September 5, 2017 at 3:32 p.m.

Two words - hot and dry

By Jim Linn- | Comments: 0 | Leave a comment

A week ago, I attended the joint annual meeting of the American Dairy Science Association and American Society of Animal Science in Phoenix, Arizona.
The main topic of conversation with everyone I visited with from across the 48 continuous states was the drought and heat. The first question in greeting people was how you are and immediately followed by how is the drought in your area? Almost everyone is experiencing the hot weather and dry conditions. Minnesota as a whole is faring much better than many other states for drought, but we still are getting the heat. States in the Central and Eastern Midwest have essentially lost all of their corn and forage crops. Finding replacement inventory for forages will be the most challenging for dairy producers in these areas. Dairy extension specialists and nutritionists in these areas indicate many dairy producers have already chopped corn in an attempt to salvage some forage. Everyone is experiencing high grain and protein prices, but the outlook looks a little less daunting when you have a good supply of forage.
Below is a synopsis of a few research reports that relate to the feed and economic conditions we are looking at this fall.
Corn silage harvest - Wisconsin researchers summarized 24 research articles to determine the effects of corn silage dry matter (DM) content, kernel processing and length of chop on milk production. Corn silage DM above 40 percent decreased milk yield an average of 4.5 lb/cow/day. There was a linear decline in fat-corrected milk production as corn silage DM increased from 32 to 40 percent. Processing corn silage with roller spacing between 1 and 3 mm increased both starch digestion and milk production (4 lb/day) over 4 to 8 millimeters (mm) processing. However, processing was ineffective in increasing starch digestibility of corn silages over 40 percent DM. Length of chop from 0.37 inches (.93 centimeters, cm) to 1.13 inches (2.86 cm) had minimal effect on lactation performance. Conclusion indicates the standard recommendation of harvesting corn silage around 35 percent DM, processing it with rollers set at 1 to 3 mm with a chop length between 0.5 and 1.0 inches results in the best starch digestibility and most milk production. In a separate report, the same Wisconsin researchers indicated shredlage (cross grooved rollers at 2.5 mm gap and length of chop at 1.2 inches) processed corn silage increased DM intake and milk yield over regular kernel processed (3 mm roller spacing and 0.75 inch chop length) corn silage..
Canola meal - As soybean meal prices increase, canola meal availability and price have interested dairy producers in the upper Midwest. Three separate studies, one each from Wisconsin, Canada and China, reported on using canola meal in lactating dairy cow diets. All three studies showed lactating cows fed canola meal had equal or slightly better milk production than cows fed soybean meal in diets containing up to 10 percent of the total diet DM as canola meal. Canola meal also supported higher milk protein yields than soybean meal. In another study from Canada, canola meal was found to be lower in rumen protein degradability (59 percent) than soybean meal (66 percent). Wisconsin researchers collected canola samples from 12 different processing facilities and found a range in crude protein (DM basis) from 37 to 44 percent and a rumen undegradable protein (RUP) range from 37 to 47 percent. If you are buying canola meal in bulk as a commodity protein source, testing the loads you receive for CP seems advisable.
Grain starch digestibility - The same University of Wisconsin researchers, who did the corn silage analysis above, looked at grain source and starch digestibility in another summary study. One hundred articles from the Journal of Dairy Science were reviewed for the effect of grain type, corn processing and mean particle size (MPS) on starch digestibility and milk production. Grain type, barley, corn and wheat, did not affect milk production or total starch digestibility, but barley starch had a higher degradability in the rumen than corn starch. Ensiled high moisture shelled or ear corn yielded more milk (2 lbs./day) than dry corn. Digestibility of starch in both dry and ensiled corn decreased as MPS increased from 500 to 4,000 microns.
Milk and fat production related to rumen volatile fatty acids - Penn State researchers investigated the relationship between rumen volatile fatty acids (VFA) and milk and fat yield. Propionic acid, which is the primary rumen VFA resulting from grain digestion, was the VFA most strongly correlated with milk yield. The ratio of acetic acid to propionic acid was negatively correlated with milk yield; however acetic acid was the VFA with the highest correlation to milk fat. This study reconfirms feeding grain increases milk production through increased propionic acid and ultimately glucose synthesis in the mammary gland, whereas feeding forages with digestible fiber increases acetic acid which is used as a precursor for milk fat synthesis. A balance between grain and forage in the diet is needed to optimize both milk and fat yield.
Molds and mycotoxins in South Dakota and Minnesota TMR - TMR samples from 27 dairy farms in western MN and eastern SD were collected by South Dakota State researchers in the summer and fall of 2011 and analyzed for molds and mycotoxins. Twenty six TMR samples were found to contain vomitoxin, but concentration in all samples was below FDA acceptable limits in animal feed. Mold growth in general was low with 55 percent of samples being below 1,000 cfu/g. Conversely, yeast counts were high at over two million cfu/g in most of the TMR samples.
Protein requirements of calves and heifers - Provimi and Penn State researchers collaborated on a review of protein nutrition in dairy calves and heifers. For unweaned calves, the optimum crude protein (CP) feeding was in a ratio with metabolizable energy (ME). In the first two months of life, a ratio of 63 grams of CP/Mcal of ME in the unweaned calf was considered to be optimal, whereas in weaned calves, the ratio could decrease to 52 to 56 g of CP/Mcal of ME. Between two and four months of age, a 19 to 20 percent CP in the total diet DM resulted in the best growth rates. From four months to breeding, diets with a ratio of 63 g of CP/Mcal of ME with 65 percent of the protein being rumen degradable was recommended. After breeding, diets of 13 percent CP were adequate to maintain good growth rates.
This is a great meeting with four to five days filled with discussion on animal health, physiology, nutrition, management and care across several species. We are fortunate to live in a country that has a Department of Agriculture, a Land Grant University system and private enterprises that support animal agriculture research and education. We need this and future research to efficiently produce a wholesome and nutritious supply of animal products to feed a growing world population.
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