The volume of calf starter grain being consumed by a calf has often been suggested as a workable guide to when we could stop feeding milk.
Some years ago we often used the threshold of 2 pounds per day. More recently the threshold has been moved up to between 4 and 5 pounds. This upper value has some good science behind it - and, it agrees with the threshold I used with my calves as well.
A recently published review of work on how calves utilize the nutrients in calf starter grains suggests that it could make sense to use an additional threshold. That is, "What is the total volume of calf starter grain consumed by the calf?"
This is not entirely new. We have been recommending that before taking calves completely off milk they should have been regularly eating calf starter grain for three weeks. That length of time implies a significant volume of grain consumed.
Quigley's work suggests that a minimum volume of starter should be consumed before rumen development will have progressed to the point where calves can be expected to be able to replace energy from milk with energy from grain.
Because calf starter grains vary widely in their composition I was not able to come up with a volume that fits all starters. However, this idea should make us think about the need to track starter intake on our "ready-to-wean calves." It's not just how much grain did she eat today - over time, has the total volume been enough to support the development of a functional rumen?
My current recommendation is calf starter grain consumption of at least one large handful daily for a minimum of three weeks and current grain intake of at least 4.5 - 5 pounds daily at full weaning.
Quigley, J.D., "Symposium Review: Re-evaluation of National Research Council energy estimates in calf starters" Journal of Dairy Science 102:3674-3683 December 2019
Sarah Morrison (W.H.Miner Agricultural Research Institute) recently reported on a study she completed while at the University of Illinois.
The key point that caught my attention was that even while scouring calves were receiving milk replacer and oral electrolytes they also drank free-choice water.
The free-water intake of these calves was recorded during the first 21 days at the research facility. Probably arriving at 3 to 5 days of age at arrival so the observation period was probably from 4 to 25 days old.
All the calves drank water. Overall, for the 21-day period it came to 12 gallons per calf. She noted that the calves with scours averaged an extra gallon of water compared to non-scouring calves.
Bottom Line? Make sure ALL the calves have water 24/7 if possible. Especially scouring calves, give them a chance to re-hydrate naturally on their own by sipping free-choice water in addition to their milk and electrolyte feedings.
Reference: Sarah Morrision "Calves with diarrhea have different intake, growth and efficiency" November Farm Report, William H. Miner Agricultural Research Institute, p3.
In a well-designed research project dairy calves were weaned either abruptly (7 days at half milk ration) or gradually (7 days at 60% followed by 7 more days at 30%).
Using several measures they estimated rumen development and ability to digest solid feeds.
The calves with the longer weaning period had superior rumen development at the end of the weaning period.
No surprise. The calves need to be eating a measurable amount of solid feed for at least three weeks before the end of milk feeding in order to have a level of rumen function that allows for replacing the energy from milk with that from solid feed. No short-cuts available. Biology always wins, no cheating.
Another research group suggests that a calf starter grain intake of at least 4.5 pounds per day is desirable for moving from a milk+grain ration to a 100% grain ration if consistent gain is desired (assumes moderate environmental temperature).
Reference: Klopp, R. N. and Others, "Effects of feeding different amounts of milk replacer on growth performance and nutrient digestibility in Holstein calves to 2 months of age using different weaning strategies." Journal of Dairy Science 102:11040-11050 December 2019.
In a presentation to a dairy audience in Minnesota Dr. Trevor DeVries (as reported in Progressive Dairy November 7, 2019, p 49) suggested these guidelines for 2-4 month-old heifers when we have a growth goal of about 2.5 pounds a day gain:
85 percent of dry matter intake (DMI) should come from concentrated feed.
Do not use fermented feeds in the ration for this age heifers because "they are too high in moisture and calves are not able to eat enough to achieve an appropriate level of dry matter."
Use a "dry" TMR that contains concentrate and chopped dry forage such as straw or hay. Dry TMR can be made in large batches, stored and fed out daily without concerns of "heating" common for high moisture TMR's.
Forage particle size in dry TMR should be limited to 1" in length to discourage sorting and should be well mixed in the TMR.
Remember to keep TMR in front of the calves (do not feed to a clean bunk) in order to discourage calves from developing the bad habit of "slug feeding."
"Benefits and drawbacks of feeding pasteurized milk to calves" is the title of an article by Ellan Dufour (Progressive Dairy, November 7, 2019 pp 41-42" that does a great job of summarizing a lot of good information on pasteurized milk feeding.
How pasteurization works
Types of pasteurizers including batch pasteurization, continouous flow or HTST pasteurization, colostrum pasteurization
Dr. Trevor DeVries at a dairy conference in Minnesota summarized his thoughts relating levels of milk intake of preweaned calves to method of reducing milk intake, weaning timing, feed type and housing management. [as reported in Progressive Dairy, November 7, 2019, pp49-50]
He observed that when calves are fed enough milk to achieve a 2 pounds a day gain from milk their initial calf starter grain intake is delayed. That means different weaning management is needed compared to calves that are limit-fed milk.
Recall, our goal for calves being weaned is to maintain a level amount of usable energy for the calves both before and after weaning - a consistent level. If we get a drop in energy at weaning we will see an undesirable drop in growth as well.
His research showed that among calves fed for high rates of gain preweaning (high milk feeding) when calves weaned at 8 weeks of age (reduced milk ration spread over 2 weeks) were compared to those weaned earlier at 6 weeks later and longer weaning resulted in maintained their growth rates through the weaning process.
His calf starter grain intake goal at the time all milk feeding is ended is 4.5 pounds of calf starter gain daily. [I can add here this should be higher during cold weather months.]
Ann Hoskins from Vita Plus has done a great job summarizing practical ways to be sure the milk fed to calves is the temperature it should be even in cold weather conditions.
On really cold days (wind chill below 0 F) in order to feed warm milk to all the calves I had to mix my milk replace in multiple batches - mix a batch, go out and feed it (hutches), come back in (get warm) and mix another batch, repeat three times until finished.
Regardless of environmental conditions I always put bottles for the youngest bottle-fed calves into 5-gallon pails of 105-110 F water (4 to a pail).
When I did not have help for bucket training the five or so young calves I ended up feeding them one at a time after the rest of the calves were fed. I observed that if I filled the milk pails for these five calves at the beginning of feeding chores I was almost always feeding cold milk to them. However, if I put the bottles into a 5-gallon pail of warm water even the last calf received 100-105 milk once I poured the milk into a feeding bucket.
Amazing as it may seem, research (Univ. British Columbia) has demonstrated that habits learned as calves frequently carry over into later life - even to adulthood.
One of the habits (and not a good one) is slug feeding.
You may say, "But, I never teach my calves to slug feed calf starter."
But, empty starter grain pails do just that. Calves learn quickly to deal with empty grain pails. "Eat up! There may not be more!" When we allow the calf starter grain pails to go empty we are signally to calves to "eat up in a hurry" when we next feed grain.
Of course it makes sense to feed at a rate close to consumption. That way we minimize the amount of grain we have to dump.
With my own calves my practice with calves eating grain regularly was to feed at a rate that the pail was never empty (if possible). "Yes," now and again a calf fooled me and licked the pail clean. I worked hard to dump grain pails twice a week in order to avoid wet grain and spoilage. This "left-over" grain went to an older heifer pen. My 6 to 8 week old calves on reduced milk rations usually were eating nearly 5 to 8 pounds per day so the challenge often was to provide enough grain so the buckets did not run out completely.
This management protocol does assume that you do not just fill a grain pail half full or more when the newborn calf goes into her pen (hutch).
By the way, remember that in order to optimize grain intake calves need free-choice water all seasons of the year.
Recently published work (A. Soufieri and Others, "Genetic parameters of colostrum traits in Holstein dairy cows." Journal of Dairy Science, 102:11225-11232, 2019) collected colostrum samples from 1,047 healthy Holstein dairy cows.
The yield was recorded as well as Brix values obtained from each cow's first milking. Laboratory analysis determined both fat and protein content.
Yield The median yield was 5kg (about 6.3 quarts). The lowest yield was less than 1 quart while the highest yield was nearly 11 quarts (23.5kg).
Brix values The median Brix was 25.9. The lowest Brix was 10.7 and the highest Brix was 41.4.
Fat percentage The median fat was 6%. The lowest fat was less than 0.1% while the highest fat percentage was 18.2%.
Protein percentage The median protein was 17.9%. The lowest protein was 4.8% while the highest protein percentage was 30.4%.
Conclusion? All colostrum is not the same. Keep using your Brix refractometer to sort colostrum before using for first feeding.
While on a calf care Internet search I came across this short two-page summary of cold weather calf care by Ryan Breuer, DVM, Iowa State Dairy Specialist.
While none of the items Dr. Breuer mentions are new and earth-shaking, they are a good reminder of our options in doing a "bang-up" job of cold weather care as we are about to move into winter weather.
Did you get this? Only 13 percent of operations were using effective methods to clean milk/colostrum feeding equipment - at start of 12 week calving season.
Frequency of cleaning
Near beginning of Near end of
12 wk calving 12 wk calving season
Daily 21% 11%
Every second day 47% 53%
Once a week 17% 28%
Every second wk 13% 4%
Once a month 2% 4%
Note: Only acceptable frequency is at least daily or more frequently as equipment is soiled.
I am not surprised that average mortality at 28 days was 6%. No data were presented on scours rates but we can guess that the rates were discouraging high.
Lots of opportunity here for improvement - anyone need a job advising Irish dairy farmers on sanitation practices?
Reference: Barry, J. and Others, "Associations between colostrum management, passive immunity, calf-related hygiene practices, and rates of mortality in preweaned dairy calves." Journal of Dairy Science 102:10266-10276 November 2019
Sometimes I feel like I have been shouting down a well when I give advice.
A client has been having some difficulty achieving his weaning growth goals. I walked the hutches looking especially at the grain pails.
My advice has been to feed only a handful of pelleted calf starter grain (they prefer to use pellets for mechanical feeding rather than textured feed) when the calf is placed in a hutch about one day of age. Then this grain can be refreshed at least twice a week until the calf begins to eat starter.
So, on this walk through I found that all the youngest calves had grain pails that were at least one-half full. Really, at least one-half full.
When the worker that feeds grain was asked about the directions he had received they were "be sure the calves do not run out of grain." He was never given instructions about the "handful" amount and changing the grain at least twice a week for the youngest calves.
They were simply providing "lots" of pellets on day one. Eventually, the feeder would notice that some of the pellets were disappearing. When that happened, the bucket was "topped off" by adding more pellets on top of those that had been in the hutch since day one. Buckets were not emptied until the calves were weaned and moved out of the hutch.
I got an extra pail and dumped some of the pails for 4 and 5 week old calves. You are right - more that half of them had moldy grain in the bottom.
I do not have grain consumption data from these hutches - but, my advice to improve grain pail management was based on the educated guess that present calf grain pail management was depressing grain intake. And, that depressed intake was partially responsible for the lower weaning weights.
Only time will tell if my recommended practices will be adopted. Like I said at the beginning of this post, sometimes it feels like I am shouting down a well!
In a July posting at www.calfnotes.com Dr. Jim Quigley asked the question, "How much energy is in my starter?" (Calf Note #209 with that title.)
As part of this discussion he observed, "the rumen develops in response to ALL of the starter a calf consumes, and not just the starter the calf consumes on a given day."
Thus, when assessing weaning readiness ideally one needs to know in addition to the current daily calf starter grain consumption but also have a rough idea of the total volume consumed over several weeks.
These observations are consistent with earlier recommendations in this blog about keeping track of how long (number of weeks) calves have been consistently eating starter. I have been recommending waiting to fully wean calves not sooner that at least three weeks after they began to consistently eat a minimum of 1/2 pound of starter daily.
My own calves on an intensive milk feeding program generally began to consistently eat 1/2 pound of starter between 21 and 28 days. After I reduced their daily milk replacer intake from 2 pounds to 1 pound of powder at about 35 days the majority of calves increased starter intakes from less than 1 pound daily to 2.5 to 3.5 pounds a day.
By the end of 7 weeks (about 50 days) most of these calves had consumed between 40 and 50 total pounds of starter - most of this between 28 and 49 days of age - about three weeks. Knowing that I would be feeding a grower pellet in the weaned pens I fed 1/2 textured calf starter mixed with 1/2 grower pellet the last week in the hutches.
When they were fully weaned sometime between 49 and 56 days most of them were eating between 4 and 5.5 pounds of this 1/2 and 1/2 blend daily. A pen of 5 in a weaning pen might eat only 20 pounds of grower pellets the first day or two after going into the pen but after a few days I usually had to feed 25 to 35 pounds of pellets daily (ad lib feeding).
As a side note, when time permitted I fed a handful of good quality alfalfa hay in each grain bucket the last week calves were in hutches. Then I only fed as much hay in the transition pens the first week after moving as the calves would clean up in roughly 30 minutes. I did not feed ad lib hay until the third week in the transition pens.
"Twins had a 68% inceased risk of all-causes mortality compared with calves born as singletons." This meant that twins were 1.7 times more likely to die than their singleton counterparts.
This was the observation of a California research team that collect calf health data from 5 California dairies. They used information from 11, 945 calves.
WATCH THOSE TWINS!
The authors explain this issue:
"An increase in mortality risk in
twin calves may be due to competition for nutrients
during gestation, resulting in reduced vigor and health
status after birth. Results of the studies by Gulliksen
et al. (2009) and Mellado et al. (2014) suggest that it
may be beneficial for calf caretakers to closely monitor
calves that are born as twins for any clinical signs of
illness during the preweaning period. [emphasis added] p7326
While raising my own calves in individual hutches I slipped a plastic cow leg strap in the rear "D" ring of the hutch. This reminded me as well as any other caretaker of the "twin" status of the calf.
As I think back to this time I recall that most of my attention to these twins was during the first two weeks when diarrhea (scours) was the most common problem.
The other time I used the "twin" identity was at weaning time. Once in a while based on too low a level of calf starter grain intake I delayed weaning on a twin. This allowed her to "catch up" with her herdmates and start life as a weaned calf with plenty of energy and protein from starter.
Reference: Dubrovsky, S. A. and Others, " Bovine respiratory disease (BVD) cause-specific and overall mortalilty in preweaned calves on California dairies: The BVD 10K study." Journal of Dairy Science 102:7320-7328 (2019).
Scours and respiratory disease in young calves are linked.
In a May 26, 2019 Hoard’s Dairyman article Dr. Ollivett (University of Wisconsin School of Vet. Med.) says “Young calves with diarrhea are much more likely to develop pneumonia than their herdmates that did not experience diarrhea.” By improvinggut heath we can expect to see fewer treatable cases of respiratory illness.
She observes “Often, abnormal manure is overlooked if the calf is not off feed or depressed. When you spend time specifically looking at fecal consistency, you might realize you have more of a problem than you thought.”
Especially where pneumonia issues are serious among 3 and 4 week-old calves, Dr. Ollivett recommends serious-level record keeping on diarrhea among 1 and 2 week-old calves.
She notes that measuring weight gain during weeks 1-2 may reveal that intestinal health is not ideal. It is “normal” when calves receive adequate nutrition that they begin gaining weight before the end of the first week. If your calves are not gaining weight or losing weight by 14 days of age you may have found one of the causes of pneumonia in the subsequentweeks.
Compare the maximum concentration of antibodies in the calf's blood between calves fed colostrum within 45 minutes after birth and calves fed colostrum 6 hours after birth.
All calves fed 7.5% of birth weight of heat-treated colostrum testing 62g/L antibodies. For example, 90 pound calf received a little over 3 quarts. This feeding contained about 180-185g of antibodies.
The maximum antibody concentration was:
Fed at 45 minutes = 25.5 mg/ml
Fed at 6 hours = 18.2 mg/ml
Difference? 40 percent!
Is it a good management decision to delay colostrum feeding even out to 6 hours after birth?
Reference: Fisher, A.J. and Others "Effect of delaying colostrum feeding on passive transfer and intestinal bacterial colonizaton in neonatal male Holstein calves." Journal of Dairy Science 101:30299-3109 (April 2018)
Conventional vs. Accelerated Rates of Milk Replacer
Will calves fed at accelerated rates of milk replacer drink more or less water when compared to calves fed milk replacer at conventional rates?
A feeding trial with calves fed ad lib water and calf starter grain starting on day 3 in addition to their milk replacer ration made this comparison.
Throughout the five weeks of the trial the calves on the accelerated milk replacer ration drank more water than those on the conventional ration. For example, during week 3 of the trial the conventional calves averaged 27 ounces (.84 qts.) per day while those on the accelerated milk replacer ration averaged 68 ounces (2.1 qts).
Take a look at the chart showing the water consumption over the 5 weeks of the trial. Paste the URL below in your browser
Sometimes a quick "checklist" helps us touch all the bases when doing a calf-related job.
For a summary of all the checklists at the www.atticacows.com website, type the word checklist in the upper right-hand corner search box.
I got 94 hits. A quick scan shows that about 1/2 of them are duplicates. There is a good chance you will find a checklist that meets your needs.
More focused searching?
By adding "protocol" to the search I reduced the hits to 60.
By adding "colostrum" to the search I reduced the hits to 54.
By adding "pneumonia" to the search I reduced the hits to 8.
Based on a sample of 75 Holstein-Friesian cows (pasture-based dairy Ireland, 2nd lactation and greater) samples were collected for the first 5 milkings after colostrum was harvested.
This is how the transition milk samples compared to colostrum (remember we want a refractometer value of 23 or greater or IgG concentration of 50 or greater for first feeding):
Sample No.Samples Median Median
Brix refractometer (%) IgG Concentration(g//L)
Colostrum 68 25.6 99.6
T#1 63 17.8 43.5
T#2 61 12.6 12.5
T#3 59 11.8 5.3
T#4 53 11.4 1.9
T#5 41 11.2 1.8
Colostrum was great stuff - use for first feeding.
First transition milking (T#1) - Still pretty strong for immunity - use for second feeding. In a pinch, this could be used for first feeding. Refractometer does a good job evaluating for immunity potential. And, for localized immunity in the gut for the first week of life this milking has great potential.
Second transition milking (T#2) - to be fed anytime during the first week of life to promote localized immunity in the gut.
3rd - 5th transition milking - not going to confer a great deal in localize immunity in the gut but super for nutritional value - still higher in solids than market milk and packs a nice extra energy boost from higher milk fat content. Refractometer readings less reliable at these low IgG concentrations compared to colostrum.
Reference: Rayburn, M.C. and Others, "Use of a digital refractometer in assessing immunoglobulin G concentrations in colostrum and the first 5 transition milkings in an Irish dairy herd." Journal of Dairy Science 102:7459-7463 August 2019.
Inadequate transfer of antibodies from the dam's colostrum into the calf's blood is a failure of passive transfer.
While the process is biologically determined how well the transfer takes place on modern dairies is determined by how well humans manage harvest, manage and feed colostrum to newborn calves.
A recently reported study of calves in California dairies shows how widely these success rates can vary.
Dairy Percent Calf Blood Serum Total
Mortality Protein (Average)
#1 3% 6.4
#2 6% 6.2
#3 7% 6.2
#4 28% 5.5
#5 39% 5.7 (huge variation here from high to low BSTP so the average here
hides many, many calves with very low BSTP)
What we do as calf enterprise managers makes a difference.
These three words describe the foundation of colostrum management and all three of them depend on calf care personnel.
Reference: Dubrovsky, S.A. and Others "Bovine respiratory (BRD) cause-specific and overall mortality in preweaned calves on California dairies: The BRD 10K Study." Journal of Dairy Science 102:7620-7328 August 2019.
Just a reminder about the need to give our twin heifer calves a little special attention.
Recent work involving 11,470 calves from 5 California dairies followed calves from birth through weaning. When considering calves that died (mortality) the overall mortality rates varied from 1.1 percent to 7.2 percent.
Specifically, twin heifer calves were found to have a 1.7 times greater risk of dying compared to singleton calves. These findings were similar to previous studies as well.
What is a manager to do?
1. Identify twin calves - if the calf care workers do not see the calves born have the maternity workers mark twins (for example, using a paint stick place a "T" on the calves' forehead).
2. Place a reminder on the housing for twins (for example, a cow leg band) - make it easy to remember that these calves need to have a little extra attention especially during the first month of life.
3. As weaning approaches provide the opportunity for an extra week or two of the milk ration for twins if they are significantly smaller that other calves the same age. Delaying moving into transition calf pens may provide them an opportunity to compete for feed and space with less risk of pneumonia.
Reference: Dubrovsky, S.A. and Others "Bovine respiratory (BRD) cause-specific and overall mortality in preweaned calves on California dairies: The BRD 10K Study." Journal of Dairy Science 102:7620-7328 August 2019.
Did you know that there are fourteen Spanish Language calf management resources at the calffacts.com website?
You go to www.calffacts.com and scroll down to SPANISH and they are all grouped together. Their equivalent resource in English is listed alphabetically in this same library (e.g., Lavando los recipientes de la leche appears as Washing Milk Containers).
It is useful to have estimates of heifer calf weights. In the absence of animal scales it has been established that the heart girth measurement is a reasonably accurate way to estimate body weights. Various tape designs have been used over time - 1936, 1961 and 1992. Heinrichs comments on the need for verifying the tape designs,
"Whereas the body weight and heart girth relationship has been reliable over time, the regression equation to estimate body weight and heart girth have changed, ... most likely due to alterations in breeding and selection programs that have affected animal conformation, in additional to other traits, over time."
Thus, it was judged to time to reassess the accuracy of the 1992 design. Based on 1,498 measurements from 586 animals the authors compared heart girth with scale weights. The correlation between the actual and predicted body weight was 0.98.
"Upon comparing the previously developed hearth girth to body weight equation with 2 independent data sets, we concluded that the previous equation converting heart girth to body weight for Holstein dairy heifers (Heinrichs, 1992) remains valid for the current genetics and type of Holstein dairy heifers."
Keep using the tape you have for Holstein dairy calves. Remember to place the tape correctly around the calf right behind the front legs. Pull tightly enough to compress hair coat but not to stretch the tape.
Reference: Heinrichs, A. J., B.S. Heinrichs, C. M. Jones, P.S. Erickson, K.F. Kalscheur, T.D. Nennich, B.J. Heins and F.C. Cardosoll "Short Communication: Verifying Holstein heifer heart girth to body weight prediction equations." Journal of Dairy Science 100:8451-8454 (2017)
This is a continuing question for the dairy industry. On one hand, there appears to be increasing concern in the general public that early separation of cow and calf is an animal welfare issue. On the other hand, do we have documented evidence that early separation has benefits for either cow or calf or both?
Two recent reviews of published research appeared in the July issue of the Journal of Dairy Science. One review evaluated the impact of suckling for some time after birth on subsequent milk production and found on effect of length of contact time between dam and calf. Regarding calf growth, holding amount of milk consumed constant, length of contact with the dam had no effect on growth rates. (Meagher)
The other review emphasized the need for consistent calf care to insure consumption of clean, high quality colostrum early in life in adequate volume. In my reading the presence or absence of the dam when this took place had no effect - some fed manually, some provided assistance for nursing to be sure calves suckled an adequate volume soon after birth - either way, adequate levels of passive immunity was achieved. Authors comment, "Various types of farmer intervention, including careful observation and supplementary feeding [of colostrum], may be beneficial regardless of whether the calf is separated from the cow."
Pathogen transfer was another question addressed. It might be possible that extended cow/calf contact might favor transfer of certain parasites and viruses while having no effect on the transfer of others. More research is needed to pin down the specifics. In the meantime we are called on to use common sense precautions.
Commenting on Johnes transmission, authors note that "in some herds, cow-calf separation has supplanted control strategies for which concrete evidence exists to tie the respective strategy to a reduction in MAP prevalence."(5793) WOW! I Agree! Don't let the practice of limited cow-calf contact blind you to other risky management practices that may have crept silently into your calf operation!
Further, the authors observe, "There is evidence for a synergism of infection risk in the calving area, based upon the level of environmental cleanliness, udder hygiene, and presence of other lactating animals. Given the evidence that we have, this review indicates that "prompt calf removal should not be viewed as a substitute for proper hygiene and management in the maternity area." [emphasis added by me]
In general, if the calf enterprise provides good colostrum management and a clean environment for calves the presence of the cow has no negative effects on calf health (scours, pneumonia). Thus, independent of these best management practices there seem to be few if any benefits for early cow/calf separation.
Where do I come down on cow/calf separation?
Whatever maternity area management rules we have on our dairy, they need to be practical so they can be followed consistently by everyone.
No matter how the colostrum gets into the calf, she always needs at least the minimum of 200gm of IgG's ASAP to insure effective passive transfer of immunity - suckle, manual feeding, and always clean.
No manure meals - the first thing in the calf's mouth should be clean colostrum regardless of how we do this. No manure in the colostrum, no manure from the pen, no manure from licking any adult animal's hair coat, no manure from dirty teats, no manure period!
Cow-calf contact in the period immediately after birth can improve the adaptation of the calf to the new world outside of mom. Dam contact with the calf (especially in unassisted deliveries) can do a world of good in stimulating normal breathing and achieving a vigorous response to the new environment.
Meagher, R. K. and Others, " Invited Review: A systematic review of the effects of prolonged cow-calf contact on behavior, welfare, and productivity." Journal of Dairy Science 102: 5765-5783 July 2019
Beaver, A. and Others, "Invited Revies: A systematic review of the effects of early separation on dairy cow and calf health." Journal of Dairy Science 102: 5784-5810 July 2019