Analysis of Uterine Blood Flow in Breeding Sows through the Estrus and Early Diestrus, and after Artificial Insemination

Abstract

This study aimed to determine uterine blood flow indices by transabdominal Doppler ultrasound in sows (n = 18) under different conditions: (i) sows after estrus detection (day 0, D0); (ii) sows 2 h after artificial insemination (AI), performed 24 h after detection of estrus (day 1, D1); (iii) sows in early diestrus (day 5, D5). Moreover, three different types of seminal doses were used for AI depending on the ejaculate fraction included (F1: doses containing only the rich fraction of the ejaculate; F2: F1 + the transition fraction between rich and poor fractions; F3: F2 and poor fraction). The statistical analysis revealed significant differences in some indices regarding the period of analysis (D0, D1, and D5). Diastolic velocity and mean velocity showed lower values at D5 in comparison with D0 and D1 (p < 0.01). On the other hand, the pulsatility index and the relationship systolic velocity/diastolic velocity indicated higher values at D5 in comparison with D0 and D1 (p < 0.01). No differences were observed regarding the type of seminal dose used in any of the time points analyzed (p > 0.05). Neither insemination per se nor the type of ejaculate fraction used immediately modified the uterine vascularity, but some indices are affected by the stage of the estrus cycle (estrus vs. early diestrus).

Keywords: Doppler ultrasound; arterial blood flow; echography; imaging; porcine.

Figure 1

(A) Timeline of the procedures carried out during the study. Black dots (D0, D1, and D5) indicate the moment when Doppler ultrasound analysis was performed. The black square indicates the moment of artificial insemination (AI). (B-i) Detail of the procedure of transabdominal ultrasonography carried out during the analysis. The assay was performed by two researchers, one in charge of the ultrasound probe, while the other was analyzing the real-time images. (B-ii) A representative image was displayed by the ultrasound apparatus (MyLab^TM alpha, Esaote España S.A., Barcelona, Spain) during the evaluation of the uterine arteries of a sow.

Figure 2

Box plot describing Doppler ultrasonography values of the uterine arteries’ blood flow at the three days of evaluation (D0, D1, and D5). Significant differences between experimental groups are indicated as ## (p < 0.01) and ### (p < 0.001). Small circles (°) and asterisks (*) in the box plot represent outliers and extreme cases, respectively.

Figure 3

Demonstrative waveform pulse–Doppler representing variation in the blood flow of uterine arteries indices measured during estrus (D 0) and after AI (D1 and D5) using Doppler ultrasonography in three selected sows. Representative Doppler ultrasound images were obtained using the MyLab^TM alpha (Esaote España S.A., Barcelona, Spain) color Doppler ultrasound machine.

Figure 4

Box plot describing Doppler ultrasonography values of the uterine arteries’ blood flow at the three days of evaluation (D0, D1, and D5) analyzed by the type of seminal dose used (F1—light grey bars, F2—grey bars, and F3—dark grey bars). The statistical comparison was performed between seminal dose types (F1-F2-F3) on each day of analysis (D0, D1, and D5). No significant differences were observed (p > 0.05). Small circles (°) and asterisks (*) in the box plot represent outliers and extreme cases, respectively.