Should I Calve on Grass or Hay?

— Written By and last updated by Patricia Burch

I have been asked by several producers if they should pull their cows and heifers off pasture and feed them hay for the last thirty to sixty days of gestation to avoid calving trouble. The main reason producers want to pull the cows is to limit the size of the calf. This is possible but will not be very effective the last 30 to 60 days of gestation. The fetus does most of its growing during months 6, 7, and 8 of gestation so little is achieved by pulling the cows at such a late date. Many factors influence the amount of difficulty at calving time, including breed, sex of calf, and the age and size of the cow/heifer, and nutritional status does play a big part. However, it is more likely to be from cows that are too fat or too thin than from large calves.

Cows should be a minimum body condition score of 5 at calving time. Heifers should be a condition score of 6. Neither should be over a 7. This will insure adequate flesh to help meet the increased physiological demands on the cow as well as enable the animal to breed back in a timely manner. Cattle that are over-conditioned (fat) will be subject to calving difficulty. On the other extreme are cows that are too thin at calving. Some producers feel by having their cow thin at calving they are eliminating the possibility of calving trouble. This is not true and, in fact, may add to the difficulty. Thin cattle tire easily and may not have the strength to deliver a calf. Also, thin cattle produce poor quality colostrum, breed back slower, and usually don’t produce as much milk as cows that are in proper condition. Additionally, these females that are allowed to get thin before calving will become bigger problems later. It is extremely difficult to put weight on a lactating animal. Without proper nutrition between weaning and her next calf she will likely be thin when she calves again, assuming she bred back, and thus perpetuate the cycle. All this ties into the calving on grass or hay.

When cows are pulled off the grass and fed hay, they will lose weight if their nutritional needs aren’t met. A heifer in the last trimester of pregnancy with an expected mature weight of 1200 pounds needs feed that is approximately 60% TDN and 10% crude protein. A mature cow would need approximately 50% TDN and 8% crude protein. Good quality hay will meet the demands of the cow but some supplementation is needed for the heifer. If medium to poor quality hay were fed neither animal’s requirements would be met without supplementation. This supplementation can be in the form of a commercial feed, corn, soybean meal, cottonseed, or any number of other commodities. The key here is to offer the proper type and amount of supplement to balance the hay ration. In order to do this, producers should have their hay and supplements analyzed by the N.C. Department of Agriculture and Consumer Services. This service costs $10 per sample but is worth much more. By knowing the analysis of the feedstuff offered, producers can be sure cattle requirements are met. While on the subject of supplementation, producers could even supplement with the forage that is available. Simply allow cattle access to the forage for a few hours each day. The cattle can consume adequate forage to meet their needs without having a surplus of nutrients. The hay then acts more like a filler to satisfy their appetite.

The grasses that seem to concern producers the most are rye and ryegrass. Those who calve in the fall should not be too concerned. At this time, there will be limited amounts of the forage available, so there won’t be adequate time for trouble to arise. Some may question the time cattle are grazing millet in late summer. By fall, the millet has probably become stemmy and less productive and will be of lower quality. Producers who calve in winter have little need for concern either. The cows may have an initial flush of forage in late fall but forage availability will be declining going into the winter months. Cattle will be on hay anyway and the forage will act more as a supplement than an actual forage source. Producers who practice spring calving may have some need for concern. The flush of new growth available along with the “maintenance” feeding of the cattle through the winter can lead to weight gains in the cattle and growth of the fetus. Producers who utilize the exotic breeds, especially those known for their growth, have experienced more trouble. The later in the spring animals calve, the greater the chance of possible problems.

Some experts say brood cows should never be allowed access to high-quality winter forages. They suggest the grass is too good for them and is being wasted when fed to cows. Instead, they recommend feeding the cows hay or lower quality forages, supplementing to meet requirements, leaving the high-quality forages for creep grazing nursing calves and for grazing weaned calves and yearling cattle that can benefit most from these forages. Another school of thought is to let the calves and yearling have first access to the forage and then allow the cows to finish what the younger cattle did not consume. Whether or not either of these systems is feasible will depend on the producer’s production practices and available resources.