Are your Jersey heifers calving in too old?

Notes from Larry Schirm – Genetic Marketing Manager/NA Jersey Business Development and Dick Smith – Manager, Jersey Sire Selection

A recent article published in Hoard’s Dairyman brought to light the ideal age of calving Holstein and Jersey heifers, and much to our surprise, the age for Jersey herds calving in their heifers averaged 25 months of age (older than what is ideal for Holsteins).

On page 168 of Hoard’s March 10 issue, Jeff Stevenson shares a California study that shows the ideal age to calve Holstein heifers is around 24 months (23 to 24.5), and yet the Raleigh data in the table shows 607 Jersey herds calving their Jersey heifers at 25 months of age…older than what is ideal for Holsteins. All Jersey owners know their Jerseys mature younger than the Holsteins – and yet these Jersey heifers are calving in on average older than what is ideal for Holstein heifers? Keep in mind this ideal age for calving Holstein heifers is based on the greatest lifetime profit potential from lifetime milk production.

March 10, 2011 Hoard's Dairyman

Chart Published in March 10, 2011 Hoard's Dairyman

There is a real issue to address here. Are all dairy producers on average – especially Jersey dairy producers – missing profit opportunities with delayed first breedings in their heifer pens? Is it because many of the Jerseys are calving in seasonal grazing operations? Is that why the average age is higher than ideal?

Or is it that there has just not been enough attention or focus brought to this topic for Jersey owners (and crossbred F1)? Jerseys are likely to perform at greater returns in their lifetime if they calve in at 23-24 months (possibly younger), rather than losing the first 45-60 days of lactating by waiting to calve them in at 25 months on average. Does the higher fertility in Jerseys tend to lesson the focus on heifer AI management in Jersey herds?

The conception and pregnancy rates between Jersey and Holstein heifers actually differ very little. The fertility of virgin heifers – Jersey or Holstein – is quite good. The breed difference shows up following that first calving, in which the dystocia levels differ dramatically between Holsteins and Jerseys. The average age at calving in the Hoard’s article data, for example, is only three weeks difference between Holsteins and Jerseys – one heat’s difference…Someone could almost say that Jerseys mature ‘one heat period sooner’…

If that’s the case, Jersey heifers are calving ‘one heat period sooner’ than Holsteins, and ideally Holsteins should be calving in that 23 to 24.5 range. Why are our Jersey heifers on average calving at 25 months and not at 22.5 to 23.7 months? If Holstein heifers should calve by 24 months on average, shouldn’t your goal be to calve in your Jerseys and F1 crossbred Jersey/Holsteins heifers by 23 months?

Here are a few things to keep in mind when deciding when to breed your Jersey heifers:

  • Heifers in milk generate more revenue than heifers that have never calved.
  • Jersey females have younger onset of puberty than Holsteins.
  • Jersey females and Jersey-cross females can have trouble-free calvings at a younger age than Holsteins in the same herd.
  • Individual herd management strategies should determine optimum calving age. In general younger is better.
  • Once the seasonal calving goals and growth rate of heifers have been determined producers should establish targets for age at first calving (This may not be the same for all seasons.)
  • Once the targeted goals are established nutrition and reproductive management programs should be intensified toward those goals.

Age at first calving is a one-time benefit that is available in all Jersey and Jersey-cross females. When you lower age at first calving you will reduce rearing cost per lactating female. Herds using Jersey genetics need to manage them in a way to realize their full potential, which is likely to differ from conventional Holstein setups.

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