Fertility of predominantly Bos taurus beef cows exposed to fixed-time artificial insemination protocols with intravaginal inserts containing different amounts of progesterone.

Autor: Pessoa GA; Universidade Federal de Santa Maria, Santa Maria, RS, 97105-900, Brazil., Fontes PLP; Department of Animal and Dairy Science, University of Georgia, Athens, GA, 30602, USA., Junior IC; Select Sires, Porto Alegre, RS, 91030-230, Brazil., Lopes Junior FR; Zoetis, Sao Paulo, SP, 04711-130, Brazil., Alves Neto N; Zoetis, Sao Paulo, SP, 04711-130, Brazil., de Sá Filho OG; Zoetis, Sao Paulo, SP, 04711-130, Brazil., Vasconcelos JLM; Universidade Estadual Paulista 'Julio de Mesquita Filho', Botucatu, SP, 18618-000, Brazil. Electronic address: jose.vasconcelos@unesp.br.
Jazyk: angličtina
Zdroj: Theriogenology [Theriogenology] 2024 Dec 02; Vol. 234, pp. 73-82. Date of Electronic Publication: 2024 Dec 02.
DOI: 10.1016/j.theriogenology.2024.12.003
Abstrakt: The aims of this study were to: 1) evaluate the impact of intravaginal progesterone (P4) inserts containing different amounts of P4 on pregnancy rates of predominantly Bos taurus beef cows exposed to fixed-time artificial insemination (FTAI) using estradiol and P4-based synchronization protocols, and 2) evaluate the impact of delayed luteolysis on the fertility of cows receiving P4 insert with less P4. Cows (n = 1744) were randomly assigned to 1 of 3 treatments: 1) 2.0 mg of estradiol benzoate together with an intravaginal P4-releasing insert containing 1.9 g of P4 (CIDR) on Day 0; 12.5 mg of dinoprost tromethamine on Day 7; 300-IU of equine chorionic gonadotropin together with 0.6 mg of estradiol cypionate and CIDR withdrawal on Day 9 (CIDR-PG7); 2) cows were exposed to the same treatment as CIDR-PG7, however a different intravaginal insert containing 0.5 g of P4 (DIB 0.5) was utilized (DIB-PG7); and 3) cows were exposed to the same synchronization treatment as DIB-PG7, however a dinoprost tromethamine injection was administered on Day 9 instead of Day 7 (DIB-PG9). All cows received a fixed-time artificial insemination (FTAI) 48 h after P4 inserts CIDR removal (Day 11). Circulating concentrations of P4 on Day 9 were greater (P < 0.01) in cows receiving CIDR-PG7 than in cows receiving DIB-PG7 or DIB-PG9. Dominant follicle diameter on Day 9 was greater (P < 0.01) in DIB-PG7 compared with CIDR-PG7 or DIB-PG9, but not different (P > 0.10) between CIDR-PG7 and DIB-PG9 treatments. Follicle diameter on Day 11 did not differ between CIDR-PG7 and DIB-PG7 (P > 0.10), which were greater compared with DIB-PG9 (P < 0.01). Dominant follicle growth between Days 9 and 11 was greater (P < 0.01) in cows receiving CIDR-PG7 than in cows receiving DIB-PG7 and DIB-PG9, which were not different (P = 0.18) among them. Pregnancy rates on experimental Days 41 and 131 were greater (P < 0.01) in cows receiving CIDR-PG7 (59.4 %; 55.5 %) compared with DIB-PG7 (40.1 %; 34.4 %) or DIB-PG9 (45.2 %; 41.4 %) cows. Compared with cows receiving DIB-PG7, cows receiving DIB-PG9 treatment tended (P = 0.08) to have a greater pregnancy rate on experimental Day 41 and 131 (P = 0.06). In summary, intravaginal P4 inserts with only 0.5 g of P4 resulted in decreased circulating concentrations of P4 and decreased pregnancy rates. Delaying induction of luteolysis only partially mitigated this negative outcome.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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