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Stunted “Peter Pan” heifers set dairies back

Breeding heifers to calve in around 2 years old puts them on a productive track to begin paying off the costs of their rearing and avoid mounting up additional expenses while they remain open. Calving age is also a balancing act, though, because when animals start their productive life before they are mature enough to do so, it can sacrifice future performance.

Reduced milk production, more disease, and greater culling are all correlated with animals that enter the milking herd at less than 85% of mature bodyweight, said Iowa State University’s Larry Tranel. Think of these as “Peter Pan” heifers — they haven’t yet grown up, and once they are milking, the development they should have experienced can’t be made up.

“They’ll try to grow, but it’s going to be at the expense of lactation,” said Tranel on a Dairy News and Views podcast. He cited that it is seven to eight times more inefficient for animals to work toward reaching that bodyweight threshold after calving than before.

Katelyn Allen

April 6, 2023



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