ABSTRACT
Abstract Background: Crocodile farming aims to produce high-quality skins from captive crocodilians. Captivity usually exposes the animals to stressful conditions, resulting in increased serum corticosterone (CORT) levels that correlate negatively with those of sex hormones and reproductive success. Objective: To evaluate serum concentrations of CORT and sex hormones and their relationship in farmed Morelet's crocodiles (Crocodylus moreletii) during the non-breeding (NBS) and breeding (BS) seasons. Methods: The study included 59 adult crocodiles (29 females and 30 males). One blood sample was collected in NBS (n=31) and BS (n=28) from each crocodile to determine serum concentrations of CORT, estradiol (E2), progesterone (P4), and testosterone (T). Crocodiles were kept in mixed-sex groups and were fed once or twice a week throughout the study. Results: In females, CORT was higher in NBS (p<0.05) but had no correlation with E2 or P4 in any season (p>0.05). In males, CORT was similar in NBS and BS (p>0.05) and had no correlation with T (p>0.5). Conclusion: The CORT levels had no effect on sex hormones. This could be explained by low CORT levels resulting from farming conditions were the animals were not expose to severe or chronic stress.
Resumen Antecedentes: La cría de cocodrilos en granja busca producir pieles de alta calidad de cocodrilianos en cautiverio. El cautiverio usualmente expone a los animales a condiciones estresantes, resultando en altas concentraciones séricas de corticosterona (CORT) que se correlacionan negativamente con los niveles de hormonas sexuales y el éxito reproductivo. Objetivo: Evaluar las concentraciones séricas de CORT y de hormonas sexuales y su relación en cocodrilos Moreletii (Crocodylus moreletii) criados en granja, tanto durante la época no reproductiva (NBS) como en la reproductiva (BS). Métodos: El estudio incluyó 59 cocodrilos adultos (29 hembras y 30 machos). Se recolectó una muestra de sangre de cada cocodrilo en NBS (n=31) y BS (n=28) para determinar las concentraciones séricas de CORT, estradiol (E2), progesterona (P4) y testosterona (T). Los cocodrilos permanecieron en grupos mixtos de machos y hembras y fueron alimentados una o dos veces por semana durante el estudio. Resultados: En hembras, CORT fue más alta en NBS (p<0,05), pero no se correlacionó con E2 o P4 en ninguna temporada (p>0,05). En machos, CORT fue similar en NBS y BS (p>0,05) y no tuvo correlación con T (p>0,05). Conclusión: Las concentraciones de CORT no tuvieron efecto sobre las hormonas sexuales, tal vez debido a que la CORT tuvo niveles bajos como resultado de las condiciones de manejo de la granja en las que los animales no se expusieron a estrés severo o crónico.
Resumo Antecedentes: A criação de crocodilos em fazenda procura produzir couros de alta qualidade de crocodilos em cativeiro. O cativeiro geralmente expõe os animais a condições estressantes, resultando em altas concentrações de soro de corticosterona (CORT) que têm correlação negativa com os níveis de hormônios sexuais e o sucesso reprodutivo. Objetivo: Avaliar as concentrações de soro de CORT e hormônios sexuais e sua relação em crocodilos Moreletii (Crocodylus moreletii) criado em fazenda, nas estações de não reprodução (NBS) e reprodução (BS). Métodos: O estudo incluiu 59 crocodilos (29 fêmeas e 30 machos). Uma amostra de sangue foi coletada de cada crocodilo em NBS (n=31) e BS (n=28) para determinar as concentrações de soro de CORT, estradiol (E2), progesterona (P4) e testosterona (T). Ao longo do estudo, os crocodilos permaneceram em grupos mistos de machos e fêmeas e foram alimentados uma ou duas vezes por semana. Resultados: Em fêmeas, CORT foi maior em NBS (p<0,05), mas não teve correlação com E2 ou P4 em qualquer estação (p>0,05). Em machos, CORT foi parecido em NBS e BS (p>0,05) e não teve correlação com T (p>0,05). Conclusão: As concentrações de CORT não tiveram efeito sobre os hormônios sexuais talvez porque o CORT foi baixo como resultado das condições de tratamento em fazenda que não expuseram os animais a estresse severo ou crônico.
ABSTRACT
ABSTRACT The objective of the study was to determine the morphological characteristics of peripheral blood cells (erythrocytes, leukocytes, thrombocytes) and the leukocyte differential count (heterophils, eosinophils, basophils, lymphocytes, monocytes, azurophils) of captive Morelet's crocodiles (Crocodylus moreletii) from Veracruz, Mexico. Peripheral blood from 80 apparently healthy farmed crocodiles (39 subadults [19 females, 20 males] and 41 adults [18 females, 23 males]) was examined for morphology through stained blood smears and manual count was used for the leukocyte differential. Blood was collected during the non-breeding (n = 42) and breeding (n = 38) seasons. Blood examination indicated similar morphological characteristics of blood cells in subadult and adult individuals and in females and males in both seasons. Erythrocytes were the largest blood cells and lymphocytes the smallest. The leukocyte differential count showed that lymphocytes were the most abundant leukocytes and basophils the least numerous. The percentages of some leukocytes showed difference by season (non-breeding and breeding) in subadult and adult males (p < 0.05) and by size (subadults and adults) in males and females but only in the non-breeding season (p < 0.05). The leukocytes that showed the greatest variation were lymphocytes, heterophils and eosinophils. The knowledge of blood cell morphology and the leukocyte differential count in healthy farmed Morelet's crocodiles will allow the accurate diagnosis of some diseases of captive and wild individuals.
RESUMEN El objetivo del estudio fue determinar las características morfológicas de células sanguíneas periféricas (eritrocitos, leucocitos, trombocitos) y el conteo diferencial de leucocitos (heterófilos, eosinófilos, basófilos, linfocitos, monocitos, azurófilos) del cocodrilo de Morelet (Crocodylus moreletii) mantenido en cautiverio en Veracruz, México. Se examinó sangre periférica de 80 cocodrilos aparentemente sanos criados en granja (39 subadultos [19 hembras, 20 machos] y 41 adultos [18 hembras, 23 machos]) mediante frotis sanguíneos teñidos para determinar la morfología celular y mediante conteo manual para el diferencial de leucocitos. La sangre se recolectó durante las temporadas no reproductiva (n = 42) y reproductiva (n = 38). El examen sanguíneo indicó similar morfología de células sanguíneas en individuos subadultos y adultos, así como en hembras y machos, en ambas temporadas. Los eritrocitos fueron las células sanguíneas más grandes y los linfocitos las más pequeñas. El conteo diferencial de leucocitos mostró que los linfocitos fueron los leucocitos más abundantes y los basófilos los menos numerosos. Los porcentajes de algunos leucocitos mostraron diferencia por época (no reproductiva y reproductiva) en machos subadultos y adultos (p < 0,05) y por talla (subadultos y adultos) en machos y hembras sólo en temporada no reproductiva (p < 0,05). Los leucocitos que tuvieron la mayor variación fueron linfocitos, heterófilos y eosinófilos. El conocer la morfología de las células sanguíneas y el conteo diferencial de leucocitos en individuos sanos de cocodrilo de Morelet criados en granja permitirá diagnosticar con precisión algunas enfermedades de individuos manejados en cautiverio y también de individuos silvestres.
ABSTRACT
The objective of the study was to evaluate embryo production in middle-aged and mature Bos taurus × Bos indicus cows induced to multiple ovulation (MO) in a tropical environment. Twenty-eight cows were assigned into two groups: (1) middle-aged cows = 4-6 years old (n = 13), and (2) mature cows = 8-12 years old (n = 15). All donors received the same MO protocol with follicle-stimulating hormone in decreasing dose during 4 days and two artificial insemination services. Total numbers of corpora lutea at embryo collection, structures collected, and viable embryos obtained, as well as recovery rate, were higher in middle-aged cows compared with mature cows (P < 0.05). A total number of degenerate embryos and unfertilized oocytes, as well as viability rate, were similar in both groups (P > 0.05). In conclusion, the mature cows responded to the MO treatment, but the average of viable embryos recovered per donor was lower than in middle-aged cows. Therefore, the inclusion of cows ≥ 8 years old as donors in MO programs in tropical environments should be avoided.
Subject(s)
Cattle/physiology , Embryo, Mammalian/embryology , Follicle Stimulating Hormone/pharmacology , Insemination, Artificial/veterinary , Ovulation Induction/veterinary , Ovulation/drug effects , Age Factors , Animals , Female , Hybridization, Genetic , MexicoABSTRACT
The white-tailed deer ( Odocoileus virginianus) inhabits a wide latitudinal range in the Americas. Deer species dwelling throughout wide latitudinal ranges have developed subspecies with variations in their reproductive seasonality. In northern subspecies of white-tailed deer, such as those from Canada and the United States, the breeding season occurs from October through December. Odocoileus virginianus veraecrucis is a subspecies that inhabits eastern Mexico, and because its reproductive season has not been studied, it is believed to be similar to that from northern subspecies. The objective of the study was to determine the onset of the breeding season and the profile of fecal steroid hormone metabolites throughout the year in captive white-tailed deer subspecies veraecrucis in Mexico. Two groups of adult deer were included: 1) six does and one buck at a Wildlife Conservation Unit, and 2) five does and one buck at a zoo. From each group of deer, representative fecal samples were collected on a weekly basis for 1 yr for fecal analysis of progesterone and estradiol in the does, and testosterone in the bucks. Data on antler casting, parturitions, and velvet shedding were recorded. Progesterone was high during pregnancy and low throughout the parturition period. Estradiol fluctuated throughout the year. Testosterone was high during the rut and low after antler casting. Antlers were cast in March and velvet was shed in August at both sites. Parturitions started in February at the zoo and in April at the Wildlife Unit. In captive white-tailed deer subspecies veraecrucis the breeding season started in July, and therefore earlier than what has been reported for subspecies from northern latitudes.
Subject(s)
Deer/physiology , Seasons , Sexual Behavior, Animal , Animals , Animals, Zoo , Antlers , Estradiol/chemistry , Estradiol/metabolism , Feces/chemistry , Female , Male , Mexico , Pregnancy , Testosterone/chemistry , Testosterone/metabolismABSTRACT
The study evaluated the concentrations of faecal cortisol metabolites (FCM) in intensively fattened beef cattle from a feedlot in a humid tropical environment. A total of 360 bulls weighing 271-371 kg were kept confined in pens from the start to the end of the fattening period (FP). At 24 h after arriving at the feedlot, cattle were distributed into the pens according to their live weight: 271-320 kg, 321-370 kg, and >370 kg. At the start of the FP, four pens of each weight group were randomly selected, and in each of them 10 faecal samples were obtained from 10 randomly selected bulls; this sampling was repeated in the same pens and in each weight group at the middle and end of the FP. The FCM were measured through enzyme immunoassay. The 271-320 kg group had higher FCM at the end of the FP (P < 0.05), the 321-370 kg group had similar FCM throughout the FP (P > 0.05), and the >370 kg group showed higher FCM at the start and end of the FP (P < 0.05). Higher FCM were observed at the middle of the FP in the 321-370 kg group, and at the end of the FP in the 271-320 kg and >370 kg groups (P < 0.05). Mean FCM obtained throughout the FP were within normal ranges for cattle, suggesting that appropriate management in feedlots in humid-tropical regions can provide bulls with a low-stress environment.
Subject(s)
Behavior, Animal/physiology , Cattle/physiology , Feces/chemistry , Hydrocortisone/analysis , Stress, Physiological/physiology , Animal Welfare , Animals , Humidity , Male , Random Allocation , Tropical ClimateABSTRACT
BACKGROUND: Little is known concerning the prevalence of Toxoplasma gondii infection in dogs in Mexico. Here, we investigated antibodies to T. gondii and associated risk factors in 101 dogs from an animal shelter in Veracruz State, Mexico. Canine sera were assayed for T. gondii IgG antibodies by using the modified agglutination test (MAT, cut off 1:25). RESULTS: Sixty eight (67.3%) of 101 dogs were seropositive with titers of 1:25 in 16, 1:50 in 8, 1:100 in 9, 1:200 in 10, 1:400 in 10, 1:800 in 10, 1:1600 in 3, and 1:3200 or higher in 2. None of the dogs' characteristics studied including age, sex, breed, and history of deworming, rabies vaccination and contact with cats was associated with seroprevalence of T. gondii infection. CONCLUSION: Using the dogs as sentinel animals, the results indicate high contamination with T. gondii of the environment in Veracruz, Mexico. Results have public health implications, and further studies in Veracruz should be conducted to establish the sources of environmental contamination with T. gondii and to determine optimal preventive measures against T. gondii infection in humans.