The objective of this study was to characterize the quality of maternal colostrum (MC) fed to newborn dairy calves in the United States and identify the proportion of MC that meets industry standards for IgG concentration and total plate count (TPC). Samples of MC (n=827) were collected from 67 farms in 12 states between June and October 2010. Samples were collected from Holsteins (n=494), Jerseys (n=87), crossbred (n=7), and unidentified dairy cattle (n=239) from first (n=49), second (n=174), third or greater (n=128), and unknown (n=476) lactations. Samples were identified as fresh (n=196), refrigerated (n=152), or frozen (n=479) before collection, as well as whether the sample was from an individual cow (n=734) or pooled (n=93). Concentration of IgG in MC ranged from <1 to 200mg/mL, with a mean IgG concentration of 68.8 mg/mL (SD=32.8). Almost 30% of MC contained <50 mg of IgG/mL. The IgG concentration increased with parity (42.4, 68.6, and 95.9 mg/mL in first, second, and third and later lactations, respectively). No differences in IgG concentration were observed among breeds or storage method; however, IgG was highest in samples collected in the Midwest and lowest in samples collected in the Southwest (79.7 vs. 64.3 mg/mL). Total plate count of samples ranged from 3.0 to 6.8 log(10) cfu/mL, with a mean of 4.9 log(10) cfu/mL (SD=0.9) and was greater in samples collected in the Southeast compared with other regions of the country. Pooled samples had greater TPC than individual samples and refrigerated samples had greater TPC than frozen and fresh samples. Almost 43% of samples collected had TPC >100,000 cfu/mL, 16.9% of the samples had >1 million cfu/mL. Only 39.4% of the samples collected met industry recommendations for both IgG concentration and TPC. Almost 60% of MC on dairy farms is inadequate, and a large number of calves are at risk of failure of passive transfer or bacterial infections, or both. Also, the data indicate that regional differences exist in colostrum quality.

Our objectives were to evaluate the use of refractometry as a means of estimating immunoglobulin G (IgG) concentration of bovine maternal colostrum (MC) and determine if fractionation of MC using caprylic acid (CA) improved estimates of IgG. Samples (n=85) of MC were collected from a single dairy in California and used to determine the method of CA fraction that produced the best prediction of IgG based on CA fractionation followed by refractometry. Subsequently, samples of MC (n=827) were collected from 67 farms in 12 states to compare refractometry with or without CA fractionation as methods to estimate IgG concentration. Samples were collected from the feeding pool and consisted of fresh (n=196), previously frozen (n=479), or refrigerated (n=152) MC. Samples were further classified by the number freeze-thaw cycles before analysis. Fractionation with CA was conducted by adding 1 mL of MC to a tube containing 75 μL of CA and 1 mL of 0.06 M acetic acid. The tube was shaken and allowed to react for 1 min. Refractive index of the IgG-rich supernatant (nDf) was determined using a digital refractometer. Whole, nonfractionated MC was analyzed for IgG by radial immunodiffusion (RID) and refractive index (nDw). The relationship between nDf and IgG (r=0.53; n=805) was weak, whereas that between nDw and IgG was stronger (r=0.73; n=823). Fresh samples analyzed by refractometry that subsequently went through 1 freeze-thaw cycle before RID analysis resulted in the strongest relationship between IgG and nDf or nDw (r=0.93 and 0.90, respectively). The MC samples collected fresh on the farm but frozen 2 or more times before analysis by refractometry or RID had low correlations between IgG and nDf and nDw (r=0.09 and 0.01). Samples refrigerated or frozen on the farm before analysis had weaker relationships between RID and nDf or nDw (r=0.38 to 0.80), regardless of the number of freeze-thaw cycles. Breed and lactation number did not affect the accuracy of either test. These results indicated that refractometry, without or with CA fractionation, was an accurate and rapid method to determine IgG concentration when samples of MC were not previously stored before refractometry and frozen only once before RID analysis.

No abstract

and Implications Samples of maternal colostrum (MC) were collected from 67 farms in 12 states between June and October, 2010 to determine IgG concentration and bacterial contamination. Samples were identified by breed, lactation, and if the sample was fresh, refrigerated or frozen prior to collection. Concentration of IgG in MC ranged from < 1 to 200 mg/ml, with a mean IgG concentration of 68.8 mg/ml. Nearly 30% of MC contained < 50 mg of IgG/ml. The IgG concentration increased with parity (42.4, 68.6, 95.9 mg/ml in 1st, 2nd, and 3rd and later lactations, respectively). No differences in IgG concentration were observed among breeds or storage method, however, IgG was highest in samples collected in the Midwest and lowest in samples collected in the Southwest (79.7 vs. 64.3 mg/ml). Total plate count (TPC) of samples ranged from 3.0 to 6.8 Log 10 cfu/ml with a mean of 4.9 Log 10 cfu/ml (SD = 0.9) and was greater in samples collected in the Southeast compared with other regions of the country. Pooled samples had greater TPC than individual samples and refrigerated samples had greater TPC than frozen and fresh samples. Nearly 43% of samples collected had TPC > 100,000 cfu/ml, 16.9% of the samples were > 1 million. Only 39.4% of the samples collected met industry recommendations for both IgG concentration and TPC. These data suggest that nearly 60% of MC on dairy farms is inadequate, and a large number of calves are at risk of failure of passive transfer and/or bacterial infections. These data also suggests regional differences in MC quality.

graduate student; Erin Conrad, graduate student; Howard Tyler, professor of animal science Summary and Implications Our objectives were to evaluate the use of refractometry as a means of estimating immunoglobulin (IgG) concentration of bovine maternal colostrum (MC). Samples of MC (n = 827) were collected from 67 farms in 12 states. Colostrum was analyzed for IgG by radial immunodiffusion (RID) and refractive index (nD) by a digital refractometer. The relationship between nD and IgG was strong (r = 0.73; P < 0.05; n = 823). Samples analyzed by refractometry fresh and went through 1 freeze/thaw cycle prior to RID analysis resulted in the strongest relationship between IgG and nD (r = 0.93 and 0.90, respectively). The MC samples collected fresh (not refrigerated or frozen) on the farm but frozen two or more times prior to analysis by refractometry and RID had a weak relationship between IgG and nD (r = 0.01). Breed and lactation number did not impact the relationship between RID and nD. These results indicate refractometry is an accurate and rapid method to determine IgG concentration when colostrum is analyzed fresh.