The western region of the Dakotas is a semi-arid region of the Northern Plains. Cow/calf operations are a very important

segment of the agricultural sector in this region. However, with the exception of recent historically high profits from cattle

marketing, profit margins in cow/calf production are slim due to high production costs (Taylor and Field, 1995). The majority

of costs in cow/calf businesses are for harvested feed (Taylor and Field, 1995). Systems that rely more on grazing and less

on harvested and purchased feedstuffs have a higher potential to be profitable (Adams, et al., 1994), but these systems can

be stressed during periods of low precipitation and drought. The development of systems that lower production costs while

adding value to calves would be beneficial to sustaining and improving rural communities in the drier regions of the western

U.S.

Early weaning is a herd management strategy that has drawn the interest of scientists investigating cow/calf production and

marketing issues. Research has shown calves weaned at 100 to 150 days of age were heavier and younger at slaughter than

normal weaned (weaned at 225-250 days) calves (Peterson, et al., 1987). Meyers, et al., (1999) reported that an early

weaning herd management strategy improved the percentage of steers grading average choice or higher and also improved

feed efficiency relative to a normal weaning strategy. These results reported by Meyers, et al., (1999) suggest early weaning

can improve profitability.

In this paper we present the research results for the first two years of an ongoing cow/calf herd management project being

conducted in the western Dakotas by North and South Dakota State Universities. We discuss the effect of early versus

normal weaning on a) steer calf feedlot performance (economic and physiological); and b) cow health and pasture utilization

rates. The research suggests that a herd management strategy of early weaning will enhance the economic sustainability of

cow/calf operations during periods of drought. Research protocols employed in this research were reviewed and approved by

the Institutional Animal Care and Use Committees in North Dakota and South Dakota.

Background1

Over a two-year period (2003-2004), cow herds from the South Dakota State University (SDSU) Antelope Range and

Livestock Research Station (136 cows) and the North Dakota State University (NDSU) Dickinson Research Extension

Center (176 cows) were used in the study. At each location, spring-born calves were weaned from cows at approximately

140 days (mid-August) or 215 days of age (early November). The steer calves from Antelope Station (Yr. 1) were transported

immediately after weaning to the NDSU Hettinger Research Extension Center for backgrounding. The project protocol

required early (EW) and normal (NW) weaned steers to undergo a backgrounding phase that lasted, on average, 52 days

after weaning. Normal weaned steers nursed, on average, 80 days longer than early weaned steers. The background diet for

both groups consisted of locally grown forage and a commercial co-product pellet. Two to four weeks prior to each weaning

date, calves were immunized against bacterial and viral diseases; they were administered a booster vaccination at

weaning. Following the backgrounding phase, Antelope and Dickinson steers were transported to Decatur County Feed

Yard, Oberlin, Kansas. The feedlot arrival weight and age for the early weaned steers was 578 lbs and 195 days old, as

compared to 748 lbs and 274 days for the normal weaned steers. The timing decision for marketing of finished cattle was

based on the electronic cattle management system employed at the Decatur County Feed Yard. Finished steers were

marketed using either a fat depth end point signal of 10 mm. or when the system indicated the animal reached its optimal

weight. Steers were slaughtered at a commercial plant and carcass data were collected.

The Effect of Early Weaning on Calf Performance

Early weaned steers arrived at the feedlot approximately 80 days younger and 170 pounds lighter than their normal weaned

lighter at slaughter (live wt.). These data agree with the findings of Peterson, et al., (1987) that reported early weaned steers

were younger at slaughter but does not agree that early weaned steers will be heavier at slaughter. Early weaned steers, on

average, gained more weight in the feedlot, but average daily gain was not affected by the treatment. Early weaning did

improve feeding efficiency by approximately 18.5 percent. This result agrees with the findings of Meyers, et al,. (1999) who

also reported an increase in feed efficiency. There is no statistical evidence that weaning treatment affected

carcass yield grade, fat depth, or dressing percentage. However, normal weaned dressed carcasses were, on average, 53

pounds heavier. This hot-carcass-weight differential explains a majority of the $55 dressed carcass revenue differential

advantage that normal weaned steers had relative to early weaned steers. On the issue of quality grade, normal weaned

steers had a slightly higher average quality grade. This result is in contrast to the findings of Meyers, et al, (1999). However,

the Meyers, et al., study reported data on early weaned steers that were heavier and much closer in age at slaughter to the

normal weaned group relative to the steers in our study. In comparison, our early weaned steers were 358 days old at

harvest as compared to 429 days in Year 1 and 440 days in Year 2 of the Meyers, et al., study. We believe age and weight

are the factors causing the contrast in quality grade results between the two studies. This issue is under investigation at this

time. On the issue of economic return, accounting profit was higher for normal weaned steers; however, these results were

not statistically significant. Increased feed efficiency does appear to have an effect on the cost side of the feedlot profit

equation. Early weaned steers, on average, only incurred an additional $10.68 per head in total feedlot cost relative to normal

weaned steers, and this differential was not statistically significant. This minimal cost differential occurred despite early

weaned steers spending an additional 31 days in the feedlot and incurring, on average, an additional $3.09 per head in

medical expenses while in the feedlot. The improvement in feed efficiency of early aweaned calves appears to have resulted

in a decline in the average cost per pound gained in the feedlot of approximately 19 percent, declining from $0.62 per pound

for normal weaned steers to $0.50 per pound for early weaned steers.

The analysis indicates that the benefits of early weaning are improved feedlot efficiency, a reduction in the lifecycle of the

calf, and a reduction in average cost of feedlot production. The disadvantage is directly related to the lower slaughter

weights, which translate into lower carcass revenue. Calf health also seems to be an important variable affected by

early weaning. Analysis revealed that when an animal is pulled for medical reasons, total cost increases by almost 10

percent. The analysis indicated that 71 percent of the early weaned steers had been pulled at least once for vet care, as

compared to only 44 percent of the normal weaned steers. This suggests feedlot entry age has an effect on the incidence of

feedlot disease events requiring intervention. Illness negatively affects feed efficiency and average daily gain as well as total

feedlot cost. Steers in this study were subjected to an aggressive animal health management program that included pre- and

postweaning vaccination and early disease detection in the feedlot. Aggressive early detection and treatment with long-

acting new generation antimicrobials reduced death loss among early weaned steers, but treatment cost directly related to

calf weaning age averaged $3.09 higher per head for early weaned steers. Backgrounding early weaned steers longer may be

one solution for reducing medical cost and lost productivity in the feedlot due to illness.

Additional Benefits of Early Weaning for Herd

Management

Preliminary evidence of an early weaning effect on herd management suggests a positive benefit for cow health and

pasture carrying capacity relative to normal weaning. The pasture management data was collected at the NDSU Dickinson

Research Extension Center. Currently, research on the effect of early weaning on pregnancy rates, grazing intensity rates,

and the economic benefits to the cow/calf production system of increasing those rates is ongoing. With respect to carrying

capacity, the data indicate that forage disappearance for cows that had calves weaned early was 803 kilograms per ha,

whereas forage disappearance for the normal weaning group that nursed their calves an additional 80 days

was estimated at 1109 kilograms per ha. This preliminary result suggests early weaning reduced forage disappearance by

approximately 28 percent. The research protocol selected cow body weight and cow body conditioning score as the proxies

for cow health. Normal and early weaning treatment cows were weighed and evaluated to determine their body condition

score (BCS) in August and November. Cows in the early treatment group, on average, gained 16 pounds and their BCS

score improved from 5.18 to 6.09.2 Cows in the normal treatment group, on average, lost 137 pounds and their average BCS

declined from 5.26 to 4.70. These preliminary results suggest that early weaning may provide potential economic benefits to

producers by increasing the production efficiency of their cow/calf production system relative to the traditional alternative of

normal weaning.

Summary

The analysis of the data from the two-year early weaning study conducted in the western Dakotas reveals that early weaning

provides a cost efficiency advantage resulting from improved feed efficiency, but early weaned steers are at a disadvantage

due to lower slaughter weights and subsequent lower carcass revenue per head relative to normal weaned steers.

Preliminary results indicate that early weaning has the potential to increase the efficiency of a producer’s cow/calf production

system. Our research indicates that early weaning improves pasture carrying capacity and cow health. Increased stocking

rate and the potential to improve reproductive rates will contribute to the producer’s bottom line. Results from this study also

suggest that early weaning can be used as a management tool during periods of low precipitation when cattlemen are forced

to separate calves from their mothers. Early weaning provides producers a herd management strategy during periods of

drought for conserving resources and improving the long-run sustainability of their cow/calf operation. Producers may view

the benefits of conserving ranch resources during periods of drought as a reasonable tradeoff for lower steer weights at

market. These efficiencies can also be effectively captured and used during periods of adequate precipitation as a means to

increase stocking rate or renovate previously overgrazed pastures.

Endnotes

1 For