High quality forages fuel top milk output
WALDO - How have more than 200 dairy herds in Wisconsin achieved a per cow average of more than 30,000 pounds of milk per year? It's a good bet that the feeding of high quality forages is a major factor in achieving those numbers.
That was the point of a presentation made by University of Wisconsin Extension Service dairy nutritionist Randy Shaver at the 2017 annual meeting of the Sheboygan County Forage Council. According to the three latest surveys of the very top producing herds, most were in the southeastern quarter of Wisconsin, including Sheboygan County.
Shaver cited statistics from October 2016 that had 155 dairy herds on AgSource testing and another 49 in NorthStar's production testing program, which recorded herd averages of above 30,000 pounds of milk as a rolling herd average for one year. He noted that the 155 herds account for 5 percent of those on AgSource testing.
The AgSource herds had between 27 and 3,542 cows on the test sheet. At an average herd size of 653 head, the per cow production averages included 31,795 pounds of milk, 1,187 pounds of butterfat and 973 pounds of protein for a cheese production potential of 3,212 pounds.
Checking the history of average milk per cow since 1945 for the entire United States, Shaver noted a doubling to 9,500 pounds by 1965 and another doubling to more than 19,500 pounds in 2005. A continuing of the statistical trend which likely topped 23,000 pounds in 2016 would push the average to more than 40,000 pounds over the next 40 years – a number that Shaver believes deserves a question mark.
But that this isn't impossible is shown by recent averages of more than 43,000 pounds for the 111 cows in the Tom and Gin Kestell family's Ever-Green-View's herd in south central Sheboygan County. (See separate story on A1.)
Role of forage
For the heart of his presentation, Shaver focused on the role of forage in supporting such milk production levels. He pointed out that forages alone can support 60 pounds of milk production per day by a cow and that one ton of forage dry matter can be converted into 3,000 pounds of milk.
Of the total nutrients in a dairy ration, high quality forage can provide more than 75 percent of the fiber, about 50 percent the energy and non-fat carbohydrates, 40 percent of the protein, and 35 percent of the starch, Shaver indicated. To allow enough dry matter intake to allow for very high milk production, that forage needs to have fiber that is highly digestible, he remarked.
Corn silage traits
That applies to both legumes and corn silage, which should be low in lignin and high in both fiber digestibility and total digestibility of all nutrients, Shaver observed. As a basic makeup of corn silage, he suggested 40 to 45 percent grain and 55 to 60 percent stover.
Achieving excellent digestibility of corn silage depends on a combination of the hybrid, the growing season's environment, the portion of lignin and neutral detergent fiber, maturity at harvest, cutting height, kernel maturity, endosperm traits, kernel particle size in the silage, and the length of silage fermentation, Shaver stated.
Shaver emphasized that the harvesting practices have a large influence on the digestibility of starch in the corn silage. He noted that the latest innovations in harvesting equipment, along with the chopping technique known as shredlage, lead to proper sizes for a high digestion of starch.
Increased lengths of fermentation and storage, up to at least 240 days for conventional corn hybrids, show continued improvement in the digestion of such major nutrients as starch and protein, Shaver stated. For fiber digestion, he noted that a similar improvement over time is not evident for either brown mid-rib or leafy corn hybrids.
Hay crop silage
For the sake of energy density and how it relates to milk production, the same standards apply to haylage and dry hay in dairy rations, Shaver pointed out. He cited the importance of high levels of fiber digestibility in order to maximize feed intake along with the values provided by non-fat carbohydrates and crude protein in forage with good numbers on the measures for the relative feed quality and value scales.
In addition to the traits provided by conventional alfalfa varieties, the recently developed reduced lignin versions promise the combination of delayed harvests, one less cutting per season, and better fiber digestibility, Shaver observed.
The same potential for supporting high levels of milk production exists with grasses harvested for silage, especially those with later maturities that come close to matching that of alfalfa and which have a lower amount of neutral detergent fiber, Shaver indicated.
Yield and quality curve
On the question on making the right choice on the matching of alfalfa yield and quality, Shaver suggested that it tends to occur at just before 30 days of regrowth for conventional varieties and a few days later for the new lower-lignin varieties. If high milk production is the goal, then the digestibility (quality) must take precedence over the possibility of a higher forage yield, he noted.
Even if the right choice is made on the timing of the harvest, there are multiple risks for the dry matter loss with both haylage and corn silage, Shaver warned. Even under the best of circumstances,the normal loss is about 16 percent with haylage and about 13 percent for corn silage, he pointed out.
For haylage, risks occur with mowing and conditioning practices, respiration timetable, rainfall, raking and merging, and chopping, Shaver said. With corn silage, there is always some loss during the filling of storage units but most of the dry matter loss occurs during ensiling, storage, and feedout, he noted.
More specifics on the research for feeding dairy cattle and on nutrition recommendations are available on the http://www.shaverlab.dysci.wisc.edu website.