19 April 2022 – The dairy cow’s ability to convert feed effectively and efficiently into milk is central to the milk production process. Rumen integrity, in turn, is central to her ability to do so and, therefore, any upset to this system can result in her performance being impacted.
Maintaining the ideal ruminal pH is one of the keys to supporting the integrity of the rumen and ensuring this system functions at its peak. The high-energy, low-fibre diets commonly fed to production dairy cows to support optimal milk production, however, can negatively affect this balance, resulting in a rumen environment that is acidic and unable to function effectively.
Sodium bicarbonate is a common buffer solution added to dairy cow rations to address rumen acidity and restore optimal pH. However, according to Timab Magnesium, it might not be the most effective solution. The company is putting forward its blended magnesium oxide product, pHix-up, as a more effective alternative that can address rumen acidity quicker and for longer periods than sodium bicarbonate. In this Industry Perspectives, Timab Magnesium’s Product Manager for Ruminants, Aurore Courillon talks us through some of the science and findings supporting this, the impact that pHix-up can have on a dairy cow’s milk quality and performance, and whether beef cattle could also benefit from its use.
[Feedinfo] What is considered the ideal rumen pH and why is this so important to a dairy cow’s milk performance?
[Aurore Courillon] Normal rumen pH for a cow is between 6.2 and 6.5 for an optimal fermentation in the rumen.
When the pH is under a certain threshold (often considered 5.5) for a long time, it means that the rumen environment is acidifying. This pH drop is linked to an accumulation of volatile fatty acids from carbohydrate digestion when the quantity produced is above the capacity for the rumen to absorb normally.
Ruminal pH is indeed a good indicator of the flora balance inside the rumen. When the energy (concentrates) level in the ration is too high relative to the fibre input (forage), as is often the case in high energy diets today, it can lead to a dominance of amylolytic flora over cellulolytic flora. Amylolytic flora secrete more acids than cellulolytic flora, resulting in an increase in rumen acidity and a decrease in cellulolytic colonies, creating a vicious cycle for the cow.
Cellulolytic flora is very important for the fat component of the milk. In fact, the general maintenance of an optimal rumen pH is vital to the efficiency of the rumen, allowing for good rumination and fermentation, maintaining feed intake and milk production, as well as seeing to the general health of the cow (i.e., lameness, reproduction, etc.).
[Feedinfo] Why exactly is it so tricky to maximise milk production without negatively affecting the pH of the rumen? What impact can this have on milk production and quality?
[Aurore Courillon] To see to the needs of highly productive cows, we need to feed them high energy rations to maximise their production, especially at the start of lactation. The lack of fibre balance in this high energy diet can negatively impact the pH of the rumen.
We need then to implement nutritional and farm management strategies to prevent disfunction of the rumen and the impact on milk production. For example, we can do this by increasing the number of meals during the day or using buffer solutions to act on the rumen pH.
[Feedinfo] Sodium bicarbonate is commonly added to dairy cow rations to help address an increase in ruminal pH. But you’re putting forward your magnesium oxide blend, pHix-up, as a solution to the problem. How do the two approaches compare in neutralising excess acid in the rumen?
[Aurore Courillon] Sodium bicarbonate is commonly used to increase rumen pH as it is chemically a buffer solution, composed of conjugated base and acid forms, meaning it maintains a certain pH despite the addition of acids.
pHix-up, which is a blend of specific magnesium oxides, is chemically an alkalinizer, which works to increase the pH.
The uniqueness of pHix-up is linked to its complementary sources of magnesium oxides, which feature a high neutralising capacity of acids in the rumen (39 mEq/g compared to 12 mEq/g for sodium bicarbonate). They also have a specific kinetic action which helps maintain an optimal pH between two meals, unlike sodium bicarbonate that is known to have more of a flash effect.
Thanks to its higher neutralising capacity, pHix-up’s required dosage is three times lower than that of sodium bicarbonate. This can really make a difference in certain regions of the world, like the US and Canada, where sodium bicarbonate can make up as much as 300g in the ration.
[Feedinfo] What about other buffer substances traditionally used on farms, like calcium carbonate, sodium sesquicarbonate, etc.? How does pHix-up compare to these solutions?
[Aurore Courillon] Sodium sesquicarbonate is quite close to sodium bicarbonate in terms of buffer capacity power and kinetics.
Calcium carbonate from marine algae has a better neutralising capacity than sodium bicarbonate, however, it is still two times lower than that of pHix-up.
Also, in addition to neutralising capacity, we also need to consider solubility. Calcium carbonate solubility is very low above pH 5.5, which is not ideal as the optimal rumen pH needs to be above 5.8. This means it cannot increase the pH fast enough and avoid the risk of acidosis developing after a meal.
[Feedinfo] Let’s talk about the impact pHix-up can have on milk performance. Can you please share some of the key findings from the recent trials you’ve conducted on lactating cows.
[Aurore Courillon] We conducted around 15 field trials with pHix-up in different countries, farm sizes and ratio profiles, employing rumen boluses and the monitoring of the ruminal pH.
Our meta-analysis revealed two important findings:
- pHix-up was able to stabilise the rumen environment, improving pH values to above 5.8
- It also significantly increased milk production (+ 1.35kg of Energy Corrected Milk) and improved milk composition (50g of total fat)
Additionally, these results were found on farms where there was already a buffer solution being used.
Also, in a study published in the Journal of Dairy Science in 2018 with Dr. Alex Bach, we looked at a pHix-up half dosage versus sodium bicarbonate at 200g/c/d in an acidosis diet challenge and found that pHix-up prevented the decline in feed intake, unlike sodium bicarbonate. It also helped to increase milk production during acidosis.
[Feedinfo] If I am correct, pHix-up was launched in 2017. What has the market’s response been to the product and what are some of the learnings gathered from dairy industry customers during this time?
[Aurore Courillon] Yes, the market remains very receptive to the product. Its high neutralising capacity, its effect on milk composition, especially on the fat content, and also its lower dosage compared to sodium bicarbonate are well appreciated by our customers and makes the product an interesting technical and economic alternative.
[Feedinfo] Have you also investigated the impact pHix-up can have on beef cattle productivity?
[Aurore Courillon] Yes, we are investigating pHix-up variations for other ruminant species, such as fattening cattle and small ruminants that can also develop sub-acidosis.
We know that fattening beef cattle, especially in feedlot systems, face brutal diet transitions and high levels of concentrates. So, we conducted two trials on this group, one in Brazil with Lavras University and the other in the US with Texas A&M University, in which pHix-up was tested alone and with ionophores (such as Monensin).
In these trials, we observed better feed efficiency (up to +24% in the Brazilian trial) during the adaptation period, which should give these animals a better start during this challenging time.
In the US trial we also observed that liver abscess incidences were 3.5 times lower in the pHix-up group compared to the control group, with no severe cases identified (p=0.01).
These trial results are promising, and they are helping us make further growthin the fattening beef cattle space.
Published in association with Timab Magnesium