Why Productive Life Matters

Around the globe there is a growing need to extend the productive lifetime of dairy cattle. There are several important drivers for this. Rising feed prices and declining water availability mean fewer livestock can or should be raised. Environmental concerns – such as soil phosphorous levels – necessitate raising fewer animal units. In some European countries this is already legislated. Furthermore, there is a strong economic and social license component to extending the productive life of cows.

What is productive life? Productive life can be defined as the time from first calving to culling, when the cow is deemed as no longer sufficiently productive. Average herd lactation is often used as a proxy for productive life. The genetic trait, productive life (PL), may influence actual productive life; this is not what we will be discussing below.

Unfortunately, the average lactation of many dairy herds is low (2.1-2.2), which means the animal’s productive life is limited. Many cows still have a replacement or “mortgage” cost when they leave the herd, as their breakeven point is invariably in the 2^nd lactation. Breakeven is that point when the heifer raising costs equal the cumulative cash return from milk production. Consequently, it makes sense that healthy high-producing mature cows (Lact>2) are most profitable since they have surpassed their raising costs. Unfortunately, all too often demographically young herds prevent the dairy from maximizing profitability. Several factors contribute to this trend, such as high heifer inventories – we could refer to this as “heifer pressure” – as well as high involuntary culls.

So, what needs to be done differently? Consider the following areas to better understand if you could be leaving money on the table.

Based on numerous dairy herd record evaluations, it appears reasonable and attainable to extend average lactations to 2.6-2.7. In other words, a further half lactation. This can only be achieved by increasing the number of Lact 5 and 6 animals to approximately 15% of the milking herd. These “Golden Girls” or “capstone cows” are critical. The conversation of the “Lactree” concept below pertains.

There has been significant recent research on productive life. Dr. Albert de Vries published a compelling article in 2019 (J. Dairy Sci 103 No 4) identifying five key factors influencing herd demographics. The five drivers of the total cost of maintaining herd structure are:

• Calf value opportunity cost
• Aged cow cost
• Lack of maturity cost
• Herd replacement cost
• Genetic opportunity cost

Increasing productive life offers economic opportunity in calf value, cow maturity, and heifer replacement costs, while an eye needs to be kept on the potential cost of aged cows and the loss of genetic opportunity.

Normally, the presiding dogma is that younger is always better. However, if these superior younger animals do not get the opportunity to mature, this is a moot point. Remember, almost any mature cow will outproduce a heifer. This belief becomes even more dangerous if these younger animals occupy a significant percentage of the herd e.g., 45-50% of the milking herd. The “Golden Girls” need to be healthy, fertile, and with a high energy corrected milk production (ECM >6lbs fat and protein/day). Furthermore, it also follows that we need MORE of them. As mentioned previously, a goal of 15% Lact 5 and 6.

Keeping cows healthy is vital as diseases, such as lameness or mastitis, and lack of good health can lead to premature exit from the herd. And in this regard, older cows do tend to have more health challenges that can increase the temptation to replace them sooner.

The successful implementation of sexed semen, improved raising of calves, improved reproductive protocols (e.g., Double Ovsynch program), as well as an industry-wide focus on the pregnancy rate traits, have resulted in a trend toward high heifer inventories. In a market where these animals are not easily sold for profit, there is a trend to calve these animals into the herd. This becomes an inordinate push that forces our “Golden Girls” out of the herd. It’s driven from below. The question that needs to be asked is how many heifers are needed to meet the herds replacement needs? There are many equations available that can help you calculate how many heifers you really need. Here’s one to consider:

2 x (herd size, dry and milking) x (TOR (turnover rate) x (AFC (age of first calving) / 24) x 1 + NCR (non-completion rate, as a decimal).

From the above equation, it follows that the turnover rate (TOR) is very important. Low culling rate lowers the needed heifers required and low culling helps reduce the “heifer pressure”.

There are four main collective reasons for cows being culled, otherwise known as the “Four Horseman of the Apocalypse”. They are transition, mastitis, lameness/injury, and reproduction/production. Heat stress is a fifth factor that detrimentally affects all the other reasons for culling. Elite mature herds have mitigated heat stress and are managing the “Four Horsemen” well.

Culling can be further subdivided into involuntary and voluntary reasons. Knowing why and when cows leave is critical because it helps focus the dairy on prevention and management of the “leaky bucket”. The voluntary reasons include poor production and being sold to a dairy. The involuntary reasons include infertility, mastitis, lameness, injuries, respiratory diseases, metritis, displaced abomasum, and death. The goal of any dairy should be to convert more involuntary culls to voluntary culls. We need to be pushing our herd’s productive life up from the bottom by retaining cows and “graduating” them into higher lactations.

Every dairy can be represented as a “tree”, where each parity group is a layer of branches with increasing parity. The lactation tree or “Lactree” is a term I coined and one that helps any dairy identify the current situation and the opportunity to improve. If you look at the image below, you can see the tree on the left is rather flat. I have heard it described as a Chinese hat or limpet. This represents a very young herd, with a large percentage of Lact 1 and Lact 2 animals. Many dairies have this shape. The figure on the right looks more like a tall pine tree, or a road traffic cone. There are more Lact 5 and 6 animals. These are the “Golden Girls” or “capstone cows” that allow a lower percentage Lact 1 and consequently a lower culling rate and heifer inventory. Note that the percentage of Lact 1 and average annual herd culling are very similar percentages.

A rule of thumb is Lact 3 and 4 should be 30% plus of the herd and Lact 5 and 6 should be 15%. Furthermore, to maintain the structure of the “Lactree” it is also critical to trim the tree appropriately. For example, if Lact 2 are heavily culled, this creates a problem because the tree will be very narrow in the ensuing years since replacements come from the bottom. In fact, some herds “lactree” look like they’ve been struck by lightning! Very few animals in later parities. Be aware that older cows require extra attention, but Lact 3 animals usually produce 5k pounds more annual milk (M305) than Lact 1 animals, and so can afford some extra attention.

Keeping healthy, mature, and productive cows through their third lactation can help you capture their full profit potential. Be aware of heifer pressures, involuntary culls, and your lactree. In the end, this can reduce your overall costs and help extend the productive lifetime of dairy cattle.