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Published on: July 8, 2020
Insulin-like growth factor I in follicular development and function in postpartum beef cows
1Alberta Agriculture, Edmonton, Canada.
Journal of Animal Science
|March 1, 1991
Summary
Restricted nutrition in postpartum cows elevates free fatty acids and lowers glucose, impacting follicular fluid composition. Further research is needed to fully understand the effects of nutrition on bovine follicular development and reproductive health.
Area of Science:
- Animal Science
- Reproductive Biology
- Nutritional Physiology
Background:
- Nutrition significantly influences reproductive performance in cattle.
- Follicular fluid composition is critical for oocyte development and fertility.
- Understanding the impact of dietary intake on reproductive hormones is essential for livestock management.
Purpose of the Study:
- To investigate the effects of restricted versus ad libitum nutrition on follicular growth and concentrations of steroid hormones and insulin-like growth factor I (IGF-I) in follicular fluid of postpartum cows.
- To assess the relationship between dietary intake, body condition, and key metabolic indicators (insulin, IGF-I, glucose, free fatty acids).
Main Methods:
- Postpartum Hereford-cross cows (n=28) were assigned to either ad libitum (14 kg/day) or restricted (7 kg/day) hay intake.
- Cows were ovariectomized at 20 or 35 days postpartum.
- Blood samples were collected regularly to measure insulin, IGF-I, glucose, and free fatty acids (FFA).
- Follicular fluid was aspirated from follicles (≥4 mm) for IGF-I, progesterone (P4), and estradiol-17 beta (E2) analysis.
Main Results:
- Restricted cows exhibited greater weight loss post-calving compared to ad libitum cows.
- Elevated FFA concentrations were observed in restricted cows from weeks 2-5 postpartum.
- Plasma glucose levels were lower in restricted cows (59.6 ± 0.4 mg/dL) than in ad libitum cows (61.8 ± 0.4 mg/dL).
- Insulin and IGF-I concentrations did not differ significantly between dietary groups.
Conclusions:
- Nutritional restriction impacts metabolic status in postpartum cows, indicated by altered FFA and glucose levels.
- While overall body condition changes were similar, weight loss and metabolic profiles differed between dietary groups.
- Further investigation is warranted to elucidate the specific effects of nutrition on follicular fluid steroid and IGF-I concentrations and subsequent follicular development.
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