Many beef producers I’ve talked to over the years have improved cow nutrition after their cows are confirmed pregnant, but there still are the diehards that don’t believe they need much nutrition.
That’s too bad, because sound research has proven that poor nutrition during the early/mid-gestation months can sharply reduce newborn calf survival and long-term performance. That’s why I advocate that a well-balanced nutritional feeding program is warranted while bred cows are still on pasture in the late summer and until the first snow. It simply rewards us with good calf performance in the foreseeable future.
Here is some proof: University of Wyoming researchers demonstrated that low-level nutrition in pastures grazed by mid-gestation cows was responsible for a significant decrease in organ and muscle fibre development in their developing fetuses, which led to lower weights when these steers were finally weaned, many months later.
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Other trials showed similar dire consequences in replacement heifers when their dams were restricted to 70 per cent of adequate nutrition during day 45 to day 185 of gestation. Unlike the steer trial, birth weights and weaning weights were similar to experimental controls, but heifers born to those nutrient-restricted cows had smaller ovaries and tissue luteal weights, which both are responsible for good post-pubertal reproduction.
These studies demonstrate that most of these problems would not be likely if the body condition of early/mid-gestation cows is maintained. For example, a properly fed cow during autumn and going into winter with an optimum body condition score of five to six (one = emaciated to nine = obese) has a great chance of maintaining health and a trouble-free pregnancy. This compares to a thinner cow with a BCS 4.0 or lower, which most likely has a difficult time surviving winter; often ending in a difficult calving season and producing poor calves.
Fortunately, early- to mid-gestation mature cows make the best candidates to either maintain or build optimum BCS. Their nutrient requirements are comparably low to other times of the year; because they are carrying a small fetus (as mentioned above), produce continuously less milk toward weaning time, and cold weather is non-existent. Therefore, these cows in order to support their own vital functions and an early-term fetus; require 52-55 per cent TDN (dietary energy), nine to 10 per cent crude protein, 0.40 per cent calcium, 0.25 per cent phosphorus, 0.20 per cent magnesium and salt, essential trace minerals and vitamins.
Consider protein supplement
During the autumn, most of these dietary requirements are often supported by decent pastures or even dried-out fields/stubble-grazing, complemented with some form of supplementation. For example, I make it a point to choose the type of molasses lick-tub to complement the quality of the pasture that the cattle are grazing. For example, a 20-30 per cent protein blocks should be placed on dried-out pasture with grass protein probably no more than five to six per cent. At the other end of the spectrum, I would place six per cent protein blocks on lush pastures, which might be a mixture of high-protein legumes (alfalfa or clover) or even medium-protein native grass.
Regardless of pasture quantity and quality, most fall pastures are usually deficient in one or more mineral and vitamins. They might contain antagonist elements that bind existing nutrients in this feeding program or upon ingestion by beef cows. For example, a test of many western pastures contains grasses with a high molybdenum content, which has been proven to contribute to many copper deficiencies in cattle.
That is why I recommend producers feed a high-quality cattle mineral that not only contain high levels of complementary calcium, phosphorus, and magnesium to lush or dried-out pastures, but also contain optimum trace minerals such as copper in their more “bio-available” forms (better known as “chelates”) as well as high levels of vitamins A, D and E.
For example, I met a beef producer that puts 200 confirmed-pregnant cows (after weaning calves) on pastures with lots of green fall regrowth. He feeds a high-copper and zinc mineral in order to strengthen their hooves (helps prevent foot rot), when introduced to such wet and lush grass.
His story is a testament to setting up an adequate fall-feeding program. This producer knows any dietary nutrient deficiency or shortage in the early/mid-gestation cow herd can jeopardize their future as well as their calves’, once they are born. He sees no point in restricting their autumn nutrition to save a few dollars now, but rob himself later on.
