Follicular and luteal morphofunctionality of dairy cows supplemented with calcium salts of fatty acids in AIFT programs

Highlights

• Crossbred dairy cows were supplemented strategically with CSFA for 30 days in AIFT programs.

• The functionality of the ovarian structures was evaluated through doppler ultrasonography and hormonal dosing.

• The strategic supplementation with CSFA 30 days before de AIFT did not improve follicular and luteal morphofunctionality.

• Further studies need to be performed to evaluate the best time to start supplementation and the duration of this strategy.

Abstract

We aimed to define the effect of strategic supplementation with calcium salts of fatty acids on the morphofunctionality of ovarian structures in crossbred dairy cows submitted to a hormonal protocol for artificial insemination at a fixed time (AIFT) A total of 20 lactating crossbred females (Bos taurus x Bos taurus indicus) were randomly divided into two groups, the control group (CON), which received concentrate with no added fat in the diet, and the treatment group (TRAT), which received concentrate with salts of fatty acid calcium (Megalac-E, Church and Dwight Co. Inc., Trenton, NJ, marketed in Brazil by Elanco-Eli Lilly and Company, Indianapolis, IN, USA). The diets were provided for 30 days. The animals started consuming the supplement 20 days before the beginning of the follicular wave and ovulation synchronization protocol (Day-20). Follicular development was monitored by mode B ultrasound and power-doppler assessments every 12 h between day D8 and the time of ovulation. By measuring the follicular diameter (DFOL), the area of the follicular wall (AFOL) and the vascularization area of the follicle wall (VFOL) were able to be determined. On days 7 and 16 after ovulation, US mode B and doppler were performed in order to analyze the corpus luteum diameter (DCL), area of the corpus luteum (ACL), and the vascularization area of the corpus luteum (VCL). In addition, blood samples were collected to measure the serum concentration of P4 using chemiluminescence methodology. There was no effect of supplementation on milk production results (p = 0.15), body weight (p = 0.57), ECC (p = 0.78), albumin (p = 0.83), and the lipid profile (CT [p = 0.36], HDL [p = 0.11], LDL [p = 0.55], VLDL [p = 0.15] and TRIG [p = 0.15]). The supplementation of SCAG, 30 days before IATF, under the conditions of this experiment had no significant influence on follicular and luteal morphofunctionality. However, suspension of supplementation caused a deficit in the luteal blood flow.

Introduction

Strategies to improve the functionality of ovarian structures and embryonic survival have been studied with a focus on increasing reproductive efficiency. Among the possible options, supplementation with calcium salts of soy fatty acids has demonstrated a direct effect on reproduction, with an increase in reproductive performance, which is subsequently reflected as an increased pregnancy rate (Lopes et al., 2011; Brandão et al., 2018).

This improved performance is reflected as a greater availability of fatty acids in the endometrium, corpus luteum, and conceptus (Cooke et al., 2014), as well as an increased concentration of circulating progesterone (P4) (Guardieiro et al., 2010; Cipriano et al., 2016), and increased expression of Interferon-t mRNA (IFNt) (Brandão et al., 2018; Cipriano et al., 2016), which is responsible for maternal recognition of pregnancy in ruminants (Hansen, Sinedino, and Spencer, 2017) .

Despite these positive results, Moriel et al. (2014) reported that 0.22 kg of calcium salts of soy fatty acids was not sufficient to increase serum P4 concentrations. Furthermore, Cardona et al. (2016) recorded an increase in serum cholesterol and P4 concentrations, however, they did not observe an increase in pregnancy rates.

Doppler ultrasonography is an important tool to help understand the influence of fatty acids on reproduction, specifically on the functionality of ovarian structures, since blood flow is a sensitive parameter with a high correlation with serum hormonal dosage (Hassan et al., 2019). Thus, the objective of the current study was to define the effect of supplementation with calcium salts of fatty acids on the dynamics, follicular vascularization, and morphofunctional characteristics of the CL, and the lipid profile of crossbred dairy cows submitted to a hormonal protocol for AIFT.