DHI Notes...

February 07| Bennet Cassell

State DHI averages for important management areas in January 2007

Management area	January 2007	Change from last year
Rolling herd average milk	21596	+378 lbs.
Peak yield in heifers	74	0 lbs.
Days to first breeding	94	-1 days
Days open	162	0 days
Net Merit of proven service sires	$297	*
Herd turnover less dairy sales (%)	28%	-2%
Monthly average SCS	3.1	0.0
Feed cost per cwt. (milking cows)	$5.30	$0.12
Milk blend price	$14.63	-$1.49

*Net Merit changed in August 2006 and averages are not comparable.

This month, I would like to focus on some of the reproductive information available on the DHI form 202. Reproductive information fills about a third of the space on the 202, which is a lot of information to watch from month to month. Below are four figures that tell much of the story about reproductive status of the herd. Time sensitive information warning: herd averages may not reflect current reproductive practices, as averages are based on all cows in the herd rather than cows on the current “to breed” list.

• There is no one target for days open, but there are useful guidelines. For a Virginia herd milking at 22,000 to 24,000 lbs, targets for days open of 130 to 150 days are reasonable. Extended days open reduces replacement heifer births and extends average days in milk, leading to lower production per cow per day.
• To reduce days open, reduce interval to first breeding. The state average of 94 days is too long for all but the very highest producing cows. To reduce the interval, increase visual heat detection of cycling cows or try one of the synchronization systems. The major benefit of well run synchronization programs is that, for many herds, most cows get bred on 70 or 80 day interval to first service.
• First service conception rate averages 39% for DHI herds in the state. If records are complete and interval to first service is 70 to 80 days, this is a very acceptable conception rate for high producing herds. Higher is always better, but may not be a reasonable expectation. Do use good AI techniques and accurate heat detection (or synchronization programs) to improve conception.
• For a cow to contribute to “% heats observed”, she either needs to be bred or have a “heat not bred” reported. Heat detection rate means different things to different farms, depending on records are kept and how cows are determined to be in heat. State average is low, at 41% of heats observed, which is to be expected with 94 days to first breeding and voluntary waiting periods of 60 days. That’s 1.5 missed heats on every cow before the first breeding is attempted.

The search goes on for a magic bullet to get cows pregnant. Meanwhile, good records will be part of the best technology currently available and DHI is a good way to keep them.

Bennet Cassell
Genetics and Management