The Impact of Heifer Supply on Production, Udder Health, Profitability & Welfare with Dr. Michael Overton, Zoetis; Dr. Tom Overton, Cornell University; Dan Siemers, Siemers Holsteins

This episode was recorded at the 2025 Western Dairy Management Conference in Reno, Nevada.

Mike gives an overview of his three presentations at the conference regarding heifer supply. The panel discusses how the industry went from too many heifers to not enough heifers. (3:46)

Clay asks Dan about his breeding philosophy from a semen standpoint right now as a purebred Holstein breeder. He suggests skating to where the puck’s going versus where it’s been, and focusing on yield and protein after such a large emphasis on fat. He also emphasizes health traits, particularly because the industry needs cows to last longer due to low heifer supply. Mike notes that this can have negative impacts, including lower milk yield, more chronic mastitis, and perhaps elongating the generation interval of genetic gain. He shares that while huge strides have been made in genetic improvement for yield and components, we have gone backwards a bit on disease resistance and fertility in the last five years or so. Tom suggests that it just ups the ante on management, especially with an older milking herd. (10:55)

The panel talks about sexed semen (beef and dairy both) and IVF/embryo transfer. (14:49)

Mike details some research in Holstein herds that decreased their replacement rate and number of heifers calving from 2020-2022 (surplus herds) compared to 2023-2024 (short herds). Short herds kept cows 25 days longer in milk, but the net impact was an average of seven pounds less milk per day over the last 30 days prior to culling. He also noted an increase in chronic mastitis in the short herds.  (20:18)

Mike describes his presentation regarding the heifer completion rate: once a heifer is born alive, what’s the expected percent of heifers remaining at first calving? Many producers have a false high assumption of this number, around 90%. In 65 herds Mike analyzed in the last year, the median completion rate was 76%. He details the different life stages during which losses occurred, along with management considerations to reduce these impacts. Dan shares his perspectives on the heifer completion rate. (24:11)

The panel discusses a variety of topics around heifer supply, including whether heifers are entering the herd at a younger age to compensate for low inventories, appropriate heifer size at calving, optimal age at first calving, and just how short the supply of heifers is.  (29:01)

Panelists share their take-home thoughts. (38:35)

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