• bST is a naturally occurring protein produced by all dairy cattle.
• POSILAC® does not alter the chemical composition of milk.
• The U.S. Food and Drug Administration has approved human consumption of milk and meat from dairy cows given supplemental bST.

Research has shown that cows given supplemental bST in the form of POSILAC become more efficient milk producers, without jeopardizing milk quality, animal health or wholesomeness in the process. Research confirms:

• bST, like other milk proteins, is digested into amino acids when eaten. It is not orally active as it cannot be absorbed from the stomach as an intact moleculein that occurs naturally in milk. Giving cows POSILAC does not cause the level of bST already present in milk to change.

• bST does not stimulate growth in humans. It affects cows and certain other animals, thus being species-limited. This was demonstrated during the 1950s when researchers at Harvard University and other schools injected people with substantial amounts of bST as a possible cure for dwarfism. bST was shown not to cause people to grow or to otherwise affect their well-being. Scientists later learned only somatotropin from humans or other primates will stimulate growth in humans.

Comprehensive analyses have been conducted on micronutrients in the milk, such as vitamins, minerals, and enzyme activities and no differences were observed. Because the chemical composition of the milk is not altered as a result of POSILAC, the manufacturing and taste properties do not change. Indeed, this was the case when numerous cheeses, yogurt, and other dairy products were manufactured with milk from cows supplemented with POSILAC.^1,2,3

In addition to these fundamental safety elements, all evidence reviewed by officials of the U.S. Food and Drug Administration resulted in their authorization as safe for human consumption the milk and meat from dairy cows given supplemental bST.⁴

The effect of POSILAC on the concentration of both bST and insulin-like growth factor (IGF-1) in milk was evaluated comprehensively. Since milk is a complete mixture of proteins that varies quantitatively with stage of lactation, breed of cattle and feed consumed normal ranges for bST and IGF-1 in milk had to be established.

bST was measured in milk collected from bulk tanks on 120 commercial farms. Using an assay that would detect levels greater than 0.3 ng/ml, bST was detected in 10 percent of these bulk tanks with levels ranging from 0.33 to 0.77 ng/ml. Administration of POSILAC did not increase the level of bST in the milk of supplemented cows.⁵

IGF-1 was measured in the milk from bulk tanks on 100 commercial farms. The average concentration of IGF-1 on these farms was 4.91 ng/ml. IFG-1 concentrations can also be affected by stage of lactation and nutrition level, so the range for a population of individual cows was also established. The mean IGF-1 concentration for milk samples for 410 cows was 2.54 ng/ml and ranged from undetectable to 30.5 ng/ml. Following three injections of POSILAC, IGF-1 was measured in the milk and compared to unsupplemented control cows. Mean milk IGF-1 in cows supplemented with POSILAC was 3.80, 5.39, and 4.98 ng/ml and in control cows 3.22, 2.62, and 3.78 ng/ml, respectively.⁶

References

1. Barbano DM, Lynch JM, Bauman DE, Hartnell GF, Hintz RL, Nemeth MA: Effect of prolonged-release formulation of n-methionyl bovine somatotropin (sometribove) on milk composition. J Dairy Sci 1992;75:1775.
2. Lynch JM, Barbano DM, Bauman DE, Hartnell GF, Nemeth MA: Effect of prolonged-release formulation of n-methionyl bovine somatotropin (sometribove) on milk fat. J Dairy Sci 1992;75:1794.
3. Van den Berg G: Milk from bST-treated cows: its quality and suitability for processing, in Sejrsen K, Vestergaard M, Neiman-Sorensen A (eds): Use of Somatotropin in Livestock Production. London and New York, Elsevier Applied Science, 1989, pp 178-191.
4. Juskevich JC, Guyer CG: Bovine growth hormone: Human food safety evaluation. Science 1990;249:875.
5. Torkelson AR, Dwyer KA, Rogan GJ, Ryan RL: Radioimmunoassay of somatotropin in milk from cows administered recombinant bovine somatotropin. J Dairy Sci 1987;70(Suppl. 1):146.
6. Collier RJ, Miller MA, Hildebrandt JR, Torkelson AR, White TC, Madsen KS, Vicini JL, Eppard PJ, Lange GM: Factors affecting insulin-like growth factor-1. Concentration in bovine milk. J Dairy Sci 1991;74:2905.