Check out the first two parts in this series focused on measuring performance in a cow-calf operation. 

Cow Herd Report Card I: Pounds of calf weaned per cow exposed

Cow Herd Report Card II: Post-partum interval & calving rates

Calving distribution and pounds of calf produced per acre are measures of performance and efficiency of the cow-calf enterprise. Calving distribution will impact total pounds of calf weaned. Calves born the first 21 days of the calving season will be heavier at weaning compared to calves born the second or third 21 days of the calving season. Without selecting to increase weaning weight, increasing the number of calves born the first 21 days of the calving season positively impacts total pounds of weaned calf and, subsequently, pounds of weaned calf harvested per acre.

Calving Distribution

Calving distribution is defined as the number of calves born in 21-day intervals (21, 42, and 63 and those born after day 63) of the calving season divided by the total number of calves born and to make the number a percentage multiply by 100. Based on guidelines established for Standardized Performance Analysis (SPA), the first 21-day calving period can begin in one of two ways:

1. 285 days following the bull turn-in date on mature cows.
2. When the 3^rd mature (3-yr old and older) cow calves.

Be consistent when calculating calving distribution. If you use method #1 described above, continue to use method #1 each year. If you use method #2 described above, continue to use method #2. Method #1 and #2 will give you slightly different results. Most producers and cow/calf record-keeping software use method #1. The 285 days is the average gestation for beef cows. We know there are breed differences regarding the length of gestation.

Research has shown that cows calving in the first 21 days are more likely to stay in the herd. Increased herd longevity can reduce the number of replacement females needed annually. Cows that continually calve the first 21 days of the calving season, have more days to get ready reproductively and become pregnant early in the breeding season, and wean older, heavier calves.

When evaluating subsequent heifer calf performance, heifers born in the first 21 days of the calving season and retained as replacements have several advantages compared to replacement heifers born later. Not only were they heavier at weaning, but they were also more  likely to be cycling at the beginning of their first breeding season, more likely to get pregnant, and more likely to calve in the  first 21-days of their initial calving season.

If more cows are calving later in the calving season, re-evaluate management practices, including nutrition and herd health. Calving distribution using Cow Herd Appraisal Performance Software (CHAPS, North Dakota State University) data, reported 63% of calves were born in the first 21 days of the calving season, 87% of the herd had calved by the end of the second 21-day period, and 96% by the third 21-day period. Strive to calve 65% or more of the cow herd in the first 21 days of the calving period and 100% of the herd calved by the end of the third 21 days of the calving period.

Pounds of Calf Weaned Per Acre

Pounds of calf weaned per acre is the total pounds of calves weaned divided by the total acres used to feed the cow herd, both grazed and harvested. We previously discussed how to calculate pounds of calf weaned per cow exposed (https://beef.unl.edu/beefwatch/2023/cow-herd-report-card-ii-measures-performance), but from a whole ranch perspective, pounds of weaning weight per acre may be a better measure of how productively land resources are being used. Land is the primary input in a cow-calf operation and is used for grazing and forages harvested for hay.

When supplemental feeding and grazing is simultaneous, pounds of calf produced per acre may be misleading unless acreage used is adjusted for the portion of cow nutrient requirements being met via supplemental feeding. Supplementing mature cows, especially in the fall and winter, is usually minimal with a protein supplement fed at 2-4 lb/hd/day. This is a small enough amount of supplemental feed and no need to account for this in the calculation. Minerals and vitamins are supplemented in the oz/hd/da and do not need to be included either. Note that forage production and cow weight determine how many cows the land base will support. Research suggests on the same acres, lighter mature weight cows tend to wean more pounds per acre than heavier cows.

Determining total acres may be difficult initially, but the process should be consistent across years. This calculation is most valuable as a within-operation metric to evaluate production over time and/or to assess year-to-year variability in land productivity.

To summarize, we will use an example herd of 400 cows. This operation requires 8 acres per cow or cow-calf pair during the growing season. They also graze an additional month on dormant winter range that is part of growing season grazing. They graze 700 acres of corn stalks (200 bu/acre corn yield) for three months. Cows are fed harvested forages for 500 tons for two months. Those forages are harvested from 200 acres. Calf weaning weights averaged 550 lbs and 88% of the cows exposed weaned a calf.

Let’s first determine the total pounds of calf weaned.

Then let’s determine the total acres used.

400 head cow herd

8 acres per cow-calf pair = 3,200 acres of owned and rented pasture

6-month spring/summer/fall grazing period

1 month of winter grazing of dormant native range (a part of the 3,200 acres)

3 month of grazing corn stalk = 700 acres at 200 bu/acre corn yield

2 months feeding harvested forages = 200 acres at 2.5 ton per acre = 500 tons of harvested forages

193,600 pounds of calf weaning weight (88% weaned of exposed and 550 lb average weaning weight-steers and heifers)

Pounds of calf produced per acre = 193,600 pounds / (3,200 acres + 700 acres + 200 acres) = 47 pounds per acre.