Acidifying urine with ammonium chloride – Targeted action against MMA syndrome by sows

Acidified rations are often used in sows around the time of birth. This primarily serves the purpose of lowering urinary pH values and the associated nutritive prophylaxis of metritis-mastitis-agalactia syndrome (MMA syndrome). A current trial on a sow farm shows that the use of a special product based on ammonium chloride leads to clear and rapid effects on the urinary pH value.

The health of sows is a decisive factor for successful pig production. Only a healthy and robust sow is able to guarantee a smooth farrowing. A prolonged birthing period, an increased number of piglets born dead and constipation are among the challenges faced by sow farmers around the time of birth. Many sows also suffer from urinary tract infections, especially in the period close to birth, with all the numerous negative consequences for both sow and piglet. MMA syndrome in particular poses a considerable challenge in breeding. It is a multifactorial disease complex with sometimes major consequences. The three diseases that give it its name are mastitis (inflammation of the udder), metritis (inflammation of the uterus) and agalactia (failure to produce milk).

The entire complex can lead to high economic losses, particularly due to reduced milk yield and the associated reduced daily weight gain and increased piglet mortality. The cause of the multi-factor disease is usually a urinary tract infection. This can be triggered, for example, by insufficient water intake, which means that the urinary bladder is no longer sufficiently flushed. Another and usually more significant cause is an alkaline urinary environment. Most pathogenic germs, which are the cause of an urinary tract disease, prefer a pH value in the slightly alkaline range (pH 7). By lowering the urine pH value to around pH 6, the germ content can be significantly reduced. This lowers the risk of urinary tract infections and MMA syndrome. A high pH value in the sow’s urine is usually due to an excessively high DCAD (dietary cation anion difference). The DCAD describes the balance of cations and anions ingested with the feed. The main alkalizing cations are calcium, magnesium, potassium and sodium. In contrast, the acidifying anions are phosphorus, sulphur and chloride.

The DCAD in feed is given in milliequivalents per kilogram of dry matter (mEq/kg DM) and is closely correlated with the urinary pH values. The correlation is shown in table 1. Based on this correlation, it can be assumed that with a target urinary pH value for sows of around 6.0, the DCAD in the sow’s ration around birth should be between 0 and -100. As guide values for the DCAD are available for all feedstuffs, the DCAD can be set relatively precisely by optimizing the compound feed.

Importance of urinary acidification and its effects on MMA

One measure to prevent MMA syndrome is targeted urinary acidification via the feed. Acidification of the urine is achieved by feeding special feed additives that have a strongly negative DCAD and therefore an acidic effect. The aim is a slight metabolic acidosis, which specifically lowers the urine pH value, as a more acidic urine inhibits the growth of pathogenic bacteria. In particular, the growth environment of Escherichia coli, one of the main causes of urinary tract infections, should be impaired by the acidic conditions. In addition, a low pH value in the urine promotes the excretion of unwanted metabolic products, which reduces the risk of infections in the urogenital tract. Studies show that targeted urinary acidification can lead to a lower incidence of MMA syndrome. As a result, the piglets benefit from improved milk yield of the sows and lower mortality. Furthermore, calcium mobilization from the bones before farrowing is also promoted. This supports muscle contraction for a rapid birth process and reduces the risk of hypocalcemia with the onset of milk production. Therefore, when acidifying feed and urine, attention must be paid to both the calcium content of the feed and always having ad libitum access to clean drinking water.

Table 1: Relationship between the DCAD of a sow ration and the urine pH of the sows

MMA complex disease manifests itself in sows through various symptoms that can affect both the sow herself and the piglet. In addition to general symptoms such as fever, apathy, reduced feed intake and impaired defecation, specific symptoms such as inflammation of the udder and uterus can also occur. Due to a reddened and hardened mammary gland, the sows react sensitively to milk production, which often causes them to reduce or even completely stop milk production. Sick sows are treated with immediate antibiotic and/or anti-inflammatory medication. The aim of the statutory minimization strategy is to permanently reduce the use of antibiotics in livestock farming. The focus here is on a ban on the prophylactic administration of antibiotics and the avoidance of antibiotic resistance. Many farms are therefore still looking for alternatives to achieve this goal, particularly in the area of feed additives.

In practice, various products have proven effective in specifically influencing the urine pH and thus preventing MMA symptoms. These range from organic acids such as formic or benzoic acid, which directly or indirectly lower the pH value in the digestive tract and thus also in the urine, to salts of organic acids (ammonium chloride, calcium chloride) and sulphur-containing sources (methionine, calcium sulphate).

Targeted urinary acidification with BEWI-FATRIX® Anionic

BEWI-FATRIX® Anionic is a combination product based on ammonium chloride and vegetable fat, which is manufactured in a special production process. Using the BEWITAL® suspension process and subsequent spray cooling, the ammonium chloride is embedded in refined and hydrogenated fat (cryotechnology). Thanks to embedding using the BEWI-FATRIX® process, the ingredients are effectively and largely protected from external influences. The special production process ensures consistent feed intake even in the highly sensitive phase around birth and ensures continuous release in the metabolism. This ensures reliable acidification. Due to the strongly negative DCAD, even a small amount used in the feed or as a top dressing is sufficient.

 

Current results from practical use

The potential of BEWI-FATRIX® Anionic for urinary acidification was investigated in a bachelor thesis at the University of Bonn. The trial took place on a farm with 110 DanBred sows in north-west Germany. The aim was to acidify the urine of pregnant sows by adding a specially processed ammonium chloride (NH4Cl).

All sows were given a standard lactation feed when they were moved to the farrowing compartment. Five sows were randomly selected for each of the trial and control groups, with the average litter size of all sows being 4.8. Urine was collected on three different days between 6:00 a.m. and 5:30 p.m. Immediately after the freshly and spontaneously collected urine, the pH value in the samples was determined using an electrochemical pH meter. The sows were fed daily at 6:30 a.m., where BEWI-FATRIX® Anionic was also added as top dressing. The calculation of the supplement was based on the feed analyses and the zero samples, which were measured on day 0.

Figure 1: pH value curve with and without addition of BEWI-FATRIX® Anionic in sows around birth.

At the start of the trial, the sows’ urine pH values were in the range of 7.0 to 7.5. 25 g BEWI-FATRIX® Anionic per sow per day was added to the test animals in order to reach the target range of around pH 6.0. The supplement was given from three days before the calculated farrowing date until three days after birth. As continuous urine samples could only be collected from four sows on each of the three collection dates, only four sows per group are shown in the results overview. The results show a clear influence of BEWI-FATRIX® Anionic on the urine pH of the sows. While the initial value on day 0 was similar for both groups (7.3 in the trial group vs. 7.0 in the control group), the addition of BEWI-FATRIX® Anionic led to a significant reduction in the urinary pH value to 6.5 after just two days. After seven days, the pH value had fallen further to 5.5 (figure 1). In contrast, the urinary pH value in the control group without supplementation remained largely constant over the entire period. The pH value here was 7.2 on day 2 and changed only slightly to 7.1 by day 7 (table 2).

Conclusions

The addition of BEWI-FATRIX® Anionic to rations for sows around the time of birth is an effective measure for targeted urinary acidification. By lowering the urine pH, the risk of infection can be minimized, the occurrence of MMA symptoms reduced and the health of the sow and the rearing performance of the piglets improved. Regular monitoring and adjustment of feeding is necessary to achieve an optimal effect. With consistent monitoring of all factors involved in the MMA complex, lasting positive effects on health and performance in pig breeding can be achieved. With BEWI-FATRIX® Anionic, farms can make a valuable contribution to keeping sows healthy around the time of birth.

Acknowledgements: Special thanks go to the Animal Nutrition Group at the Institute of Animal Sciences at the University of Bonn for conducting the trial and providing the results.

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