Reproductive performance in gilts submitted to non-steroidal therapies to prolong the luteal phase of the estrous cycle

• Published in: Domestic animal endocrinology 2024-01, Vol.86, p.106821-106821, Article 106821
• Main Authors: Brito, Camila R.C., Cordeiro, Ágatha D., Baldessar, Pricila, Schultz, Carolini, Quirino, Monike, Ulguim, Rafael R., Gonçalves, Paulo B.D., Lucia, Thomaz, Bianchi, Ivan, Gasperin, Bernardo G.
• Format: Article
• Language: English
• Subjects: blood serum; cloprostenol; domestic animals; eCG; Estrus; hCG; herds; inter-estrus interval; litter size; luteal phase; luteolysis; menstrual cycle; periodicity; progesterone; protocols; reproductive performance; sodium
• ISSN: 0739-7240; 1879-0054
• DOI: 10.1016/j.domaniend.2023.106821

•Two doses of hCG (hCG treatment) lead to progesterone levels above 60 ng/mL•PGF administration in gilts 10 d after hCG treatment did not promote luteolysis•Both eCG+hCG and hCG treatments were efficient to prolong luteal phase in gilts•Total litter size of gilts was negatively affected by the hCG treatment Synchronized cyclicity of replacement gilts is crucial to optimize breeding herd management, however, protocols with oral progestogen are expensive and require daily administration. This study tested two synchronization protocols without progestogens during the luteal phase in gilts. In Experiment I, on the day of the expression of the third estrus (D0), gilts were assigned to three groups (n = 6, each): control, with no treatment; PGF25: in which gilts received two doses of hCG (1,500 IU each) on D12 and D15 and two doses of a prostaglandin F2α (PGF) analogue (sodium cloprostenol; 250µg) 6-h apart, on D25; and PGF30: in which gilts received two doses of hCG (1,500 IU each) on D12 and D15 and two doses of the PGF analogue (sodium cloprostenol; 250µg) 6-h apart, on D30. The interval between PGF treatment and estrus expression was shorter in PGF30 than in PGF25 (P < 0.01). The PGF treatment failed to decrease serum progesterone (P4) for gilts from the PGF25 group (P > 0.05), but it was effective for gilts in the PGF30 group (P = 0.01). In Experiment II, gilts were assigned to three groups (n = 12, each): control (no treatment); eCG+hCG (400 IU eCG on D10 plus 500 IU hCG on D12); and hCG2 (two hCG doses, 1,500 IU each on D12 and D15). On D30, gilts from eCG+hCG and hCG2 that did not express estrus received two doses of the PGF analogue (250 µg each, 6-h apart). All gilts were inseminated after estrus detection. Serum P4 concentrations were similar for all groups on D10 (P > 0.05) and greater on D20 and D25 for gilts in eCG+hCG and hCG2 (P < 0.01) than for those in the control, whereas P4 concentration was greater in hCG2 than in eCG+hCG, on both moments. The inter-estrus interval (IEI) was shorter for control gilts and intermediate for gilts in eCG+hCG, while the longest IEI was observed for gilts in hCG2 (P < 0.01). Total litter size was larger for gilts in the control (P = 0.02) compared to those in hCG2 and did not differ from the other groups for gilts in eCG+hCG (P > 0.05). In conclusion, Experiment I showed that PGF treatment did not induce luteolysis 10 days after the second hCG treatment but was effective 15 days after the second hCG. Additionally,