HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Interpretive Summary Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Garnsworthy, P. C. Articles by Webb, R. Search for Related Content PubMed PubMed Citation Articles by Garnsworthy, P. C. Articles by Webb, R.

Nutrition, Metabolism, and Fertility in Dairy Cows: 2. Dietary Fatty Acids and Ovarian Function

University of Nottingham, School of Biosciences, Sutton Bonington Campus, Loughborough LE12 5RD, UK

¹ Corresponding author: Phil.Garnsworthy{at}nottingham.ac.uk

Plasma insulin has important implications for ovarian function in dairy cows. Previous work demonstrated that plasma insulin increased with increasing dietary starch and decreasing dietary fatty acid concentrations. The objective of this experiment was to investigate hormonal and ovarian responses to dietary fatty acid content with no change in other dietary components. Thirty cows were fed a standard diet from calving until 40 d in milk (DIM) and then 6 cows were transferred to each of 5 diets containing 0, 8, 15, 23, and 30 g/kg of dry matter (DM) of calcium salts of palm fatty acids (CaPFA; Megalac) until 70 DIM. Estrus was synchronized at 60 DIM. Between 60 and 70 DIM, energy intake, milk yield, and energy balance were similar among diet groups. Plasma insulin decreased when dietary concentration of CaPFA exceeded 15 g/kg of DM (insulin: 0.46, 0.41, 0.46, 0.33, 0.28 ± SE 0.034 ng/mL for diets containing 0 to 30 g of CaPFA/kg of DM, respectively). Maximum plasma insulin to glucagon ratio was observed with 15 g of CaPFA/kg of DM (ratios: 3.99, 4.33, 4.67, 3.45, 2.89 ± SE 0.156 for diets containing 0 to 30 g of CaPFA/kg of DM, respectively). Plasma concentrations of growth hormone, insulin-like growth factor-I and leptin did not vary between diets. The number of small (<5 mm) ovarian follicles was negatively related to plasma insulin concentration (r = –0.328) and was stimulated by CaPFA supplementation at all rates tested compared with cows receiving zero CaPFA (small follicles preovulation: 6.7, 11.2, 11.5, 11.3, 11.9 ± SE 1.48 for diets containing 0 to 30 g of CaPFA/kg of DM, respectively). The number of medium-sized follicles, and diameters of the ovulatory follicles and corpora lutea, were not affected by CaPFA supplementation. It is concluded that dietary total fat concentration should be below 50 g/kg of DM to avoid depressing plasma insulin concentration in cows at the start of the breeding period.

Key Words: dairy cow • insulin • fatty acid • ovarian function

This article has been cited by other articles:

				P C Garnsworthy, A A Fouladi-Nashta, G E Mann, K D Sinclair, and R Webb Effect of dietary-induced changes in plasma insulin concentrations during the early post partum period on pregnancy rate in dairy cows Reproduction, April 1, 2009; 137(4): 759 - 768. [Abstract] [Full Text] [PDF]

				P. C. Garnsworthy, J. G. Gong, D. G. Armstrong, J. R. Newbold, M. Marsden, S. E. Richards, G. E. Mann, K. D. Sinclair, and R. Webb Nutrition, Metabolism, and Fertility in Dairy Cows: 3. Amino Acids and Ovarian Function J Dairy Sci, November 1, 2008; 91(11): 4190 - 4197. [Abstract] [Full Text] [PDF]