The value of colostrum continues to rise, as both a calf-health enhancement, and possibly an additional source of farm revenue.
Researchers at Cornell University recently completed a study to evaluate whether supplemental oxytocin at the first milking could improve colostrum volume, quality, or both.
Working with a commercial dairy with more than 5,000 cows, fresh cows were treated intramuscularly with either 40 international units (IU) of oxytocin, 20 IU of oxytocin, or no oxytocin. The cows were milked in a rotary parlor, and treated approximately 45 seconds before attachment of the milker until.
Colostrum yield was measured via weight, and quality was evaluated for total immunoglobulin G (IgG) using radial immunodiffusion. Dry-matter percentage was determined via oven drying.
After evaluating a total of 636 fresh cows, including 201 first-calf heifers, the researchers found:
- The median colostrum yield, encompassing all cows in all treatment groups, was 13.2 lb./cow. This number ranged from 0-45.4 lb.
- The median IgG content was 98.5 g/L.
- First-calf heifers responded favorably to the highest dose of oxytocin (40 IU). The average production of the 40-IU group was 11.9 lb./cow, compared to 9.0 lb./cow for the 20-IU group, and 8.4 lb./cow for the untreated control group.
- Multiparous cows did not show the same production response to oxytocin, with no significant difference in colostrum yield between treatments.
- There were, however, sub-groups of cows in the multiparous population that did show a significant production response to the highest dose of oxytocin. They included second-calf cows; cows giving birth to male calves; cows with the highest milk production at week 4 of lactation; and cows with a dry period longer than 65 days.
- In terms of quality, oxytocin use had no influence on IgG levels in either first-calf or multiparous cows. As a whole, and independent of oxytocin dosage, IgG concentration was significantly higher for 4th-lactation and older cows, and cows with dry periods of longer than 65 days.
The Cornell researchers concluded that the supplemental oxytocin was valuable in helping first-calf heifers achieve milk let-down as they navigated the novel stressors of being milked for the first time in a rotary parlor. The treatment had little appreciable effect, however, on the colostrum yield of older cows, or the quality of colostrum produced by any animals in the study.
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