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.

How Much Hay is Needed to Make

A Difference in a Calf's Rumen?

How much hay (on a dry matter basis) is needed in a calf's ration to make an observable difference in her rumen (difference defined as rumen pH, concentration of total volatile fatty acids and plaque formation)?

In their work (Bieranvand, H. and Others, "Interactions of alfalfa hay and sodium propionate on dairy calf performance and rumen development". Journal of Dairy Science, April 2014, 97: 2270-2280) the authors compared rations with and without alfalfa hay at levels of 5 and 10 percent of concentrate ration. The "control" ration was a grain "meal" and the hay was chopped and added to get the desired feeding level.

In my reading of the results it looks as though the critical value for including chopped hay was ten percent of the starter grain ration. This was chopped to small pieces (average length only 0.1 inch). When hay was included this way the calves actually ate more "starter" during the first six weeks (over 1 pound a day compared to just under three-fourths of a pound daily - 33% more). 

Using a threshold of daily "starter" intake of 2.2 pounds a day to wean calves the 10 percent hay ration calves average weaning age was 45 compared to control (no hay) calves at 59 days. 

At 70 days the 10 percent hay calves averaged 196 pounds while the control calves came in at 176 pounds. 

I was impressed by the microscopic images from the rumens. The keratin layer was much thinner for the 10 percent hay calves than for the control calves (keratin builds up on the rumen wall reducing the efficiency of absorption of nutrients). 

These findings are from small samples of calves and from only one study. Nevertheless, they suggest that we think about how to introduce small amounts of nutritious roughage to relatively young calves. I am sure that chopping forage is only one way to accomplish this goal.

Ice on the Truck Windshield

Yes, there was ice on my truck windshield at 6:00 am this Wednesday, May 7. My sweatshirt felt just fine. None too warm here in western New York State.

I comment on this fact to emphasize that the weather and the calendar do not necessarily go together. It may be a little too soon in some parts of the US to consider adopting "summer" practices. 

If you need to wear a sweatshirt when you start the morning feeding your calves have been burning fuel to maintain their core body temperatures. Remember during the spring season of the year it is not 2:00 PM highs that determine energy needs for the young calves but rather the 4 AM lows. 

If your calf barn has curtain walls remember to make that last check late in the day. Depending on the weather forecast these curtain settings may be important in reducing drafts on calves during the nighttime hours.

Early  Vaccination for Lepto

How early can heifer calves be vaccinated for Lepto and be protected? That was one of the questions asked by the research team that reported their finding in Cortese, V.S. and Others, "Efficacy of a flexible schedule for administration of a Leptospira borgpetersenii serovar Hardjo bacterin to beef calves." American Journal of Veterinary Research 75:507-512, May 2014.

Very condense protocol: 55 calves in 3 treatments

1. Control - no vaccine

2. One dose of L. Hardjo vaccine (about 20-29 days of age)

3. Two doses of L. Hardjo vaccine (1st on between 20-29 days old, 2nd dose average 136 days after first)

22 days after the second vaccination all three groups were challenged with L. Hardjo pathogen.

Findings: Was it possible to isolate in either urine or kidneys the pathogen to which they were exposed in the challenge?

Control (no vaccination) had 10 out of 11 positive.

One vaccination between 20 and 29 days had 0 out of 21 positive

Two vaccinations (1st between 20-29 days, 2nd about 136 days later) had 0 out of 20 positive.

The authors conclude:

"Results of the present study indicated that administration of a single dose of L. borgpetersenii serovar Hardjo bacterin to young calves provides protective efficacy to 4 to 5 months and that administration of a second dose of the bacterin 4 to 5 months after the initial dose will elicit a substantial anamnestic response. [or, "4 to 5 months after the initial dose will significantly increase protection against infection]

Maybe it is time to dust off our vaccination protocol and see if any changes are needed?

Small Group Housing and Illness

Real, on-farm conditions for research. Unusual but welcome. 

"Group housing of Holstein calves in a poor indoor environment increases respiratory disease but does not influence performance or leukocyte responses." C. J. Cobb and Others, Journal of Dairy Science, 97:3099-3109, May 2014.

These were well managed calves (excellent colostrum management, very good blood serum total protein values, 2.2 pounds of 28-20 milk replacer fed daily, ad lib. water and calf starter grain) in a very common farm housing situation - the approximately 100 x 70 barn had only two sidewall openings of 12' x 9'.

Calves were in pens that provided about 23 square feet per calf. The three compared treatments were 1 calf in a 6' x 3.8' pen, 2 calves in a pen double that size and 3 calves in a pen triple that size. 

Health and mortality:

                              % treated                           % Died

                             for resp. disease

1 calf per pen             10                                     7

2 calves per pen         23                                    23

3 calves per pen         34                                    17

These calves were in a poorly ventilated barn in the summer, humidity ran around 74% and temperatures varied from 67F to 94F. You can imagine the air borne pathogen load in this barn. Evidently being housed with other calves seemed to be the straw that broke the camel's back for respiratory infections. My observations is that only good colostrum management and nutrition kept the infection rates as low as they were.

Growth:

No observed differences among the three housing arrangements either during the preweaning period or out to 161 days of age.

There was an interesting profile of growth rates during the preweaning period. By the end of three weeks the calves had ramped up to 1.8 pounds per day.

Then, (no explanation given in research report) growth rates dropped to about 1.1 pounds per day from 21 to 54 days of age. There was not mention of milk refusals so I have to assume all the calves drank their milk (fed 2X with 3 quart bottles). However, when one looks at calf starter intake, even at 5 weeks of age the calves were averaging less than 1/2 pound of starter daily. 

That starter intake matches my experience - under hot humid conditions and plenty of milk replacer powder calves just lag on eating their starter. The poorly ventilated barn just made a bad situation worse. 

Bottom line? Poor facilities compounded with elevated pathogen exposure can overcome good colostrum management and nutrition.

Costs to Raise Heifers

$2,084. Yes, that was the total cost to raise a replacement heifer in New York in 2012.

This recently released report may be found at 

http://ansci.cornell.edu/pdfs/DairyReplaceCost12-3.pdf or click Here.

This summary was posted at the Pro-Dairy website:

Dairy Replacement Programs: Costs & Analysis 3rd Quarter 2012 Published

The analysis of the costs to raise dairy replacements during the 3rd quarter of 2012 are complete, and the final report is now available on the PRO-DAIRY Web site at http://ansci.cornell.edu/prodairy/resources/fbmpubs.html.   This is the fourth time that the costs were reviewed on dairy farms located across New York State. The average total cost to raise the dairy replacement (not including the value of the animal when born) until they entered the herd for each of these studies was: 1993      $1,044 2003      $1,429 2007      $1,734 2012      $2,084 The top five expenses per heifer completing the dairy replacement program for the 3rd quarter of 2012 are:  Feed per Heifer:  $1,112  53.3%  Labor per Heifer:     $252  12.1%  Interest on Daily Investment per Heifer:     $143    6.9%  Bedding per Heifer:       $90    4.3%  Building Ownership per Heifer:        $90    4.3% These five expenses represent 80.9% of the total cost to raise the dairy replacement. Average raising cost per day per heifer was $2.995 with an average calving age of 23.0 months. The average daily costs ranged from almost $6.50 while the calf was on liquid feed, to $2.00 to $2.20 per day from weaning to breeding to $2.60 to $2.70 from breeding to close-up and back over $3.50 right before calving.