With large amounts of feed comes the risk of increased mycotoxin exposure, higher passage rates and less time available for proper feed digestion. As animals are fed increasing quantities of feed to increase milk yields, it becomes more difficult to guarantee that mycotoxins can be effectively deactivated in the rumen. Complete mycotoxin degradation in the rumen is therefore not possible.
Various mycotoxins are able to modify the rumen microflora as they exert antimicrobial, antiprotozoal and antifungal activity. In practical terms, this means that mycotoxins escape detoxification and are absorbed by the intestine. In other words, mycotoxins disrupt the rumen function before impacting the animal itself.
Drastic changes in feed composition and a high percentage of protein-rich concentrates in the daily diet also impair the cleavage capacity of rumen microorganisms. Reduced ruminal motility, decreased dry matter intake, acid detergent fiber and starch digestion are some negative impacts reported due to the ingestion of mycotoxin-contaminated feed.
Impaired dairy fertility
Because fertility and milk yield are parameters that are closely related, all factors disrupting fertility have a negative economic impact on herds. Zearalenone (ZEN), an estrogenic metabolite, shows a structural similarity to the female hormone estradiol, and is able to activate specific estrogen receptors. Thus, ZEN causes abnormal estrous cycles which ultimately impair fertility.
Reduced fertility in dairy cattle has also been reported as a result of ergot alkaloids and aflatoxins.
Case Study 1: Dairy farm in Europe, 50 Holstein dairy cows
The problems experienced in the herd included reduced fertility and more abortions, among others. Feed analysis for mycotoxins revealed levels of ZEN at 120 ppb and B-trichothecenes at 1,000 ppb.
The low conception rates before the treatment are indicated by the high percentage of third artificial inseminations.
Reduced milk production
Deoxynivalenol (DON) has also been associated with reduced feed intake and weight gain and decreased performance.
Several field reports and clinical data have associated DON with reduced feed intake in non-lactating dairy cattle and poor performance in dairy herds.
Case Study 2: Dairy farm Europe, 110 Holstein dairy cows
Feed intake of dairy cows decreased overnight (55% lower) accompanied by lowered milk production, diarrhea and reproduction failure. Mycotoxins were detected in the corn silage (600 pbb DON, 50 ppb ZEN; based on fresh matter)
The farm started using Mycofix® at 30 g/cow/day. After just 4 days, feed intake was completely re-established. Mycofix® was used for one month (2 weeks at 30 g/cow/day; thereafter at 20 g/cow/day) and parameters such as feed intake and milk production were back to normal.
After a month the farmer decided to stop using Mycofix®. Within 2 days, the same problems resurfaced with a rapid decrease of feed intake. Milk characteristics during the affected period were as follows: SCC: 400.000; Fat: 3.95%; Protein: 3.35%; Lactose: 5.00%; Urea: 24 mg/dl.
Mycofix® was again added to the ration. After a few days, feed intake and milk production were again stabilized. Milk characteristics also returned to normal as follows: SCC: 160.000; Fat: 3.75%; Protein: 3.30%; Lactose: 5.00%; Urea: 24.5 mg/dl.
Toxic residues in milk
In the case of aflatoxins, the most worrying effect is their carry-over ranging from 1.8 to 6.2% into milk as aflatoxin M1 (AfM1). Aflatoxins are considered carcinogenic by the Institute of International Agency for Research on Cancer (IARC).
Case Study 3: Dairy farm Asia, 90 crossbred dairy cows
About 1 to 1.2 ppb of aflatoxin M1 (AfM1) was found in milk.
Mycofix® was supplied at 15 g/cow/day and data was collected over a period of 30 days. AfM1 content in milk was reduced by 67% on this farm.
Figure 2. AfM1 decrease in milk after Mycofix® was added to.
Mycotoxins increase the incidence of metabolic problems in dairy animals
Figure 1 provides an overview of the effects of mycotoxins in dairy cattle.
The most common and difficult challenges to identify occur when rations contain low levels of mycotoxins. Subclinical mycotoxicoses decrease profitability by lowering milk production and quality, and increasing veterinary expenses, sometimes with inappropriate therapies. The presence of mycotoxins in feed is very often connected with increased incidences of metabolic disorders such as ketosis, retained placenta, displaced abomasum, mastitis, metritis, lameness, elevated somatic cell count and consequently, decreased milk production.
Avoiding mycotoxin formation must begin on the field, should continue in the silage production process and end with correct management of the open silo and feedstuffs.
Most grains and feedstuffs are afflicted by a wide variety of mycotoxin types. The Mycofix® product line of BIOMIN combines three modes of action—adsorption, biological degradation of non-adsorbable mycotoxins, and protection of the liver and immune system. Accurate feeding of dairy cows in combination with continuous mycotoxin risk management is the key to managing the optimal performance of the livestock business.
Case Study 4: Dairy farm in the Americas, 1,100 Holstein dairy cows
Comparing average SCC for the first 2 months of the trial period (most reflective of pre-treatment) with average SCC for the last 2 months, a reduction of approximately 40% can be observed. Along with the reduction in SCC, the farm found that they had fewer reasons to cull cows from the herd: better production, less mastitis and less breeding issues. This allowed the herd to retain older cows with greater production, and sell younger heifers as an additional source of income.
Figure 3. Somatic cell count reduction over a year with Mycofix®.
Case Study 5: Dairy farm in Asia, 600 Holstein dairy cows
Mycotoxins (mainly ZEN, 200 ppb and DON, 1,200 ppb) were detected in the total mixed ration (TMR).
Figure 4. Disease incidences in the control and trial groups.