Colostrometers and refractometers are two tools that are available to assess the IgG concentration of colostrum on-farm. Surprisingly, there is very little research that has evaluated the use of the colostrometer versus the refractometer in a typical on-farm setting. The purpose of this project was to assess the ease of using a digital refractometer and colostrometer to measure colostrum quality on-farm. In addition, we sought to determine the possibility of creating a criteria to pre-select animals at risk of producing low quality colostrum. From spring 2015 through fall 2015, colostrum samples were obtained from 20 multiparous cows and 20 primiparous cows. The concentration of immunoglobulins in the colostrum samples was assessed with both the colostrometer and Brix refractometer. In addition, parameters such as color and consistency of the colostrum, parity of the dam, average milk production and somatic cell count of previous lactation, any calving difficulties and sex of the calf were also recorded. There was no correlation between parity and colostrum quality. The average quality for colostrum visually appraised as yellow or thick was higher than that appraised as white or thin. However, there were several instances in which color and consistency did not correspond to quality. A lower energy ration (0.64 MCal/lb NEL) in the weeks prior to calving was associated with inferior quality colostrum (p < 0.05), as opposed to a higher energy ration (0.78 MCal/lb NEL). In addition, one cow family was identified in which all of the members produced poor quality colostrum, regardless of parity, energy intake or any other measured variables, which suggests a possible genetic influence on colostrum quality as well. Outreach was performed by creating a brochure of the study results, which was distributed at the county crop day, county fair and posted on the farm facebook site.
Several factors constitute colostrum management, such as proper assessment of colostrum quality, timely feeding, adequate volume of consumption and proper storage. Good colostrum management is associated with an adequate passive transfer of immunity to calves. Poor colostrum management can result in failure of passive transfer of immunity to the calf, which in turn leads to an increase incidence of morbidity and mortality in the first two months of life. Despite solid evidence to support the importance of proper colostrum management, surveys have indicated that colostrum management on small farms (<100 cows) is often inadequate. The majority of small dairy producers continue to assess colostrum quality by visual factors alone, based on the general perception that consistency and color are good indicators of quality. While there may be some correlation between visual characteristics and quality, actual IgG concentrations can vary greatly.
Colostrometers and refractometers are two tools that are available to assess the IgG concentration of colostrum on-farm. Surprisingly, there is very little research that has evaluated the use of the colostrometer versus the refractometer in a typical on-farm setting. Although the measurement of IgG for every cow’s colostrum can prove to be impractical in a production setting, a colostrometer or refractometer could be a powerful tool for identifying animals that produce colostrum of exceptionally high or exceptionally low quality.
The purpose of this project was to assess the ease of using a digital refractometer and colostrometer to measure colostrum quality on-farm. In addition, we sought to determine the possibility of creating a criteria to pre-select animals at risk of producing low quality colostrum. This work was performed on Hazel-Rod farm, which is a small, family-run dairy operation in northeastern Pennsylvania. Hazel-Rod farm has an average of 60 milking cows and a RHA of 23,000 lbs. The primary investigator, Sarah Hazelton, has been an owner/operator of this dairy farm for ten years. Dr. Marsh Rosanelli, the technical adviser, is a large animal veterinarian at a local veterinary clinic. She helped with determining the selection criteria for the animals and with data interpretation. The other technical adviser, Mr. J. Craig Williams, is a local Penn State Extension agent. He helped with the outreach efforts.
The first objective was to assess the ease of use and accuracy of the colostrometer and Brix refractometer in assessing colostrum quality on farm. The second objective was to develop a selection criteria to identify animals that are at risk of producing poor quality colostrum.
All of the cows and pregnant heifers at Hazel-Rod farm were housed in a tie-stall barn, with seasonal access to pasture. Dry cows and pre-fresh heifers were moved to a particular section of the barn, where they were assured individual access to a complete, balanced diet. Daily feed intake, fecal output and overall animal health was visually monitored on a daily basis.
Cows and heifers were milked for the first time within 6 h of calving. Colostrum was collected directly into a clean, stainless steel bucket milker. The bucket milker and milking claw were cleaned with the same system and chemicals used to clean the milk pipeline. Immediately after collection, the colostrum was transferred directly from the bucket milker to a clean calf bottle. Typically calves were fed at least 3 quarts of colostrum at first feeding. Each animal received an additional 3 quarts of colostrum 12 h after the first feeding. Animals were fed via milk bottle, unless they failed to consume colostrum within the first 12 h. If they did not consume colostrum from a bottle, the calf was fed colostrum via an esophageal feeder.
Parameters such as calving difficulty and leakage of colostrum prior to calving were recorded for each cow. Parity of the cow and SCC for the previous lactation, if applicable, were recorded, as well. The colostrum of every cow and heifer was tested for IgG concentration via colostrometer and refractometer at the time of collection. IgG concentration of each sample was recorded for both the colostrometer and refractometer.
From April 2015 – November 2015, a total of forty colostrum samples were taken from twenty primiparous cows and twenty multiparous cows. Three small aliquots (1.5 mL) of each colostrum sample were frozen for IgG ELISA analysis. ELISA was chosen over radial immunodiffusion, because ELISA is more precise, accurate and less labor intensive. In order to minimize the effect of freeze/thaw cycles on sample quality, sample aliquots will only be thawed once and then discarded. ELISAs were run on half of the colostrum samples, in the molecular biology lab at Mansfield University. The samples were run in duplicate.
The selection criteria for animals that may be at risk of producing low quality colostrum was any animal with one of more of the following characteristics: high SCC or chronic mastitis in the previous lactation, calving difficulties that could be linked to nutritional deficiency during the dry period, leakage of colostrum prior to calving and primiparous animals. Statistical analysis was used to determine possible correlations between lower quality colostrum and animals that fit the selection criteria.
The colostrometer and refractometer produced similar results. The refractometer was more convenient for on-farm use due to the greater durability of the equipment, smaller sample size required and ease of preparation. The results of the ELISA analysis were not reliable, due to operator error and equipment failure. Therefore, these results were not included.
There was no correlation between parity and colostrum quality. The average quality for colostrum visually appraised as yellow or thick was higher than that appraised as white or thin. However, there were several instances in which color and consistency did not correspond to quality. A lower energy ration (0.64 MCal/lb NEL) in the weeks prior to calving was associated with inferior quality colostrum (p < 0.05), as opposed to a higher energy ration (0.78 MCal/lb NEL). In addition, one cow family was identified in which all of the members produced poor quality colostrum, regardless of parity, energy intake or any other measured variables, which suggests a possible genetic influence on colostrum quality as well.
With the chosen parameters, it was not possible to develop a set criteria to select animals that would produce low quality colostrum. Current industry recommendations to test the quality of all colostrum samples is warranted, due to the numerous individual and possible genetic variables that can impact colostrum quality. In particular, colostrum from animals that experienced a lower energy intake prior to calving or that produced colostrum that visually appraised as thin or white in color should receive a higher priority for quality testing.
I am unaware if other farmers have adopted the practice of testing colostrum quality. Hopefully, the results of this study will make producers not only consider on-farm testing of colostrum quality, but also take a critical look at their dry cow nutrition program, since it appears to be linked to colostrum quality. One unusual development of this project is that a Mansfield University students were able to use the extra samples to try to validate a PCR protocol for Mycoplasma bovis. In addition, one student is currently recreating this colostrum study, but including additional parameters to test for pathogen load in the colostrum sample and passive transfer of immunity in the calf.
Education & Outreach Activities and Participation Summary
I created a brochure outlining the details and outcome of the project. The first outreach event was the Tioga County Crop Day on March 17th, 2016. Crop Day was heavily attended by regional dairy farmers. I set up a table with a display and distributed brochures. I also brought the colostrometer and refractometer for the farmers to view. The brochure about the study was also posted on our Hazel-Rod Farm Facebook site. The Hazel-Rod Facebook site has over 360 followers from around the world. In addition, I distributed brochures in the dairy barn during the Tioga County Fair.
The potential benefit to other farmers is that measuring colostrum quality on-farm removes the guess work involved in visual appraisal of colostrum samples. In addition, if producers are able to identify animals that consistently produce poor colostrum, possibly due to genetics, the producer can use this information as a tool in making decisions to cull.
Another important benefit to farmers is that they will hopefully assess their current dry cow nutrition program. Especially in times of economic hardship, farmers are more likely to make cuts to the dry cow ration. In this study, a decrease in net energy of the dry cow ration, by removal of corn silage, was associated with a significant drop in colostrum quality. So, not only will the inadequate energy intake affect the dam, putting her at risk for post-partum metabolic issues, but it will also impact the health of the calf.
Although we were not able to establish a clear cut criteria for selecting cows that produce low quality colostrum, we were able to determine that visual appraisal of colostrum quality is ineffective. Therefore, all colostrum should be tested on-farm, before making the decision whether or not to feed it to a newborn calf. The refractometer proved to be easier to use based on durability of the machine, smaller sample size required and less sensitivity to temperature of the sample.
Since energy intake of the dam appeared to influence colostrum quality, provision of a ration that ensures adequate energy intake to the dam, prior to calving, is essential. The next logical step would be to further examine energy intake in relation to colostrum quality. For example, one could examine colostrum samples from farms that feed a low energy ration to dry cows versus those that feed high energy rations. One could also examine the protein content of these rations, to see if there is an influence of digestible protein on colostrum quality. In addition, one might also want to further examine the possible genetic influence on colostrum, by examining the pedigrees of animals that produce low quality colostrum and looking for possible genetic links.