Meeting Cattle Nutritional Needs

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.

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. 

Growing cattle

In the Midwest corn residue and distillers grains provide a distinct advantage for growing calves in the winter.  Due to the typical rental rates for corn residue and the cost of distillers, these two feed resources together make one of the lowest cost growing rations possible. In ruminant diets, not all protein is created equal and this can particularly become apparent for animals with high protein requirements such as growing calves.  Ruminally degradable protein is used by rumen microbes to grow, which then become a source of protein for the animal called bacterial crude protein. Degradable protein supplied in excess of the microbes requirements is converted to ammonia in the rumen which cannot be used by the animal as a source of protein. When the animal’s protein need is high and the bacterial crude protein does not meet the animal’s demand, and a source of undegradable protein is needed. A good example of this concept is the comparison of urea as a source of protein vs distiller grains for growing calves grazing corn residue (Table 2). Urea is 100% ruminally degradable whereas the protein in distillers is only 37% ruminally degradable meaning 63% of the protein bypasses the rumen and can be absorbed and used as a source of protein for the animal itself.  When a similar amount of energy and protein was supplied from corn plus urea vs. distillers grains, the performance of calves receiving distillers was more than double that of the calves receiving the corn plus urea. 

Distillers grains have consistently been the lowest cost source of bypass protein in the Midwest. In addition, distillers grains are very high in energy (greater than corn). Thus, distillers grains make an ideal low cost supplement for calves grazing corn residue. Table 3 provides the amount of distillers grains that would need to be fed to achieve various rates of gain based on data gathered from multiple trials where distillers grains have been fed to calves grazing corn residue. In forage based systems, we observe similar performance with dry, modified and wet distillers as long as the same amount of dry matter is fed.  It is important to note that the estimates in Table 3 are based off of calves being fed in a bunk. Feeding on the ground will increase waste and thus increase the amount needed to be provided. In trials, evaluating the waste with ground feeding, waste of 5% was measured for modified distillers, 20% for wet distillers and as much as 40% for dry distillers when compared to bunk feeding.

If you are looking to background calves or grow replacement heifers this winter grazing corn residue and providing supplemental distillers may be a system to consider.

For more on this topic, explore the related video: Understanding protein needs of growing calves

References

Welchons, C. A. and J. C. MacDonald. 2017. Pooled Gain Analysis of Steers Grazing Corn Residue and Supplemented with Distillers Grains. Nebraska Beef Report p. 34-35.

Tibbitts, B. T., J. C. MacDonald, R. N. Funston, C. A. Welchons, R. G. Bondurant and F. H. Hilscher. 2016. Effects of Supplemental Energy and Protein Source on Performance of Steers Grazing Irrigated Corn Residue. Nebraska Beef Report. p 31- 32

Gillespie, K. L., L. A Stalker, T. J. Klopfenstein, J. D. Volskey, and J. A. Musgrave. 2014. Replacement of Grazed Forage and Animal Performance when Distillers Grains are Fed in a Bunk or on the Ground on Summer Range. Nebraska Beef Report. p34-35.