The optimal heifer-calving age

Resize text

A growing body of research-based evidence suggests there is an ideal age to freshen first-calf heifers. The “magic” number: 23 to 24 months.

Dr. Jim Quigley, Technical and Research Manager with Provimi North America, shares his rationale for this conclusion in a recent issue of his CalfNotes.com newsletter. He says age at first calving (AFC) has been shown in a wide range of studies – both in the U.S. and internationally -- to have a strong influence on a heifer’s ability to make milk. The trend is true in both the first lactation and over her lifetime.

As further evidence, he cites a recent University of Wisconsin study that evaluated the records of 69,145 Holstein cows that calved in 2005. The researchers evaluated the effect of AFC on both first-lactation milk yield and lifetime milk production. They divided the animals into four data sets:

1) 3X milking and rolling herd average (RHA) = 12,750 kg (3X-H)

2) 3X milking and RHA = 11,250 kg (3X-M)

3) 2X milking and RHA = 11,250 kg (2X-M)

4) 2X milking and RHA = 9,250 kg (2X-L)

The following table shows the significant difference in lifetime milk production that occurred when heifers were calved either before or after the optimal window of 23 to 24 months.

 AFC, mo. 3X-H, kg Diff, kg 3X-M, kg Diff, kg 2X-M, kg Diff, kg 2X-L, kg Diff, kg 20 38,545 1,784 33,142 -622 30,211 -2,040 25,156 -2,397 21 38,107 1,346 32,229 -1,535 31,190 -1,061 26,393 -1,160 22 36,655 -106 33,764 0 31,709 -542 26,464 -1,089 23 36,761 0 33,032 -732 32,251 0 27,015 -538 24 36,486 -275 31,332 -2,432 32,078 -173 27,553 0 25 35,846 -915 31,714 -2,050 31,978 -273 26,819 -734 26 35,506 -1,255 31,254 -2,510 31,293 -958 26,917 -636 27 34,780 -1,981 29,821 -3,943 30,415 -1,836 26,449 -1,104 28 33,989 -2,772 29,360 -4,404 30,696 -1,555 25,764 -1,789 29 32,889 -3,872 28,640 -5,124 29,710 -2,541 26,241 -1,312 30 33,110 -3,651 27,835 -5,929 29,717 -2,534 25,029 -2,524

Based on this data, Quigley provides an example of a 3X herd with a rolling herd average of 28,109 pounds of milk that calves its heifers around 28 months of age. In addition to the additional expenses for feeding and housing those heifers for an additional three to four months, that herd would sacrifice approximately 6,111 pounds of milk over each animal’s lifetime. At \$23.00/cwt., lost milk income per heifer would total \$1,386.00.

To read the full text of Quigley’s Calf Note, “Calf Note 180 – A Milk Production ‘Penalty,’ follow this link: http://www.calfnotes.com/pdffiles/CNlatest.pdf

Name
e-Mail (required)
Location

Comment:

characters left

Mycogen® brand Silage-Specific™ Corn Hybrids

No other company has more experience with silage than Mycogen Seeds. Mycogen® brand TMF corn silage hybrids are bred specifically ... Read More

)