Colostrum is the multifaceted secretion produced by mammalian mammary glands during the initial postpartum period, which is a crucial part of the well-being and survival of new-born livestock.

 

As an essential component to the success of any breeding operation, increasing your knowledge surrounding colostrum and the management thereof is vital. Colostrum is the multifaceted secretion produced by mammalian mammary glands during the initial postpartum period, which is a crucial part of the well-being and survival of new-born livestock. It is a highly concentrated, bio-active fluid exhibiting a yellowish colour and a thick, creamy consistency - replete with nutrients and antibodies. As a complex biological fluid, colostrum plays a pivotal role in the development of an infant’s immune system by providing a myriad of immune, growth, and tissue repair factors. Its composition includes significant quantities of complement components, which function as natural anti-microbial agents. These components actively stimulate the maturation of the infant’s immune system, fortifying their ability to combat potential infections and diseases during the early stages of life. 

 

Colostrum is not only rich in nutrients but also contains non-nutrient factors that promote immune system development and intestinal maturation in calves. 

 

Colostrum can mean the difference between life and death for new-born calves, as it is the primary source of passive immunity. Passive immunity - acquired from an external source - is crucial in protecting the calf during its vulnerable early stages. Colostrum delivers essential proteins known as immunoglobulins (Ig), which help establish this protective shield. A calf is considered to have attained adequate passive immunity when blood IgG concentrations are greater than or equal to 10 g/L at 24 hours of age. Calves with blood Ig levels below this threshold are at an increased risk of death. Colostrum is a vital source of vitamins A, D, and E, which are essential for the calf’s growth, reproduction, and immune response. The transfer of these vitamins across the placenta is limited, and the neonate relies on colostrum consumption to establish adequate tissue stores.

 

Colostrum is also abundant in magnesium, which is essential for the calf’s health. Magnesium absorption decreases as the calf ages, highlighting the importance of colostrum intake. The absorption of nutrients, including carbohydrates, amino acids, fatty acids, and large molecules like immunoglobulins, occurs primarily in the small intestine through various processes such as active transport, passive diffusion, and pinocytosis. Proper maturation and functioning of the neonatal intestine enable the calf to digest and absorb nutrients from colostrum and milk, supporting postnatal growth and organ development. The somatotropic axis, a major postnatal endocrine regulatory system for body growth, is stimulated by the intake of colostrum and milk, promoting anabolic metabolism in calves. 

 

The first weeks of life are critical for new-born calves due to their high pathogen susceptibility. Cows, like other ruminants, have an epitheliochorial placenta that prevents passive immunity transfer to the neonate during gestation. As a result, new-born calves are agammaglobulinemic and depend almost entirely on colostrum for their initial immune protection.

 

Colostrum quality is determined by the presence of immunoglobulin G (IgG), which makes up approximately 85-90% of the total immunoglobulins in colostrum. There are two main types of IgG: IgG1 and IgG2. Colostrum also contains IgM (7%) and IgA (5%), both in multiple forms. While new-born calves absorb all three types of immunoglobulins, IgA partially returns to the calf’s intestines to provide local protection, and IgM mainly contributes to the primary immune response. Since IgA and IgM have a shorter lifespan compared to IgG, their protective functions are limited.

 

High-quality colostrum typically has an IgG concentration of over 50 g/L. It is widely accepted that a calf’s blood should have an IgG concentration of at least 10 mg/mL between 24 and 48 hours after birth to indicate successful immune transfer. Failure to achieve this level is associated with higher calf illness and death rates. The concentration of immunoglobulins (Ig) in colostrum can vary depending on factors such as the cow’s disease history, the volume of colostrum produced, the season, the breed, the cow’s nutrition during the dry period and the age of the cow. 

 

Colostrum from cows that produce more than approximately 8.16 litres at the first milking usually has a lower Ig concentration (18 lb. or 8.16 litres rule). However, this is only a general rule, as the relationship between Ig concentration and volume is not constant.

 

The difference between 20 and 100 g/L of IgG in colostrum can mean the difference between colostrum deficiency and adequate colostrum status in the calf. Older cows often produce better quality colostrum than younger cows. However, if older cows are not exposed to many pathogens, the colostrum produced may not have high levels of antibodies. The type of antibodies in colostrum depends on the antigens to which the cow was exposed, either through disease exposure or vaccination. Furthermore, cattle raised on a farm will produce colostrum with antibodies specific to the organisms on that farm, which is an added benefit. Milking or leaking of milk from the udder before calving can significantly reduce the concentration of antibodies in colostrum.

 

Generally, colostrum produced in large volumes will have lower Ig concentrations than colostrum produced in smaller volumes. Colostrum from cows that produce more than approximately 8.16 litres at the first milking usually has a lower Ig concentration (18 lb. or 8.16 litres rule). However, this is only a general rule, as the relationship between Ig concentration and volume is not constant. The timeframe for colostrum uptake is imperative, and ensuring an immediate and sufficient colostrum supply after birth is crucial for successful calf rearing. The calves’ ability to absorb immunoglobulins (Ig) diminishes significantly after 12 hours and is completely blocked at 24 hours of age. 

 

If the calf cannot nurse, it is essential to use high-quality frozen or fresh colostrum (with a minimum of 50 g of IgG/L). If colostrum availability is limited, a bovine-serum based commercial supplement can be used either to fortify an existing colostrum source or to replace colostrum when none is available. It is imperative that absorption of Ig occurs before gut closure, the process by which the calf’s intestine becomes impermeable to the large Ig proteins. In a healthy calf with access to liquid feed or colostrum, gut closure typically occurs within 24 hours after birth. Inadequate colostrum management practices, such as on-farm storage and feeding methods, can impact the immune components in colostrum and subsequently the immune status of the new-born calf. The small intestine is widely considered the primary site of absorption for colostrum in new-born calves. The high pH level in the abomasum of new-born calves helps prevent proteolytic digestion of immunoglobulins (Ig). However, research findings are not entirely consistent in determining whether the absorption process is selective or not. The ability of a new-born calf’s intestinal epithelium to absorb colostrum demonstrates a linear decrease from birth until gut closure. 

 

In general, calves are believed to absorb Ig up to twelve hours after birth. It is recommended that new-born calves receive two litres of colostrum within twelve hours of birth. 

 

Some studies suggest that the presence of the dam may have a positive effect on absorption, however various factors can influence the validity of this. The role of breed in Ig absorption is also debated in the literature, with no clear consensus. While corticosteroids or hormones might have a marginal impact on Ig absorption, their use is generally not recommended for pregnant cows or new-born calves due to potential risks and side effects. Ensuring an adequate supply of high-quality colostrum, within the critical timeframe, can make a significant difference in the calf’s immunity and overall development. If fresh colostrum is not available, commercially available colostrum supplements or replacers can be used as an alternative. It’s essential to consult your veterinarian on the use of these supplements or replacers to ensure they meet the nutritional requirements of the new-born calf. Storing colostrum for later use is a valuable practice for producers who may not always have access to fresh colostrum. 

 

Colostrum can be stored by freezing it in milk cartons or plastic containers, which can later be thawed and mixed with warm water for feeding. To preserve the antibodies, it is crucial to thaw colostrum using a warm water bath, avoiding boiling temperatures that may destroy its immune properties. 

 

Having a stored supply of high-quality colostrum can be achieved by freezing the colostrum collected from the first milking after calving. A colostrometer can be used to measure colostral quality on the farm, warranting that the colostrum contains at least 50 g of Ig/L. Proper storage of colostrum allows for quick thawing when needed, ensuring that calves receive the necessary immune protection in a timely manner. By understanding and implementing best practices for colostrum storage and alternatives, producers can provide their new-born calves with the essential immune protection and nutrients needed for optimal growth and development. It is evident that effective colostrum management on farms plays a pivotal role in ensuring successful immunity transfer and providing new-born calves with the optimal foundation for growth and development.

 

By adhering to the “Three Q’s” guideline, which encompasses Quantity, Quality, and Quickness of feeding, as well as additional factors such as quantifying immunoglobulin transfer and maintaining cleanliness, producers can significantly improve calf health. Key aspects of colostrum management include timely provision of sufficient high-quality colostrum, minimizing bacterial contamination, and closely monitoring calves’ blood IgG levels within the first 24 to 48 hours of life. Despite the wealth of existing knowledge on colostrum management and its impact on colostrum quality and immune transfer to calves, there is still room for further research and development. Current studies are exploring various aspects of colostrum management, such as milking methods, treatment and storage procedures, and administration techniques, to continue refining best practices and enhancing the well-being of calves.