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Words supplied by AHD, Dr Lucy Waldron, PhD RNutr (UK NZ) R Fellow (Massey)

Preparing for calf rearing involves several issues, of which housing, bedding and biosecurity are key factors. Newborn calves are especially at risk from infections, as, unlike other mammals, they lack any immunoglobulin (the proteins that confer immunity) transfer via the placenta and need to obtain these from colostrum immediately after birth. In many cases the immature immune system in calves leaves them vulnerable to disease.

Sanitising drinking water sources (e.g. tanks and troughs) with, a long term and effective sanitiser is essential as this is a major vector for disease. Effective biosecurity is important to protect calves against pathogens spread by vehicles and personnel.

Calf rearing in New Zealand is typically done indoors, as calves are mainly born in late winter when weather can be bad. This makes it important, prior to stocking, to disinfect the walls and floors as well as feeding and other equipment.

Research has shown that main causes of diseases in calf rearing come from poor disinfection of housing and equipment, bedding and transport vehicles. Research by McGuirk (2008) sampled bedding and transport for calves (Table 1) and showed that contamination in bedding increases quickly once calves are introduced to the pen. However, bacterial loading in transport was the major problem identified. From this work, they made some recommendations for maximum contamination levels to ensure calf health.

Table 1. Bacterial contamination in calf housing (McGuirk, 2008)

The data showed that, even in a ‘clean’ hutch, significant numbers of bacteria remain. Just because a shed looks clean does not mean it is – many bacteria, especially Mycoplasma spp. which have been much in the news recently, exist in biofilms – greasy areas which are resistant to water and many cleaning products.

Effective, long-lasting disinfectants, such as Credence (a stabilised form of chlorine), have been proven to be animal safe, as one of its applications is to sanitise drinking water. It is a highly effective disinfectant for on-farm biosecurity programs and has been used in NZ research facilities conducting calf feeding trials since 2010.

Credence can be used in varying concentrations in calf rearing, especially for easy cleaning of difficult equipment, such as calfeterias, bottles and teats, as well as in foot baths and housing and is not as corrosive as other common cleaning products. Credence is effective against a wide range of bacteria (including Mycoplasma spp.), viruses (including rotavirus for calves), fungi and toxic algae. It is in an easy to use tablet form, and concentrations for various applications are shown in table 2 below.

 Table 2. Credence use on farm for biosecurity, cleaning and disinfection.

  
Proper disinfection has a carry-on effect in calf pens. When calf pens were disinfected with Credence, which can penetrate biofilms effectively, the numbers of pens classified as highly contaminated (which were linked to high disease outbreaks, such as scours) were greatly reduced over the rearing period (table 3). In total, 53% of pens disinfected with Credence at the start of the rearing period had little or no contamination, whereas none of those that were just simply washed down were in this category.

Table 3. Effect of using Credence, a long acting, stable disinfectant, on bacterial levels in calf pens over the rearing period.

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