Dr. Bill Weiss, Professor and Extension Dairy Specialist, Department of Animal Sciences, The Ohio State University
The numerous freeze-thaw cycles and wet ground last winter were very hard on alfalfa stands, resulting in substantial winter kill. Numerous stands across the State were completely destroyed. Other stands may have suffered less damage, but first cutting yields will likely be substantially lower than normal. In addition to first cutting yield loss, nutritional quality may also be lower than normal because of increased proportion of grass and other weeds in the stands. To make matters worse, many producers rely on rye or small grains to provide late spring and early summer forages. The wet spring delayed harvest on many farms, turning what usually is a good quality forage into lower quality ‘heifer feed’. This double whammy will put significant pressure on forage inventories and especially high quality forage supplies. Although less than ideal, several options exist that will stretch forage inventory and allow inclusion of lower quality forages without substantial negative effects on milk yield.
- Estimate inventory of corn silage and determine if you can increase the feeding rate without running out before the new crop is harvested. If increased feeding rate of corn silage is an option, increase inclusion of corn silage and reduce concentrations of other lower quality forages. The concentration of forage NDF should be kept around 20% of dietary dry matter (DM). Diets will likely need more supplemental protein because alfalfa and rye have more protein than corn silage. Cows may also benefit from increased supplementation of potassium and/or sodium buffers. High corn silage diets are usually low in Dietary Cation-Anion Difference (DCAD) which can reduce milk fat yields.
- Include lower quality forages but keep forage NDF concentration at <20% of dietary DM. At lower inclusion rates, the negative effect of lower quality forage on feed intake is reduced. Keeping forage NDF at 19 to 20% of dietary DM reduces (but does not eliminate) the negative effect of low quality forage on intake. Because the more mature forages have more NDF, the percentage of forage in the diet will decrease which may raise concerns about reduced milk fat yields. However, the amount of forage fiber, not total fiber, is what is important with respect to milk fat. Reducing the amount of forage in the diet means that inclusion rates of other feeds must increase. Be careful about replacing forage with corn grain; maintain diet starch concentrations around 25% as forage is reduced. Byproducts, such as wheat midds, soyhulls, brewers, or distiller grains, can replace some of the forage if excess starch is an issue.
- Based on cow responses, whole cottonseed can replace normal forage almost on a pound for pound basis. Whole cottonseed has about 40% NDF (similar to average alfalfa) which means replacing 8 lb of alfalfa silage or hay dry matter with 8 lb of whole cottonseed should have little effect on the cow (protein and minerals may need to be adjusted and supplemental fat, if fed, may need to be reduced).
- If forage inventory is not adequate to last until the end of summer, options for growing more forage include Brown Midrib (BMR)-summer annuals or pea-small grain mixes. Pea-small grain mixes produce good quality forage, but they need to be planted soon, probably no later than mid-May. They should be harvested in about 60 days. The mix has higher nutritional value than small grains by themselves. BMR sorghum, BMR sorghum-sudan, or BMR sudangrass can be planted beginning in late May and early June when soil temperatures are at least 60 to 65oF and up to late June in northern Ohio and mid-July in central and southern Ohio. They are ready to harvest in 50 to 60 days (early August to late August). The resulting silage from BMR sorghum is almost as good as regular corn silage (although lower in starch) when fed to dairy cows. The nutritional value of BMR sudangrass or BMR sorghum-sudan have not been evaluated with dairy cows but likely is similar to that of BMR sorghum. Fiber digestibility is very good with the BMR summer annuals and inclusion rates can be high.
Overall, several options are available for using lower quality forages. The key is to limit forage fiber. Because lower quality forages are high in fiber, diets will contain less forage and more concentrate than typical, which will likely increase ration costs, but feeding too much low quality forage will reduce milk yields which is worse than higher feed costs.