Science in Society Archive

First Commercial Bt-Maize was Toxic, Scientist and Farmer Confirm

German Farmer harassed and persecuted by Syngenta for years for finding its Bt-maize 176 highly toxic to his cows now tells the whole story Dr. Mae-Wan Ho

A long struggle for justice in vain

Gottfried Glöckner had a conventional dairy farm in Weidenhof, Wölfersheim, Hesse, Germany, which he managed for years [1]. He was one of the first farmers to support genetically modified (GM) crops. And as soon as the first GM crop, Syngenta’s Bt-maize 176 was commercially approved for food and feed in the European Union in 1997, he adopted it on his farm.

Bt176 was engineered to express the Cry 1Ab protein to target Lepidopteran pests. It is stacked with glufosinate herbicide tolerance and resistance to ampicillin and other b-lactam antibiotics [2]. But Glöckner did not use glufosinate herbicide on his Bt crop (personal communication from Glöckner).

The entire farm was 80 ha, on which 10 ha was given over to growing maize. Glöckner began with 5 % of Bt maize on the 10 ha in 1997, and progressively increased to 10 % in 1998, 50 % in 1999, and finally 100 % in 2000. On average 62 dairy cows were maintained in optimal milk production in a year. As the proportion of Bt maize in his fields increased, so was the amount fed to his cows, which increased from 0 % to 40 % (the maximum amount of maize in the feed). That was when the cows started dying after long periods of horrendous illness [3], and his lengthy struggle with Syngenta began (see also [4] Cows Ate GM Maize & Died, SiS 21).

The proportion of healthy cows in the herd decreased to 40 % in 2002 when maximum amount of Bt maize was fed, and up to 10 % of cows died preceded by long partial paralysis with signs of kidney failure and mucosal and epithelial problems but no sign of microbial infection [1]. He wrote to Syngenta stating that the diseases and deaths were linked to the Bt maize, and stopped feeding his cows with the Bt maize on the advice of his lawyer. Official test materials examined by the German Ministry of Health and universities confirmed the lack of microbial infection. Syngenta denied any link of the diseases and deaths to the GM maize. But after numerous oral and written requests from the farmer Syngenta paid €43 224 out of the €97 374 of the farmer’s losses in 2001 in death of cows, veterinary analysis, milk production and feed. To avoid a court case, Syngenta proposed to compensate Glöckner for 50 % of his losses, which for 2002 alone, amounted to €143 213. Glöckner refused and sued Syngenta. The case went to court in December 2005 and was completed the same month. Just a year before, the dairy farm was closed, and all the remaining cows were sold because of persistent health problems since they were last fed with Bt maize in 2001. Bt176 maize was officially withdrawn by the European Union in 2007.

After the 2005 court case, Syngenta again proposed a financial settlement. Glöckner finally lost the case however in 2009 over a technicality: his wife’s signature was missing on a document. They divorced in 2005 after she had left the family – including three children aged 17, 15, and 13 - and the farm in 2000, and acquired a new partner.

In 2003, out of the blue, Glöckner’s estranged wife complained for the first time of violence ‘in October 1999 or new year of 2000’, without any medical or other testimony. Just before this complaint was filed, Syngenta had put pressure on Glöckner to accept 50 % compensation for his losses. When he refused and said he would sue Syngenta, the company’s representative told him ‘something was going wrong with his wife’. Due to unfortunate circumstances, both Glöckner and his lawyer were absent when the case was heard in the Higher Court in Frankfurt in November 2005, and the judge sentenced him to one year in prison for violence towards his ex-wife he never acknowledged. Glöckner subsequently had to change his job as his share from the sale of the farm by his ex-wife was confiscated by the court.

The full story

Undaunted, Glöckner has now teamed up with French molecular toxicologist at University of Caen Giles-Eric Seralini to give a full account of what amounts to the longest and first on-farm experience of livestock being fed a GMO-rich diet [3]. Glöckner has kept meticulous records, including pathological reports by veterinarians during the period when unusual problems emerged with the herd.

The Bt maize was grown and used raw to make silage on the farm. The feed contained an average of 40 % maize silage, 24.5 % grass silage, 15.5 % malt draft, 7.8 % barley, 7.8 % wheat, 4 % soy, and 0.4 % minerals. The cows were Holstein, Friesian and Schwartzbund. Around 62 cows per year were kept and regularly followed by certified veterinarians. Cows were replaced every 3 years or when diseased in order to maintain high milk production, as is usual in dairy herd management. From 1997 to 2002, the animals were fed increasing amounts of Bt maize, from 2 – 40 % in the total feed. The results are summarized in Figure 1.

Figure 1   Summary of condition of cows as Bt maize in feed increased

As the proportion of Bt maize in the feed increased to 40 %, healthy cows dropped from 70 % to 40 % and deaths increased from 0 to 10 %. The number of calving cows decreased approximately one year after the maximum level of Bt maize was reached, as pregnancy lasts 282 days.

Before the introduction of Bt maize, the farm had all the signs of being successful and well-run. In 1997, one cow was given an award by the German Holstein Friesian Herd Book Organization for high milk production (114 tons) over its life-time, in which it gave birth to 14 calves. The farm itself received the German Food Society award in Frankfurt for 10 years of high yield and good quality milk production from 1991-2000.

Between May and August 2001, when the Bt maize in the feed had reached its maximum level, 5 abnormal deaths occurred in the herd of 66 cows, which was unprecedented in the history of the farm. Careful examinations were carried out for bacterial and viral infections, and the presence of parasites and mycotoxins. The deaths were not linked to infectious diseases. As a preventive measure, 52 % of the cows (34) were removed from the dairy milk production programme.

The first diagnosis of the pathologies was paresis (partial paralysis) comparable to what is observed after calving, but much longer lasting. Similar pathologies became more frequent in other cows. The symptoms were atypical because they recurred irregularly for months. The usual treatment of paresis, an infusion of glucose, did not produce lasting effect. Analysis of blood and urine revealed that sodium in urine was 400-700 % over the normal upper limit (10 mM/L), 100 % more in one other case, and in a few cases almost undetectable. This was indicative of kidney problems.

Some animals were analysed in more detail before or following their deaths. The cow Gisela died 13 August 2001 from chronic pleuritis, endometritis, and severe paresis. She tested negative for BSE, viruses, Chlamydia and other pathogenic bacteria or parasites in blood and uterus. She had no genetic disease or malformations. In the plasma, urea was at the maximum level compared to all animals measured 12 days before death. There was also high sodium in the urine (5 times higher than the normal upper limit), while potassium was reduced by half. The kidneys appeared to be dysfunctional.

In 2001-2002, 6 new animals died. Veterinary examination in July 2002 concluded that 8 cows had chronic paresis, liver disease, and mucosal problems evidenced by a dry, white muzzle and tongue. There was no viral or bacterial infection. Urea in plasma was 2 times above the norm, and urine sodium elevated 3-15 times over the normal upper limit, while potassium was half the level of the upper limit.

The cow Lilie died at the veterinary clinic at Giessen in May 2002 after paresis. She was tired and lay down often, had irregular heart function and muscle paresis including that of the tongue. She had very low calcium level in the plasma at death. Another cow Liesel died 27 June 2002, euthanized because she could not stand, was always sleeping and had no energy. Urea in plasma was high (41 % above norm), sodium in urine was low (20% of norm). Again, kidney function appeared the most disturbed.

On 17 June 2003, a new analysis was done because some unusual symptoms were still seen in the herd after the removal of Bt maize from the feed, and even though only one cow died. No sign of infection was visible or detected. Urea in plasma was double the norm and 4 animals had high ketone levels in urine. Urine sodium was 10 to 30 % norm. There were some double openings of the teats and mucosa and epithelial problems in the mammary gland, in one case heavily cracked and bleeding. The exposure to Bt toxin or other GM maize metabolite during foetal life of these animals may have induced a malformation of the mammary gland, and the epithelial tissue may have been affected during its first differentiation.

The fourth analysis was performed in August 2004 more than 2.5 years after Bt maize was removed from the feed. These animals had been exposed to Bt maize only during their foetal life. Only one death with characteristic abnormal symptoms occurred, and no infection was found in any of the cows. Plasma urea was high in one case.

At the time the proportion of Bt maize increased in the feed to its maximum level, 8.3 ng/g Cry1Ab toxin was detected in the silage, 1.5 years after harvest, corresponding to a minimum exposure of ~0.15mg/cow/ration/day. In 2000, milk tested positive for the Bt176 DNA specific fragment, it was detected 2 times in milk fat and once in cells. In addition, traces of the small fragment of the specific probe for Roundup Ready tolerant gene EPSPS from GM soy was detected once.

Rough justice & a permissive regulatory system

But why had Glöckner so conspicuously failed to obtain justice? It transpired that when this Bt maize was first developed, Novartis (later Syngenta) performed an initial trial for the authorities in the US. Records obtained by Séralini as expert on GMOs for the French government, which are not available to the public, showed that only 4 cows were fed with the maize over a 2-week period, as reported from Iowa State University for Novartis; one cow died in the course of the experiment with electrolyte and mucosal problems and was removed from the protocol (but see an earlier report [5] Syngenta Charged for Covering up Livestock Deaths from GM Corn, SiS 55).

In a report on the Glöckner feeding trials dated 1 September 2015 [6], it appears that Syngenta withdrew its market permission in 2001 because of serious risks for animals, resulting in bans of the crop in several European countries.  According to the German genetic engineering code, this should have resulted in market permission in Germany being scaled down, but the Federal Office for consumer protection and food safety failed to do so. Consequently, the strict liability of Syngenta for Bt176 was effectively switched off. And this was one of the main reasons why Syngenta in civil trials later could not be made responsible.

Support from the scientific literature for the toxicity of Bt maize

A comprehensive review of the effects of Cry toxins on mammals published in 2015 [7] showed that the insecticides may induce kidney and liver toxicities even when fed for subchronic periods, as consistent with the findings on Glöckner’s farm.  Biochemical

disruptions in the kidney and liver have also been found previously in Seralini’s laboratory [8, 9]; and biochemical disruptions were reported in embryonic kidney cells exposed to Bt maize [10].

To conclude

The detailed documentation of the pathological symptoms and corresponding biochemical disruptions in the first long-term on-farm feeding trial of Bt maize adds valuable data to the public domain, which are also remarkably consistent with scientific findings. Glöckner, who suffered huge personal and financial losses as a result is fully vindicated, and has done a great service to humanity as well as science and society.

Article first published 01/02/16


  1. Séralini G-E. The experience of one of the first GM crop farmers in Europe. Scholarly Journal of Agricultural Science 2016, 6, 9-10.
  2. Event Name: Bt176, ISAAA GM Approval Database, accessed 27 January 2016,
  3. Glöckner G and Séralini G-E. Pathology reports on the first cows fed with Bt 176 maize (1997-2002). Scholarly Journal of Agricultural Science 2016, 6, 1-8.
  4. Ho MW and Burcher S. Cows ate GM maize and died. Science in Society 21, 4-6, 2004.
  5. Sirinathinghji E. Syngenta charged for covering up livestock deaths from GM corn. Science in Society 55, 4-5, 2012.
  6. Legal assessment (criminal law) of the Glöckner feeding trials. 1 September 2015, Cologne.
  7. Rubio-Infante N. and Moreno-Fierros L. An overview of the safety and biological effects of Bacillus thuringiensis Cry toxins in mammals. J Appl Toxicol doi: 10.1002jat 3252.
  8. Séralini G-E, Cellier D and Spiroux de Vendômois J. New analysis of a rat feeding study with a genetically modified maize reveals signs of hepatorenal toxicity. Arch Environ Contam Toxicol 2007, 52, 596-602.
  9. Spiroux de Vendômois J, Roulier F, Cellier D and Séralini G-E. A comparison of the effects of three GM corn varieties on mammalian health. Int J Biol Sci 2009, 5, 438-43.
  10. Mesnage R, Clair E, Gress S, Then C. Székacs A and Séralini G-E. Cytotoxicity on human cells of Cry1Ab and Cry1Ac Bt insecticidal toxins alone or with a glyphosate-based herbicide. J Appl Toxicol 2013, 33, 695-9.

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Sue Edwards Comment left 3rd February 2016 18:06:16
Thanks for this well documented summary. It is very sad that Glockner had to suffer so much personal and economic loss in the process. I hope he, and others that have suffered similar mis-carriages of justice, will continue to support the use of transparency and good science for a better and fairer world in the future.

Ijaz Siddiqi Comment left 5th February 2016 06:06:57
Any information about the effect on people who use the produce (Milk and Meat) of this Gottfried Glöckner conventional dairy farm in Weidenhof.

Todd Millions Comment left 6th February 2016 02:02:55
Ijaz Siddiqi-'milk & meat'. The N. Americian release was starlink bt maize by Aventis. The pollen took off and contaminated all corn stocks before the approved US release-only for pig feed. Milk product changed how it aged-black mold instead of normal souring. Higher still birth and abortions in cattle about this time. No proper testing done on any of it. I paid a rather higher price than this farmer did via food contamination and under the NAFTA TIPP precursor, have no redress. Canadian federal health minister after actual testing via pollen drift 4 years after release-"We can't have a problem with this, we never approved it". Later ministers were at least this stupid. Start with reports of joint inflammation in livestock (including dopey bipeds-featherless),any residue measurements in muscle and guts may still be posted in those.