Abolish Summer
Every fall we can look at our preg rate chart and see who has abolished summer and who has let it takes its toll. Production lags into the fall, increased lameness, and cull rates tell us heat stress has costs. We are told with epigenetics, the effects on calves in utero during heat stress decrease performance for generations.

You may have updated your heat stress tools years ago but maybe it is time to audit if they are good enough now. February might have been the right time for some work, but the heat of the third week of May was needed to test the systems.

The holding pen is the first priority. For robot dairies, having open space and fans around the robots, can increase visits and decrease fetch. In holding pens, cows pack together increasing their internal body temperature 1 to 3 degrees.  ft takes

8 to 12 hours to dissipate that heat in a cooled barn, then we pack them together again.

Flies Have Arrived
It took only a few days in a row of 70 degree weather to go from no flies to enough flies to cause bunching on some dairies. Our fly control products are enclosed and we are happy to discuss strategy.

Partial Herd Hoof Trimming Results in a Higher Economic Net Benefit than Whole Herd Hoof Trimming in Dairy Herds
M Waldbauer*, E. Spackman, H W Barkema, E. Pajor, S. Knauss, K. Orsel

Sole ulcers, a common cause of lameness is the costliest non-infectious foot lesion in dairy cows and one of the most prevalent non-infectious foot lesions in freestall housing systems. Costs associated with sole ulcers are treatment costs, plus

increased labor and decreased productivity and fertility. Routine hoof trimming is part of a strategy to manage sole ulcers. However, hoof trimming strategies differ among farms. The two most frequently applied strategies are: 1) partial herd hoof trimming with a 2-month interval between trims; and 2) whole herd hoof trimming at 6-month intervals. A Markov model was developed to investigate whether every 2 months partial herd hoof trimming or whole herd hoof trimming every 6 months was the most cost-effective strategy to avoid costs associated with sole ulcers. In this model, the net benefits for a 100-cow herd and the average productive life span of a dairy cow in intensive dairy systems of 3 years were evaluated. Partial herd hoof trimming was the most cost-effective strategy 100% of the time compared to whole herd hoof trimming, with a difference in 3-year net benefits of US$4,337 (95% CI: US$2,713-US$5,830). Based on sensitivity analyses, variables that were the sources of the biggest uncertainty in the model were herd size, the probability of being trimmed in a partial herd trim, and the prevalence of sole ulcers. To further investigate the impacts of herd size and of probability of being trimmed, various scenario analyses were conducted. With increasing herd size, the difference in net benefits in favor of partial herd hoof trimming increased even more. Scenario analyses about the probability of getting trimmed all indicated that targeted intervention increased the difference in net benefits in favor of partial herd hoof trimming. However, if the selection of cows to be trimmed in a partial herd trim was random, the whole herd hoof trimming strategy became cost­ effective. Therefore, targeted selection and early intervention are necessary to decrease costs associated with sole ulcers.

Culling Strategy
The Dairy Performance Monitoring Workshop took us through an exercise to consider replacing cows. Using $20 milk and $10 feed cost per cwt milk this chart was developed:
 

You may have OPEN cull cows at all of these production levels. Who should go now and who should wait? Many would still try to breed the 100 pound cow and if she is less than 180 to 200 DIM, that makes sense. The dry cows better be pregnant or we made her the most expensive cow on the farm the day we dried her up. The 25 and 50 need to go because $4 won't come close to covering variable costs. They need to be replaced with a heifer that should be at 100 pounds within a month. If your heifers don't reach 100 pounds we need to figure out why. The 75 pound open cow requires some thought. She is a break even cow considering variable costs in the $7 to $9 range. We can't milk too many break even open cows. Is there a heifer available to replace her?

We have a current heifer shortage because too many dairies didn't calculate their needs correctly when they went beef on dairy. We need to consider that only 80% of heifers born, freshen. Some didn't calculate at all. They just instituted a simplistic program that 3^rd and greater service gets beef. Philosophically, that can work if first service is to sexed at 35% CR and second is to conventional at 40% CR generating 36 freshening heifers per 100 animals bred to supply a 36% cull rate.  All services to conventional semen at 40% CR we only generate 26 freshening heifers per 100 animals. This barely supports an unachievable cull rate. Sexed semen on the heifers may have higher conception rates, but you still have to do the math with your numbers. Heifers are very difficult to buy, so strategize to secure what you need.

What about culling pregnant cows? Historic, conventional wisdom was that we don't sell pregnant cows. We work so hard to get them pregnant that we would never sell them. That may be even more true now as we consider both the value of the calf and future production potential. If we use a $500 calf (they aren't all $800 and they won't be forever) with a 8% stilllbirth rate (4% is the goal), we have $460 pregnancy value with a feed cost and overhead to get her to calving. If overhead is $1 per day and maintenance feed cost is $3, she could be dry 115 days to break even on the calf. We don't stay in business breaking even. Replacing her with 100 pound heifer generating $14 IOFC takes 33 days to pay for the value of the calf in the pregnant dry cow. Assuming the overhead is the same, but it is more for the lactating cow. There is also the transactional cost of about $1000 for selling an 1800 pound cow and replacing her with freshened heifer. At $14 per day IOFC, it takes 71 days to make up the transaction. What about the production potential of the 4 month pregnant cow making 75 pounds of milk? She is going to milk for 3 more months averaging 60 pounds per day or $5.40 IOFC per day or $486 IOFC plus $460 for the pregnancy and a dry cow cost of $240 for a net of $706. Meanwhile if there was a heifer available to give 100 pounds of milk for 5 months at $14 IOFC or $2100 minus the $1000 transaction costs nets $1100.  This is food for thought and I invite you to think through this process with your numbers. So, "Replace potential culls sooner than I ever thought." Of course, the numbers change with cheaper calves and culls.