"They are making an easy 80 pounds of milk. Body condition score is good. The herd's reproduction and culling are going extremely well, but I just can't get over how much smaller their Holsteins are than most herds." This was a recent conversation I shared with another consultant while evaluating a dairy in central California.
The cows at this farm were noticeably smaller than most Holstein dairies I visit, but their milk production was above average reaching about 82 pounds on twice a day milking with no rBST and a higher forage ration than most dairies. This is not an isolated phenomenon. There are Holstein dairies scattered across the countryside with smaller framed cows getting as good or better milk production compared with their neighbor's larger framed cattle. Genetic selection for smaller framed Holsteins is a trend gaining serious momentum as dairies have been hard-pressed to maximize feed efficiency with several consecutive years of high feed prices and certainly more high feed prices to come.
The old adage is big strong cows make more milk and last longer. However, research on the relationship between type traits and production traits is variable at best¹,². If you were to look at bulls with high reliability for PTA Type and PTA Milk you would find the correlation between those traits is low (< 0.02), meaning bulls with high PTAT do not necessarily have daughters that produce a lot of milk. Conversely, bulls with high PTA Milk won't necessarily have daughters with high final score.
What we know for certain is a larger framed cow needs to consume more feed to make the same amount of milk as her smaller framed herd mate. When milk production is the same, regardless of body size, there is a clear negative correlation between feed efficiency and body weight (Figure 1). This point was emphasized in research on Jersey cattle published in the January 2012 issue of the Journal of Dairy Science³. The researchers found Jerseys are not only more feed efficient than Holsteins but also require less water, produce less waste and have a lower carbon footprint. All of these facts would hold true for small framed Holsteins compared to large framed Holsteins too.
Highlighted in Table 1 you can see that a 1,400 pound cow producing 80 pounds of milk has the same feed efficiency as her 1,600 pound counterpart making 90 pounds of milk. At this level you can make an argument as to which cow is truly more profitable in the herd. While feed costs make up the bulk of any dairies operating costs, that extra 10 pounds of milk produced by the second cow may indeed make her more profitable than the first.
However, in the case that both cows are making the same amount of milk it's obvious the smaller cow is more profitable. Furthermore, body weight gain is not free. It takes extra energy for a first lactation cow to grow to full body size or for a cow to increase in body condition score. The energy required for the 1,600 pound cow to reach mature body weight was unquestionably more than that of the 1,400 pound cow. Now consider during their first lactation the 1,600 pound mature cow was already less feed efficient than the 1,400 pound mature cow. Then you add on the extra energy that was needed to obtain mature body weight while the cows were lactating.
An example of five dairies (Table 2) randomized for body weight and milk production demonstrates the most efficient cows in the herd are smaller framed cows that produce large amounts of milk. In all five simulated farms the average feed efficiency of the cows weighing less than 1,450 pounds is 0.06 or 0.07 greater than the feed efficiency of the cows weighing more than 1,650 pounds (compare the far right two columns).
The reason the median feed efficiency is substantially higher than the average feed efficiency in Table 2 is that the less feed efficient cows migrate further from the average than the most feed efficient cows. For example, an 1,800 pound cow making 20 pounds of milk has a feed efficiency around 0.5 (or 2 pounds of feed consumed per pound of milk produced) while a 1,300 pound cow making 140 pounds of milk has a feed efficiency of 1.8 (or 0.45 pounds of feed consumed per pound of milk produced).
We can agree then that a 1,400 pound cow producing the same amount of milk as a 1,600 pound cow is more profitable. Now comes the tricky part. To get smaller cows through genetic selection you have to take one of two approaches. You can either:
1) select against bigger cows (USDA's Lifetime Net Merit selection index already does this with a negative emphasis on body size) or
2) remove selection emphasis on traits that lead to larger framed cows (such as stature, PTAT and TPISM)
If you use an index (Lifetime Net Merit, Cheese Merit or Fluid Merit) to select bulls, then the first option is a good way to penalize bulls for having larger daughters. If you do not utilize one of those indexes and instead choose bulls by traits like stature, PTAT and TPI, it may be more beneficial to remove the trait(s) from your selection criteria completely rather than setting a ceiling for it. For example, if your current selection criteria are >1,000 PTA Milk and at least one point on PTAT, Udder Composite and Foot & Leg Composite, you are better off removing PTAT from your criteria altogether than switching it so that you won't take any bulls with more than a point on PTAT. The reason this proves to be tricky is that people have different ideals. For many the "showy cow" or the cow that can win at the county fair is perceived as being the ideal cow. To be frank that cow is ideal, but she is ideal for the show ring not for the milk parlor, feed alley or freestalls. The ideal cow for a commercial dairy has high feed efficiency, stays out of the hospital pen, conceives easily and produces enough milk over her lifetime to far exceed her raising costs. That smaller cow may likely not do well in the show ring but has an easier time reaching a high level of feed efficiency and thus a higher probability of making a profit for the farm.
I am reminded of conversations that took place on two dairies regarding sire selection criteria. The first producer told me, "Even though I know they aren't the best cows for my dairy, I just want a herd of cows that I can feel good looking at."
Not long after another producer told me that he selected for PTAT and TPI above all other traits because "that's what a judge would look for" in cows at a show.
The irony is neither operation even participates in cattle shows yet they were both picking bulls that produced showy daughters. The first producer chose to stick with selection criteria that will lead to larger framed cattle that will have a more difficult time achieving a high feed efficiency ratio. The second producer decided he would begin selecting bulls based on Lifetime Net Merit and combined fat and protein instead of PTAT and TPI.
This brings us to the question you have to ask yourself: Given the choice would you rather have a herd of cows that are picture perfect or profitable to milk? Often times those characteristics are not one in the same.
1Capper, J. L., Cady, R. A. 2012. A comparison of the environmental impact of Jersey compared with Holstein milk for cheese production. J. Dairy Sci. 95:165-176.
2DeGroot, B. J., J. F. Keown, L. D. Van Vleck, E. L. Marotz. 2002. Genetic parameters and responses of linear type, yield traits, and somatic cell scores to divergent selection for predicted transmitting ability for type in Holsteins. J. Dairy Sci. 85:1578-1585.
3Vallimont, J. E., Dechow, C. D., Daubert, J. M., Dekleva, M. W., Blum, J. W. Barlieb, C. M., Liu, W., Varga, G. A., Heinrichs, A. J., Baumrucker, C. R. 2011. Heritability of gross feed efficiency and associations with yield, intake, residual intake, body weight, and body condition score in 11 commercial Pennsylvania tie stalls. J. Dairy Sci. 94:2108-2113.