Pregnancy and bovine somatotropin in nonlactating dairy cows: I. Ovarian, conceptus, and insulin-like growth factor system responses.
Nonlactating dairy cows were used to examine effects of bovine somatotropin (bST) on components of the insulin-like growth factor (IGF) system. Estrus was synchronized in cows with a Presynch + Ovsynch protocol and timed AI (TAI; n = 55) or not TAI (cycling, C; n = 23) on d 0 (time of synchronized ovulation). On d 0 and 11, cows received bST (500 mg) or no bST, and were sacrificed on d 17. Pregnancy rates were less in bST cows (27.2%, 9 of 33) than in controls (63.6%; 14 of 22). In contrast, conceptuses were larger in bST-treated cows (39.2 +/- 4.8 cm) than in controls (20 +/- 4.3 cm). Total interferon-tau in uterine luminal flushings (ULF) was greater in bST-treated cows (7.15 > 2.36 microg). Number of class 2 follicles (6 to 9 mm) was less in bST-C cows on d 7 and 16. On d 17, corpus luteum (CL) weight tended to be greater in bST-treated cows. Concentrations of progesterone were greater after d 10 in C than in pregnant (P) cows. In the ULF, IGF-binding protein-3 was greater in bST-P cows than in pregnant cows. A tendency for an increase in IGF-I hormone concentrations in the ULF was detected on d 17 in bST-treated and cyclic cows. Endometrial mRNA for IGF-I, IGF-II, IGFBP-2, and IGFBP-3 increased in bST-C, but not in bST-P cows. Treatment with bST increased plasma concentrations of insulin, IGF-I, and growth hormone (GH). In conclusion, bST may have hyperstimulated plasma IGF-I and insulin to cause asynchrony between conceptus and uterus that was detrimental to pregnancy.
Bilby
T R
TR
Department of Animal Sciences, University of Florida, Gainesville 32611, USA.
Guzeloglu
A
A
Kamimura
S
S
Pancarci
S M
SM
Michel
F
F
Head
H H
HH
Thatcher
W W
WW
D000818:Animals; D015152:Blotting, Northern; D002417:Cattle; D003338:Corpus Luteum / Q000033:anatomy & histology; D004717:Endometrium / Q000737:chemistry; D004973:Estrus Synchronization; D005260:Female; D020567:Fetal Weight / Q000187:drug effects; D005333:Fetus / Q000187:drug effects*; D013006:Growth Hormone / Q000097:blood / Q000494:pharmacology*; D007315:Insemination, Artificial / Q000662:veterinary; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000235:genetics; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000235:genetics; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000235:genetics; D007335:Insulin-Like Growth Factor II / Q000235:genetics; D007371:Interferon-gamma / Q000032:analysis; D009929:Organ Size / Q000187:drug effects; D006080:Ovarian Follicle / Q000033:anatomy & histology / Q000187:drug effects; D010053:Ovary / Q000187:drug effects*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D012333:RNA, Messenger / Q000032:analysis; D013002:Somatomedins / Q000502:physiology*
D018971:Insulin-Like Growth Factor Binding Protein 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D012333:RNA, Messenger; D013002:Somatomedins; C073294:growth hormone, bovine; D011374:Progesterone; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D007371:Interferon-gamma; D013006:Growth Hormone