Contents The study aimed to evaluate pregnancy per artificial insemination (P/AI) of cows subjected to synchronization and resynchronization in ovulation protocols using intravaginal progesterone‐releasing insert (P4) before pregnancy diagnosis (PD) and the relationship of PR with the diameter of preovulatory follicles (ØPOF) before TAI. Cows (n = 378) were distributed into two groups: a resynchronization group with new devices (GRN; n = 185) and resynchronization group with used devices (GRU; n = 193). On Day 0, both groups received a new P4 and estradiol benzoate (EB). On D8, P4 removal + D‐cloprostenol + eCG + estradiol cypionate (EC) was done. On d10, TAI was conducted. On d32, cows were resynchronized and divided into two groups, GRN (n = 185) and GRU (n = 193). The GRN group received a new P4 + EB, and the GRU group received a used P4 + EB. On d40, the P4 was removed + PD. The non‐pregnant cows received D‐cloprostenol + eCG + EC. US was done again on d42 to determine ØPOF before the second TAI. The P/AI of the GRN and GRU groups after synchronization were 56.2% and 57.0% (p = 0.87), respectively, and those after resynchronization were 58.0% and 37.3% (p < 0.008), respectively. The P/AI of the GRN and GRU groups observed after TAI (synchronization + resynchronization) were 81.6% and 73.1%, respectively (p = 0.047). No difference (p = 0.067) in ØPOF between the pregnant and non‐pregnant cows in the GRN was found, whereas the GRU group showed a significant difference (p = 0.003). Resynchronization protocols optimized the P/AI in both groups. New intravaginal devices resulted in greater P/AI and P/AI accumulation in resynchronization as compared with the GRU; the ØPOF was related with P/AI.

Bovine semen thermoresistance tests and their correlation with pregnancy rates after fixed-time artificial insemination  [Testes de termoresistência do sêmen bovino e sua correlação com taxas de prenhez após inseminação artificial em tempo fixo] ABSTRACTThe objective of the study was to determine whether or not there is a correlation between thermoresistance tests (TT) after semen thawing and pregnancy rate (PR) after fixed-time artificial insemination (FTAI). Four different TT were performed on ten samples used for AI; a rapid test (RTT) (30min / 46°C) and three slow tests (STT): STT1 (60min/38°C), STT2 (180min/38°C), and STT3 (300min/38°C). Two hundred and fifteen multiparous crossbred cows were submitted to FTAI under the following protocol: on day zero (d0) the animals received a P4 device +EB; on d7 PGF 2α ; on d8 P4 was removed and eCG+EC were administered; IATF was performed on d10. Three gestational diagnoses (G D) were performed on d40, d70 and d120. The mean sperm motility (%) in RTT and STTs were 19.84±6.13, 28.55±10.48, 17.62±5.87 and 8.63±3.46, respectively, and TP in the three DG 61.86%, 57.67%, and 55.81%, respectively. Through Person test a significant negative correlation (P< 0.05) was found between STT2 and PR at 60 days (r= -0.644) and between STT3 and all TPs (r= -0.774, -0.752, 0.748). It was concluded that TT parameters are not able to determine correlation between semen quality and TP.

mg injection of GnRH was administered either via Vena caudalis (n=60), or via Longissimus dorsi (n=60). Cows were inseminated with the same sire and by a single AI technician. Pregnancy was determined by the transrectal ultrasonography on d 40 after AI. Cows receiving the intravenous administration of GnRH had higher (P = 0.04) pregnancy rates than the cows receiving the intramuscular injection of GnRH (65 vs 46.6%, respectively). It was concluded that the intravenous administration of GnRH at the time of AI improved the pregnancy rates of crossbred Bos indicus beef cows submitted to FTAI.

The goals were to compare the conception rate in cows subjected to timedartificial insemination (TAI) with one AI, two AIs, or resynchronization (RES), and verify the effects of POF (preovulatory follicle) diameter on the CR. Two hundred and seventyfour cows (Bos taurus indicus) were assigned. In the group with one AI (1AIG; n=88), cows were subjected to intravaginal P4 and EB (2mg, IM) on day zero (D0); PGF2α (500μg, IM) on D7; P4 removal on D8; EB on D9; TAI and ultrasonography for POF diameter measurement on D10; PD (pregnancy diagnosis) and natural service on D41; bull removal on D90; and final PD on D110. The same protocol was used in the two AI (2AIG; n=88), except a second AI 20h after the first AI. The resynchronization group (RESG; n=98) was subjected to the same protocol as 1AIG, except a PD was performed on D40, and the non-pregnant cows received the P4 device and EB; PGF2α on D47; P4 removal on D48; EB was administered on D49; TAI was performed on D50; PD was performed, and bulls were introduced on D80; bulls’ removal on D110; final PD on D160. CR of 50, 58, and 73.4% were observed in 1AIG, 2AIG, and RESG, respectively, increasing to 85.2, 88.6, and 87.7% after natural service. The POF diameter at the first TAI was 12.8, 12.1, and 12.7mm in 1AIG, 2AIG, and RESG, respectively, and 12.6mm in RESG and 13.6mm in 2AIG (P=0.031) at the second AI. Groups 1 and 02 inseminations remained with bulls for 49 days and resynchronization for 30 days. In conclusion, RESG yielded a higher CR than TAI with one or two AIs. AI with follicles larger than 12.1mm resulted in a higher CR.

The study aimed to compare two techniques for plasma semen removal from 11 stallions using semen centrifugation and semen filtration. Two hundred and thirteen semen samples were frozen and evaluated. The samples were distributed into two groups: centrifuged semen group (GSC) and filtered semen group (GSF). The semen was evaluated fresh and after freezing based on sperm movement (vigor) and sperm motility. After the analysis of the fresh ejaculate, the samples were submitted to centrifugation (600 g/10 minutes) or filtration through synthetic hydrophilic membrane SpermFilter and were frozen. Significant differences were found for the characteristics of motility (P = 0.0002) and vigor (P = 0.0221) between GSC and GSF groups in the pre-freezing time. Sperm motility was observed in 74.6 % (GSC) and 79.4 % (GSF) in pre-freezing time. After freezing phase, sperm motility resulted in 63.4 % (GSC) and 65.8 % (GSF) (P = 0.2303); and vigor showed a reduction in the number of samples classified for score 4, and a predominance of the samples classified in scores 2 and 3 in both groups with no difference between groups. It was concluded that the different methods of seminal plasma removal used (centrifugation or filtration) did not influence sperm quality after freezing; the semen filtration was better in the pre-freezing moment showing the best technique for the use of fresh semen.

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O presente estudo objetivou verificar a influência da cetose, das afecções de casco, da lipidose hepática, do deslocamento de abomaso, do cisto folicular ovariano e de endometrite sobre o desempenho reprodutivo de vacas leiteiras de elevada produção e sobre a taxa de descarte animal. Foram levantados dados individuais relativos a 2008, 2009 e 2010, de vacas da raça Holandesa Preta e Branca com produção média de leite de 10.750 litros/305 dias/vaca. Dois grupos (G) de animais foram constituídos: o G1 (enfermos, n = 38) constou de animais acometidos por uma ou mais afecções, como cetose clínica, afecções de casco (laminite), lipidose hepática, deslocamento de abomaso, cisto folicular ovariano ou endometrite; e o G2, formado por animais sadios (n = 25). No tratamento estatístico dos dados foram utilizados os testes do Qui-Quadrado e o de Mann-Whitney. Os resultados demonstraram a incidência de, respectivamente, 68,4%; 23,6%; 15,7%;13,1%; 15,7% e 7,8% de cetose, afecções de casco, lipidose hepática, deslocamento de abomaso, cisto folicular ovariano e endometrite. Houve diferença de incidência entre a cetose e as outras afecções citadas (p < 0,05). Ocorreu, nesta ordem, maior número de serviços/prenhez, maior taxa de descarte de animais, maior intervalo parto/concepção para as variáveis cetose, afecções de casco, lipidose hepática e cisto folicular ovariano (p < 0,05), deslocamento de abomaso e endometrite (p > 0,05) nos animais enfermos do que nos sadios. A taxa de prenhez entre os grupos foi de 78,9% e 92,0%, respectivamente, para os animais enfermos e sadios (p > 0,05). Concluiu-se que as afecções pesquisadas no pós-parto reduziram a performance reprodutiva dos animais enfermos em relação aos sadios, destacando-se os cistos foliculares, as afecções de casco, a cetose e a lipidose hepática sobre o intervalo parto/concepção (p < 0,05), além do deslocamento do abomaso e das endometrites (p > 0,05); e que os animais enfermos tiveram maior número de serviços/prenhez, maior taxa de descarte (p < 0,05) e menor taxa de prenhez (p > 0,05).

The study aimed to determine the patterns of serum progesterone concentration in estrous cycle in dairy cows by a chemiluminescence assay (CLIA). Four non-lactating multiparous Jersey cows were used. Animals with a corpus luteum (CL) in any of the ovaries were induced into estrus. Day zero (d0) of the estrous cycle was defined as the day of visible estrus. Blood samples were collected and ultrasonography (US) of the ovaries were performed until a new manifestation of visible estrus was observed. The lengths of the estrous cycles (estrus to estrus) of the four cows were 20, 21, 22, and 23 days. The mean serum concentrations of P4 (x ± s) were 2.8 ± 1.4 ng/mL in proestrus, 2.4 ± 1.5 ng/mL in estrus, 2.0 ± 1.8 ng/mL in metestrus, and 11.9 ± 5.7 ng/mL in diestrus. The follicular and luteal phases of the estrous cycle were established based on P4 concentrations. P4 serum concentrations ≥5.48 ng/mL indicated the presence of functional CL, which was observed from d3 to d12 of the cycle. P4 concentrations decreased from d13 until next estrus. Thus,