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The objective of this study was to evaluate the effect of a PGF2α-analogue (PGF) on ovulation and pregnancy rates after timed artificial insemination (TAI) in cattle. In experiment 1, crossbred dual-purpose heifers, in a crossover design (3 × 3), were given an intravaginal progesterone-releasing insert (controlled internal drug release [CIDR]) plus 1 mg estradiol benzoate (EB) intramuscularly (im) and 250 μg of a PGF-analogue im on Day 0. The CIDR inserts were removed 5 days after follicular wave emergence, and the heifers were randomly divided into three treatment groups to receive the following treatments: (1) 1 mg of EB im (EB group, n = 13); (2) 500 μg of PGF im (PG group, n = 13); or (3) saline (control group, n = 13), 24 hours after CIDR removal. Ovulation occurred earlier in EB (69.81 ± 3.23 hours) and PG groups (73.09 ± 3.23 hours) compared with control (83.07 ± 4.6 hours; P = 0.01) after CIDR removal. In experiment 2, pubertal beef heifers (n = 444), 12 to 14 months of age were used. On Day 0, the heifers were given a CIDR insert plus 2 mg EB im. On Day 9, the CIDR was removed and the heifers were given 500 μg of PGF im. Heifers were randomly assigned into one of three treatment groups: (1) 1 mg of EB (EB group; n = 145); (2) 500 μg of PGF (PG group; n = 149), both 24 hours after CIDR removal; or (3) 600 μg of estradiol cypionate (ECP group; n = 150) at CIDR removal. Timed artificial insemination occurred 48 hours after CIDR removal in the ECP group and 54 hours in the PG and EB groups. The percentage of heifers ovulating was higher in the PG group compared with the other groups (P = 0.08). However, the pregnancy rates did not differ among groups (47.6%, 45%, and 46.6%, for EB, PG, and ECP, respectively; P = 0.9). In experiment 3, 224 lactating beef cows, 40 to 50 days postpartum with 2.5 to 3.5 of body condition score were treated similarly as described in experiment 2, except for the ECP group, which was excluded. The treatments were as follows: 1 mg EB (EB group; n = 117) or 500 μg PGF (PG group; n = 107), 24 hours after CIDR removal. The calves were temporarily separated from their dams from Days 9 to 11. No difference was detected on the pregnancy rate between the EB and PG groups (58.1% vs. 47.6%, respectively; P = 0.11). Taken together, the combined results suggested that PGF2α could be successfully used to induce and synchronize ovulation in cattle undergoing TAI, with similar pregnancy rates when compared with other ovulatory stimuli (ECP and EB).

The objectives of this study were to: 1) evaluate the relationship of the angle formed between the left and right sides of the rump with body condition score (BCS) in cattle; and 2) develop an objective tool to select cows for timed artificial insemination (TAI) based on their BCS. In Experiment 1, 801 lactating Nelore cows, 3-12 years old and weighing 400-625 kg were enrolled. All females were evaluated according to BCS (scale 1-5). In addition, the angle formed between both sides of the rump was measured in all cows with a goniometer. The relationship between BCS and the rump angle was analyzed by linear regression. There was a positive relationship between BCS and rump angle (P < 0.0001). The linear regression equation was angle =77.76+9.94 x BCS; R 2 =0.67. The aim of Experiment 2 was to evaluate BCS in a simple, direct and objective way using rump angle and related BCS to TAI performance. A device was developed called Vetscore ® to determine BCS according to rump angle. Using the Vetscore, cows were classified into three different categories of BCS using a color-based method: red, BCS < 2.75; green, BCS between 2.75 and 4.5; and yellow, BCS > 4.5. A total of 429 Nelore suckling cows, 4-8 years old, were subjected to a TAI protocol based on estradiol benzoate, exogenous progesterone, prostaglandin F2α, equine chorionic gonadotropin and estradiol cypionate. At Day 0, all cows were evaluated with the Vetscore ® and classified according to the device's BCS color scale. Pregnancy diagnosis was performed by ultrasonography 30 d after TAI. Pregnancy per AI (P/AI) was analyzed using the chi-square test. A good level of agreement was observed between Vetscore's scale and visual BCS (82.9%). Cows classified as "green" had higher P/AI than cows classified as "red" and "yellow" (60.4%, 168 of 278; 42.4%, 61 of 144; and 28.6%, 2 of 7; respectively; P < 0.001). These results demonstrate that Vetscore ® is an efficient and low-cost methodology for the assessment of BCS and, indirectly, nutritional status of beef cows. Finally, cows classified as adequate according to Vetscore ® color scale had higher P/AI at 30 d compared with those considered inadequate.

The objective of this study was to evaluate the effect of a PGFα-analogue (PGF) on ovulation and pregnancy rates after timed artificial insemination (TAI) in cattle. In Experiment 1 cows received an intravaginal progesterone-releasing device (CIDR) plus 2 mg im of estradiol benzoate (EB) on Day 0. The CIDR devices were removed on Day 8, and all cows received 150 μg im of d-cloprostenol (PGFα-analogue), 300 IU of eCG and 1 mg of estradiol cypionate (ECP) im. On Day 9, cows were randomly assigned into two groups: 1) ECP Group (n = 17), that did not receive any further treatment; and 2) ECP-PG Group (n = 14) that were given 150 μg of d-cloprostenol (PGF) as adjuvant stimulus for ovulation. No difference between groups was detected in interval for ovulation (P = 0.5), and in the proportion of cows ovulating (P = 0.09). In Experiment 2, multiparous suckling crossbred Aberdeen Angus cows (n = 260), were treated into two groups, similarly as Experiment 1; ECP group (n = 122), and ECP-PG group (n = 138). All females were TAI on Day 10. The proportion of cows treated with ECP that became pregnant was 54.9% (67/122), and cows treated with ECP plus PGF was 55.1% (76/138; P = 0.9). In Experiment 3, 686 Nelore cows, 40 to 50 days postpartum, were treated as Experiment 1 (ECP group), however, on Day 8 cows were divided into 3 groups: ECP Group (n = 216); PGF-SC Group (n = 228), in which cows did not receive ECP and were given an additional subcutaneous injection of PGF on Day 8; and PGF-IM Group (n = 242), in which cows also did not receive ECP on Day 8 and were given an additional injection of PGF im on Day 9. On Day 10, estrus was evaluated at timed AI (TAI). There was no difference in the diameter of the dominant follicle at CIDR removal and at TAI, and pregnancy per AI among groups (P > 0.05). However, the proportion of cows that displayed estrus between CIDR removal and TAI was higher in ECP group than in PGF-SC and PGF-IM groups (P < 0.001). Cows that displayed estrus has higher P/AI than cows that did not (P = 0.008). In conclusion, these results suggested that intramuscular or subcutaneous injection of PGFα could be successfully used to induce ovulation in cattle undergoing TAI, with similar pregnancy rates when compared with ECP. The subcutaneous injection of PGF on the same day of CIDR removal could be an interesting alternative due it reduces cattle management to obtain similar results.

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-The objective of this work was to compare two types of ovulation inducers -estradiol benzoate (EB group) or prostaglandin F2α (PG group) -, in postpartum dairy cows subjected to timed artificial insemination (TAI). Lactating Holstein-Gir crossbred cows (n=118) with 60 to 120 days of milk production were used in this study. All cows were treated with an intravaginal progesterone-releasing device (CIDR) plus 2 mg of estradiol benzoate (EB) on day 0. The CIDR inserts were removed on day 9, and all cows received 500 µg sodium cloprostenol. Twenty-four hours after CIDR removal, cows were randomly assigned into two treatment groups and were given either 1 mg of EB i.m. (EB group) or 500 µg sodium cloprostenol i.m. (PG group). TAI were performed at 52 to 54 hours, in both EB and PG groups, after CIDR removal. No differences were observed in the ovulation (85.2% vs 72.7%) and pregnancy rates (40.7% vs 38.2%) between the EB and PG groups, respectively. Fertility is similar in the TAI protocols that use prostaglandin F2α or EB to induce ovulation in lactating dairy cows.Index terms: artificial insemination, cattle, estrus, synchronization, withdrawal period. Prostaglandina F2α ou benzoato de estradiol para induzir a ovulação em vacas leiteiras inseminadas em tempo fixoResumo -O objetivo deste trabalho foi comparar dois indutores de ovulação -benzoato de estradiol (grupo BE) ou prostaglandina F2α (grupo PG) -, em vacas leiteiras pós-parto submetidas à inseminação artificial em tempo fixo (IATF). Neste estudo, utilizaram-se vacas Girolando lactantes (n=118) com 60 a 120 dias em lactação. Todas as vacas foram tratadas com um implante intravaginal liberador de progesterona (CIDR) associado a 2 mg de benzoato de estradiol (BE) no dia 0. O CIDR foi retirado no dia 9, e todas as vacas receberam 500 µg i.m. de cloprostenol sódico (análogo à prostaglandina F2α Termos para indexação: inseminação artificial, bovinos, estro, sincronização, período de carência.

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O objetivo deste estudo foi avaliar o efeito in vitro do extrato aquoso, extrato hidroalcoólico, extrato hidroalcoólico concentrado e óleo essencial de citronela (Cymbopogon wynterianus) sobre larvas e teleóginas de Riphicephalus (Boophilus) microplus. Os extratos foram preparados de folhas secas de citronela. Para realizar os testes com as larvas foram utilizadas seis concentrações (3,12; 6,25; 12,5; 25; 50 e 100%) de cada extrato, além dos grupos controle. A sensibilidade das teleóginas aos extratos foi testada utilizando o Teste de Drummond (biocarrapaticidograma), sendo utilizados no teste: extrato aquoso a 100%, extrato hidroalcoólico a 100%, extrato hidroalcoólico concentrado a 50% e óleo essencial nas concentrações de 6,25; 12,5 e 25%. As teleóginas também foram testadas frente a três produtos comerciais disponíveis no mercado. Os resultados indicaram que a citronela tem ação acaricida, principalmente, quando utilizada na forma de óleo essencial, pois a partir da concentração de 12,5% foi capaz de causar 100% de mortalidade larval, e a 25% demonstrou índice de eficácia de 100% no teste com teleóginas, resultado superior ao observado com os produtos comerciais testados. Conclui-se que citronela, na forma de óleo essencial, foi eficaz no controle de Riphicephalus (Boophilus) microplus nas condições deste experimento.