There are countless external variables in the life of a cow, such as heat, lighting, ventilation and forages. Producers do their best to control these, because they know consistency equals less stressed and healthier cows. Within the cow, there are also countless variables to consider. These variables impact the integrity of the microbiome and how it responds to daily pH fluctuations and pathogens. A stable environment is critical to ensuring proper nutrient breakdown and absorption. It is challenging for producers to control these internal factors. This is why the finding of a recently published paper, indicating medium-chain fatty acids support a less variable rumen pH throughout the day, is insightful for helping producers and their herds.
Commonly used in monogastrics for their antimicrobial properties, medium-chain fatty acids (MCFA) role in ruminants is exiting the exploratory phase of research to being applied on cattle farms. This lag of integrating MCFA, compared to the swine and poultry industries, is mainly due to the mystery of the rumen and how it reacts to MCFA. Current findings indicate large dosages of MCFA (>1% of DM) can positively reduce methane emissions. However, these changes are likely due to a high disruption in the microbiota resulting in reduced dry matter intake, decreased NDF digestibility, lower ruminal volatile fatty acid production and a drop milk production. Therefore, current studies are testing the role low-dose of MFCA (<0.2% of DM) has on rumen health and development. A recently published study, partially funded by Agrimprove, by Burdick et al., tested and measured the impact of low-dose MCFA (0.063% of DM) on mid-lactation dairy cows and its impact on dry matter intake, nutrient digestibility, rumen fermentation, rumen microbiota, and nutrient utilization. The findings of this study suggest a more stable rumen is possible with low-dose MFCA. This consistency in the rumen aligns with improved immune health observed in other low-dose MCFA research.
MCFA interaction with the immune system
An interesting finding from previous MCFA research includes its positive role on polymorphonuclear neutrophilic leukocytes (PMNL or neutrophils). This type of white blood cell is a first responder when the inflammation cycle is triggered in any mammal. High numbers of them flood the infection area (e.g. an udder exposed to mastitis-causing bacteria) to combat pathogens and clean up damaged cells. When the PMNL are weak, they are easily damaged and die after phagocytosis—the enveloping/consuming of pathogens and damaged cells—and require the body to remove the remains from the site of infection. This initial flood, and subsequent death, of neutrophils is one of the primary causes of swelling and pustulence and can be seen in somatic cell count (Figure 1).
Polymorphonuclear neutrophilic leukocyte initial inflammation response
To remain healthy, a sufficient count of white blood cells, like PMNL, indicates a healthy immune system. In addition to a high count, the survival ability of PMNL is also a sign of animal health. A study, measuring PMNL activity to a MCFA diet, found that dairy cows fed MCFA 6–8 weeks prior to partition and through lactation had increased PMNL longevity, suggesting a stronger immune system (Piepers and Vliegher, 2013).
Stable pH leads to efficiency
Following these observations, additional research was needed to explore the rumen microbiome’s reaction to MCFAs to indicate if the immune benefits originated there. In a recently published article by Burdick et al., an analysis on the rumen microbiota of mid-lactation dairy cows when MCFA is added to the diet was performed. In the study, no significant differences were found for dry matter intake, nutrient digestibility, rumen fermentation, or nutrient utilization. This consistency of nutrient intake and uptake with MFCA allowed the noteworthy changes observed to present unique insights into rumen health by evaluating pH and microbiome changes.
The first finding was a higher minimal pH (5.66 vs. 5.54; P = 0.08) and significantly decreased diurnal fluctuations (1.17 vs. 1.40; P = 0.02) (Figure 2). In high-producing dairy cows, a less diverse microbiome can indicate higher feed efficiency. To understand how a changing rumen impacts the diversity of the microbiota, one must think about the variance of pH. A highly variable pH will encourage higher diversity of microbes as some are better suited for the extremes a rumen will experience daily. If the pH is stable, meaning less time in those extremes, then the microbes that thrive in extreme environments will be present in lower numbers. The stable environment will result in a numerically similar total number of microbes but with lower diversity. These specialized microbes, at a higher density, are less strained by varying pH and therefore are more efficient at breaking down fiber and other nutrients into useful metabolites. A stable pH also supports volatile fatty acid absorption through the rumen epithelium. This stabilization of the microbiome was seen in the study as the diversity of the bacterial species fluctuated to be less diverse. Presumably as a consequence of decreased diurnal rumen pH fluctuations, the total bacteria in the rumen also increased.
Visualization of varying pH and microflora composition
Dairy cows are notorious for their love of consistency. Consistent feeding and milking techniques help the herd maintain health and performance. This regularity is true in the rumen too. The recent study by Burdick et al., suggests MCFA support a stable rumen pH, providing a less rich and more efficient microbiome. Though not statistically significant, the change in diet did result in a 0.5 liter increase in milk, without impacting components or body condition score. It is worth noting, this increase was without significantly increasing intake and occurred during mid lactation, a time milk production typically decreases. This new evidence indicates MCFA, like Agrimprove’s Aromabiotic® Cattle, create a positive impression on the rumen environment to support cow health and in turn longevity. By striving to extend the cow’s longevity, a positive impact on the sustainability of dairy production can be achieved.
Burdick, M., Zhou, M., Guan, L.L., and Oba, M. Effects of medium-chain fatty acid supplementation on performance and rumen fermentation of lactating
Holstein dairy cows. Animal. Vol. 16, no. 4, 2022, doi: 10.1016/S1751731122000428.
Piepers, S. and De Vliegher, S., 2013. Oral supplementation of medium-chain fatty acids during the dry period supports the neutrophil viability of peripartum
dairy cows. Journal of Dairy Research. Vol. 80, no. 3, 2013, pp. 309-18, doi:10.1017/S0022029913000228.