Mammary Specific Transgenic Over-expression of Insulin-like Growth Factor-I (IGF-I) Increases Pig Milk IGF-I and IGF Binding Proteins,with no Effect on Milk Composition or Yield |
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Authors: | Marcia?H?Monaco Derek?E?Gronlund Gregory?T?Bleck Walter?L?Hurley Matthew?B?Wheeler Email author" target="_blank">Sharon?M?DonovanEmail author |
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Institution: | (1) Department of Food Science and Human Nutrition, University of Illinois, Urbana, IL 61801, USA;(2) Department of Animal Sciences, University of Illinois, Urbana, IL 61801, USA;(3) Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, IL 61801, USA |
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Abstract: | IGF-I regulates lactation by stimulating mammary mitogenesis, inhibiting apoptosis, and partially mediating the effects of
growth hormone on lactogenesis. Herein, lactation performance during first and second parity was assessed in transgenic swine
(TG) that over-expressed human IGF-I in milk under the control of the bovine α-lactalbumin promoter, regulatory regions and
signal peptide coding sequence. Milk samples were collected throughout lactation (farrowing to d24) from TG sows and non-transgenic
littermates (CON) and IGF-I, IGF-II, and IGFBP determined. Colostral (<24 h postpartum) IGF-I content was 26-fold greater
(p < 0.001) in TG sows (949 ± 107 μg/L; range 228–1600 μg/L) than CON (36 ± 17.8 μg/L) and was 50- to 90-fold greater (p < 0.001) in mature milk (d2-24 postpartum). There was no effect of parity on milk IGF-I content. Milk IGF-II concentration
was unaffected by IGF-I over-expression. Low molecular weight IGFBP (IGFBP-2 and -5) in the milk of TG sows were higher (p = 0.02) than CON in the early postpartum period, but did not differ in mature milk. Milk yield, determined by weigh-suckle-weigh,
was similar in TG and CON as was litter weight gain. Milk nutrient composition was not significantly affected by IGF over-expression.
Thus, mammary specific transgenic over-expression of IGF-I significantly increased milk IGF-I and IGFBP content, but did not
impact lactation performance in swine. |
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Keywords: | IGF-I IGF binding proteins lactation pig milk transgenic |
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