Agronomist, nutritionist roles vital for milk production
As dairy herd milk production averages and herd sizes continue to increase, the quality of forage in the cows' rations will be more important than ever but so will the per-acre yields of those forages as land costs and rents also increase.
Reaching a happy medium on those challenges will require a good connection and close cooperation of the crop agronomists and dairy nutritionists serving many of the dairy herds at the upper production levels, University of Wisconsin Extension Service dairy nutritionist Randy Shaver reminded attendees at the Calumet County Forage Council's summer twilight meeting.
Given what's at stake, the decisions being made are not likely to be easy ones in many cases, Shaver observed. He pointed out that when land is cheap there tends to be less focus on yield while high yields are sought when land is expensive.
The latest variable in that scenario is the introduction during the past two years of the low-lignin trait alfalfa, which offers an extended cutting interval without sacrificing forage quality for about an extra seven days, Shaver noted.
Why the roles of agronomists and nutritionists are important in the dairy farm management plan is shown by milk production data for 2015 obtained for Wisconsin's dairy herds on production testing with AgSource and NorthStar Dairy Herd Improvement, Shaver indicated.
The top 100 herds on AgSource testing have a rolling herd average of 31,297 pounds of milk, 1,154 pounds of butterfat, 961 pounds of protein and 3,150 pounds of cheese yield, Shaver noted. Those herds have an average of 486 cows.
When the criterion is an average of at least 30,000 pounds of milk, there are 111 AgSource herds in Wisconsin plus another 30 herds with NorthStar. They account for about 3 percent of all the dairy herds on production testing in the state, Shaver stated.
From another perspective, rolling herd averages for herds have doubled twice in the past 70 years — from 4,789 pounds in 1945 to just over 9,788 pounds in 1970 and then up to 19,576 pounds in 2005, Shaver pointed out. By 2015, that average was up to 22,498 pounds of milk in Wisconsin.
New era challenges
Achieving and maintaining such numbers is likely to depend even more on the yields and quality of forage, given that the use of bovine somatotropin is being voluntarily reduced on some dairy farms and being prohibited on others due to limitations being set by milk buyers and processors, Shaver suggested.
Underpinning the challenge that accompanies the production of forage is the statistic, though current only through the end of 2012 but probably even pronounced today, that 14 percent of the dairy herds in the United States account for 71 percent of the milking cows, Shaver observed.
Applying the forage needs to an operation with 3,200 milking and 800 dry cows if forage provides 54 percent of the overall dry matter intake of the two groups, the daily forage needs would be 51 tons, Shaver explained.
Assuming a daily milk production of 80 pounds per cow and an annual yield of six dry matter tons of forage per acre, that operation would need the equivalent of 9 crop acres per day or 3,574 acres to cover the entire year, Shaver pointed out. Even a yield drag of 10 percent or other reason for yield loss would require another 397 acres for a 4,000 cow dairy operation on which the heifers are not part of the feeding group, he warned.
Quality vs. quantity
Within those parameters is where the roles of both the agronomist and nutritionist become more prominent, Shaver indicated. 'The key' is to find 'the sweet spot' at which the elements of forage yield and quality are combined rather than emphasizing one or the other.
The quality of forage is vital because it can provide the nutritional elements that enable 60 of a cow's potential 100 pounds of daily milk production — the equivalent of 3,000 pounds of milk from one ton of forage dry matter, Shaver pointed out. Forage also has the potential of providing 75 to 80 percent of the fiber in the ration, 45 percent of the protein, 40 percent of the starch, 50 percent of the energy and 60 percent of the nonfat carbohydrates.
With corn silage, for which Shaver recommends 35 percent rather than 30 percent of dry matter at harvest and storage, the important point to is have a high portion of grain which is the top supplier of starch. He also recommends at least a three-month carryover in the corn silage supply.
Losses along the way
If there is one advantage with corn silage compared to forage, it is that losses due to harvesting, chopping, storage, fermentation and feedout typically range from 12 to 23 percent while with alfalfa haylage those losses can range from 17 to as high as 64 percent, according to Shaver's Extension Service colleague Brian Holmes (an agricultural facilities specialist).
Even with excellent management during silo storage, expect dry matter losses of 8 to 10 percent, Shaver remarked. He said this is due to a combination of respiration, fermentation, and aerobic activity during storage. Seepage should not occur with good management but it can be more than 5 percent with poor management.
The gradual introduction of low-lignin trait alfalfa can help to offset some of the risks associated with harvesting the crop, especially with delays due to rain, Shaver observed. That's because the new trait adds about 7 days to the regrowth period without sacrificing quality while also adding a bit to the yield of the particular cutting, he pointed out.
Because of the potentially high number of dollars that can be involved, connections between the agronomist and nutritionist when working with the practicalities and constraints on possible ranges of 35 to 60 percent forage in the ration and differing percentages of neutral detergent fiber in that forage, Shaver indicated.
How that is determined will differ from farm to farm depending on the crop rotations, feed inventory and nutritional requirements of the dairy cattle being fed there, Shaver stated. The yield vs. quality decision pertains to the targets set for feed quality for differing cattle groups, the associated harvest maturity of the crop, the proportion of haylage to corn silage, the possible inclusion of grasses in the forage, variety and hybrid selections and fungicide applications.
Other factors which are likely to affect the nutritionist's recommendations are the custom harvesting practices; the harvest maturity and moisture; chopping length and kernel processing; silo packing and covering; silage inoculant and feedout management. He also mentioned the occasions when wheat straw might be added to a ration to protect dairy cattle health when the potassium content is too high in forages.
Agronomists and nutritionists should also work with the owners to place a value on feeds based on the nutrient content, Shaver advised. This would serve as a guide for pricing on purchases and sales and in executing contracts, he explained.
What Shaver describes as the 'agronomist — dairy nutritionist interface' should extend to the farm management team meetings for defining roles, providing leadership, setting and reviewing goals, offering help with planning, making benchmark comparisons, identifying bottlenecks and providing farm staff and employee training.
Shaver can be contacted on the www.shaverlab.dysi.wisc.edu website.