Taylor, V. J.; Cheng, Z.; Pushpakumara, P. G. A.; Wathes, D. C. and Beever, D. E.
|DOI (Digital Object Identifier) Link:||http://dx.doi.org/10.1136/vr.155.19.583|
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The relationships between insulin-like growth factor-I (IGF-I) and the fertility and milk yield of Holstein-Friesian dairy cows were investigated. The concentration of IGF-I in blood was measured weekly from one week before to 12 weeks after calving in 177 multiparous cows and at four times during this period in 142 primiparous cows; the concentration of IGF-I in milk was measured in 50 of the multiparous cows. The plasma concentrations of IGF-I were higher in the primiparous than in the multiparous animals. in the primiparous cows, high concentrations of IGF-I before calving were associated with longer calving to conception intervals. Conversely, in the multiparous cows low concentrations of IGF-I before and after calving were associated with a failure to conceive, despite repeated services. Multiparous cows with IGF-I concentrations of greater than 25 ng/ml in the week after calving were 11 times more likely to conceive to first service than those with lower concentrations. Concentrations of IGF-I greater than 50 ng/ml at first service increased the likelihood of conception five-fold. Cows with higher peak milk yields had lower plasma concentrations of IGF-I and took longer to return to ovarian cyclicity. The negative relationship between milk yield and return to cyclicity was stronger in the multiparous cows (P<0.04) than in the primiparous cows (P<0.002). The concentrations of IGF-I in milk followed a different pattern and were not associated with the changes in plasma IGF-I or fertility.
|Item Type:||Journal Article|
|Copyright Holders:||Not known|
|Keywords:||factor-binding-proteins; hormone-releasing-factor; body condition; estrous-cycle; igf-i; nutritional regulation; early-pregnancy; somatomedin-c; bovine uterus; expression|
|Academic Unit/Department:||Science > Life, Health and Chemical Sciences
|Interdisciplinary Research Centre:||Biomedical Research Network (BRN)|
|Depositing User:||Astrid Peterkin|
|Date Deposited:||08 Feb 2007|
|Last Modified:||14 Jan 2016 16:27|
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