Welcome to this insightful review on the pivotal role of antioxidants in the growth and overall health of dairy calves. You’ll learn here about how the neonatal period, a crucial stage for immune, metabolic, and physical development in dairy calves, leaves them vulnerable to diseases. Despite the industry’s reliance on colostrum and vaccination for early life immunity, several hurdles persist when vaccinating calves during this period.
Three primary challenges exist in vaccinating neonatal calves:
- The inability to mount an effective immune response
- Interference with maternal antibodies
- The onset of Oxidative Stress (OS)
Oxidative stress denotes an imbalance between pro-oxidants and antioxidants leading to cellular oxidative damage or dysfunction or both. It has garnered interest due to its negative impact on lymphocyte function, potentially affecting vaccine response which is vital in the neonatal period. This imbalance has been widely studied in mature cattle, with antioxidant supplementation showing promising potential to enhance reduction-oxidation balance and immune response.
But here’s the kicker – evidence supporting the use of antioxidants such as vitamins and minerals in neonatal calves is far less abundant, though necessary for optimizing immunity and disease resistance. This review will bring to light research conducted on the effects of antioxidant supplementation on calf immunity, health, productivity, and the still-existing gaps in knowledge.
Overall, micronutrient supplementation, comprised of vitamins and minerals, has enhanced immune responses in both preweaning and postweaning calves. But, the jury is still out on its consistent positive effect on calf health and overall growth performance.
The Importance of Antioxidants for Calf Immunity and Growth
You may be aware that the mortality rates for newborn calves are quite high worldwide. This remains a significant concern with a troubling 5% in the US and an even more alarming 33.8% in regions like Canada, Europe, and China. The implications of these figures are not to be taken lightly as they impose a substantial financial burden on those in animal production, affecting both current and future yields.
You might wonder, why do these mortality rates remain so high? Well, the crux of the issue lies in the fact that calves are born with exceedingly immature immune systems. This vulnerability leaves them exposed to a host of diseases, crippling their natural ability to respond effectively to vaccinations and various preventative measures.
Immune Development and Vaccination Challenges
Just like human newborns, calves arrive in this world with an immune system that’s still developing – in essence, they are immunologically naive. To protect them, nature has equipped their mothers with colostrum, a richly nutritious fluid filled with antibodies, cytokines, and immune cells. But these defenses can take several months to fully mature.
During the neonatal stage, calves grapple with high metabolic demands, which in turn can make them more vulnerable to diseases. Vaccinations are employed as a standard preventive measure to control the incidence of diseases, chief among them respiratory disorders, but even these aren’t without their challenges.
For starters, maternal antibodies can often interfere with the working of vaccines. Moreover, oxidative stress (OS), brought on by an imbalance of free radicals and antioxidants in the body, can also affect the efficacy of vaccinations.
Intranasal vaccinations present a promising solution to this problem. Designed to stimulate the production of antibodies on the mucosal surfaces – where many diseases take hold – these can provide more effective protection. But even they can’t fully guard calves for the entire period of disease susceptibility.
The ray of hope in this scenario? Antioxidants. By improving redox balance in the body and mitigating oxidative stress, these substances could enhance the response to vaccines.
Considering these facts, it may be beneficial to pair intranasal vaccination with supplementation of antioxidants. Through this integrated approach, calves may better handle the challenges of early life disease susceptibility and vaccination interference.
Indeed, the role of antioxidants in calf immunity, growth, and health, seems promising. But as with any scientific discovery, more research is needed to truly understand their potential and how best to leverage their beneficial attributes.
Oxidative Stress During the Neonatal Period
At birth, mammals are exposed to an oxygen-rich environment, increasing the production of reactive oxygen species (ROS). This can lead to increased oxidative stress (OS) for up to four weeks, potentially affecting cell development and cell death. Calves have higher blood concentrations of ROS compared to their dams and before colostrum ingestion. Colostrum intake also contributes to circulating ROS concentrations, as it contains pro-oxidants and antioxidants. However, colostrum concentrations are less than those in milk, making calves at greater risk for developing OS when fed colostrum compared to normal milk. Other stressors during early life, such as metabolic demands for growth and disease susceptibility, also contribute to the risk of OS. The oxidant status index (OSi) is a validated tool to assess redox balance in cattle. Antioxidant supplementation can improve redox balance and reduce OS by improving antioxidant capacity. However, OS in calves is still an emerging area of research.
Enter the Power of Antioxidants…
There’s a powerful secret nestled within the realms of science and nature. By harnessing the benefits of supplemental antioxidants, which include essential vitamins, trace minerals, and herbs, we can considerably fortify the immune systems of newborn calves. The result? Our calves become better equipped to fend off infections and respond more effectively to vaccines.
In simple terms, think of a supplemental antioxidant as a superhero recruited to help a calf’s developing immune system. Like a shield protecting a warrior from attacks, these substances act as a first line of defense, helping our newborn calves thrive in their initial stages of life.
However, here’s the rub – the availability and consistency of these essential elements. To ensure the optimal health and growth, these nutrient superheroes need to step in on a regular basis. But, as you can imagine, this turns into quite a challenging task, especially in areas of scarcity or inadequate supplies.
If we consider the wider implications, guaranteeing these supplements for all calves becomes an imperative yet complex mission. Yet, the reward is significant; imagining a world with healthier, stronger calves capable of reaching their maximum potential, contributing significantly to the agricultural economy and shaping robust farming communities.
Antioxidant Function
When it comes to understanding the antioxidants defense system in calves, it’s essential to consider both enzymatic and nonenzymatic components. These could encompass elements like antioxidant enzymes, vitamins, and trace minerals to combat oxidative stress. Various trials during the preweaning period of calves have focused on antioxidant supplementation, paying special attention to micronutrients such as Selenium (Se), Copper (Cu), Zinc (Zn), Manganese (Mn), Chromium (Cr), and vitamins like A, E, and D.
However, while our understanding is ever-expanding, current literature on the effect of antioxidant supplementation on calves’ redox balance still has gaps to fill. One bright spot in recent research found that newborn calves showed a significantly improved redox balance when they received injectable antioxidants immediately after birth.
As a general rule, the total antioxidant status is often scrutinized as a potential response to antioxidant supplementation. This insight strengthens our understanding that antioxidants might play a significant role in combating oxidative stress in calves. But we are still far from completely understanding this complex biological phenomenon.
Therefore, despite these exciting occurrences, we must underline the requirement for further intensive research. A comprehensive understanding of redox balance in calves and the interaction of antioxidants could have significant implications for calf health, growth, and immunity.
Antioxidant Supplementation Effect on Calf Immunity
Micronutrient supplementation is a promising avenue in bolstering both innate and adaptive immunity responses in calves. Clear markers of improved immune function often include increased leukocyte concentrations, heightened white blood cell function, and enhanced antioxidant enzyme activity. Injectable trace minerals (ITM), in particular, yield compelling results when supplemented to weaned calves. These animals showed an increase in platelet counts following a challenge with bovine viral diarrhea virus, comparing favorably to their non-supplemented counterparts.
However, this enhanced immunity isn’t limited to weaned calves. Antioxidant enzyme activity and concentrations also saw a noteworthy increase in both dairy and beef neonatal calves when supplemented with the same ITM, standing as a testament to the versatility of antioxidants.
Not only does antioxidant supplementation have a profound impact on innate immunity, but it also extends its reach to improving humoral immunity. A stellar example comes from two research studies, where 3.5-month-old bull calves—supplemented with ITM alongside a modified live virus parenteral vaccine for bovine herpes virus 1, bovine viral diarrhea virus, and parainfluenza 3 virus, and a parenteral bacterin for Mannheimia haemolytica and Pasteurella multocida—showed faster and increased antibody production against bovine viral diarrhea virus 1 and M. haemolytica.
However, like any area of scientific pursuit, contradictions are all part of the journey. Some evidence suggests no difference in antibody production against Salmonella spp., in calves treated with ITM at two weeks old, when paralleled with control calves. Despite these variances, the body of research largely agrees that antioxidant supplementation boosts both innate and adaptive immunity in calves.
While studies revolving around trace mineral supplementation are gaining momentum in the field, there is a noticeable lack of focus when it comes to vitamin supplementation. However, wherever they do make an appearance, vitamins promise improved neutrophil function, increased concentrations of antioxidant enzymes and elevated serum concentrations of IgA in mature cows. However, applying these benefits to the immature immune systems of neonatal calves remains uncertain and ripe for further exploration. Antioxidant supplementation offers impressive boosts to humoral immunity, with studies touting increased antibody production against various viruses and bacteria. Nevertheless, some studies have cast doubt over these findings, particularly when it comes to antibody production against Salmonella spp., in calves treated with ITM at two weeks old. Despite these discrepancies, the majority of evidence overwhelmingly supports the use of antioxidant supplementation in improving both innate and adaptive immunity in calves.
Antioxidant Supplementation Effect on Calf Growth and Health Status
- Calf Growth
Studies show no significant difference in ADG between calves supplemented with antioxidants and control calves, suggesting antioxidant supplementation doesn’t affect growth performance during the pre- or postweaning period. However, crossbred calves receiving ITM (Se, Cu, Zn, and Mn) showed greater ADG compared to control calves. Additionally, studies on dairy heifers reported increased ADG during the pre- and postweaning period when supplemented with chromium, liquid, and solid. There is no consistent evidence to suggest that antioxidant supplementation influences ADG in calves throughout the pre- or postweaning period. - Calf Health
There is conflicting evidence on the impact of antioxidant supplementation on calf morbidity and mortality. Some studies suggest that calves supplemented with antioxidants (Se, Cu, Zn, and Mn) have lower prevalence of diarrhea and respiratory disease during the preweaning period. However, others find no differences in mortality or preweaning treatment between calves supplemented with selenium and vitamin E at birth and their control counterparts. Crossbred calves supplemented with ITM 1 day post arrival have lower rates of bovine respiratory disease mortality compared to control calves. Further research is needed to determine appropriate supplementation strategies, including frequency and dose, to improve calf growth, morbidity, and mortality. Strategies for exploration include comparing supplementation type, optimizing timing of supplementation to target times of susceptibility, and considering supplementation differences based on breed.
The Bottom Line
All things considered, this review sheds light on the crucial role of antioxidant supplementation in calf health and growth. Despite a limited body of research when it comes to newborn calves, existing data strongly suggests that such supplements can bolster calf immunity both prior to and after the weaning stage. However, it’s essential to acknowledge that evidence surrounding the impact of antioxidant supplementation on calf health and growth performance remains somewhat contradictory.
The variable results hint towards the importance of considering certain factors in these studies. For instance, the age at which calves receive supplementation, the specific type of supplement – whether that be trace minerals, vitamins, or a blend of the two, and an accurate assessment of the calf’s initial oxidant status all have the potential to affect the outcomes. As such, these areas command further research to flesh out our current understanding.
Together, the concerted efforts of both researchers and veterinary professionals is absolutely vital to broadening our knowledge in this arena. This collaborative work ensures the correct application of antioxidant supplements within the cattle industry, optimizing the use of these beneficial compounds for improving calf health, growth, and overall wellbeing.
