Dry Pregnant Cows
When cattle are stocked at the appropriate rate in one field for the entire winter, they have a high plane of nutrition early when they are eating more corn early in the winter, followed by a higher proportion of husk, and finally primarily leaves late in the winter. The problem with this system is that with spring-calving cows, requirements are increasing late in the winter because the fetus is starting to grow more rapidly. However, in a 5 year study, supplementation of a distillers based cube at 2.2 lb to cows grazing corn residue did not improve pregnancy rates or weaning weights over non-supplemented cows (Table 1) when grazed to the recommended stocking rate. Additionally, supplementation did not appear to have a fetal programing effect on the heifer progeny as replacement heifers born to cows grazing corn residue with and without supplementation had similar gains, age at puberty and pregnancy rates. At the start of the winter, the cows were in good BCS (BCS 5) and non-supplemented cows were able to maintain BCS over the winter when grazing residue alone.
| Dam | SUPP | CON | P-value |
| Oct BCS | 5.4 | 5.4 | 0.89 |
| Feb BCS | 5.6 | 5.4 | 0.02 |
| Preg rate, % | 94 | 91 | 0.18 |
| Calf birth wt, lb | 86 | 86 | 0.27 |
| Calf weaning wt, lb | 548 | 552 | 0.35 |
| Heifer progeny | SUPP | CON | P-value |
| ADG, lb | 0.97 | 1.01 | 0.2 |
| Age at puberty, d | 343 | 336 | 0.23 |
| Preg rate,% | 75 | 78 | 0.64 |
| Warner et al., 2012 | |||
If mature gestating cows are thin (BCS 4), they will respond to protein supplementation. Typically, we suggest feeding 0.3 lb of protein. This would be 1 lb of dry distillers or 2 lbs of modified distillers. This can allow thin cows to increase BCS before calving and may improve their rebreeding rates.
Because total intake, digestibility, and protein content of the diet declines during the grazing period, if greater than recommended stocking rates are utilized both supplemental energy and protein may be needed to maintain BCS of mature cows after they have reached the recommended stocking rate.
A free choice mineral to provide supplemental phosphorus, copper, zinc and vitamin A is needed. For a free choice mineral, with a target intake of 4 oz per day, suggested concentrations would be 4 to 5% phosphorus, 1500 to 2500 ppm copper, 3000 to 5000 ppm zinc and 140,000 IU/lb of vitamin A.
For more on this topic, explore the related YouTube video: Corn Residue Grazing: Current Recommendations and Adjustments Based on New Data
References
Funston, R. M., J. Nartin, D. C. Adams and D. Larson. 2009. Effect of Winter Grazing System and Supplementation on Beef Cow and Progeny Performance. Nebraska Beef Report. p 5-8.
Warner, J. M., J. L. Martin, Z. C. Hall, L. M. Kovarik, K. J. Hanford, R. J. Rasby and M. Dragastin. 2012. Supplementing Gestating Beef Cows Grazing Cornstalk Residue. Nebraska Beef Report p 5-7.