Administration of PGF2α at the moment of timed-AI using sex-sorted or conventional semen in suckled nelore cows with different intensity of estrus behavior.

The aim of this work was to evaluate pregnancy rates (PR) and ovulatory characteristics of Nelore cows receiving PGF2α at the time of AI (artificial insemination) in a progesterone(P4)/estradiol-based timed-AI protocol. We also compared the effects of PGF2α treatment at AI in cows inseminated with conventional or sex-sorted semen, with the absence or expression of estrus. In experiment 1, a total of 701 suckled, multiparous Nelore cows from two commercial beef farms were submitted to the same protocol. All cows received a 12.5 mg (IM) injection of dinoprost tromethamine (Dinoprost; Lutalyse®; PGF treatment) at days 7 and 9 of a timed-AI protocol. Following P4 device removal (day 11; D11), AI was performed 48 h later with conventional or sex-sorted semen from two different sires. At AI, cows received an additional dose of 12.5 mg (IM) of Dinoprost (PGF treatment) or 2.5 mL (IM) of sterile saline (Control). Estrus behavior was determined at D11 by activation of an estrus detection device (Estrotect®). The overall PR was 32.8% (n = 348) at Farm 1 and 42.3% (n = 353) at Farm 2 (P = 0.01). Despite PR differences between farms, the same factors affected PR at Farms 1 and 2. Body condition score (P = 0.02), estrus behavior (P = 0.01), and type of semen (P < 0.001) were factors affecting PR. Conventional semen had a 2.73x greater chance of successful pregnancy than sex-sorted semen. Cows displaying estrus had a 2.5x greater chance of successful pregnancy than cows that did not display estrus. No treatment effect (P = 0.67) was detected in cows receiving conventional or sex-sorted semen. However, there was a tendency (P = 0.08) for an interaction between treatment (PGF or control) and estrus behavior (estrus or no estrus). PGF2α at the time of AI tended to increase PR of cows that did not display estrus (P < 0.10). In experiment 2, 29 suckled, multiparous Nelore cows were compared using B-mode and Doppler ultrasongraphy to assess the ovulatory characteristics of cows receiving the 12.5 mg (IM) injection of Dinoprost (PGF treatment) or saline solution (control) at D11. No significant effects of PGF2α treatment at D11 were observed in follicular characteristics and/or ovulation performance. It was concluded that fertility of sex-sorted semen was lower than conventional semen, regardless of the PGF2α treatment. The 12.5 mg treatment of Dinoprost at AI did not accelerate the occurrence of ovulation; however, it was interesting to note that PGF2α treatment at timed-AI appeared to increase the fertility of cows that did not display estrus, independent of semen type.

Sire contribution to pregnancy loss and pregnancy-associated glycoprotein production in Nelore cows.

Pregnancy loss is a major contributing factor to reproductive inefficiency in both the beef and dairy industries. Sires can have a significant influence on the amount of pregnancy loss; however, this relationship is still poorly investigated. The primary objective of this study was to identify sires associated with high or low incidence of pregnancy loss (between d 30 and 100 of gestation) and investigate their effect on concentration of circulating pregnancy-associated glycoproteins (PAGs). Postpartum multiparous Nelore cows were inseminated artificially at a fixed time (FTAI, d 0) after synchronization of ovulation. A total of 736 cows were assigned randomly to be inseminated with semen from either of 6 Angus sires, whereas a separate subset of 492 cows were inseminated randomly with semen from either of 3 Nelore (n = 235) or either of 2 Angus sires (n = 257). Estrus expression was evaluated on d 0 using Estrotect Heat Detector patches. Blood samples were collected on d 30 of gestation for quantification of PAGs and pregnancy diagnosis was performed by ultrasound on d 30 and 100 after FTAI. Cows diagnosed pregnant at the first examination but not pregnant at the second were defined to have pregnancy loss. Overall pregnancy rate at d 30 was 54% (660/1,228) and pregnancy loss was 6.21% (41/660). Cows receiving semen from Nelore sires had greater (P < 0.001) pregnancy rate, greater (P = 0.014) pregnancy loss, and lesser (P = 0.002) PAG concentrations at d 30 of gestation compared with cows receiving Angus semen. Circulating PAG concentrations were lower (P = 0.008) in cows that had pregnancy loss (9.76 ± 0.25 vs. 7.41 ± 1.02 ng/mL). Angus sires were retrospectively classified according to percentage of pregnancy loss as either high pregnancy loss (mean of 7.25% or 67% of total) or low pregnancy loss (mean of 3.93% or 33% of total). Cows receiving semen from high pregnancy loss sires had 1.9 times greater (P = 0.123) rate of pregnancy loss and had lower (P = 0.059) PAG concentrations at d 30 of gestation compared with cows mated to low pregnancy loss sires. In summary, PAG concentrations reflected probability of pregnancy maintenance and were influenced by both sire and sire breed used at FTAI. Variation in the incidence of pregnancy loss was detected among sires that could not be predicted with standard semen fertility evaluations. Exploring the relationship of sire and PAG production might be promising to improve sire selection with regard to pregnancy loss.

Assessment of in vitro sperm characteristics and their importance in the prediction of conception rate in a bovine timed-AI program.

The aims of this study were to assess in vivo fertility and in vitro sperm characteristics of different sires and to identify sperm variables important for the prediction of conception rate. Multiparous Nelore cows (n = 191) from a commercial farm underwent the same timed artificial insemination (timed-AI) protocol. Three batches of frozen semen from three Angus bulls were used (n = 9). A routine semen thawing protocol was performed in the laboratory to mimic field conditions. The following in vitro sperm analyses were performed: Computer Assisted Semen Analysis (CASA), Thermal Resistance Test (TRT), Hyposmotic Swelling Test (HOST), assessment of plasma and acrosomal membrane integrity, assessment of sperm plasma membrane stability and of lipid peroxidation by flow cytometry and assessment of sperm morphometry and chromatin structure by Toluidine Blue staining. For statistical analyses, Partial Least Squares (PLS) regression was used to explore the importance of various sperm variables in the prediction of conception rate. The following in vitro sperm variables were determined to be important predictors of conception rate: total motility (TM), progressive motility (PM), TM after 2 h of thermal incubation (TM_2 h), PM after 2 h of thermal incubation (PM_2 h), Beat Cross Frequency after 2 h of thermal incubation (BCF_2 h), percentage of rapidly moving cells after 2 h of thermal incubation (RAP_2 h), intact plasma membrane evaluated by HOST, intact plasma and acrosomal membranes evaluated by flow cytometry, intact plasma membrane suffering lipid peroxidation, major defects, total defects, morphometric width/length ratio, Fourier_0 and Fourier_2 and Chromatin Heterogeneity. We concluded that PLS regression is a suitable statistical method to identify in vitro sperm characteristics that have an important relationship with in vivo bull fertility.

Origem e distribuição da artéria celíaca em aves (Gallus gallus, Linnaeus 1758) da linhagem Arbor Acres / Origin and distribution of celiac artery in fowl (Gallus gallus, Linnaeus 1758) of Arbor Acres Lineage

Estudou-se em 30 exemplares de frangos de corte Gallus gallus da linhagem Arbor Acres, com aproximadamente 7 a 8 semanas de idade, a origem e distribuição da artéria celíaca. Foi injetada solução aquosa corada, a 50 por cento, de Neoprene látex 450, para marcar o sistema arterial dos exemplares, via artéria isquiática direita, sendo em seguida as aves fixadas em solução aquosa de formol a 10 por cento. Após as dissecações e análises dos resultados pode-se concluir que a artéria celíaca origina-se como primeiro ramo ventral da artéria aorta abdominal, e depois envia ramos para o esôfago, saco pericárdio, proventrículo, ventrículo, baço, fígado, vesícula biliar, duodeno, pâncreas, jejuno, íleo e cecos.

Origens e distribuição das artérias mesentéricas cranial e caudal em aves (Gallus gallus, Linnaeus 1758) da linhagem Arbor Acres / Origins and distributions of cranial and caudal mesenteric arteries in fowl (Gallus gallus, Linnaeus 1758) Arbor Acres lineage

As artérias mesentéricas são importantes vasos responsáveis pela nutrição de grande parte do aparelho digestório. Estudou-se as origens e distribuições das artérias mesentéricas cranial e caudal em 30 aves da linhagem Arbor Acres, com idades variando de 7 a 8 semanas. Após a injeção dos sistemas arteriais das aves, via artéria isquiática direita, com solução aquosa corada de Neoprene Látex 450 à 50 por cento e fixação em solução aquosa de formol à 10 por cento por no mínimo 48 horas, iniciou-se a dissecação, obtendo os seguintes resultados: a artéria mesentérica cranial emite as artérias ileocecal, 7 a 15 jejunais e de 2 a 7 ileais. A artéria mesentérica caudal emite um ramo cranial que envia de 5 a 9 ramos e outro caudal que emite de 2 a 5 ramos. O ramo cranial da artéria mesentérica caudal em todos os casos anastomosou-se com a artéria ileocecal. A maior parte do intestino delgado e cecos são irrigados pela artéria mesentérica cranial, enquanto que o reto e a cloaca são irrigados pela artéria mesentérica caudal. Esta artéria, pode também, emitir ramos à parte final do ceco.

Prevalência de resíduos de antibióticos em amostras de leite cru na região do Triângulo Mineiro, MG / Prevalence of residues of antibiotics in samples of raw milk in the region of the Triângulo Mineiro, MG

A cadeia produtiva do leite no Brasil vem enfrentando mudanças rápidas e significativas nos últimos anos. Assim, a qualidade do leite tem recebido crescente atenção por parte dos vários segmentos do setor lácteo. O objetivo da presente pesquisa foi avaliar a qualidade do leite produzido na região do Triângulo Mineiro, observada pela Contagem de Células Somáticas (CCS) e pela presença de resíduos de antibióticos. A pesquisa foi desenvolvida em 21 fazendas, com diferentes tipos de ordenha: manual, mecânica circuito fechado e “balde ao pé”, com sete propriedades cada. As colheitas de leite foram realizadas em cada fazenda, durante a ordenha da tarde, aleatoriamente de 30 animais, na quantidade de 50ml e acondicionadas em frascos, com conservante e identificados com código de barras para cada animal, para análise de CCS. Cerca de 2 ml de leite de cada animal foi colhido para formar uma amostra composta, acondicionada em frasco, sem conservante, para análise de resíduo de antibiótico. O diagnóstico da qualidade do leite foi feito pelo aparelho SOMACOUNT 300*¹ (CCS) e pelo DELVOTEST (“kit” para detecção de resíduos de antibióticos (beta-lactâmicos) foi da ordem de 33,3 por cento, sendo todas essas amostras de leite com CCS acima de 750.000 células/ml. Observou-se que, das amostras que apresentaram resíduos de antibióticos, 23,8 por cento foram da ordenha circuito fechado; as amostras de leite da ordenha manual foram negativas.