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Crop residues lower cost of development for replacement heifers

published: October 30th 2009
by: Sandy Johnson

Total cow/calf production costs, which include heifer development, have risen over 25% since 2005. The breakeven cost to produce a heavy springer heifer in the 2008 KSU farm management guide budget was $1534. The return on this investment does not begin until the female is 2 1/2 years old or later depending on when the calf crop is marketed.
    Rick Funston from the University of Nebraska, West Central Research & Extension Center in North Platte was a speaker at the recent K-State Beef Conference in Manhattan, Kansas. His work has shown heifers reaching 55 to 58% of mature body weight by breeding time had similar reproductive ability as heavier heifers through the fourth pregnancy diagnosis. At the meeting he discussed his research aimed at lower cost heifer development systems.
    First he compared a more traditional dry lot development system from weaning through AI to heifers grazing corn residue for 145 days. Heifers received 1 lb of a 28 % crude protein supplement daily while on stalks and were moved to a dry lot for 42 days prior to breeding. The net cost to develop one pregnant heifer was $40 per head less for corn residue compared to the dry lot.
    Gain on stalks was less than in the dry lot system, however while on pasture as yearlings, heifers developed on stalks exceeded the gain of dry lot fed heifers by 0.44 lbs per day. Pregnancy rate to AI tended to be lower in the corn residue heifers however, after a 45 day breeding season there was no difference in pregnancy rate or the proportion that calved in the first 21 days of the calving season. At calving time, corn residue heifers were still 40 lbs lighter. Despite this weight difference, the pregnancy rate to AI and the season long pregnancy rate was similar between the two treatments when bred as two-year-olds.
    Funston’s work has also compared heifer development systems on crop residue to winter range in two additional studies. In either system, heifers received 1 pound per day of a 28% crude protein supplement from shortly after weaning until 40 to 60 days before breeding. Average gain during the wintering period ranged from .3 to 1 pounds per day.
    During the pre-breeding period, the ration was adjusted to boost gain to the range of .6 to 1.2 pounds per day. Gains from breeding to pregnancy diagnosis ranged from 1 to 1.6 pounds per day. Production systems resulted in 83 to 89% pregnant as yearlings and 77 to 100% pregnant as two-year olds with no difference between winter range or corn residue grazing treatments.
    Another study compared the performance during gestation of heifers grazing crop residues and winter range from weaning to breeding to heifer calves grown in a dry lot.
    Individual feed intake data was collected for a 70 day period when heifers were fed a grass hay and protein supplement diet. Heifers developed on crop residue and winter range ate less, weighed less and tended to be more efficient during gestation than heifers developed in a dry lot. Even if developed to lighter weights prior to breeding as yearlings, it is still important for heifers to achieve the goal of 85% of mature weight prior to calving.
    Grazing corn residue as heifer calves was a benefit to pregnant yearling heifers that grazed corn residue for their second fall. Pregnant heifers were placed on stalks that were either developed in a dry lot or on corn residue as heifer calves. Average daily gain was greater for heifers that grazed corn residue as calves than those developed in a dry lot.
    Funston concludes that grazing low quality forage during development may produce a heifer better adapted to a lifelong grazing system and reduce costs. For producers that utilize AI on replacement heifers and would like to utilize winter range or crop residues during development, the target of 60% of estimated mature weight at breeding is still a good guide. To achieve this weight, supplementation could be increased slightly later in the winter grazing period and/or a higher rate of gain could be targeted just prior to breeding. In the Nebraska studies, heifers that were open as yearlings were sold off grass at a profit in most cases.
    Keeping more heifers than normal and developing in a lower cost grazing system with the plan that several would be marketed as yearlings is another option.
SLS