The best way to ensure a successful breeding season is to design a late-gestational nutrition program for cows and heifers. Getting heifers and cows ready for calving and subsequent breeding seasons is not about weight, but rather body condition score (BCS).
First, it is essential to manage cows and heifers as independent groups. That does not mean you have to keep two completely separate groups of cattle, but rather that you evaluate each group separately, target different body condition scores and provide different levels of nutrition depending on gain needs.
During late gestation, in order to maintain BCS, a mature cow requires at least 8% protein in the total diet. A heifer entering her first calving season needs 10% protein. If an animal needs to pick up condition, the requirements increase by 0.5% to 1%.
Payment in pounds per calf. Research from the University of Nebraska indicates nutritional management during the last 100 days of gestation can have significant effects on the fetus. Increasing a cow’s total daily crude protein intake from 7% to 8% increased calf weaning weight by 10 lb., which translates into $12 to $15 per calf in today’s market. Protein nutrition is integral to colostrum quality in cows. As a result, 10% fewer bull calves born to protein-supplemented cows became sick after birth. Steer calves from protein-supplemented cows netted an additional $30 at slaughter.
Heifer calves born to protein-supplemented cows had a 13% greater pregnancy rate than heifers born to nonsupplemented cows. It is clear that protein nutrition during late gestation is important to fetal development as well as to the cow’s rebreeding potential.
After calving, during lactation prior to breeding, protein needs vary according to milking ability and weather. Generally, cows require 9% to 9.5% crude protein and first-calf heifers require 11% crude protein to maintain a BCS of 5 or greater.
While genetics play a significant role, target a BCS of 5.5 for mature cows and 6 for first-calf heifers to help ensure they are in adequate condition for the next breeding season. In order to maintain a 365-day calving interval, cows and heifers should be at a BCS of at least 5.
Cows calving at a BCS of 5 to 6 will resume cycling 55 days post-calving. However, cows with a BCS of 4 or less will require as many as 80 days to resume cycling. In the calendar year, with a 280- to 285-day gestational period, there are 80 to 85 days remaining for a cow to resume cycling and rebreed.
Choose carefully. The biggest challenge—and opportunity —of feeding cows is the variety of forage sources and choosing the correct one at the lowest cost.
Low-cost forage sources such as cornstalks, bean stubble and low-quality hay are all adequate sources of nutrients, with some supplementation. Alfalfa hay or corn silage, while excellent feedstuffs, are not essential for cows to produce a calf.
Supplemental sources, such as corn gluten feed, distillers’ grains or wheat midds, provide economical flexibility in designing cow diets. Corn, however, is not an adequate cow supplement as it provides only 8% crude protein.
The most beneficial strategy is to supplement fiber-based diets with fiber-based energy and protein sources, such as corn gluten feed, distillers’ grains and wheat midds.
- Mid-February 2011