Challenges and Best Practice

Implementing best practice when it comes to bedding for Dairy cows is multifactorial and consideration of housing, ventilation, temperature, stocking density and bedding type are all important considerations.

Following a wet winter, and extremely dry spring/summer cereal crops have been largely affected, and the obvious shortage will be yet another challenge, both practically and financially for farmers this winter who are sourcing material for both feed and bedding. Professor Richard Ellis of Reading University said, “in a wet year grass will grow a bit but in a dry year it will stop growing completely”.

Combined with challenges on farm such as limited winter forage due to reduced yield and limited resources for quality bedding, there remains the ever-present environmental factor. Defra recognises housing and bedding management as key controls to measure building and bedding effects and aims for 16% reduction of ammonia losses compared to 2005 levels. For further reading on Code of Good Agricultural Practice, the latest version (2024) is available online https://www.gov.uk/government/publications/code-of-good-agricultural-practice-for-reducing-ammonia-emissions/code-of-good-agricultural-practice-cogap-for-reducing-ammonia-emissions.

Both moisture and organic matter such as dung within bedding substrate will support bacterial survival and proliferation and therefore this must be considered when choosing the right bedding and how it is managed on farm.

Bedding will quickly become contaminated, combined with warmth and humidity, an increase of bacterial growth can be observed. Adding fresh bedding daily, removing spoiled bedding frequently combined with good drainage, appropriate stocking density and regular scraping can all form part of a strategy to reduce and limit the spread of environmental mastitis-causing pathogens and other disease-loads within herds (Godden and Royster, 2025). Patel et al. (2021) and Alanis et al. (2021) also observed a significant correlation between bedding type and bacterial proliferation, largely due to their varying characteristics such as water retention, porosity, particle size, and moisture content.

Factors affecting hazards and risks associated with bedding materials in dairy cow housing. Sources: modified figure according to Bradley et al., 2020.

Bedding Types

Each bedding type will have varying properties including pH. Sand is typically pH 6-8, relatively neutral and low moisture-retention which can prevent environments suitable to pathogenic growth. However, increased urine within sand over time can increase pH contributing to ammonia losses.

Properties of sand offer advantages in terms of durability and resistance to microbial growth but management of such can prove difficult (Ray et al., 2022). Shavings and straw are effective at absorbing excess moisture but can create favourable environments when it comes to bacteria (Robles et al., 2022).

Straw ordinarily is a cost-effective and widely used bedding choice. The pH is on average 5.5-7 so more acidic than sand and can absorb increased moisture creating a more hygienic and comfortable environment for the cow. However, straw absorbing excess urine can create damp microenvironments, combined with both sources of carbon and nitrogen as feed for pathogenic bacteria.

Wood shavings have a lower pH of approximately 4.5-6.5 so can maintain more acidity within the bedding, preventing ammonia losses. It has moisture-absorbing capacity and a lower microbial activity than straw. However, it decomposes very slowly, and this must be considered as part of a manure/slurry management plan.

This can be managed with the application of “good” bacteria which populate and dominate within the bedding, maintaining pH and reducing ammonia losses. Application of Effective Microorganisms, including strains such as Lactobacillus can dominate within these environments, outcompeting “bad” bacteria and creating a more stable environment. Due to the dominance of Lactic acid, this supports a more acidic pH within the bedding area resulting in less ammonia being released into the atmosphere.

Bedding Conditioners, alkaline vs acidic.

Controlling the spread of pathogenic growth within bedding can help mitigate the risk of intramammary infections, and general disease burden particularly within intense dairy farming (Frechete et al., 2021). In historical studies, alkaline based conditioners have shown to create environments inhospitable to pathogens including mastitis-causing pathogens in substrates such as sawdust and recycled manure (Paduch et al., 2013). Whilst studies looking at the efficacy of lime-based conditioners within bedding observed a decrease in bad bacteria such as Streptococcus uberis, the effectiveness was closely related to bedding-type and characteristic of specific pathogenic strain (Poli, S.F., 2025), as described above and the various components of different beddings.

The reduction of pathogenic growth is largely associated to pH and hydrated lime achieves this result by rapidly raising this within alkaline range. However, an increase in pH combined with moisture and temperature can accelerate the conversion from urea to ammonium and therefore volatilisation of ammonia from bedding. There is a lot of evidence supported the use of hydrated lime due to low bacterial counts however for this effect to be maintained, the quantity/frequency of application has seen significant irritation to the delicate skin and udder tissue caused by caking of hydrated lime with manure, urine and milk. Teat open lesions (TOL), offering pathways to mastitis-causing bacteria have been studied and the main contributing factor to these is poor condition on the skin of teats and udder. Various bedding substrates can aggravate this particularly seen with sand and moisture (Virkler and Wieland, 2023) as well as high alkalinity which can cause severe irritation to delicate udder areas, particularly during long periods of laying. Bacteria such as S. uberis was not detected in any samples from a previous study from clean or used sawdust and was stated this is most likely due to the natural low pH of sawdust as a substrate (Sherwin et al., 2021).

One such study highlighted that whilst hydrated lime showed reduced bacterial counts within bedding and mattresses, this supressed growth was not seen on the teat ends suggesting the risk of disease and infection remains (Kristula et al., 2008).

By contrast acid-based conditioners showed efficacy in reduction of environmental pathogens within bedding, and teat ends with no compromise to teat condition and reduced environmental impact. Research by (Proietta et al, 2013) using an acidic bedding conditioner found the pH remained below 5.15 for 7 days which coincided with the greatest results being observed in teat end bacterial counts, thus reducing risk of infection.

The main tank of environmental pathogens remains the environment in which the cow is living, therefore creating and managing this is a key factor in the reduction and mitigation of environmental mastitis, mastitis-causing pathogens (Kristula et al., 2008) and other bacterial growth. Another factor in disease prevention is dry matter of bedding (Freu et al., 2023). Several other studies have observed positive correlations between bacterial counts of environmental pathogens in bedding combined with counts on teat ends (Hogan and Smith, 1997; Zdanowicz et al., 2004) from cows kept on bedding treated with acidic conditioner, which may suggest acidity within the bedding is more effective at maintaining reduced bacterial growth both in the bedding, and on the teats.

Natural Bedding: Zeolite structure

Zeolite, natural clay-like minerals offer a holistic alternative to typical alkaline and acidic based bedding conditioners.

The cations contained within zeolite are not strongly bonded, meaning they can be “swapped” for others within their surrounding environment whilst maintaining its strong, 3-dimensional frame. Due to this, ammonium which will be found in the bedding (from urine and organic matter) can “swap” places within Na+ or Ca2 thus trapping ammonia, helping prevent odours and losses from nitrogen as well as creating a more hygienic environment.

They can also increase both absorption and adsorption of moisture, making it less favourable for the spread of mastitis-causing and other pathogenic bacteria. In a recent study looking at microbial load within turkey bedding, the application of 50% zeolite and 50% egg shell (To buffer acidity) demonstrated a significant decrease in bacterial proliferation (Giraz and Emin, 2025).

The use of zeolite within the animal industry have been implemented to improve litter deterioration, thus increasing the welfare and well-being of animals (Naseem and King, 2008). As above, the effectiveness of zeolite within bedding is also largely determined by its own characteristics, such as the particle size, the porosity of individual particles and degree of aggregation (Dumitru et al., 2017). In a study by Szymula et al. (2021) looking at the use of natural sorbents to reduce ammonia emissions, a combination of bentonite and zeolite were the most effective.

Micronized zeolite as a powder is a powerful antioxidant and it is known these play a key role in maintaining the health of animals.

Summary

To summarise these findings, all bedding materials will offer both advantages and disadvantages for housed cows, and calves. They bring a variety of different characteristics and therefore considerations should be made based on the understanding of these, the system and slurry management already in place, as well as logistic and financial restrictions.

In terms of bedding conditioners, we know these can increase longevity of bedding substrate; help retain excess moisture, offer benefits to hygiene and comfort of the cow and mitigate environmental pressures such as ammonia losses.

However, alkaline based conditioners have a limited effect over a short duration without regular reapplication which can lead to skin irritation and teat lesions. It remains a popular choice due to finances and historical use however it can contribute to ammonia losses and potential udder damage, increasing risk, regardless of bedding substrate.

Choosing a natural alternative to traditional hydrated lime, reducing pH within those microenvironments could prolong longevity of bedding and absorption capacity, offer more hygienic stalls, safer and reduced application and could result in increased lying down times, reduced disease pressure and less environmental impact.

Reference List

Alanis, V. M., Zurakowski, M., Pawloski, D., Tomazi, T., Nydam, D. V., & Ospina, P. A. (2021). Description of the characteristics of five bedding materials and association with bulk tank milk quality on five New York dairy herds. Frontiers in Veterinary Science, 8. https://doi.org/10.3389/fvets.2021.636833

Fréchette A, Fecteau G, Côté C, Dufour S. Clinical mastitis incidence in dairy cows housed on recycled manure solids bedding: a Canadian cohort study. Front Vet Sci. (2021) 8:1–8. doi: 10.3389/fvets.2021.742868).

Freu G, Garcia BLN, Tomazi T, Di Leo GS, Gheller LS, Bronzo V, et al. Association between mastitis occurrence in dairy cows and bedding characteristics of compost-bedded pack barns. Pathogens. (2023) 12:1–13. doi: 10.3390/pathogens12040583; Leso L, Barbari M, Lopes MA, Damasceno FA, Galama P, Taraba JL, et al. Invited review: compost-bedded pack barns for dairy cows. J Dairy Sci. (2020) 103:1072–99. doi: 10.3168/jds.2019-16864).

Godden, S.M. and Royster, E. (2025). Bedding management with a view to promoting udder health. Veterinary clinics of N America: Food Animal Practice, 41, 2, 237-248. https://doi.org/10.1016/j.cvfa.2025.02.007

https://zenodo.org/records/16987086

Naseem, S. and King, A.J., 2018. Ammonia production in poultry houses can affect the health of humans, birds, and the environment — techniques for its reduction during poultry production. Environmental Science and Pollution Research, 25, 15269-15293. https://doi.org/10.1007/s11356-018-2018-y.

Paduch, J., Mohr, E., & Kromker, ¨ V. (2013). The association between bedding material and the bacterial counts of Staphylococcus aureus, Streptococcus uberis and coliform bacteria on teat skin and in teat canals in lactating dairy cattle. Journal of Dairy Research, 80, 159–164. https://doi.org/10.1017/S0022029913000046

Patel, K., Godden, S. M., Royster, E., Crooker, B. A., Timmerman, J., & Fox, L. (2019). Relationships among bedding materials, bedding bacteria counts, udder hygiene, milk quality, and udder health in US dairy herds. Journal of Dairy Science, 102, 10213–10234. https://doi.org/10.3168/jds.2019-16692

Ray, T., Gaire, T. N., Dean, C. J., Rowe, S., Godden, S. M., & Noyes, N. R. (2022). The microbiome of common bedding materials before and after use on commercial dairy farms. Animal Microbiome, 4. https://doi.org/10.1186/s42523-022-00171-2

Robles, I., Kelton, D. F., Barkema, H. W., Keefe, G. P., Roy, J. P., von Keyserlingk, M. A. G., & DeVries, T. J. (2020). Bacterial concentrations in bedding and their association with dairy cow hygiene and milk quality. Animal: An International Journal of Animal Bioscience, 14, 1052–1066. https://doi.org/10.1017/ S1751731119002787

Sherwin, V. E., Egan, S. A., Green, M. J., & Leigh, J. A. (2021). Survival of Streptococcus uberis on bedding substrates. Veterinary Journal, 276. https://doi.org/10.1016/j. tvjl.2021.105731

Virkler, P.D. and Wieland, M. (2023). Teat Open Lesions can lead to challenges at milking time on dairies in the Northeast US. AVMA, 261, 1. S103-S108. https://doi.org/10.2460/javma.22.12.0567

Zigo, F., Sasáková, N., Gregová, G., Výrostková, J., & Ondrašovičová, S. (2020). Effects of Using an Alternative Bedding Composition on the Levels of Indicator Microorganisms and Mammary Health in Dairy Farm Conditions. Agriculture, 10(6), 245. https://doi.org/10.3390/agriculture10060245

Bedding, friend or foe