Brix Refractometer to Measure Immunity in Calves

We have another research report on the use of Brix refractometry to measure immunity in female dairy calves. If you do not care to read any farther just remember the number 8.4 to indicate passive transfer failure. 

The report, "Deelen, S.M. and others, "Evaluation of a Brix Refractometer to estimate serum immunoglobulin G concentration in neonatal dairy calves," Journal of Dairy Science 97:3838-3844 June 2014," is summarized by the authors:

"Brix refractometer measurements were highly correlated with serum IgG. A value of <8.4% most accurately predicted FTP [failure of passive transfer], providing a reasonable estimate of serum IgG concentrations in the majority of the calves tested." (page 3843)

The one reservation the authors point out is that their study population of calves was from well-managed dairies that had low rates of passive transfer failure (about 5 percent). From a practical point of view I doubt that this bias invalidates their recommendation to use 8.4% as the threshold for passive transfer failure. This number was over 94% accurate in identifying positive calves (adequate immunity similar to 5.5 BSTP). It did misclassify some calves as positive that were actually failures - at the BSTP level of 5.2 about 5% of negatives (below 5.2) were misclassified as okay.

Overall, pretty accurate for an on-farm super quick test. My recommendation now is to purchase a unit that can be used to test both colostrum and blood serum using Brix scales.

Quantity and Quality of Colostrum varies by Quarter

Start out with the assumptions that both the quantity and quality of colostrum yield is the same for each quarter on a cow. To what extent are these two assumptions true?

In an article, "Immunoglobulin variation in quarter-milked colostrum" (Baumrucker, Craig R. and Others, Journal of Dairy Science, June 2014 97:3700-3706) reported initial results looking at these assumptions.

Keep in mind that only 8 mature cows were used. As would be expected the total volume of colostrum varied widely among the 8 cows. Among cows with low colostrum yields the variation by quarter was low. Among cows with high colostrum yields the variation by quarter was quite wide. For practical purposes neither of these findings should suggest that we manage milking fresh cows any differently that we do now.

There were some small differences between front and rear quarters in antibody (IgG) concentration. The sample of cows was so small, however, that these differences could easily been due to chance.

Bottom line is keep milking all four quarters, and, at first milking, keep milking cows out (no partial milking - since if there is a difference between fore and rear quarters the rear quarters, according to these data,  have the higher antibody concentration.

The research team is continuing to look into these potential differences - so watch this space in the next year or two for the next chapter.

Electrolytes - New Developments

This 2-page summary written by Maureen Hanson for Bovine Veterinarian is worth reviewing. 

See especially:

1. Guidelines for best products

2. Importance of alkalizing agents

3. Recommended levels for contents and characteristics of commercial oral electrolytes solutions

Here is the link:

Electrolytes

Enjoy.

Giardia Challenge

Situation: Calves between 4 and 8 weeks of age with diarrhea. Already gone through three threatments with Corid for coccidiosis. No apparent response to Corid - diarrhea continuing in intensity and duration. A few calves dying.

Water samples from the source used to mix milk replacer and water calves sent to lab. Results came back: "20 immature Giardia in sample." 

Well, isn't that an unwelcome piece of news? With all the rain and runoff this spring in the western part of New York State this is not the first dairy to have their water supply compromised with surface water.

For a short information piece on this parasite see

Giardia Resource.

Why Bacteria Counts Do Make a Difference

I had a discussion this week with a calf manager about the significance of high standard plate counts of bacteria in milk being fed to calves. 

My best estimate on his TNTC (too numerous to count) as-fed milk samples for standard plate count is between 100,000 and 200,000cfu/ml.

The calf manager's point of view is that as long as he is not having serious problems with scouring calves the high bacteria counts are not worth his attention. And, to be fair, he is using electrolytes on less than twenty percent of the calves - most of those cases being concentrated in the seven to fourteen days of age calves. And, we know that cyrptosporidiosis is endemic in this herd setting. 

My point of view was different. I made the point that they are feeding somewhere between one and two billion bacteria a day to all the calves. Even if the immune systems in his calves are successful enough in coping with this exposure level there has to be an expense. Both protein and energy are being diverted from growth due to the unnecessary bacteria load in the milk.

And, if the calves are exposed to other pathogens, for example bacteria that cause pneumonia, the calves are unlikely to be able to mount as robust defense against the respiratory bacteria as they would in the absence of the huge bacteria load in the milk.

Thus, the risk of lower feed efficiency and other infections would, to me, seem to go up as calves are loaded down with bacteria in their gastrointestinal tract.

On-farm Vulnerability to Post-

Pasteurization Contamination 

Here are the data:

Farm                               Pasteurized              Fed to Calves

   A first day                      400 cfu/ml               TNTC

   A second day                 0     cfu/ml               TNTC

   A third day                     200 cfu/ml               10,700 cfu/ml

   D                                  0     cfu/ml               16,700 cfu/ml

   E                                   0    cfu/ml                2,900  cfu/ml

Pasteurized counts were directly from the pasteurizer. Fed to calves were collected as the milk was being poured into the feeding pails.

On one hand, in all cases the pasteurizer was doing its job. The two positive counts could easily have been contamination while taking the samples. 

On the other hand, all the locations managed to add some bacteria to the clean pasteurized milk. Farms D and E added a mix of Staph species, Strep species and coliforms.

Farm A on the first two samples days had TNTC for both Staph and Strep species in the "as-fed" samples . In addition in excess of 5,000 cfu/ml coliforms were present. 

It will take some time to determine what happened on the first and second day to allow such high levels of post-pasteurization contamination. With no other facts in hand my best guess is that the wash cycle for the tank that is used to transport pasteurized milk to the calves did not function properly on days one and two.

While not the case on Farm A I did discover on another farm that the effectiveness of a transport tank wash cycle was related to wash water temperature. If the operator tried to wash the tank at a time too close to the parlor wash routine the water heaters had not yet recovered - water used to wash the transport tank was well below 120F.

On another farm the regular calf care person set up the wash equipment properly so that 10 washes per week were done well. The week-end relief person was inadequately trained to do this job. Thus, the transport tank did not clean correctly for the 4 week end feedings. 

When is a Vent Not a Vent?

Two days ago I walked all the calves on a dairy in central New York State. They are housed in hutches with collars and tethered at the front of the hutch.

At this time of the year the rear vents are opened. A auto-size tire is slid under the rear of the hutch. The combination of these two adjustments should be to increase air movement through the hutch.

It was a warm day at noon. My recording thermometer read 87 F sitting on a bale of straw sitting in an unused hutch. Thus, some air movement inside hutches would be helpful.

However, when is a vent not a vent? When the person(s) bedding hutches places too much bedding too far back in the hutch. Many of the hutches were bedded well - the combination of long wheat straw and sawdust was placed far enough forward in the hutch to leave the base at the rear open for air entry. 

However, more than a few hutches had the bottom rear vent space fully blocked with bedding. So, like any other protocol, folks need to be re-trained in the spring to adopt "summer-time" bedding practices.

Perhaps you have other seasonally-specific protocols on your dairy - remember that nearly every year workers need to be refreshed on correct techniques.