The Environmental Impact of rbST

Dr. Normand St-Pierre, Dairy Management Specialist, The Ohio State University


  • Often forgotten in the rbST debate is the positive environmental impact of technology in general, and rbST in particular.
  • A recent study calculated the amount of various pollutants that are not produced from one million dairy cows supplemented with rbST. Manure excretion is reduced by 3.3 billion pounds per year. The emission of CO2 equivalents is reduced by 1.3 billion pounds per year - the equivalent of over 350,000 family cars.


What has often been forgotten in the debate about the use of rbST is the very favorable impact that technologies such as rbST have on our environment. A recent study conducted by Capper et al. (2007) at Cornell University calculated the amount of various pollutants that are not produced and released into the environment from one million dairy cows supplemented with rbST. The numbers are staggering.

Millions and billions of pounds

Nitrogen excretion is reduced by more than 15 million lb/year; phosphorus excretion, by more than 3 million lb/year. The excretion of manure is reduced a phenomenal 3.3 billion pounds per year - that's billion with a "b". The emission of CO2 equivalents (a form of universal "currency" to express green gas emission) is reduced by 1.3 billion pounds per year. As can be seen in Table 1, rbST has a significant and positive impact on our environment. Viewed this way, rbST is in fact a green technology.

Technology is green

Invariably, technology is being researched and used to address all sort of environmental concerns. Hydrogen fuel cells are being developed to power our cars in the future. High-technology synthetic compounds are being developed to improve the insulation of our homes. In fact, across all other industries, technology is the common denominator to finding green remedies to environmental problems. Technology is green. In dairy, we already have green technologies. They are called artificial insemination, rumen inert fats, synthetic vitamins, teat disinfectants, 3 times-a-day milking, sprinklers, rbST, organic minerals, estrus synchronization, sire proofs, fans, cation-anion balance, rumen buffers, pedometers, direct-fed microbials, rumen-protected amino acids, etc.

Table 1. Current annual resources saved from 1 million rbST-supplemented dairy cows.1

Nitrogen excretion (lb/year)
Phosphorus excretion (lb/year)
Manure excretion (lb/year)
Methane emission (lb/year)2
Nitric oxide from manure (lb/year)
CO2 equivalents (CH4 and N2O; lb/year)
Herbicides (lb/year)
Insecticides (lb/year)
Fossil fuels3 (MJ/year)
Electricity (kWh/year)

1 Adapted from Capper et al., 2007
2 Includes methane from enteric fermentation and methane emitted by manure fermentation.
3 Only includes fuel used for cropping.

(References are available on request.)