During normal weather patterns, supplementation during late spring and summer is relatively simple. Grass should be lush and green, and at the very most all cattle need is a mineral supplement. Most producers simply buy a commercial product, but the best plan is to have your grass analyzed. In that way you can have a custom product made up to contain exactly what you do or do not need (in some cases you may not need anything at all).

But during drought, supplementation becomes more complicated. To begin with, we must not confuse supplementation with feeding. If we are trying to make up for a lack of grass, that is not supplementation; that is feeding. Feeding is expensive and among cow-calf ranches is the primary cause of bankruptcy. (Feeding is another subject beyond the scope of this article, but if interested E-mail me for a copy of this month's client newsletter on feeding during drought.)

Supplementation is defined as providing only what is not contained in the forage. That is, the cattle must have all the grass they can eat. This is the age-old axiom that grass is your cheapest source of feed, and therefore it is only to be supplemented (not replaced). The minute we begin feeding (replacing grass we don't have), we enter into a practice that is grossly inefficient. The reason is that cows are animals of low productivity. Feedlots barely break even by feeding cattle 4 to 5 months to produce 400 to 500 lbs. of gain. With a cow we feed all year to likewise produce 400 to 500 lbs. of calf. The only way we can make that work is to have extremely cheap feed (range grass). When we start purchasing feed to make up for grass we don't have - we enter into an enormously unprofitable business.

With respect to supplementation, during drought the grass will often be dry and mature (vernalized) and thus will require more than just an ordinary mineral mix. It will need more mineral than usual as vernalized grass is usually much lower in phosphorous and trace minerals. But another item lacking will be nitrogen (protein). Normally native grasses are more than adequate for protein during spring and summer, but during drought that may not be the case. If in doubt, you can have the grass analyzed. However, as a general rule if it is yellow or brown rather than green, nitrogen (protein) supplementation will be required.

While mineral and protein supplementation will be required for all cattle, heifers will require energy as well. Indeed, if the grass is totally dormant, during breeding the cow herd will also require supplemental energy.

It is important to realize that, energy is what controls estrus. By it-self, of course, protein can increase energy intake by increasing consumption of mature, dormant grass. In most cases, if adequate protein is provided, a dry cow can be brought to conceive on dormant grass. But that is not true of a lactating cow or a growing heifer.

The reason is what is known as priority for nutrients. If a cow is nursing a calf, Mother Nature is saying, "Take care of the calf on the ground, and if there's enough (nutrition) left over, then we'll see about making another one." In other words, all nutrient requirements must be met for lactation, before a cow will ovulate. In most cases the digestibility of dormant grass is not enough to meet the requirements of a lactating cow, even with adequate protein supplementation. Additional energy is required.

This is especially true for first calf heifers. In this case not only are they lactating, but they're still growing. Growth, like lactation is a nutrient priority that takes precedence over ovulation. Until enough nutrients are provided to meet the growth requirement, the heifer will not ovulate.

Where this is most evident is in South America. While drought is a recurring anomaly in North America, in most of South America drought occurs every year; i.e. drought is part of their normal seasons. Instead of spring, summer, fall and winter; they have a dry season and a wet season. The dry season is when breeding takes place, and because most South American ranchers do not supplement; breed-back on first-calf heifers is about 10 percent! (Tropical grass is much coarser than native temperate grasses, but failure to supplement first-calf heifers on dormant temperate grass will result in breed-backs of about 30-45 percent.)

Replacement heifers will likewise require energy supplementation, as they too (obviously) are still growing. Provided they have attained enough weight to cycle (650-720 lbs.), failure to supplement will not result in as severe a reduction in conception as first calf heifers (since they don't have the added burden of lactation), but it will still be substantial.

In the western U.S., extension services report that, during drought years, ranches that do not supplement wean calf crops of between 50 and 60 percent. Keep in mind this is no supplement at all (other than mineral). Protein supplementation would probably buy another 10-15 percent. But if anywhere near normal calf-crops are to be expected . . . energy, in addition to protein and mineral will be required. ©