A good start on having a profitable dairy farm is a high milk price; however, the fundamental need is astute management of the cows, facilities, personnel, and the flow of funds.
Good managers need information on which to make decisions, rather than it “just feeling right from the gut”. Information can be gathered from many different sources for decision making, but some of it can only come from gathering the information (data) on the farm.
The slogan by DHI for years was “If you don’t measure it, you can’t manage it.” Production records on dairy farms, regardless of which milk metering or computer software system is used, is very important for assessing how well the animals are performing and to monitor the impacts of changes.
So in this article, we will review some of the important aspects of using milk production records.
First, let’s review of the terms used to describe milk production and some bench marks:
Peak Milk: Period of time (days in milk; DIM) when milk yield within a lactation reaches its maximum level (usually about 60 DIM). First calf heifers will peak later than older cows, possibly as much as 30 to 40 days later.
Research has shown that for every increase in peak milk yield, total lactation milk yield will increase by about 220 lb. In general, the pounds of peal milk for heifers should be within 75% of parity 3+ cows, heifers should peak within 80% of second lactation cows, and second lactation cows should peak within 90% of the 3+ cows.
However, you must keep in mind that a high percentage relative to another group could mean the older group is not peaking high enough. The expected peak milk yield to result in a given total lactation milk yield is reflected in Table 1.
Low peak milk yield can be attributed to poor transition diets, under conditioned cows at calving, over conditioned cows that experience metabolic problems (subclinical or clinical), limited bunk space, and social dominance of older animals with first calf animals.
Summit Milk: The average of the two highest testdates for a cow among the first three tests within a lactation. Thus, the summit milk will be lower than peak milk.
Persistency of milk production: Average decrease in milk from peak lactation (lb/day or week or month). In general, first lactation cows will decrease about 2.5 lb/day and older cows decrease by about 5.0 lb/day over a 30-day period; however, persistency of milk yield is much less related to total lactation milk yield than peak milk yield. So although cows that peak higher are usually less persistent in their milk yield, these cows will produce more milk in the total lactation than lower peaking cows.
Mature equivalent: This is a means of standardization of a lactation record to the level of yield that would have been attained if the cow had been mature and calved in the month of highest calving frequency for her breed. Thus, the amount of adjustment is much greater for first than second lactation animals.
Fat-corrected milk (FCM): This is a means of adjusting the milk yield for the amount of fat in the milk to reflect the relative energy concentration in the milk, thus if reflects the amount of energy required to produce the given amount of milk.
This is especially useful in comparing the yields of milk among different breeds of dairy cattle. Historically, the milk production was adjusted to a common fat percentage of 4%, but the most common adjustment today is to 3.5% since most the prominent breed of dairy cattle is Holstein, which average about 3.5% fat in milk.
The respective equations for making these calculations are: 4% FCM = (0.4 x lb milk) + (15 x lb fat); 3.5% FCM = (0.432 x lb milk) + (16.23 x lb fat).
Energy-corrected milk (ECM): The ECM is similar to FCM, except that it takes into account all the major components in milk that affect its energy concentration (lactose, fat, and protein), not just lactose and fat. The ECM adjusts milk yield to an equivalent energy basis assuming 3.5% fat and 3.2% protein; ECM = (7.2 x lb protein) + (12.95 x lb fat) + (0.327 x lb milk).
Extended 305 milk: Partial lactation records can be extended to 305 DIM based on current production, date of calving, breed, etc. The first lactation cows should be producing at 80% or higher of the 3+ parity cows.
When comparing extended 305 d ME milk yields among different parity groups, the increasing genetic potential within a herd should result in each younger generation having a higher yield (first lactation > second lactation > 3+ lactation); however, this is not what is usually observed.
Because of the intensive culling that often occurs at the end of lactation for first-lactation cows, the second lactation cows usually result in being the elite group.
So in general with typical culling practices, the second lactation cows should have about a 500 lb edge on milk yield versus the first-lactation group, but the first lactation group should be about 500 lb higher on yield than the 3+ lactation group.
We often want a reference for a herd or cow on yearly average production, often referred to rolling herd average (RHA; this is based on the rolling off and on of additional measurements of milk yield so the average reflects 12 months).
You can estimate the RHA for milk by multiplying the average daily milk yield by 365. The RHA for milk should be within about 90% of the ME milk yield.