Effect of season on dairy buffalo reproductive performance when using P4/E2/eCG-based fixed-time artificial insemination management

Abstract

This study aimed to compare the reproductive efficiency of dairy buffaloes subjected to TAI protocols based on progesterone, estrogen, and equine chorionic gonadotrophin (P4/E2+eCG) during the fall/winter (n = 168) and spring/summer (n = 183). Buffaloes received an intravaginal P4 device (1.0 g) plus estradiol benzoate (EB; 2.0 mg im) at a random stage of the estrous cycle (D-12). Nine days later (D-3), the P4 device was removed and buffaloes were given PGF (0.53 mg im sodium cloprostenol) plus eCG (400 IU im). GnRH (10 μg im buserelin acetate) was administered 48 h after P4 device removal (D-1). All animals were subjected to TAI 16 h after GnRH administration (D0). Frozen-thawed semen from one bull was used for all TAI, which were all performed by the same technician. Ultrasound examinations were performed on D-12 and D-3 to ascertain cyclicity (presence of CL), D-3 and D0 to measure the diameter of the dominant follicle (ØDF), D+10 to verify the ovulation rate and diameter of the corpus luteum (ØCL), and D+30 and D+45 to detect pregnancy rate (P/AI 30d and 45d, respectively) and embryonic mortality (EM). Fetal mortality (FM) was established between 45 days and birth, and pregnancy loss between 30 days and birth. There were significant differences between fall/winter and spring/summer only for cyclicity rate [76.2% (128/168) vs. 42.6% (78/183); P = 0.02]. The others variables did not differ between the seasons: ØDF on D-3 (9.6 ± 0.2 mm vs. 9.8 ± 0.2 mm; P = 0.35); ØDF on D0 (13.1 ± 0.2 mm vs. 13.2 ± 0.2 mm; P = 0.47); ovulation rate [86.9% (146/168) vs. 82.9% (152/182); P = 0.19]; ØCL on D+10 (19.0 ± 0.3 mm vs. 18.4 ± 0.3 mm, P = 0.20); P/AI on D+30 [66.7% (112/168) vs. 62.7% (111/177); P = 0.31]; P/AI on D+45 [64.8%% (107/165) vs. 60.2% (106/176); P = 0.37]; EM [1.8% (2/111) vs. 3.6% (4/110); P = 0.95]; FM [21.9% (18/82) vs. 8.0% (7/87); P = 0.13]; and PL [23.8% (20/84) vs. 12.1% (11/91); P = 0.13]. In conclusion, dairy buffaloes present similar reproductive efficiency in fall/winter and spring/summer when subjected to P4/E2/eCG-based protocol for TAI.

Different times to perform timed artificial insemination when using a P4/E2/eCG-based protocol in buffalo

“…Although in the present study buffalo cows had similar diameter of the DF at TAI between treatment groups, it was verified that the diameter of the DF had an effect on the P/TAI. This result corroborated with a recent study that verified a positive correlation between diameter of the DF at TAI and ovulation and pregnancy rates in buffalo (MONTEIRO et al, 2018) and previous studies performed in cattle (VASCONCELOS et al, 2001;PERRY et al, 2007;SÁ FILHO et al, 2010). Also, it was demonstrated that the diameter of the DF at TAI showed a negative correlation with the occurrence of embryonic mortality in buffaloes (MONTEIRO et al, 2018).…”

“…Palavras-chave: anestro, benzoato de oestradiol, folículo, indução da ovulação, inseminação artificial. ANIMAL REPRODUCTION al., 2014;MONTEIRO et al, 2016;CARVALHO et al, 2017;MONTEIRO et al, 2018). Currently, TAI can be used throughout the year with satisfactory ovarian responses and pregnancy outcomes in buffaloes (CARVALHO et al, 2016;CARVALHO et al, 2018).…”

“…The AI should occur near the time of ovulation to maximize sperm access to the ovum, but not so late that an aging ovum awaits sperm arrival and capacitation (DALTON et al, 2001). A lower P/AI had been associated with a reduced fertilization rate due to receiving AI close to or after ovulation in cattle (DRANSFIELD et al, 1998;ROELOFS et al, 2005;ROELOFS et al, 2006) and in buffaloes (MONTEIRO et al, 2018). However, an optimal pregnancy rate could be achieved when AI is performed 16.2 (MAATJE et al, 1997), 15.3 (AYRES et al, 2008, 14.7 (SÁ FILHO et al, 2013) and 21.8 (SALES et al, 2015) hours before ovulation in cattle.…”

Assisted reproductive technologies (ART) in water buffaloes

“…Therefore, during the nonbreeding season, when a high incidence of anestrus is expected, lower pregnancy rates are encoutered in buffaloes synchronized with the Ovsynch protocol for TAI. On the contrary, studies have demonstrated similar pregnancy per TAI in both breeding and nonbreeding seasons after the use P4, E2, and eCGbased protocols Carvalho et al, 2013;Monteiro, 2018; Table 2).…”

“…These data demonstrate that it is possible to establish an effective AI program in buffaloes throughout the year, however it is relevant to understand the interactions between ovulation synchronization treatments and the season of the year. Baruselli et al (2003b); Monteiro (2018).…”