In this new era of elevated feed costs (both grain and hay), developing heifers from weaning to breeding involves a substantial investment. And, if heifers developed this winter fail to re-breed after their first calf next summer, much of the cost associated with developing them will not be recovered.

To avoid non-pregnant 2- and 3-year old cows at the end of the breeding season, producers are considering altering the nutritional development of heifers between weaning and first breeding. One of the quickest ways to maximize reproductive performance is to provide more nutrients. However, based on recently-reported data, this is probably not the most economical solution.

A New Approach
Historically, heifers have been developed to weigh approximately 60-65% of their mature body weight at breeding time (about 13-14 months old), in an effort to increase pregnancy rate. This practice has been based largely on evidence that: 1) increased energy intake during development improves heifer pregnancy rate, and 2) heifers developed to a body weight less than 65% take longer to re-breed after calving as a 2-year old. Yet, some argue that increasing the amount of feed provided (which increases costs substantially) in order to increase pregnancy rate leads to a long-term cycle of elevating costs and declining profitability on a cattle operation.

Several researchers have begun to explore the possibility of developing heifers at a slower rate, which ultimately leads to weights at first breeding that are lighter than historical averages. Nebraska research led by Dr. Rick Funston compared the long-term reproductive performance of two groups of crossbred heifers developed to 53% (low gain) and 58% (high gain) of mature body weight. The heifers were developed on identical rations (hay, wheat middlings, corn, and supplement), except for a difference in corn to reflect the increased gain in the “high gain” heifers. Interestingly, there was no difference between the two groups for pregnancy rates through the fourth breeding season (Table 1).

Table 1. Breeding results for crossbred beef heifers developed in low gain (53% of body weight) and high gain (58% of body weight) scenariosa

Trait

Low Gain

High Gain

Developing heifers:

Beginning weight of heifers (lbs)

469

469

Daily gain during winter (lbs/day)

1.1b

1.4c

Pre-breeding weight (lbs)

636b

689c

Pregnancy rate with first calf (%)

92

88

First-calf heifers:

Pre-calving body weight (lbs)

913b

937c

Body condition at first calving (1-9)

5.2

5.3

Body condition at weaning (1-9)

5.1b

5.3c

Pregnancy rate with second calf (%)

91

91

Second calvers:

Body condition at weaning (1-9)

5.0

5.0

Pregnant with third calf (%)

94

92

Third calvers:

Body condition at weaning (1-9)

5.1

5.2

Pregnant with fourth calf (%)

96

96

aAdapted from Funston and Deutscher (2004).

b,cTreatment means in a row without common superscripts are different (P < 0.05).

Is Reduced Gain Economical?
An economic evaluation was conducted by University of Nebraska researchers to follow-up on the reduced gain concept. The above data were used, in addition to data from an experiment by Creighton (also in Nebraska) where two development systems were compared: low gain (to 50% of mature weight, prior to breeding for 60 days) vs. high gain (to 55% of mature weight, prior to breeding for 45 days). Similarly, the low gain heifers had a pregnancy rate of 87% in a 60-day season compared to a pregnancy rate of 89% in a 45-day breeding season in the high gain heifers.

Using estimated feed costs and cattle prices over an 11-year period, the “low gain” heifers cost $27 per bred heifer less than the “high gain” heifers (Table 2), when data were averaged over the 11-year period. Average calf birth date, weight, difficulty, and loss were similar for both treatments, as well as calf gain and weaning weight. It should be noted that this analysis was conducted prior to the recent hike in grain and hay prices. Thus, it’s possible that cost savings could be even larger today.

Table 2. Comparison of heifer development costs from weaning time to pregnancy check for “low” and “high” gain heifersa

Item

Funston and Deutscher (2003)

Creighton (2004)

Low gain

$608

$580

High gain

$635

$603

aAdapted from Clark et al. (2005), using data from two experiments that evaluated the effect of low vs. high gain on reproductive performance.

An Opportunity for Flexibility

Based on these studies, reducing gain and weight may not affect reproductive performance, and will certainly cost less. However, there may be some increased risks associated with the lower gain option, which might include a low pregnancy rate and increased calving difficulty in smaller, lighter-weight heifers. Early research in Kansas documented that heifers developed to 55% of body weight at breeding time had more calving difficulty than heifers developed to 65%.

However, it appears that some heifers do not need to reach 65% of body weight prior to breeding. If this goal is not as crucial as previously thought, daily gains during the development phase could be accomplish more easily and at less cost. Traditionally, a heifer calf destined to weigh 1,200 lbs as a mature cow would be developed to a target weight of 780 lbs (or 65% of 1,200 lbs).

Using a lower target weight, this same heifer could be developed to 660 lbs (or 55% of 1,200 lbs), which would reduce the amount of gain necessary by 120 lbs. Therefore, if a heifer that weighs 500 lbs at weaning has to put on 160 lbs of gain during the 6-month period between weaning and breeding, the average daily gain required could be reduced from over 1.5 lbs/day to less than 0.9 lbs/day.

The Bottom Line

Proper heifer development must be accomplished at a low cost without hindering short- or long-term reproductive performance. To be successful, a heifer needs to reach puberty early, conceive early during the first breeding season, calve unassisted, and conceive early with a second calf. The historical target of reaching 65% of mature weight will result in high pregnancy rates; however, costs can be reduced without affecting reproductive performance if heifers are fed to a lower target weight. Care must be taken so that major risk factors (including unacceptably low pregnancy rates and elevated rates of calving difficulty) are minimized.