Monday, July 21, 2014

If All Else Fails, Read the All the Directions!

This was a case of many too many cases of passive transfer failure. The farm was facing a management challenge due to Johne's disease. One of the control measures adopted was to feed a colostrum replacer rather than maternal colostrum to newborn calves. The bag indicates the product should be mixed with 5 cups of 110-120F water and that feeding 2 bags is recommended for good passive transfer of immunity.

Following an extended episode of scouring calves the herdsman was convinced to check immunity levels among baby calves. The results revealed that too many of the calves had blood serum total protein levels below 5.0 - a commonly accepted threshold to determine passive transfer failure.

A review of mixing procedures showed that the water being used was both the correct temperature and volume. Since time of birth and time of colostrum replacer feeding were recorded for each calf it was easy to confirm that feedings were being done promptly after birth.

As we talked a worker came into the utility room to mix colostrum replacer for a newborn calf. She ran water in a pail, opened two packages of the colostrum replacer and proceeded to mix. 

You need to know that the dairy initially used a colostrum replacer with 100g IgG per package and fed 2 packages to each calf. Somewhere along the line the decision was made to switch to a colostrum replacer packaged with 60g IgG per package. Have you already guessed what happened?

Yes, you are correct. The new product's mixing instructions used the same temperature water but a different volume. That part got through to the folks mixing the product. However, the new product says, "To replace maternal colostrum feed calf 3 bags."  Ooops! Somehow that part of the directions was overlooked. Instead of feeding the recommended 180g IgG the calves were only receiving 120g.

The story does have a good ending. Once the protocol was corrected to use 3 bags of product per calf the blood serum total protein values improved and the proportion of calves needing treatment for scours went down. Amazing, reading ALL the directions does improve performance of a product.

Thursday, July 17, 2014

The BVD-PI Test Can't be Positive!

A heifer aborted a late gestation calf. As part of our routine in this situation a tissue sample was sent for BVD-PI testing. The result was positive. The dairyman said, "The BVD-PI test can't be positive."

Let's step back for a moment. The  BVD-PI test is for an animal that was exposed to the BVD virus in utero during a window of time when the fetus incorporates the virus as a "normal" part of her body. Thus, she becomes "persistently infected" and though she is not ill she continuously sheds the virus as long as she lives.

Clearly we do not want BVD-PI animals on the dairy. This huge load of virus particles is a constant challenge to the immune system to all the other animals, both young and mature.

So, why did the dairyman exclaim, "Can't be positive" ?

He knew about  BVD and the challenge of BVD-PI animals. Before he buys springers he has them tested to be sure they are not PI positive. We had talked about testing heifer calves born to purchased heifers but he decided that he couldn't be bothered with that. Besides, he "knew" he would be able to tell by looking at a calf if she was a PI calf.

Our practice recommends that all replacement calves born to purchased dams be tested for BVD-PI status. This is not the first time a calf born to a purchased springer has come back positive at our practice. And, over the years we have seen heifers that look as normal as can be turn up positive when tested.

So where were the weak links in this situation. First, in spite of our explanation about how PI calves are created, he was so sure that if the dams were negative the calves had to be negative, too. False! Second, he was sure that even if a PI animal was born, he could reliably visually identify her. False!

What is this owner planning to do? The last I heard his regular vet and he are planning to collect samples for BVD-PI testing. Will they check all the animals? Just sample animals from purchased springers?

I have not had the opportunity to talk with this veterinarian this week to find out if this dairy has seen an increase in number of services per conception and abortions over the past year or two. If these have been increasing I would advise testing all the animals. There could be a "Typhoid Mary" out there in the freestalls!

Saturday, July 12, 2014

What Percentage of IgG's End up the Blood?

This is just a reminder that all the antibodies that go into the front of a newborn calf do not necessarily end up her blood.

In a recently reported research project calves were fed 185g of immunoglobulins (IgG) using a lactation-based colostrum replacer in either one or two feedings. [Cabrel, R.G. and Others, "Colostrum replacer feeding regimen, addition of sodium bicarbonate, and milk replacer: The combined effects on absorptive efficiency of immunoglobulin G in neonatal calves." Journal of Dairy Science 97:2291-2296 April 2014].

Absorption Efficiency - that is a measure that compares the amount of IgG fed and the amount of IgG that ends up in the blood of a calf.

The different treatments for feeding the colostrum replacer (CR) were:
  • One feeding of the 185g IgG between 30 and 60 minutes after birth [They fed 3 packages of Calf Choice Total Gold brand colostrum replacer as 3L total volume]
  • Two feedings, 123g IgG between 30 and 60 minutes after birth and 62g IgG  six hours later. [same product split into 2/3 and 1/3 feedings]
Results:

Absorption efficiency - one-feeding treatment = 31.3% efficiency
                                   two-feeding treatment = 33.7% efficiency

Conclusion: Roughly about 1/3 of IgG fed are absorbed into the blood.

These values are similar to those reported in earlier research (e.g., Quigley and Others, " Absorption of protein and IgG in calves fed a colostrum supplement or replacer." JDS 85: 1243-1248, 2002. 

There was no significant difference between one-feeding and two-feeding treatments (only 10 calves per treatment so I have some reservations about the findings)

Blood IgG levels - one-feeding treatment = 15.9 g/L (above 6.0 refractometer reading)
                             two-feeding treatment = 16.5g/L (above 6.0 refractometer reading)

When absorption efficiency was compared between calves that were fed with a bottle and those fed with an esophageal feeder there were no significant differences in absorption efficiency.

Conclusions:
1. Equal levels of efficiency of absorption of IgG's can be achieved with either one-time or two-time feeding given that the first feeding is ASAP after birth. This reinforces findings from earlier studies.

2. Good levels of immunity as measured by IgG's in blood can be achieved by feeding a sufficient volume of IgG's (in this case 185g).

Interpretation my part - I currently recommend feeding 200g of IgG soon after birth in either one or two feedings in order to achieve the goal of successful passive transfer of immunity to 95% of the calves (that is, 95% with blood serum total protein readings at 5.0 and higher).

Have you remembered to share with your friends how easy it is to access Calves with Sam? Just Google the blog name, Calves with Sam, to bring up the link. 

Friday, July 11, 2014

Milk Yield at Second Milking

How good is your memory? Have you milked many fresh cows for their first three or four milkings? How much milk did you collect at second milkings compared to first milkings?

I milked all the fresh cows for a 800-cow dairy for about eight years. My memory for cows (compared to heifers) is that second milking yields were substantially less than yields at first milking. What, however, does a recent study say?

Study: 39 Holstein cows, milk weights recorded for first 10 milkings. [Kessler, E. C. and Others, "Milk production during the colostral period is not related to the later lactation performance in dairy cows." Journal of Dairy Science 97:2186-2192 April 2014]

  • As expected, lots of variation among cows in first milking (colostrum) yields varying from about 2 quarts and 21 quarts (about 46 pounds). Fully 75 percent gave at least 5 quarts.
  • The variation in first milking yield for cows second lactation and greater was not related to the amount of time between calving and first milking and was only weakly related to previous lactation performance. 
  • Average colostrum (first milking) yield was between 16 and 17 pounds.
  • Second milking for cows averaged nearly 14 pounds. Compared to first milking yield that is 82 percent.
Yes, that number at second milking was 82 percent. I fear that my memories from 20 years ago are not very accurate - if I had to make a guess based on my recall I would have come up with 50 percent yield at second milking compared to first.

Could I have a problem with selective memory? I recall very well the cases where the cow gave 20 plus pounds first milking and 10 or less pounds at second milking? All the cows that yielded 3/4 or more of first milking at their second milking all blurred together and I don't really remember them? 

True that these results are based on only 39 cows. However, these data are much more definite than my recall. I will keep watching for another study. 

BTW, the title of the article reflects the study's main findings, milk production during the first 10 days in milk is not a good predictor of later production performance.




Thursday, July 10, 2014

To Buy or Not To Buy a Digital Refractometer

Digital refractometers are now available in the price range of $350 to $450 that can be used to assess the quality of colostrum, estimate dry matter content of milk and evaluate blood serum total protein.

A question that came up today is whether or not these digital units are more accurate than the hand-held style analog refractometers. Part of the answer is found in the specifications of the unit that is purchased. The digital units will specify resolution and precision (+/-). 

Another part of the answer when you compare the two styles is whether or not the units are automatically temperature compensated. And, how recently have the the units been calibrated?

Another part of the answer is user-related. All of us that have used the hand-held analog units know the challenge of interpreting where the boundary line crosses the scale divisions. My experience is that blood serum total protein samples have fairly sharp boundary lines, milk samples for dry matter are more fuzzy and colostrum quality sample boundary lines are very fuzzy. 

The values assigned for a sample get more and more subjective as the level of fuzziness goes up. Thus, if more than one person at the dairy is taking readings the potential for variation among persons is much higher with analog units than with digital ones. That is, with a digital unit the readings are more consistent and less dependent on who takes the reading.

Maybe the more important question is how accurate do we need to be when using the information to make on-farm decisions? Is a difference of 0.1 in a blood serum total protein reading going to change the decisions we make in colostrum management? When we assess dry matter content of milk how large a difference from our target value do we need to have in order to add  milk powder? If our Brix target for colostrum is 22 are we willing to live with values that are accurate plus/minus 1.0?

My opinion is that whether or not to purchase the multi-scale digital unit is mostly a matter of convenience rather than either accuracy or consistency. One unit is used regardless of the medium to be evaluated. Plus, as a guy I enjoy having high tech stuff around.



Wednesday, July 9, 2014

You Cannot Bleach Your Way to Clean

I just had yet another question about the concentration of a chlorine bleach solution to use soaking calf feeding equipment. The assumption is that if the one uses the proper concentration of the active ingredient somehow the tube feeders and bottles will become clean. All the bacteria will be gone. 

WRONG!

There are two resources at www.calffacts.com that shed light on this issue. The first is "Bleach is Not Enough to Kill Bacteria" - click HERE to access the text. This note explains why bleach is ineffective in situations where there is significant biofilm accumulation.

The second is "Biofilms Threaten Calf Health" - click Biofilms to access the text. This note includes the topics
  • What are biofilms 
  • Why are they a threat to calf health 
  •  How do biofilms get started 
  •  How do biofilms grow 
  •  What can we do about biofilms
So, the bottomline? Soaking equipment in a bleach solution when there are biofilms present is simply an exercise - you are not killing the bacteria.

Monday, July 7, 2014

Gizmos or Guesses

That is the title of a presentation by Steve Hayes on managing calves for success. 

Here is the place to click to access this paper. 

In this presentation Steve highlights the use of "gizmos" (tools) to promote better calf management. It is a quick read, his points are well organized. You might even what to print a copy so you can read it two or more times. 

Enjoy.