Questions from a reader
Matt Steiner of Pine-Tree Dairy, OH: Share more information on your statement about the size of a cow: “The facts are in – a cow doesn’t need to be larger to be a top producer, and larger cows have more health problems, reduced fertility, and greater maintenance costs.” As you know, many people still make the claim that a cow needs to have as lots of size and capacity so that she can consume lots of feed to make milk. What research are you speaking of and what were the findings?
Dr. Les Hansen: There is no scientific evidence that a dairy cow needs to be bigger to “sustain” high milk production. Currently, the observed relationship between the production traits and body size composite is +.06 (on a +1.00 to -1.00 scale) of Holsteins in the U.S. This means there is a very slight tendency for production to increase with body size. Historically, this correlation has been about +.05, and it likely reflects those cows that have been stunted during development due to poor overall management, especially due to lung damage. A cow that has been provided a poor environment for growth is likely to have diminished potential for milk production. This observed relationship is near zero, but it makes sense that it should depart slightly from zero.
On the other hand, the underlying GENETIC relationship between the production traits and body size composite is -.10 (again, on a +1.00 to -1.00 scale), and this is the relationship used to calculate the Net Merit index by USDA. Historically, the genetic relationship between body size and production had been right at zero; however, as we have made Holsteins bigger and bigger (for god knows what reason!), the correlation has tipped negative.
Also, I have considerable first-hand experience with body size of Holsteins because of our ongoing body size study with Registered Holsteins at the University of Minnesota (the herd is located at our research station in far northern Minnesota at Crookston), in which we have selected for large versus small Holsteins for 40 years (the study was initiated in 1966 by my predecessor, Dr. Charles Young, and I have continued it). There is a huge difference for body size in the two genetic lines of Registered Holsteins in the study — after all, body size traits are highly heritable (are heavily controlled by genetics). However, the cows in our small Holstein line have significantly better fertility, longer productive lives (3 months), and fewer health disorders than their herdmates in the large Holstein line. For production, there has never been a statistically significant difference in production for the two body size lines across the 40 years of the study. In recent years, the herd average production has been about 27,000 lbs of milk (sometimes as high as 29,000 lbs), with a slight advantage (but not statistically significant) in favor of the cows in the SMALL line. Because smaller Holsteins have fewer health problems than larger Holstein cows, it probably makes sense for them to have a tendency for somewhat higher milk production.
Any comments about needing a larger cow to consume lots of roughage, etc., are just a lot of hearsay based on human intuition. I especially hear the claims by grazers that they need a cow with lots of width and depth to eat lots of forage. Numerous studies in the world have documented that shorter-legged, narrower (between the front legs), and shallower cows live longer than their larger herdmates. Most of us want a “stronger” Holstein cow, but we shouldn’t be measuring strength as width between the front legs. More BODY CONDITION is what Holstein cows need most for health and survival, and cows with more body condition appear much “stronger” than ones that are a rack of bones (or a “coat hanger” as Europeans say).
Research on the antagonistic relationship of cow body size with longevity applies in most countries in the world. An exception is Canada – in that country, bigger cows live longer. I assume that has something to do with Canada’s much higher price of milk compared to most of the world, which is propped up with a quota; therefore, Canadian dairy producers would have the luxury of keeping cows in their herd that they like to look at.
Matt Steiner of Pine-Tree Dairy, OH: What specific recommendations do you have for the Holstein Association USA to address the needs of the breed?
Dr. Les Hansen: The Holstein Association USA desperately needs a revised model of the Ideal Holstein Cow. There have been only two versions through history that I am aware of – the original one, which some of us grew up with, that reigned from 1922 to 1977, and the newer one that has been considered the ideal since 1977. All recent research suggests the “smaller and rounder” version, that was considered ideal for 55 years until 1977, is closer to the sort of cow that commercial dairy producers seek today.
Secondly, the TPI index needs major modification. That index still places 13% weight on final score type, and final score type continues to reward taller and sharper cows. Supposedly, classifiers have been trained to place somewhat less emphasis on these two traits, but the comments I hear from the field suggest there is tremendous variation from classifier to classifier on the extent of this shift. Furthermore, there clearly is no penalty in classification for cows that are extremely large and/or extremely sharp. Therefore, final score type should be removed from TPI. Another option is for “as-scored” final score type to be replaced by a “computer assigned” final score type, which has been done by the American Jersey Cattle Association for many years. With “computer assigned” final score type, individual linear traits are weighted as appropriate to improve the profitability of cows. Furthermore, the Net Merit index published by USDA is based on research and economic analysis, and it places nearly twice the weight as TPI on Productive Life (17% versus 8%) and Daughter Pregnancy Rate (9% versus 5%). Lastly, TPI currently ignores stillbirth rates.
A big part of my life has revolved around showing and judging of Registered Holsteins. However, cows with more moderate body size and with adequate body condition need to once again place near that top of classes (as they did in my youth back in the 1960s). A new trend is needed. I love to hear the word “balance” in a set of reasons.
Matt Steiner of Pine-Tree Dairy, OH: What changes should the association implement (which cows are recognized, etc.)?
Dr. Les Hansen: My observation is that the Holstein Association USA and the A.I. organizations are aware the fertility of Holstein cows must be improved, the length of productive lives of Holstein cows must be increased, and the death rates (on-farm) of Holstein cows must be reduced. However, many seem to want to force these fertility and health-related traits into a tall and sharp cow. Instead, it would make more sense to embrace the smaller and rounder body form of daughters of, for example, the Manfred sons (especially O-Man) and other bulls such as Ramos. Why attempt to force function into a body form that isn’t biological ideal for function? We have turned the Holstein cow into an ultra-slim, long-legged bovine version of a fashion model. That’s probably a pretty silly thing to do.