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Highlights from the Dairy Science Annual Meeting

Jim Salfer, Extension Educator-Dairy

August 25, 2012

Every year I have the opportunity to attend the American Dairy Science Association annual meeting to learn the latest research being conducted throughout the world. This year the meeting was in Phoenix, AZ, in the middle of July. I had to go to Phoenix to get away from the heat of Minnesota! Here are some short summaries of a few of the sessions that I attended.

Ecology of subclinical ketosis in transition dairy cattle.

Researchers from Cornell University and University of Wisconsin did a field trial where they tested 1717 cows in 4 herds for subclinical ketosis from 3 to 16 days in milk (DIM). Forty-three percent of all cows had at least one positive ketosis test during the trial with the peak prevalence occurring at 5 DIM when 29% of cows tested positive. Cows testing positive in the first week after freshening were 6.1 times more likely to develop a displaced abomasum, 4.5 times more likely to be removed from the herd in the first month after calving, and 30% less likely to conceive at first service than cows that tested positive later. Cows testing positive in the first week also produced an average of 5 pounds of milk per day less for the first 30 days than cows testing positive later. Take home message: Focusing on encouraging dry matter intake and good cow health during the first week after calving is important in preventing disease, early lactation culling and increasing milk production.

Impact of milk yield, herd size and feed efficiency on economic change between and within California dairies from 2006-2010.

Researchers examined the factors affecting profitability of 97 California dairies from 2006 to 2010. The total cost of production averaged $1.48 per cwt higher for herds producing less than 70 pounds per cow per day than for herds producing more than 80 pounds per cow per day. Overall herds with lower cost of production had higher profitability. Milk net income average $-0.29 per cwt for herds averaging less than 70 pounds per cow per day compared to a $1.12 for cows averaging greater than 80 pounds per cow per day. From 2006 to 2010 the average cost of production increased $0.40 per cwt each year. But the cost of production only increased $0.26 per cwt for herds that were able to increase average milk production by 2 pounds per cow per day every year.

Effect of AI technicians on reproductive performance and economics of lactating dairy cows.

There is a wide variation in skills among inseminators. Ohio State and University of Florida researchers used a computer simulation model to estimate the effect on profitability of three different technician conception rates (26, 32 and 38). Using the assumption of this model, each 1% increase in conception rate (from 26 to 38%) increased profit $6 per cow per year. Take home message: Investing in training of on-farm technicians or using a professionally trained technician can have a large effect on profitability.

Methods of reducing milk replacer to prepare dairy calves for weaning when large amounts of milk replacer have been fed.

Most trials feeding large amounts of milk replacer (like an accelerated program) and weaning over 7 days have reduced average daily gain after weaning due to less starter intake compared to control calves. These trials were designed to compare different weaning strategies to try and eliminate the post weaning decrease in performance with higher milk diets.

In one trial, a 27% protein, 7% fat milk replacer was fed to one group of calves at 1.94 pounds per day for 21 days and then decreased to 1.5 pounds for the next 21 days. The other group was fed the same milk replacer for the entire 42-day period. Calves were fully weaned by day 42. Growth was measured until calves were 56 days old. Calves fed the higher milk replacer for the first 21 days after birth had higher average daily gains and similar starter intake to the calves fed the lower level of milk for the entire 42-day period.

In another trial, there were three treatments using the same 27% protein, 17% fat milk replacer. One group of calves was fed 1.5 pounds of milk replacer per calf for the entire 42-day period, a second group was fed 2.1 pounds of milk replacer until they were 21 days old and then milk replacer was reduced to 1.5 pounds of milk replacer per calf for the next 21 days. A third group was fed 2.1 pounds of milk replacer per calf for 28 days and then the milk replacer level was gradually reduced over the next 14 days until calves were weaned.

Results showed that calves fed the higher level of milk replacer early in life had higher average daily gain than calves fed the lower amount during the entire 42-day pre-weaning period. Take home message: You can avoid the post-weaning decrease in performance associated with the typical one week step down weaning period associated with higher milk feeding programs by decreasing the amount of milk fed over a 2 to 3 week period.

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