Agrastim®, BIOAGRA’s trademark for yeast derived Beta-1,3/1,6-D-glucan, has been shown to enhance the ability of farmed animals to combat infections and to replace antibiotic in the feed of poultry and swine. However, no studies had yet been done in slaughter cattle. To demonstrate whether Agrastim® would have a beneficial effect in cattle, it had to be shown that Agrastim® would not be degraded in the rumen. The rumen is the first digestive chamber in cattle and other cud-chewing animals where ingested feed is partially digested by microbial fermentation.

In an in vitro study done at the University of West Virginia, Agrastim® was mixed with rumen fluid and the disappearance of dry matter measured. Since Agrastim® was the only dry, insoluble material added, the disappearance of dry matter equals the degradation of Agrastim®. Figure 1 shows that during the first 4 hours less than 15% of the Agrastim® is degraded in rumen fluid.

Figure 1. Degradation of Agrastim® by rumen fluid. Agrastim® is only slowly degraded by the Rumen fluid, which contains an array of enzymes derived from the feed, rumen and bacteria. After 4 hours of incubation in the rumen fluid, less than 15% is degraded.

In a second study, it was determined that Agrastim® clears the rumen within 2 hours. These studies clearly show that Agrastim® administered orally would reach the Peyer’s patch and enhance the activity of the immune system of cattle.

A small farm in West Virginia suffered a high rate of mortality of newborn calves from Cryptosporidiosis and upper respiratory infections. To determine the effect of Agrastim® on survival, 13 calves were administered 500 mg of Agrastim® in the replacement milk on the first day and 250 mg every day for the following 8 weeks.

The results show that survival is greatly improved in the calves treated with
Agrastim® Effect of Agrastim® on calf survival.

The data suggests that an improved immune system is essential
to maintain the health of newborn calves.

Mastitis, an inflammatory reaction of udder tissue most commonly associated with bacterial infections, is the most common and most costly dairy cattle disease. The inflammatory response consists of an increase in blood proteins and white blood cells (somatic cells) in the mammary tissue and the milk. High quantities of somatic cells in milk dramatically reduce the value of milk to the processor, and often render it unfit for human consumption.

It has been estimated that mastitis costs the dairy industry about $200 per cow per year, and that up to 40% of dairy herds are affected.

Reduced milk production accounts for approximately 70% of the total loss associated with mastitis. Other costs include treatment cost, discarded milk, death and premature culling, decreased genetic advancement, and reduced milk quality. Persistent inflammation can lead to permanent tissue damage and reduced milk yield.

Bacteria, such as forms of Streptococcus and Staphylococcus are by far the most common causes of mastitis. Bacterial infections can be transmitted from one cow to another during milking.Yeast mastitis can be caused by overuse of antibiotics.

The vast majority of mastitis is “subclinical” (symptoms not apparent). For every case of clinical mastitis (severe inflammation, fever, shivering), there are 20-40 times as many cases of subclinical mastitis. Subclinical mastitis may progress and develop into clinical cases, or it may persist for a long time at a subclinical level. Without some form of testing, subclinical mastitis goes undetected.

Somatic cells are a normal constituent of milk and only when they become excessive do they indicate a problem. The udder’s response to infection or injury results in an increase in somatic cells in milk. The number of somatic cells indicates the severity of the mastitis. Measurement of somatic cells (Somatic Cell Count) has become an effective means of detecting subclinical mastitis. Somatic Cell Count (SCC) is expressed as cells/ml of milk.

Milk with less than 200,000 somatic cells/ml is considered the highest quality.Higher counts are considered abnormal and indicate possible infections. To be used for human consumption, milk must have less than 750,000/ml SCC. Milk markets rely routinely on SCC to help ensure good quality milk, and usually pay a premium for milk with low SCC.

The Effect of Oral Agrastim® on Somatic Cell Counts in Milk: Dose-Response:The purpose of this trial was to determine the dose necessary to affect a decrease in somatic cell counts in milk. In this first trial, 320 dairy cows were divided into 4 groups and treated as follows:

  Group 1: Control- normal feed
  Group 2: 2 grams/Agrastim®/day/cow in the feed
  Group 3: 4 grams/Agrastim®/day/cow in the feed
  Group 4: 6 grams/Agrastim®/day/cow in the feed

Agrastim® was weighed and mixed in the feed which was prepared daily. For groups 1, 2, and 3, somatic cell counts were obtained at day 0 (beginning of trial), 20, 27 and 33. For group 4, somatic cell counts are only available for day 0 (beginning of trial) and day 33. It is evident from the results (Figure 2) that somatic cells increased during this period in the control group (58%), but decreased significantly in all three groups that received Agrastim® The largest decrease was observed in the group receiving 2 grams/day/cow (34%) and the least decrease was observed in the group receiving the largest dose, 6 grams/day/cow (18%).

Figure 2. Effect of Agrastim® on somatic cell counts in milk: Dose-response. The somatic cell counts increased in the untreated group, whereas decreased in all groups treated with Agrastim® The largest decrease at 33 days(34%) was obtained in the group treated with 2 grams/day/cow.

The fact that the smaller dose was more effective than the higher doses should not be surprising. Agrastim® is a biological material and its effects are modulated by a series of biological mechanisms, among which is “receptor downregulation”. Receptor downregulation means that too large an amount of Agrastim® will overwhelm the system and the cells of the immune system will no longer respond. Increasing the dose, therefore, will not give better results but will actually make Agrastim® ineffective.

In the Eastern United States, a herd of 115 milk cows with high somatic cell counts was fed a feed containing Agrastim® at 2 grams/day/cow. Somatic cell counts were recorded on day 0 (February 13) and on day 30 (March 14). On Day 0, the average cell count was 906,693, and on day 30, the average cell count was 483,300, a decrease of 47%.

Figure 3. Effect of Agrastim® on Somatic Cell Counts in Milk. Somatic cell counts in the milk of 14 cows with the highest somatic cell counts 30 days after the inclusion of Agrastim® in their feed.

Table 2
Somatic cell counts in the collected milk in two tanks from a Midwest dairy farm.