Ensure Pre-Weaned Calf Health by Focusing on These 5 Key Areas

There are several important aspects related to pre-weaned calf management as illustrated in Figure 1. Timely diagnosis of disease and administration of the correct treatment is also an important component of calf rearing. Although calves are not actively contributing to milk sales, it is in the best interest of the farm to closely monitor calf health in an effort to produce high-quality replacement heifers.

Reasons for calf illness

Despite advances in management and technology on farms, the National Animal Health Monitoring System (NAHMS) 2007 dairy report estimated the average mortality rate at 7.8% during the pre-weaning phase on North American dairy farms (USDA, 2007). Diarrhea or digestive problems accounted for 56.5% of the deaths in pre-weaned calves, and respiratory problems accounted for another 22.5% of the deaths.

Death due to diarrhea is mainly related to dehydration and septicemia (infection of the blood). When looking at pre-weaned calf morbidity, 23.9% had diarrhea (74.5% of calves with diarrhea or digestive problems were treated with antimicrobials) and 12.4% of calves had respiratory diseases (93.4% of calves with respiratory issues were treated with antimicrobials). Additionally, 1.6% of pre-weaned heifer calves suffered navel infections (92.3% of calves with navel infections were treated with antimicrobials). Regular monitoring and good record keeping may hasten the diagnosis of sick calves. Supportive therapy during the early stages of illness may help reduce calf loss.

Figure 1. Five important aspects related to pre-weaned calf management Source: BIOMIN

Figure 1. Five important aspects related to pre-weaned calf management
Figure 1. Five important aspects related to pre-weaned calf management

Hygiene and maternity pen management

Proper hygiene is necessary in all aspects of calf management. This begins in the maternity pen. Maternity pens should be well bedded with clean, dry bedding, ideally separated from pens housing sick animals. Bedding should be changed regularly and pens disinfected between uses in order to reduce pathogen loads.
Calves are born with little to no immunity so reducing exposure to pathogens is important. Additionally, calves have very little fat reserves at birth, so the maternity pen should be draft-free, especially in colder climates and seasons.
Maternity pens should be well supervised so that calves can be removed from the dam in a timely manner. This will help reduce pathogen exposure as well as reducing the potential for injury, which may occur especially in group pens. Cleanliness of the maternity pen is essential, as poor hygiene can contribute to navel infections.
The use of a 7% tincture of iodine dip shortly after calving can help reduce navel infections.

Colostrum

There are many important aspects of pre-weaned calf management, but the quality, amount, and timing of colostrum fed to calves is the main focus on most farms. Feeding four liters of high-quality colostrum (> avoid breaking off of immunoglobulins) within 6 to 12 hours of birth is commonly recommended. Absorption of immunoglobulins in the intestinal tract decreases over time; therefore, it is important to deliver these nutrients to the calf in a timely manner. Immunoglobulins help provide protection during the first two weeks of life while the calf develops its own active immunity.
Colostrum quality is also key. The quality of the colostrum can be estimated easily on-farm with the use of a colostrometer or hydrometer. This tool is reliably used to distinguish good-quality colostrum from poor-quality colostrum. A Brix refractometer is another tool which can be used on-farm to determine colostrum quality. Regardless of which tool is used, it is best to measure colostrum quality at room temperature (23°C) as samples at lower or higher temperatures can provide false readings.
Another indicator of colostrum quality is bacterial content. Bacterial counts can be limited with sanitary collection and handling. Colostrum should be fed to the calf, or refrigerated or frozen within one to two hours after collection to prevent excessive bacterial growth. Additionally, colostrum (or milk) can be pasteurized to reduce bacterial loads.
Studies have shown that batch pasteurization for 60 minutes at 60°C significantly reduces bacterial counts with minimal destruction of immunoglobulins. Pasteurizers require proper cleaning and regular maintenance to ensure they are effectively reducing bacterial counts. One good way to monitor pasteurizer efficiency is to test the bacterial counts of milk samples both before and after pasteurization to ensure that bacterial content is being reduced. Again, hygienic handling of the pasteurized milk is important to prevent re-contamination prior to feeding.

Nutrition

Dairy calves have traditionally been limit-fed with liquid feed (at approximately 10% of body weight, which is estimated to be half the normal consumption) in an effort to accelerate weaning and reduce input costs. Multiple studies have investigated the potential benefits of increasing the amount of milk or milk replacer offered to calves. Data suggest that more intensive feeding programs promote growth, improve feed efficiency, improve health and animal welfare, and potentially improve future milk production. These improvements may be due to increased availability of nutrients for growth, improved immune function, and improved ability to deal with climate-induced stress.
Limit-feeding may only provide enough nutrients and energy for maintenance requirements. During cold weather (and also hot weather), more energy is required to maintain body temperature. Additionally, energy requirements are increased when a calf is ill in order to mount an immune response, but dietary intakes typically decline during this period of increased need, putting the calf at an even greater disadvantage. Calves that received greater amounts of milk or milk replacer experienced lower mortality and morbidity than those with restricted intakes, most likely due to their improved ability to cope with challenges.
In addition to reconsidering the sheer volume of milk or milk replacer fed, the formulation of traditional milk replacers has also been investigated. A 20% protein, 20% fat powder is commonly fed. Higher nutrient density formulations have been created with nutrient profiles closer to whole milk. These are especially beneficial during cold weather and for small breeds such as Jerseys, which are at a greater risk of heat loss.
Feed additives are available for use in milk replacers and also calf starters. Table 1 lists some of the categories of feed additive and their benefits in calf production. Many products on the market are beneficial in calf production, but none of them can overcome excessively poor hygiene or extremely poor-quality feeds.

Table 1. Feed additives and their benefits

Category of feed additive

Benefit

Prebiotics and probiotics

Help establish beneficial gut flora, improving resistance to gastrointestinal disease

Phytogenic feed additives

Increase feed intake

Antimicrobial effects improving gut health

Anti-inflammatory effects improving gut health

Antioxidative effects improving gut health

Yeast and yeast cell wall

Bind Gram-negative bacteria to support digestive health

Acidifiers

Improve feed hygiene Improve digestibility of feed

Housing

Housing is also important to raising healthy calves. Proper hygiene is key and calves should be provided with plenty of clean, dry bedding. Ventilation is also important to maintain good air quality and reduce respiratory issues. Most calves are housed individually prior to weaning, but recent research has seen benefits in performance parameters and social interactions for calves housed in pairs. Cross-suckling is a concern when calves are housed together, but non-nutritive suckling can also be detrimental to the health of individually housed calves due to potential pathogen ingestion. Further research is needed into group housing and the reduction of all types of suckling.

Many factors influence pre-weaned calf health and can have carry-over effects later in life. During times when milk prices are low it may be tempting to cut input costs, especially at a stage of production where earnings are not apparent. However, poor calf rearing will eventually affect profits when those heifers enter the milking herd. Spending time and money to raise healthy calves will pay off in the future.

This article originally appeared in Progressive Dairyman

In Brief

  • Raising healthy calves is essential to optimizing the future performance of the dairy herd.
  • Critical factors to consider include maternity pen management, hygiene, colostrum intake, housing and nutrition.
  • Supporting the calf from birth will minimize animal losses and promote higher future performance levels when the animal joins the milking herd.

Reference

USDA. (2007). Dairy 2007 Heifer Calf Health and Management Practices on U.S. Dairy Operations, 2007. https://www.aphis.usda.gov/animal_health/nahms/dairy/downloads/dairy07/Dairy07_ir_CalfHealth.pdf

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