Cow nutrition: From calving to breeding
April 26, 2014
Many producers are now in full swing of calving season in the Northern Plains. This comes after a long, cold winter. Although most areas haven't had a lot of snow since the disastrous October blizzard, it still has been colder than average for a long time. Overall, it feels like we are in a pattern like a year ago with a high likelihood it could stay cool into spring and we could have a late green-up. If this happens, managing cow nutritional status from now until adequate green grass will become very important to ensuring that cows will be cycling and fertile when the breeding season starts.
It all comes down to managing the body condition score (BCS) of your cows. There is strong evidence that cows with a moderate BCS of 5 (on a scale of 1 to 9) will be more likely to restart estrous cycles before breeding and more likely to get pregnant than cows in thinner BCS (less than 5). The energy needed to maintain body temperature during this cold winter may have lowered BCS more than desired this year. Most beef cow nutritionists will recommend that a producer should score body condition on their cows at calving. I suggest taking this very literal. If a producer is tagging and weighing calves as they are born, take a look at the cow and write down her BCS along with the calf data. As calving season progresses, keep track of the running average of the BCS of the cows. If the running average is 5 or 6, the cows are in great shape and it will be a simple matter of feeding them adequate nutrition to maintain BCS. If the running average is less than 5, then the feeding program should be changed to give them the opportunity to gain BCS before breeding begins.
A second important aspect of managing cow BCS between calving and breeding is whether it is increasing or decreasing over time. If the running average is decreasing as time goes on, the cows are in a negative energy balance and pulling fat off their bodies (losing BCS). For example, lets say the running average after the first week of calving is 5.2, but at the end of the second week it is a 5.1, and by the end of the third week it is 4.9. In this example, there is evidence that BCS is slipping. An average BCS of 4.9 seems close enough to 5 to consider the herd to be at the status you want, but the problem is that it needs to remain there until breeding and the fact the running average is declining suggests that it will not. Therefore, this is another indicator that your feeding program should be adjusted to provide the nutrients to gain body weight and therefore body condition.
Now if we consider the previous concern that we may be looking at another cold spring with a late green-up, it may be an unwise choice to keep feeding them the same under the assumption that they will pick up weight and condition when grass greens up. That may come too late to get them ready for breeding. Thus, if the average BCS is less than 5 or is moving lower as calving proceeds, it would be wise to consider improving the nutritional value of the diet for cows to ensure that they will be ready for breeding season regardless of what the spring weather turns out to be.
Another caveat to consider is that first-calf heifers are the group that is most likely to lose BCS after calving. They are young and still growing while lactating for the first time. This creates greater nutritional challenges for them than mature cows and makes them more likely to fail to have adequate nutritional status to be reproductively sound when breeding begins. I recommend that it is even more important to keep records of BCS status over time on them and make appropriate adjustments. Keeping them separate from the mature cows is an important step in this process. They cannot compete at the feed bunk with larger, older cows and will get cheated out of their share of feed and supplements. Additionally, keeping them separate will allow the opportunity to adjust their diet if needed and not have to provide additional but unneeded feed to the mature cows.
There are an abundance of feedstuffs that could be used if needed to improve nutrient intake. These include distiller's grains, wheat midds, and a large variety of other byproducts and commodities. Good to high quality hay can also be used as a supplement to improve nutrition. Fortunately, the prices on almost all of these feedstuffs have dropped dramatically since last year. Wise shopping can lead to improved nutrition at the best possible price. Nutritionists can play a critical role in determining which feedstuff provides the needed nutrients at the best price. Don't be afraid to contact your Extension Service or another source of livestock nutritionists for assistance in this effort.
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Ken Olson is an Extension Beef Specialist for SDSU.