Effect of dietary conjugated linoleic acid (CLA) on the metabolism and reproduction of dairy cows

G Esposito,Ro Gilbert,Va Absalón Medina,Wr Butler,A Schneider

doi:10.4314/sajas.v43i5.6

Abstract

Rumen-protected conjugated linoleic acid (CLA) reportedly improves fertility in lactating dairy cows by reducing the postpartum interval to first ovulation and enhancing the circulating insulin-like growth factor-I (IGF-I) levels. The objectives of this study were to evaluate the blood metabolites, hormones, follicular fluid (FF) and liver for the effect of CLA supplementation (50 g top-dressed daily from 15 days pre-partum to 65 days in milk –DIM -). Pre-partum Holstein cows (n = 24) were assigned to two treatments: a Control and CLA group (n = 12 cows/group). Dry matter intake (DMI) and milk production were recorded daily. At 26 DIM, ovulation was synchronized and at 34 DIM, plasma and FF were analysed for paraoxonase 1(PON) levels. Moreover plasma was analysed for IGF binding protein 2 and 3 (IGFBP). From 34 DIM, blood samples and FF from follicles >9 mm were collected and analysed for estradiol, progesterone, IGF-I and lipoproteins. A liver biopsy was performed at 65 DIM and analysed for the expression of IGF-I, growth hormone receptor (GHR), pyruvate carboxylase (PC) and cytosolic phosphoenolpyruvate carboxykinase (PECK). CLA supplemented cows, compared to the control group, recorded a significant lower milk fat production, improved DMI and energy balance and recorded significant increased plasma concentrations of IGF-I, cholesterol, low density lipoprotein (LDL) and IGFBP-3 (interaction treatment x DIM). The concentration of IGF-I, high density lipoprotein (HDL) and LDL tended to be higher in FF than plasma. This study confirms the positive effects of dietary CLA supplementation on the metabolism, by improving the energy intake and reducing the negative energy balance. Moreover, the improvement of plasma IGF-I levels observed in this study, coupled with a better energy balance support previous studies showing a positive effect of CLA supplementation on reproduction. However, CLA did not alter the plasma and the FF concentration of PON, nor the liver gene expression.Keywords: Follicular fluid, liver gene expression, postpartum cows

Highlights

High-yielding dairy cows are typically in a negative energy balance postpartum, because of the amount of energy required for maintenance, plus milk production exceeds the amount of energy that cows ingest
Liver tissue samples were analysed for gene expression of growth hormone receptor (GHR), insulin-like growth factor-I (IGF-I), pyruvate carboxylase (PC) and cytosolic phosphoenolpyruvate carboxykinase (PECK)
Individual daily milk production and Dry matter intake (DMI) values were transformed to weekly means before analysis and the yields for milk fat, protein and lactose content were calculated using the weekly mean for milk production

Summary

Introduction

High-yielding dairy cows are typically in a negative energy balance postpartum, because of the amount of energy required for maintenance, plus milk production exceeds the amount of energy that cows ingest. An insufficient energy supply generally results in a poor reproductive performance that is associated with a delay in the onset of the oestrous cycles postpartum (Butler & Smith, 1989; Reist et al, 2000), low conception rates and a high rate of early embryonic deaths (Lucy, 2001). Dietary fat supplements in early lactation may benefit the reproductive outcome by improving the energy intake and reducing the extent of the negative energy balance, as well as by increasing the size of the ovulatory follicle and lifespan of the corpus luteum (Mattos et al, 2000). It has been shown that with CLA supplementation, the URL:http:// www.sasas.co.za ISSN 0375-1589 (print), ISSN 222-4062 (online) Publisher: South African Society for Animal Science.

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