Monday, August 28, 2017

My Ruminations about Rumen pH Among Weaned Calves

By using intensive data collection methods a research team was able to monitor rumen pH in  calves before, during and after weaning. Because of practical limitations (equipment, rumen canulas) the number of calves was limited to six.

"Pre-weaning the average daily pH was low (5.6 ) implying rumen acidosis. The pH reached its lowest levels during the week after weaning (wk 7) with a mean of 5.5 and did not increase before wk 11. Furthermore, ruminal pH was below 5.5 and 5.2 for approximately 745 and 220 minutes daily during wk 7 and 8, respectively. The pH increased significantly in wk 11 and 12 with a mean pH of 6.1."

Even when calves were not eating very much calf starter grain the pH levels were low. I did not expect that finding. In addition to 900g of milk replacer powder daily these calves had free-choice access to chopped straw - supposedly that ration should modify the rumen environment to achieve more favorable pH conditions. Among these few calves clearly the addition of straw did not improve pH conditions pre-weaning.

I noted that rumen pH dropped to 5.2 during weeks 7 and 8 for 220 minutes a day. Those prolonged low pH times suggest a depression of the favorable rumen microbial populations. The article did not mention whether or not  fresh concentrate was provided  before these periods of low pH. If calf "slug fed" on concentrate (usually due to not having a consistent supply 24/7) I would expect depressed pH conditions post feeding.

When feeding my own calves I thought that feeding a big handful of palatable alfalfa hay daily to my older calves would lead to more favorable rumen conditions - the fiber would form a stabilizing mat in the rumen, the calve would be encouraged to spend more time chewing a cud thus delivering more pH neutralizing fluid for the rumen. 

Now ,I wonder about feeding the hay. How well did this dietary rumen adaptation post-weaning work to manage rumen pH? My intent was to start building the appropriate rumen microbial population for fiber digestion (alfalfa hay). I didn't even think about rumen pH.

 I do know that I tried to be sure that after the calves had a milk step-down as part of weaning they always had access to plenty of clean water and palatable calf starter grain - never let either of those run out. At the time I thought that this was a best management practice. I wanted to prevent "slug" feeding (that is, eating an excessively large volume of grain at one time).

I recall that a few of my calves would cycle in their grain intake during weeks six and seven - up and down, up and down over a period of three to five days.  Maybe these were the ones where the rumen pH was very low for prolonged periods of time - perhaps they "went off-feed" because of this - then after recovering they dug into the grain, often eating six or more pounds of grain for the next several days. Then, off-feed again.

Perhaps the take-home message from this research is that we need to pay closer attention to the dietary transitions from weeks 5 through 12 to gradually ease the rumen into the most favorable pH conditions. 

J.K. van Niekerk and Others, "Ruminal pH in Holstein dairy bull calves from pre-weaning to post-weaning." Journal of Dairy Science, 100:178 July 2017

Wednesday, August 23, 2017

Pair Housing of Preweaned Dairy Calves

There is a growing body of evidence that housing preweaned calves in small groups (for example, pairs) results in higher rates of gain and more positive social behavior when placed in larger groups. They tend to have less stress when weaned and moved into larger pens. These paired-housing studies have been done in barns.

But, if the farm is raising calves in hutches that will not work. Right?

Well, maybe no so impossible.

Research compared (only a small number, however) raising calves individually in hutches and along side them placing 2 hutches next to each other with a common run. Same farm, same calf care procedures, just that some  hutches were paired.

Now, these findings are from a small number of calves (14 individual housed, 16 calves housed as 8 pairs). So, the results should be considered more exploratory rather than conclusive.

The dairy fed milk twice daily. Calves started out at 6L per day and worked up to 10L per day (until 35 days) and then back down to 6L per day (until 56 days). 

Starter intake:
Up to 35 days (period of high milk intake) no difference in calf starter grain intake between individual and paired calves. Figures below are averages for each type of housing.

Between 35 and 56 days (milk cut back to 6L a day)
     Individual-housed calves = 2.2 lbs daily (1.02kg)
     Pair-housed calves = 3.8 lbs daily (1.72kg)

That is 68 percent more starter intake!

In the post-weaning period (days 56 through 67)
    Individual-housed calves = 3.8 lbs. daily (1.71lg)
    Pair-housed calves = 7.7 lbs. daily (3.51kg)

That is 105 percent more starter intake!

Interesting outcomes from a very small sample.

L. Whalen and Others, "Pair housing of dairy calves in modified individual calf hutches." Journal of Dairy Science 100:227 July 2017

Friday, August 18, 2017

Take Time to Care for the Dystocia Calf

The August 2017 calf management newsletter is now posted at or click HERE to directly to the letter. 

The key points:
·  Calving difficulty, often called dystocia, affects between 13 to 15 % of Holstein calves.
·   Treatment rates are higher for dystocia calves (scours 17%, pneumonia 70%) compared to calves experiencing unassisted births.
·      Providing special care, both in the first few hours and first two weeks, can cut both death losses and treatments for scours and/or pneumonia.
·        Give lots of stimulation during first few hours.
·        Be sure to follow up for the next two weeks.

Thursday, August 17, 2017

Pneumonia Among Preweaned Calves Cuts
1st Lactation Production 1,155#

These were the findings of a research project completed involving 215 animals from 3 southwestern Ontario herds.

Calves were assessed using thoracic ultrasonagraphy weekly for the first 8 weeks of life. At least one diagnosis of lung consolidation was found in 57 percent of the animals. They were followed through their first lactation.

"The presence of lung consolidation [evidence of bovine respiratory disease] at least once in the first 8 weeks of life was associated with a 525kg (1,155 lbs) decrease in first lactation."

Given this study population, preventing pneumonia (bovine respiratory disease) was an important factor in allowing the animals to express their genetic potential for milk production. 

T.R. Dunn and Others, " The effect of lung consolidation, as determined by ultrasonography, on first lactation milk production in Holstein dairy calves." Journal of Dairy Science 100:194 July 2017.

Monday, August 14, 2017

Yes, Air Quality Can Make a Difference!
Increased BRD Among Group-Housed Calves

Seventeen dairy farms in southern Ontario, Canada, using automatic feeders for preweaned calves were visited 4 times over a year.

Sharing air with cattle 5 to 8 months of age was a significant risk factor for bovine respiratory disease (BRD) (p<.01) 

The range of BRD among the 17 farms was from 0 to 28 percent (median 17%). 

Air quality can make a difference for group-housed calves on automatic feeders. Once weaned, the calves belong in another barn - not mucking up the air for the younger ones. 

The authors also found that frequently cleaning of the feeder and pen helped reduce both scours and BRD.

Reference: Medrano-Galarza, C. and Others, "Association of Management practices and calf health on dairy farms using automatic milk feeders in southern Ontario." Journal of Dairy Science 100:340 July 2017

Thursday, August 10, 2017

How Long Does it Take for Antibodies from Colostrum to Reach their Maximum Concentration in Calf Blood?

Using blood drawn from 20 calves received one feeding of 3 liters of colostrum at or less than 2 hours after birth they found this: (this delivered at least 200g of antibodies)

Average time to maxiumum concentration:

Colostrum fed with nursing bottle = 786 minutes (13.1 hours)
Colostrum fed with tube feeder     = 966 minutes (16.1 hours)

The variation was from an estimated low of 625 and estimated high of 1127 (18.8 hours).

Given the small number of calves in the study the difference in these times was not statistically reliable and could have been due to chance variation among calves.

Practical conclusion if we want to estimate maximum antibody blood level?

Wait to draw blood to assess effectiveness of passive transfer of antibodies until at least 18 hours after the last feeding of colostrum.

Reference: Desjardins-Morrissette, M. and Others, "The effect of nipple bottle vs. esophageal tube feeding of colostrum on absorption of IgG and plasma glucagon-like peptide-2 concentrations." Journal of Dairy Science 100:215 July 2017

Tuesday, August 8, 2017

Timing of Colostrum Feeding Makes a Difference

A study reported efficiency of absorption of colostral antibodies. The research team claimed that all 20 calves were fed colostrum at 2 hours after birth.

They reported efficiency of absorption of 54%. Most of the literature reports values around 30 to 35%.

Why so high in this study compared to the other reported data? In my opinion it was due to the timing of feeding. None of the calves went more than 2 hours before the first feeding of colostrum of 200 grams of antibodies (IgG). 

The much lower efficiency of absorption values reported in the literature includes data from calves receiving their first feeding of colostrum anytime before 24 hours.

I really like the protocol followed at the Cornell University Ruminant Research Center in Dryden, NY. They have a collect and feed protocol. The cow is milked as soon as practical right in the calving pen. After the colostrum is tested to be sure it meets the minimum antibody concentration the calf care person feeds the calf. Collect and Feed. No delay.

Timing of colostrum feeding makes a difference. Sooner is better.

As a side note, the research objective was to compare bottle and tube feeding of colostrum. They fed 3 L of adequate quality to provide at least 200g of antibodies. No differences were found in blood serum total protein, time to maximum concentration of BSTP, and efficiency of absorption.

Desjardins-Morrisssette, M. and Others, "The effect of nipple bottle vs. esophageal tube feeding of colostrum on absorption of IgG and plasma glucagon-like peptide-2 concentrations." Journal of Dairy Science 100:215 July 2017.

Thursday, August 3, 2017

Pelleted compared to Textured
Calf Starter Grain
[Yet, another chapter]

A research project run between August and October 2016 in Minnesota had the objective of comparing starch levels in calf grains to see if there would be differences in rates of gain and feed conversion efficiency. Calves were fed 20-20 milk replacer at the rate of 1.25# of powder daily.

The comparison grain was a textured calf grain with 30 percent starch. The pelleted grains had starch levels of 18, 24 and 30 percent.

Gain findings
1. There were no significant differences in gains among calves fed the three pelleted feeds that contained different levels of starch.

2. The textured starter gains among calves were 1.5 #/day compared to 1.3 #/day for the pelleted feeds. That is a 17.5% difference when comparing textured to pelleted feeds.

Feed conversion findings
1. There were no significant differences in feed efficiency among calves fed the three pelleted feeds that contained different levels of starch. 

2. The gain-to-feed ratio (measure of feed conversion efficiency) was 0.57 for textured-starter fed calves compared to 0.52 for calves receiving the pelleted feed. That is a 9% reduction in feed efficiency when pelleted is compared to textured feed.

Other observations: No differences in health costs and daily fecal scores among the four feeds.

Conclusion by authors:

"Under the conditions of this study, calf performance was reduced with a complete pelleted starter regardless of starch level compared with the textured starter with 30 percent starch." (p116)

They continued, "Cost savings with a complete pelleted starter may still provide economical gains over a textured starter with 30 percent starch." (p116)

Sam's observations:

I checked our local mill (in July 2017) for prices. For a 20% protein product, the textured feed delivered to our vet clinic cost was $351 per ton bulk [minimum 3 T) compared to $327 for the pelleted product. 

The choice of product may have more to do with the on-farm facilities for storage and feeding rather than either the rate of gain and/or price of feed. 

When caring for my own calves I chose to feed the textured product until calves were about seven weeks old, fed a 50:50 blend of textured:pelleted for a week, then grower pelleted feed from then on. Recall that I was feeding milk replacer at a maximum of 2.2#/day from weeks 2-5 so getting calves to eat starter before 5 weeks was challenging.

Reference: Zeigler, D. and Others, "Pre- and post-weaning performance and health of dairy calves fed complete pelleted calf starters formulated for three different starch levels." Journal of Dairy Science 100:116 July 2017.

Tuesday, August 1, 2017

Greater Feed Conversion Efficiency with More Gradual Weaning of Intensively-Fed Calves

More evidence that gradual weaning is preferred for calves on an intensive-feeding program is reported by the Nurture Research Center run by Provimi North America. 

Calves in the study were fed selected levels of milk replacer varying from a low of 1.4 lbs/day to a high of 2.2 lbs/day. They had weaning programs as short as 7 days and as long as 18 days. 

Feed efficiency (gain per pound of dry matter intake) was highest for the high feeding rate calves weaned over the longest (18 days) period of time.

As I look back at my own weaning practices for intensively-fed calves there were two trends that were significant for me:

1. Although my goal was to complete my step-down weaning in one week nearly all my calves took two weeks to arrive at my goal of calf starter grain intake. Thus, rather than calves completing weaning between 42 and 49 days, most of them were completely weaned between 42 and 56 days - thus the weaning took two weeks. 

2. I participated in a feeding trial involving these intensively-fed calves. We had rates of gain for each week up to when they were completely weaned. The majority of these calves taking two weeks to wean gained over two pounds a day between 42 and 56 days. It seems to me that we were getting very acceptable rates of feed conversion among these calves even though I admit I did not have dry matter intakes for them.

Dennis, T.S. and Others, "Effects of milk replacer feeding rate and age at weaning on calf performance and digestion through 8 weeks of age." Journal of Dairy Science, Supplement 2, 100:301 July 2017.