Long-acting injectable progesterone treatment prior to puberty induction in gilts.

Progesterone (P4) has a pivotal role on female puberty attainment in most farm animals. However, there are no studies evaluating the effect of P4 treatment previously to boar exposure for puberty induction in gilts. Therefore, serum P4 concentration, estrus expression and reproductive performance after boar stimuli were evaluated in gilts intramuscularly treated with long-acting P4 before boar exposure. In Experiment I, prepubertal gilts received either 1 mL of saline (control) or intramuscular (I.M.) P4 treatment (150 mg, 300 mg or 600 mg; n = 6 per treatment). Serum P4 concentration for P4-treated gilts was greater than for control gilts for at least 8 d for P4300 and P4600 groups (P < 0.05), but greater until after 16 d only for those treated with 600 mg (P < 0.05). In Experiments II (prepubertal) and III (peripubertal), gilts received either saline (control) or 300 mg P4 I.M. and those showing estrus signs were artificially inseminated (AI), whereas gilts without estrus expression were culled. In prepubertal gilts (Exp. II), estrus expression rate did not differ (P < 0.05) for control (79.1%; n = 110) and P4-treated gilts (81.5%; n = 108). In peripubertal gilts (Exp. III), although estrus expression did not differ between control (77.6%; n = 106) and P4-treated (69.6%; n = 102) gilts (P > 0.05), P4-treated gilts presented longer (23.1 ± 1.4 days) interval from treatment to estrus expression than control gilts (17.1 ± 1.3 days; P < 0.05). In Experiments II and III, the proportion of culled gilts with ovarian structures consistent with normal estrous cycles, farrowing rate, and litter size did not differ between treatments (P > 0.05). In conclusion, I.M. treatment with 300 or 600 mg of long-acting P4 was efficient in maintaining high P4 concentrations in prepubertal gilts for at least 8 days. However, P4 treatment over this time interval did not benefit the reproductive performance of prepubertal and peripubertal gilts.

Embryo transfer in no cycling Crioula and Quarter horse breeds treated with estradiol cipionate and long-acting progesterone

The aim of this work was to prepare the mares for embryo transfer. In group 1 (G1,treated, n=15), recipient mares in anoestrus or in a transition period were treated with 5.0, 3.0 and 2.0 mg of estradiol cipionate at the days 0, 1 and 2 respectively, beginning at the day of ovulation (DO). From the fourth day on, the mares this group received long-acting progesterone weekly, up to the 120 day of gestation. At D8, the embryo was collected from the donor and transferred to the recipient. At D12, the ultrasonographyc diagnosis of pregnancy was carried out. The control group (G2, not treated, n=20) was formed by cycling recipient mares, displaying ovulation at each 2 to 3 days after the donors mare ovulation. The pregnancy rate was higher (p<0.05) in the mares from G2 (85.0 percent) than from G1 (53.3 percent). Thus, it could be concluded that the treated mares although showed lesser pregnancy rate than the cycling mare, were satisfactory alternative to be used mainly when there is no available cycling recipient.

Concentração sérica de progesterona em bezerras da raça nelore e mestiças tratadas com progesterona em veículo de liberação lenta / Serum progesterone concentration in Nelore and crossbreed heifers treated with long-acting progesterone

Avaliaram-se a eliminação da progesterona em veículo de liberação lenta (P4LA) em animais zebus e mestiços e sua potencial aplicabilidade em programas de sincronização de estro, utilizando-se 60 bezerras, 30 da raça Nelore e 30 mestiças (Gir x Holandês), entre 120 e 150 dias de idade e peso médio de 150kg. Em cada grupo experimental as bezerras foram divididas em três subgrupos (G) de 10 animais, sendo GI = controle (tratado com 5ml de solução fisiológica por via intramuscular); GII = tratado com 450mg P4LA (3ml IM); e GIII = tratado com 750mg P4LA (5ml IM). Amostras de sangue foram coletadas no dia zero, 7 e 13 (D0, D7 e D13) e procedeu-se à análise hormonal por radioimunoensaio de fase sólida. A progesterona de ação prolongada (P4LA), administrada por via intramuscular, manteve-se por 13 dias na corrente sangüínea em concentrações superiores a 1ng/ml. As doses de 450mg e 750mg de P4LA não ocasionaram efeitos adversos sistêmicos clinicamente perceptíveis, e o metabolismo da P4LA foi mais lento nas bezerras Nelore, cuja concentração de progesterona foi maior na corrente sangüínea do que nas bezerras mestiças.(AU)

The clearance of long-acting progesterone in microspheres (P4LA) in zebu animals and its potential for use in estrus synchronization were evaluated using 30 Nelore and 30 crossbreed (Holstein x zebu) heifers, with aging between 120 to 150-day-old and weighting 150kg in average. For each breed the animals were divided into three groups of ten animals each, GI= control group treated with saline; GII= treated with 450mg of P4LA; and GIII= treated with 750mg of long-acting progesterone (P4LA). Blood samples were colleted on days 0, 7 and 13 and analysed for progesterone using radioimmunoassay in solid phase. The serum concentration of progesterone was different on days 0, 7 and 13 in relation to the dose of P4LA given. All treated animals presented basal values for progesterone on day 0, increased on day 7 and decreased on day 13, but with values over 1ng/ml. The results show that the drug was absorbed rapidly after its administration and remained in satisfactory concentration in the circulation until day 13. The average total concentration of serum progesterone was higher in Nelore heifers when compared to the concentration in crossbreed ones, indicating difference in the metabolism of the drug between the two genetic groups.(AU)

Concentração sérica de progesterona em bezerras da raça nelore e mestiças tratadas com progesterona em veículo de liberação lenta / Serum progesterone concentration in Nelore and crossbreed heifers treated with long-acting progesterone

Avaliaram-se a eliminação da progesterona em veículo de liberação lenta (P4LA) em animais zebus e mestiços e sua potencial aplicabilidade em programas de sincronização de estro, utilizando-se 60 bezerras, 30 da raça Nelore e 30 mestiças (Gir x Holandês), entre 120 e 150 dias de idade e peso médio de 150kg. Em cada grupo experimental as bezerras foram divididas em três subgrupos (G) de 10 animais, sendo GI = controle (tratado com 5ml de solução fisiológica por via intramuscular); GII = tratado com 450mg P4LA (3ml IM); e GIII = tratado com 750mg P4LA (5ml IM). Amostras de sangue foram coletadas no dia zero, 7 e 13 (D0, D7 e D13) e procedeu-se à análise hormonal por radioimunoensaio de fase sólida. A progesterona de ação prolongada (P4LA), administrada por via intramuscular, manteve-se por 13 dias na corrente sangüínea em concentrações superiores a 1ng/ml. As doses de 450mg e 750mg de P4LA não ocasionaram efeitos adversos sistêmicos clinicamente perceptíveis, e o metabolismo da P4LA foi mais lento nas bezerras Nelore, cuja concentração de progesterona foi maior na corrente sangüínea do que nas bezerras mestiças.

The clearance of long-acting progesterone in microspheres (P4LA) in zebu animals and its potential for use in estrus synchronization were evaluated using 30 Nelore and 30 crossbreed (Holstein x zebu) heifers, with aging between 120 to 150-day-old and weighting 150kg in average. For each breed the animals were divided into three groups of ten animals each, GI= control group treated with saline; GII= treated with 450mg of P4LA; and GIII= treated with 750mg of long-acting progesterone (P4LA). Blood samples were colleted on days 0, 7 and 13 and analysed for progesterone using radioimmunoassay in solid phase. The serum concentration of progesterone was different on days 0, 7 and 13 in relation to the dose of P4LA given. All treated animals presented basal values for progesterone on day 0, increased on day 7 and decreased on day 13, but with values over 1ng/ml. The results show that the drug was absorbed rapidly after its administration and remained in satisfactory concentration in the circulation until day 13. The average total concentration of serum progesterone was higher in Nelore heifers when compared to the concentration in crossbreed ones, indicating difference in the metabolism of the drug between the two genetic groups.