The contributions of high-quality colostrum to the health and productivity of dairy calves — in both their early stages and throughout their lifetimes — have been well-documented. But just how much of the colostrum produced in the United States can be classified as “high-quality”?

Researcher Kim Morrill and a team of colleagues at Iowa State University conducted a study to find out.

Study: 60 percent of colostrum on dairy farms is inadequateThe team collected 827 samples of first-milking colostrum from 67 farms in 12 states between June and October 2010. The parity of donor cows was recorded, as was the storage method of the colostrum when it was sampled — either fresh, refrigerated or frozen.

What the team found is rather revealing. Only 39.4 percent of the samples met industry standards for both immunoglobulin (IgG) concentration and a bacteria measure known as total plate count (TPC). Therefore, slightly more than 60 percent of colostrum on dairy farms is inadequate, putting a large number of calves at risk of failure of passive transfer and/or bacterial infections.

If judged only on the basis of IgG, without looking at TPC, a sizeable number of the samples still fail to pass muster. Almost 30 percent of the samples had IgG concentrations that fell below the industry standard, which is defined as having more than 50 milligrams of IgG per milliliter.

Nearly 43 percent of the samples had total plate count or TPC that failed the industry standard, which is defined as having less than 100,000 colony-forming units per milliliter.

Nearly 17 percent of the samples had TPCs that exceeded 1 million colony-forming units per milliliter. Among the other findings:

• IgG concentration ranged from <1 to 200 mg. per milliliter, with a mean concentration of 68.8 mg. per milliliter.

• IgG concentration increased with parity (42.4, 68.6 and 95.9 mg. per milliliter in first, second and third or later lactations, respectively).

• No significant differences in IgG levels were noted among breeds or storage methods.

• IgG was highest in samples collected in the Midwest (79.7 mg. per milliliter) and lowest in the Southwest (64.3 mg. per milliliter).

The findings were reported in the July 2012 edition of the Journal of Dairy Science.