IM Sometribove SC Sometribove
Day 7 Control Day 7 Sometribove Day 21 Control Day 21 Sometribove Day 35 Control Day 35 Sometribove
Milk IGF-1 (ng/ml) 3.5 ± (0.67) 5.9 ± (0.59)* 6.1 ± (0.60)*
Study 2c (Cows Mixed Parity) Milk IGF-1 (ng/ml) 3.17 (range 2.85-4.29) 3.50 (range 1.56-7.05)
Milk IGF-1 (ng/ml) 3.9 ± (0.39) 5.9 ± (0.37)* 5.6 ± (0.39)*
* Means are statistically significantly different from controls at p < 0.05. a Least-squares means + SEM.
b Study assessed the effects of 500 mg sometribove administered intramuscularly (IM) or subcutane-ously (SC) over 10 injection cycles on mean milk concentrations of IGF-1. Effects on primiparous and multiparous cows compared. cStudy assessed the effects of 500 mg sometribove administered over three injection cycles on milk IGF-1. Levels measured in the middle of the two-week injection cycle when IGF-1 blood levels would be highest.39
When biotechnology-derived bST is administered to dairy cows, the production of IGF-1 in the cow is increased and concentrations in milk may also be slightly increased.39,16,120 The modest increases in milk IGF-1 following sometribove treatment are within the natural variation in milk IGF-1 observed during lactation, as illustrated in Table 1.4. Milk IGF-1 levels from bST-supplemented cows also fall within the range of human milk IGF-1 concentrations.120 The concentration of IGF-1 in milk from both control and bST-supplemented cows are considerably below endogenous blood levels in humans (11 to 180 ng/ml, Table 1.5). Thus, even if all ingested IGF-1 in milk was not destroyed in the digestive tract and could be absorbed intact, the addition of a few nanograms of undigested IGF-1 into the large, -101 ng/day, endogenous pool of IGF-1 in humans would constitute a physiologically insignificant change. This is further demonstrated in the dietary risk assessment provided below.
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