Peroxisome proliferator-activated receptors (PPARs) as a mediator of dietary fatty acids affects reproductive performance in broiler breeder roosters

Highlights

• Unique fatty acids are abundant in the fish oil (FO) and sunflower oil (SO).

• PPAR-γ mRAN expressions in the sperm were affected by the FO and SO.

• The FO and SO diets improved reproductive performance in roosters.

• PPAR-γ modulate the adverse effects of ageing in rooster fertility potential.

Abstract

This study analyzed the effects of dietary sources of omega-3 and omega-6 fatty acids on semen parameters and fertility potential in broiler breeder roosters. The mRNA and protein profiles of peroxisome proliferator-activated receptors-γ (PPAR-γ) expression in sperm as potential mediator of FAs were considered. Roosters were categorized into three groups and received their diets for 24 weeks as follows: 1) control diet received a basal diet (CTRL); 2) Fish oil based diet (FO) received the basal diet supplemented with 15 g/kg of diet fish oil; and 3) sunflower oil based diet (SO) received the basal diet supplemented with 15 g/kg of diet sunflower oil. While the different diets had significant effects on semen parameters, the effect of sampling time was not significant. The effect of the diets on sperm parameters were significantly higher in the SO and FO groups in total motility, progressive motility, amplitude of lateral head displacement, linearity, straightness, wobble and viability (P ≤ 0.05). Fertility rate was significantly improved in the FO and SO groups (P = 0001). The highest value for PPAR-γ mRNA was observed in the SO group compared to other groups (P ≤ 0.05). Moreover, supplementation of the roosters’ diets with FO and SO increased PPAR-γ protein expression compared to the control. It seems that PPAR-γ could be a strong potential mediator of the underlying mechanism of improvement in semen parameters and reproductive performance of roosters under the effects of both dietary omega-3 and omega-6 polyunsaturated fatty acids.

Introduction

The reproductive performance of roosters is important in breeder production, as it plays a critical role in the production of fertilized egg [1,2]. However, there is a considerable reduction in semen quality and reproductive potential of broiler breeder roosters after 45 weeks of age, which is a typical response to aging. Several factors such as hormonal levels, the development of testicular tissue, behavior, and physical body composition are thought to be affected during this period [3].

Recent studies in reproductive biology have shown new mediators such as peroxisome proliferator-activated receptors (PPARs) to have a direct relationship with fertility performance and metabolism [4]. PPARs are members of the nuclear receptor superfamily of ligand-activated transcription factors [4] and are expressed in different compartments of the reproductive axis such as the hypothalamus, pituitary, ovary, uterus, and testes [5]. Recent studies have shown that PPARs can be activated by several natural and synthetic ligands, one of which is fatty acids (FAs) [6]. Among the various FAs, omega-6 and omega-3 FAs in appropriate ratios are proving to be immensely useful in numerous biological, physiological, developmental, reproductive, and beneficial health functions [7,8]. These FAs participate in metabolism, endocrine, and plasma membrane fluidity in the sperm, and in several functions related to fertilization [9,10].

It has been shown that FAs stimulate PPARs expression, and consequently affects the expressions of crucial enzymes involved in steroidogenesis [11]. Uniquely, it was suggested that FAs can also regulate glucose and lipid metabolism [12] through adjusting the PPAR-γ function.

In mammals, effects of FAs on PPAR-γ genes have been reported; however, there are few studies regarding the effects of FAs on the PPAR-γ changes in poultry [13]. In chickens that were fed a diet containing safflower oil or linseed oil, a significantly greater of PPAR-γ mRNA in abdominal adipose tissue was observed compared to those that were fed the control diet [14].

The amount of PPAR-γ level was elevated in broiler chicken livers in response to dietary conjugated linoleic acid (CLA) [13]. Similarly, Duszka et al. [15] reported differences in PPAR-γ mRNA expression in mice when they were gavaged with canola oil.

Although several recent studies have claimed the beneficial effects of different profiles of FAs for rooster reproductive performance [16,17], the mechanism underlying these effects have not been elucidated. In this work, we investigated the effects of omega-3 and omega-6 FA sources on PPAR-γ expression at both the gene and protein levels. We then analyzed the semen parameters, reproductive hormonal profile (testosterone, LH and FSH) as well as fertility potential to see if there could be a relationship between the PPAR-γ and the above-mentioned parameters.