1. How are agrochemicals used to manipulate the food species?
Learning Outcomes
Describe the uses of plant hormones.
Describe the advantages and risks of animal hormones.
Describe the uses of BST

2. Agrochemicals
Hormones and other chemicals can be used to control aspects of plant and animal growth
Hormone/substance
Effect
Indoleacetic acid (IAA)
Apical dominance
Ethylene gas
Promotes fruit ripening
Indolebutyric acid
Stimulates root growth
Zeranol
Improves unsaturated fatty acid content of beef
BST
Improves milk yield
Progesterone
Increases growth efficiency

3. Hormones Potential problems
Steroid hormones such as Progesterone exert effects when we or other species ingest them
There may be a link between intake of e.g. Zeranol and incidence of breast cancer
Growth promoting hormones are released in manure, contaminating surface and groundwater. Female fathead minnows downstream of cattle feedlots have developed male characteristics and male fish have developed abnormally small testes and almost feminized heads
Monsanto News Story

4. Bovine somatotropin (BST)
Bovine somatotropin (BST) is a protein naturally produced by cows:
Essential for growth and development of the mammary gland and for milk production
Farmers in the US and 33 other countries inject BST into cows to increase milk production
Some studies have suggested that BST also improves fertilization rate, accelerates embryo development, and improves embryo quality
But it has been banned in the EU since 1994

5. Bovine somatotropin (BST)
Reasons for the ban:
1. Animal welfare
May make cows more vulnerable to hoof-splitting, udder infections and reproductive problems
2. Human health
One concern is that the use of BST may trigger breast and prostate cancer
Cows given BST have more IGF-1 in their milk. High concentrations of IGF-1 are found in the breasts of women suffering from breast cancer
3. Socioeconomic worries
Small farmers are worried that they will be forced out of business by bigger farms that can afford to treat their bigger herds with bigger doses of BST

6. Bovine somatotropin (BST)
Will drinking milk from BST – treated cows also increase our
levels of IGF-1 and therefore the chances of developing cancer?
There are several arguments suggesting the answer is No
• There is little evidence that IGF-1 can survive eating and cross into the bloodstream
• Humans naturally produce IGF-1
• Three pints of milk contain less than 1 per cent of the IGF-1 that we produce naturally
• It assumes that it is the high concentrations of IGF-1 that is causing the cancer

7. Bovine somatotropin (BST)
The graph shows the effect of different levels of nutrition on cows that have been treated with BST and control cows not treated with BST
Severe
undernutrition
Adequate
nutrition
Moderate
Basal
BST 50
100
150
200
BST (ng/ml)
Why are BST-treated cows likely to need greater quantities of high-nutrition food than the control cows?
Why might BST-treated cows be more likely to suffer hoof problems?
Some scientists have argued that use of BST may help stop global climate change as fewer cows will be needed. Explain the scientific basis of this claim.