Using Records to Evaluate Production
Dr. Allen Young
USU Extension Dairy Specialist
Evaluating production is necessary, but sometimes hard, because everyone has a different idea of what constitutes good milk yield. Everyone has different likes, dislikes, and goals. From my side of the tracks, it becomes a problem of trying to tell someone their milk production is too low without arousing hard feelings that are counterproductive to the discussion. Having said that, I have certain things I look at when evaluating someone�s production, and hope sharing them might help you. Some of these things have been mentioned in other articles I have written.
- In terms of importance, I want to know where your herd has been (historical), where you want to go (goals), then where are you at now. If you are at 60 lbs and want to be at 90 lbs in the next month or two, I know there are unrealistic expectations/goals involved. I want to know how your 1st, 2nd, or 3+ lactation cows are producing in relation to each other because then I can start to determine if there are management practices holding you back from reaching your goals.
- The demographics of your herd are important. I look at the percent of 1st, 2nd, and 3+ cows in the herd. If a large percent of the herd are first lactation cows, then I expect the herd average milk to be lower because of the influence age and maturity have on production.
- Fat and protein % - I am very interested in historical as well as >current levels of milk fat and protein %. If fat % is in the low 3's it >is a yellow light and below 3.0 % it becomes a red light. Protein % >below 2.8% is a red light. I also look for protein: fat inversions - >especially by DIM and by string. This can give you a �heads-up� on potential or developing problems. Low milk fat % can signal an acidosis situation brought on by low fiber or over processed feeds. Milk production and cow health can be compromised.
- Peak milk and DIM at peak - I am a big believer in monitoring peak milk. It is an excellent way to monitor transition and early lactation management and nutrition. Every year I run reports from DHI-Provo that list peak milk by production and lactation number. I use these frequently to determine whether or not a herd is on target. It is important to look at peak by lactation number. Industry average of the ratio of 1st lactation to 2nd lactation peak milk is 77-78%. Lactation 1 vs 3+ ratio is 74-75%, and lactation 2 vs 3 ratio is 96-97%. Over the past 10 years, average peak milk has gone up, and DIM at peak has also increased from about 55 - 60 DIM to about 67 DIM for 2+ lactation cows. First lactation cows have increased DIM at peak from 80 to 93. If DIM at peak has increased on your dairy without an increase in peak production, you should consider making a management change.
- Persistency (measured by 30-Day Change in FCM) - when you think of a normal lactation curve, you have milk production that increases, peaks, then decreases. Persistency is a measure of how fast that decline is taking place. Provo-DHI uses a system based on total pounds of FCM lost during a 30-day period (month). Average 30-day change in FCM in 2001 (Rocky Mt DHIA), showed that first lactation cows decreased by 1.4 lbs, second lactation by 4.0 and third and greater by 4.6 lbs for an overall average of 3.2 lbs. If your numbers are larger than these, then your persistence is LESS than the industry average. If your numbers are less than these, your cows are MORE persistent than average. When I am determining the effects of extended DIM in a herd, I use 0.15 - 0.17 lb
milk per day loss as a benchmark. This corresponds to a persistency of 4.5 to 5.1 lbs per 30-day month (see below for an example). The 30-day change in FCM for the average of all cows is 3.2 lbs and is equivalent to a decrease of about 0.11 lb per day.
- Average DIM - The industry average is over 200 DIM and has steadily increased until the last 3 years, during which it has leveled off. This increase in DIM is primarily due to poor reproduction efficiency. High DIM will put a lid on milk production, because as DIM increases you have a greater percent of your herd in late lactation. As stage of lactation increases, milk production decreases. Dairy producers with long DIM who want to increase daily milk production per cow become frustrated when little change is made. When comparing milk production between lactation groups or strings, MAKE SURE you correct milk per day to reflect differences due to DIM. You do this by using the persistency values above. For example, ignoring DIM, the difference in production between a 1st lactation cow producing 62 lbs milk (230 DIM) and a 3+ lactation cow producing 70 lbs of milk (160 DIM) looks normal until you correct for the DIM. After making the correction, there is no difference between the two, not something you want to see ((230 - 160) * 0.11 = 7.7 lb difference; 70 - 7.7 = 62.3).
Evaluating production is necessary. An under-standing of milk yield and milk components dynamics is necessary to understand what is going on at your farm. Milk production is your primary source of income and should be maximized for your situation and goals. If you would like help in this area, give me a call at (435) 797-3763 or write to email@example.com