By now many cow-calf herds are in the home stretch in the race towards the start of calving season. Our primary focus is doing everything that maximizes the number of live calves born and eventually weaned and marketed. We also need to keep in mind that to be successful we have to get these cows in a position to breed back in a timely manner. That’s where monitoring body condition now before calving comes in to play to make sure that our herd is on the right track.
Ideally we want our cows to be in moderate condition at calving. That is often described as a Body Condition Score 5 on a 1 to 9 scale. Visually those cows will still have one or two ribs visible but not the outline of their spine (See Photo 1). If cows are thinner than this, they are much less likely to be cycling at the beginning of the breeding season. Feeding mature cows to a body condition score greater than a 5 offers very little additional improvement in reproductive success. An exception might be bred heifers where some additional body reserves increases the likelihood of those females getting pregnant for their second calf.
One of the reasons we want to be monitoring body condition now is that this period in late gestation is our last, best chance to influence the body condition or energy status of a beef cow. It is much more difficult and costly to increase her body condition after calving using harvested feedstuffs. Cows tend to use additional nutrients to produce more milk rather than increase their own body reserves. So if we try to increase nutrient intake after calving, in many cases we end up with cows that milk a lot more, but aren’t necessarily in any better condition.
In some situations cows can increase body condition while on excellent pasture during late spring and early summer, enough to overcome being in marginal condition at calving. But getting that response assumes that we have enough soil moisture or rainfall to support a large amount of early season grass production, which certainly isn’t guaranteed. This strategy also doesn’t work well in early-spring or late-winter calving herds, because those cows aren’t on that high quality pasture long enough before breeding to gain back enough weight.
We can still get some additional weight on cows ahead of calving, even in the last two months or so, but probably not on hay alone. Some higher energy feedstuffs, whether it’s silages, grain or by-product feeds are going to be needed to increase the energy density of the ration enough to improve body condition scores ahead of calving season. If you’re considering sorting off some thin cows and feeding them at a higher level, make sure you introduce diet changes gradually. Sudden increases in higher energy feeds, especially starch based diets, can cause digestive upset and acidosis.