FROM THE FARM REPORT: DIRECT-FED MICROBIALS FOR CALF HEALTH

The preweaning period is a pivotal stage that can have lasting consequences, influencing growth and future milk production. It has been found that calves experiencing illness within the first four months of life have negative effects on first lactation 305-d mature equivalent milk, actual milk, protein and fat production (Heinrichs and Heinrichs, 2011). Antibiotics are a common way of preventing or treating illness during this timeframe, and they can significantly decrease milk yield during the first lactation, as much as 493 kg or approximately 1,086 lb less than calves who were not treated with antibiotics. Additionally, increased average daily gain (ADG) is associated with increased milk production during the first lactation (Soberon et al., 2012).

A review written by Davies et al. in 2022 outlined the nutritional and therapeutic factors that influence the health and welfare of calves and the potential use of direct-fed microbials (DFM) in promoting their performance. In this review, the authors concluded that antibiotics should be used for the sole purpose of therapeutic treatment of infectious diseases, while DFMs may be better suited for promoting calf performance and gastrointestinal health, which would be extremely beneficial during this time frame as preweaning calves are at a higher risk of mortality due to enteric diseases (Davies et al., 2022; NAHMS, 2008).

A multistrain DFM was found to significantly decrease mortality and antibiotic treatment, while increasing the health index of calves (Maldonado et al., 2018) and decreasing the duration of diarrhea (Renaud et al., 2019; Stefańska et al., 2021), and increasing ADG (Zábransky et al., 2021). Multistrain DFMs are not the only products available, single strains such as Saccharomyces Cerevisiae Boulardii CNCM I-1079 have also been reported to decrease the severity of diarrhea, decrease antibiotic treatments (Villot et al., 2019), increase starter dry matter intake, decrease fecal scores (Lee et al., 2019), and lastly increase weight gain (Renaud et al., 2019). In a recent study, where chronic stress was induced on calves through changing the time of feeding, it was found that the inclusion of a DFM during times of chronic stress improved growth performance (Davies et al., 2025).

Key takeaways for producers and nutritionists include a focus on preweaning calf health specifically on ADG and careful consideration when using antibiotics. Direct-fed microbials could be an additional tool to support growth and performance during the pre-weaning period. Although, there are some considerations when using DFM’s on-farm. This includes the strain of organism, as the type of strain may respond differently in the intestinal environment. Ensuring that it is stored and handled according to the company’s guidelines to maintain stability of the product. If mixing with water, knowing the level of chlorine, temperature and mineral content to make sure it won’t affect the viability of the product. Some considerations when mixing with milk replacer, include the temperature of the milk replacer and if it contains any antimicrobials, as these may interfere with the action of the DFM (Quigley, 2011). I’m curious to know if anyone is currently using a DFM during the pre-weaning period? If so, how are you using it? Are you feeding it in milk replacer or starter?

— Victoria Blaney

vblaney@whminer.com