantity is dependent on the parity of the dam, herd nutrition, and vaccination program. For example, underfed cows will have lower colostrum yield along with producing calves that do not get up and nurse as aggressively. The combination results in lower calf passive immunity. The vaccination program of the cows will also directly impact the scope and density of antibodies in a dam’s colostrum.
With last year’s calves already marketed and before this year’s calving season starts, it is generally the slowest time of the year for commercial cow-calf producers. Although it is the “off season,” decisions and practices implemented now will directly impact a producer’s success in the spring. Cows kept in adequate condition with a good health and vaccination program will result in a higher percent calf crop weaned, and cows that will rebreed faster. — Dr. Bob Hough, WLJ correspondent
