Effect of beef heifer development systems utilizing corn residue and late summer planted cover crops on growth, reproductive performance, and economics

Authors: SPEER, HANNAH - University Of Nebraska; Cushman, Robert - Bob; FREETLY, HARVEY - Retired ARS Employee; PARSONS, JAY - University Of Nebraska; WINDH, JESSICA - University Of Nebraska; DREWNOSKI, MARY - University Of Nebraska

Submitted to: Translational Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2024
Publication Date: 7/24/2024
Citation: Speer, H.F., Cushman, R.A., Freetly, H.C., Parsons, J., Windh, J., Drewnoski, M.E. 2024. Effect of beef heifer development systems utilizing corn residue and late summer planted cover crops on growth, reproductive performance, and economics. Translational Animal Science. 8. Article txae111. https://doi.org/10.1093/tas/txae111.
DOI: https://doi.org/10.1093/tas/txae111

Interpretive Summary: This study examined three winter development systems for beef heifers, focusing on their growth and reproductive performance. Over three years, spring-born heifers were assigned to one of three treatments: grazing corn residue with either distillers grains (CD) or wheat midds (CW) supplementation, or grazing oat-brassica cover crop followed by corn residue grazing with distillers grains supplementation (CC). The goal was to achieve a similar target body weight in all three treatments by the end of the winter period. Results showed that heifers grazing the oat-brassica cover crop initially gained weight faster than those on corn residue with supplements. Thus, during the latter part of winter, when CC were grazing corn residue, less distillers was supplemented to achieve a slower rate of gain than the other two treatments. However, the CC had greater winter average daily gains overall compared to the corn residue groups. Pregnancy rates were not significantly different between the CC and CD heifers, though CC were greater than CW, which did not differ from CD. Despite differences in cost and heifer value, economic returns were similar across treatments. In conclusion, the study suggests that all three systems, yield comparable results in developing beef heifers effectively.

Technical Abstract: The objective of this study was to evaluate growth and reproductive performance of heifers developed using 3 different winter systems in the midwestern U.S. Spring-born heifers (n = 1,156; 214 d of age; SD ± 17 d) were used in a 3-yr study to evaluate performance in winter development systems, which utilized cover crop and corn residue grazing. Heifers were assigned to 1 of 3 treatments: grazing corn residue with 0.77 kg/d dried distillers grains (CD) or 1.69 kg/d wheat midds (CW) supplementation followed by a grower ration in the drylot, or grazing late summer planted oat-brassica cover crop followed by corn residue grazing with 0.35 kg/d dried distillers grains supplementation (CC). Supplementation during the corn residue phase was targeted to result in a common BW (276 kg; ~45% of mature BW) by the end of the winter development period. Grazing of corn residue (CD and CW) and cover crop (CC) began in early November. After 63 d, heifers assigned to CC were moved to corn residue; on d 77 heifers assigned to CD and CW began receiving a grower ration in the drylot. In mid-February (d 98), heifers were comingled and managed in a single group. Breeding season began in June and lasted for 29 d. The ADG of heifers assigned to CC when grazing cover crop (d 1 to 63) was greater (0.76 kg/d; P < 0.01) than those assigned to CD or CW (0.58 kg/d and 0.49 kg/d, respectively). Gain during the last 35 d of the winter period for heifers assigned to CC (0.36 kg/d) was less (P < 0.01) than those assigned to CW (0.49 kg/d) but not different from CD heifers (0.41 kg/d). Overall (d 1 to 98), winter ADG was greater (P < 0.05) for heifers assigned to CC (0.62 kg/d) than CD (0.53 kg/d) or CW (0.50 kg/d), which did not differ (P = 0.42). Percent of mature BW in May (27 d pre-breeding) was greater (P < 0.01) for heifers assigned to CC (52%) than for those on CD and CW (50%), which did not differ (P = 0.64). Pregnancy rates were affected by treatment (P < 0.03), with heifers assigned to CC (76%) being greater than CW (64%) and CD heifers being intermediate (70%). When accounting for the differences in cost and the value of open and bred heifers, the economic return tended to differ (P = 0.07) among treatments, with CC and CW not differing (P >/= 0.20) from CD but return for CC being $73 greater than CW (P = 0.02). Utilizing oat-brassica cover crops early in the winter followed by a slower rate of gain while grazing corn residue with distillers supplementation appears to be as effective for developing beef heifers in the midwestern U.S. as supplementing distillers grains.