March 7 2022 08:00 AM

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Calf scours are inherent to calf rearing and are too often a headache for calf managers. The problem is multifactorial, and, despite decades of research, it is still the largest cause of mortality and treatment in pre- weaning heifers.

The three main goals of treatment therapy are to: 1. combat the scours inducing pathogen, 2. meet the calf’s physiologic needs (hydration, energy, acid/base balance) and 3. restore gut health.

The mode of action of calf scours is complex, but it often starts with an infection that affects gut wall integrity.

The osmotic effect of unabsorbed lactose leads to diarrhea, loss of nutrients, and dehydration. Symptoms (sunken eyes, tented skin, and cold legs) are related to the compensatory mechanisms to fight against dehydration. Another problem of a scouring calf is decreased blood pH, typically known as metabolic acidosis. In conjunction with hypoglycemia (low blood glucose), this leads to depression and reduced suckling reflex.

When treating scours, it is critical to address dehydration as early as possible. A good oral rehydration solution should meet the calf’s physiologic needs (Smith, 2009). It should provide the proper amount of sodium and amino acids, including glycine, to promote sodium absorption. It should also have energy sources such as glucose to correct hypoglycemia, and, finally, a buffer to correct metabolic acidosis, of which acetate and propionate are preferred (rather than bicarbonate). An osmolarity (concentration of particles of a solution) of 400 to 600 mOsm/L is ideal.

Continue to feed milk as it will be the calf’s main source of energy, but resist the urge to mix electrolyte with milk or milk replacer to save labor. This practice can cause osmolarity, which may increase and worsen diarrhea.

If necessary, antimicrobial products can be used and antibiotics should be the last resort in your protocol. Remember, in more than 80 percent of scours, two or more pathogens are involved. Most treatments are very pathogen specific, while there are some natural alternatives that offer a broader spectrum of antimicrobial activity.

For example, oregano essential oil has demonstrated a potent antibacterial effect against both Gram-positive and Gram-negative bacteria and some virus types. Although research is still limited, there are studies showing a lower incidence and duration of calf scours, as well as a synergistic effect with other antibiotics, allowing decreased use.

Mannan oligosaccharides, commonly referred to as MOS, have binding capacity against some types of bacteria and toxins, as well as immunomodulatory effects and a role as prebiotics for beneficial bacteria. Finally, probiotics have a role due to their immunomodulatory effects and competitive exclusion against harmful bacteria.

Ideally, a combination of natural solutions with different modes of action should be used together to reduce the pathogen load and support digestive health independent of the pathogen involved. Timing of administration soon after the first sign of symptoms is critical to effectiveness of non-pharma solutions.

* The Dairy Calf and Heifer Association does not support one product over another and any mention is not an endorsement by DCHA.

First published in DCHA Heifer Notes