Calves are born with what is called a naive immune system. This means that they need to consume immunoglobulins in order to kick start their immune system.
The main immunoglobulin calves get from their mum's colostrum (first milk after calving) is immunoglobulin G (IgG), however, some cows have more IgGs than other cows and hence have a better quality colostrum.
For more on calves ability to absorb immunoglobulins from colostrum read our summary here:
This weeks summary is based on a study out of the USA comparing calves fed good quality colostrum and those fed colostrum replacers.
Key Points
Calves fed maternal colostrum (MC) had higher IgGs 24 hours after birth compared with those fed low-quality maternal colostrum with added IgGs from colostrum replacer (LMC-CR).
Feeding more IgGs (150 g) from colostrum replacer (CR) resulted in greater levels of IgG in calves 24 hours after birth compared with feeding 110 g of IgGs.
There were no differences found among the treatments for weight gain or body composition (weight, height and hip width).
This study used 80 heifers split into 4 treatment groups:
Maternal colostrum (MC) from 1st milking
Low-quality maternal colostrum with added IgGs (LMC-CR)
Colostrum replacer with 110 g of IgG fed (CR-110)
Colostrum replacer with 150 g of IgG fed (CR-150)
The aim of this study was to see if a commercial colostrum replacer (CR) could be (a) fed to replace colostrum (CR-110 & CR-150) or (b) fed to "bump-up" low-quality colostrum (LMC-CR).
Specific details of how much colostrum and how much IgGs were fed to calves is given at the end of this summary.
The calves were collected at birth and fed within 1.5 hours.
Interestingly, the researchers took blood samples of calves before feeding them, this was done to test the baseline levels of IgG and total protein of the calves.
As we mentioned in our previous colostrum summary (here), calves are born with no IgGs - these must come from the colostrum. And the study we have summarised here proved that nicely, the IgG concentration in calves at birth was zero!
The total protein at birth was on average between 3.88 and 4.05 g/dL and was not different for the 4 treatments.
After feeding the calves their maternal colostrum (MC or LMC-CR) or colostrum replacer (CR-110 or CR-150) by 1.5 hours after birth, blood samples were taken again at 24 hours to test how well the IgGs had been passed from the colostrum to the calf.
What was the IgG concentration for calves fed colostrum vs colostrum replacer?
The calves fed the MC (maternal colostrum - what we would call "gold colostrum") had the highest on average IgG concentration at 27.04 mg/mL (blue in figure below). Second highest was the calves that were fed the low-quality MC that was topped up with colostrum replacer (LMC-CR; black).
The calves fed the two colostrum replacers had the lowest IgG concentrations on average (grey and purple in the figure above). Although, the calves that were fed CR-110 (purple) had lower IgGs than the calves that were fed CR-150 (grey).
Although for these four treatments the average IgG concentration for calves is above the "cut-off" of 10 mg/mL, there were 20% of calves in the CR-110 treatment that had failure of passive transfer (FPT; read this summary for more on FPT).
This goes to show that using a colostrum replacer instead of maternal colostrum straight from the cow can still provide IgGs to the calf, but the amount of IgGs provided is still important.
Are you enjoying this summary? Have a read of one of these while you're here!
How efficient were the calves at absorbing IgGs from this variety of colostrum sources?
The authors calculated the "Apparent Efficiency of Absorption" or AEA for all calves.
The AEA was calculated based on the calf's birth weight, blood IgG and the total amount of IgG fed to that calf. A higher value (closer to 100%) is good and a lower value (closer to zero%) indicates poor absorption.
The calves that were fed LMC-CR had the highest AEA of 54% which was greater than that of the calves fed MC (black higher than blue in figure below).
Both groups of calves that were fed colostrum replacers (CR-110 and -150) had similar AEA of close to 40% (grey and purple).
It appears that the AEA of the calves fed MC was lower than for those fed CR-110 or CR-150, but, unfortunately, the authors did not statistically test the AEA of the calves fed MC vs those fed CR-110 or CR-150. What can happen is that although the average AEA can seem quite different, the range in AEA's can be so large that there is not a statistical difference between two treatments. From the data presented in this paper, we can't comment on these numerical differences in AEA.
As well as measuring indicators of immunity, the authors weighed the calves and measured their heights and hip widths. They found no differences at any stage for any of the body measurements taken.
Here are their reported body weights from week 1 to week 7 of the experiment.
The authors concluded that using colostrum replacers instead of first milking colostrum or to increase the IgG content of 2nd or 3rd milking colostrum could be a successful strategy to transfer immunity to young calves.
I had a quick squiz and found a colostrum replacer available in NZ called Jumpstart (I found it on PGG's website). Another one is from AgriVantage called Launchpad18. There were a few others but had limited info available online on what they contained.
From first glance it is very different to what has been used by the USA study we have summarised here. Jumpstart appears to have high amounts of casein and fat, whereas, the USA colostrum replacer was whey-based and had casein and fat removed. Importantly, both products contain IgGs though! Likewise, Launchpad claims to have 18% IgG in order to supply 108 grams of IgG per feed and contains a minimum 18% fat.
From my limited understanding, this maybe a good thing for us in NZ as the predominant protein that is found in colostrum is casein not whey. But it would definitely pay to chat with your vet about this if you are interested in having some colostrum replacer on-hand this spring!
As we have said before (and we will say it again!) The AgriSciencer is not about telling you what to do, or how to farm, but to expose you to science that may relate to your farming practices and give you something to think about.
On that note:
What did you think of this week's post? Have you used a colostrum replacer before? How about you share this research summary with a friend or neighbour and discuss it over a beverage?
Details on colostrum feeding:
Treatment 1: MC
fed 3.79 litres of maternal colostrum from first milking
IgG concentration of 106 g/L
Mass of IgG fed to each calf in first feed: 401 grams
Treatment 2: LMC-CR
fed 3.79 litres of low quality maternal colostrum from 2nd and 3rd milkings
IgG concentration of 30 g/L from colostrum
Topped up with colostrum replacer to be 41 g/L of IgG
Mass of IgG fed to each calf in first feed: 154 grams
Treatment 3: CR-110
fed 1.3 litres of colostrum replacer
IgG concentration of approx. 85 g/L from colostrum replacer
Mass of IgG fed to each calf in first feed: 110 grams
Treatment 4: CR-150
fed 1.3 litres of colostrum replacer
IgG concentration of approx. 115 g/L from colostrum replacer
Mass of IgG fed to each calf in first feed: 150 grams
All calves were tube-fed and the colostrum was warmed. For the first 2 treatments, the colostrum was thawed in a warm water bath. For the colostrum replacer treatments, the powder was whisked with warm water.
One last little point of interest which may be slightly different to advice that is currently circulating around colostrum and calf feeding is this point made by the authors...
"A volume difference existed between calves fed CR (1.3 L) and calves fed LMC-CR and MC (3.79 L); however, Stott and Fellah (1983) found that total IgG mass fed was more important than IgG concentration, which is affected by volume due to dilution"
Now, current advice is to use a Brix refractometer to estimate IgG concentration in colostrum. Above 22% Brix is considered a "good quality" based on IgG concentration and below 22% Brix is considered "poorer quality".
If the above statement is correct, then maybe advice should be based on the volume fed to the calf at each Brix value, rather than a "good" or "bad" classification? Something I will investigate further! Stay tuned!
Full Paper:
Comments