DHI Notes...
April 07| Bennet Cassell
State DHI averages for important management areas in March 2007
Management area
March 2007
Change from last year
Rolling herd average milk
21542
-68 lbs.
Peak yield in heifers
73
-1 lbs.
Days to first breeding
95
0 days
Days open
162
-1 days
Net Merit of proven service sires
$305
*
Herd turnover less dairy sales (%)
29%
-1%
Monthly average SCS
3.0
-0.1
Feed cost per cwt. (milking cows)
$5.51
$0.46
Milk blend price
$15.42
-$0.31
*Net Merit changed in August 2006 and averages are not comparable.
Recent DHI Notes have suggested how to use DHI records for milk quality and udder health through use of SCC data, for herd reproductive performance, and for genetic improvement. This month, the focus will be on nutritional management of the herd. One question to keep in mind in all areas of herd management, but especially for nutritional management is how old is the data? Nutritional status of the herd can change daily, as new feeds are introduced, new silos opened, TMR preparation changes, and so forth. Cow response to nutritional changes likewise is rapid, and can happen often unless care is taken to provide consistent, high quality rations. Many of the cow performance parameters in DHI records are affected by performance in previous months. Rolling herd averages are based on yields over the previous 12 months, and are not very sensitive to what happened most recently in the herd. Production of milking cows on test day is at the other extreme, using only last test day information. One really useful and very current figure is the standardized 150 day milk average in the Yearly production and mastitis summary. This figure adjusts for days in milk, and won’t be affected by higher yields (compared to last month or the same month last year) that result from fewer average days in milk. However, average age of the herd will affect this figure, as it is not adjusted for maturity. The Stage of Lactation Profile contains some of the best information to evaluate nutritional management. Pay close attention to average milk yields and fat, protein, and SCS data for transition cows, those in milk less than 40 days. Are cows milking up to expectations as they go through their first test day? Is fat percentage sufficiently higher than protein percentage to suggest healthy rumen function? Are there mastitis problems with fresh cows? One important caveat to using recent, timely information in Virginia’s smaller herds is that some of the averages are based on very few animals. For instance, the Virginia Tech herd had two fresh Holstein heifers on March test day. We won’t learn much about herd management from two animals. Be sure to separate the problems with a single cow from problems associated with overall nutritional management.
Bennet Cassell
Genetics and Management
