Adapted by Noelia Silva del Rio, DVM, PhD, VMTRC, Tulare
Providing newborn calves with adequate IgG supply from colostrum is recognized as an essential management practice in calf rearing. Calves that fail to reach serum IgG levels above 10 g/L within the first 2 days of life are considered to undergo failure of passive transfer (FPT). Economic losses associated with FPT have been estimated to average $65 per calf when accounting for calf mortality, morbidity, and decrease in average daily weight gain.
Industry standards define colostrum as high quality when IgG concentration is greater than 50 g/L (measured with radial immunodiffusion assay). Parity, pre-partum diet, season, breed, dry-period length, vaccination of the dam, and delayed colostrum collection are factors associated with colostrum quality. In a recent survey, almost 30% of maternal colostrum failed to reach IgG concentrations above 50 g/L. Thus, to prevent FPT, it is essential to know the IgG concentration of colostrum and to restrict the first feeding to colostrum that meets the standard of quality. On-farm %Brix refractometry can be successfully used to estimate IgG concentration.
In a recent extension meeting, a dairy producer asked if %Brix readings on second milking colostrum is an appropriate method to estimate colostrum IgG. After evaluating multiparous Jersey cow colostrum samples from first and second milkings, we are able to provide an answer: YES. In Figure 1, we see there was a strong association between IgG concentrations of colostrum from first and second milkings and Brix readings. We also found that nearly half of the second milking colostrum samples from cows on their third or greater lactation (42.7%) met industry standards for desirable IgG concentrations. This warrants %Brix readings on second milking colostrum from mature cows, especially during colostrum shortage periods
Figure 1. Association between %Brix readings and IgG concentration by radial immunodiffusion assay from multiparous Jersey colostrum at first (red diamonds; n = 134) and second milking (black dots; n = 68).
Link to PDF Version: Colostrum Immunoglobulin G Concentration in First and Second Milking from Multiparous Jersey Cows