BLOOD CELL MORPHOLOGY AND LEUKOCYTE DIFFERENTIAL OF MORELET'S CROCODILE (Crocodylus moreletii) (CROCODYLIDAE) / Morfología de células sanguíneas y recuento leucocitario del cocodrilo de Morelet (Crocodylus moreletii) (CROCODYLIDAE)

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.

Effect of stress during slaughter on carcass characteristics and meat quality in tropical beef cattle.

OBJECTIVE: This study aimed to determine the effects of stress during slaughter of beef cattle on physiological parameters, carcass, and meat quality at a Federal Inspection Type slaughterhouse located in the southeast of Mexico. METHODS: A total of 448 carcasses of male Zebu×European steers with an average age of 36 months were included. Carcass assessment of presence of bruises and bruise characteristics was carried out on each half-carcass. Blood variable indicators of stress (packed cell volume, neutrophil to lymphocyte ratio, glucose, cortisol concentration) and meat quality parameters (pH, color, shear force, drip loss) were evaluated. RESULTS: Of the 448 carcasses evaluated, 81% of the carcasses showed at least one bruise; one bruise was detected in 36.6% and two bruises in 27.0% of animals. Of the 775 bruises found, 69.2% of the bruises were grade 1 in region 3. Of the 448 carcasses studied, 69.6% showed hyperglycemia (6.91 mmol/L); 44.3% and 22.7% showed high (74.7 ng/mL) and extremely high (108.8 ng/mL) cortisol levels, respectively, indicative of inadequate handling of animals during preslaughter and slaughter. Of the carcasses evaluated, 90.4% had a pH ≥5.8 with an average of pH 6.3. In both pH groups, meat samples showed L* values >37.0 (81.6%) and a shear force >54.3 N; meat pH≥5.8 group showed a drip loss of 2.5%. These findings were indicative of dark, firm, and dry (DFD) meat. According to principal component analysis, grades 1 and 2 bruises in region 3 and grade 1 bruises in region 5 were highly associated with cortisol, drip loss, and color parameters b* and h* and were negatively associated with L*, a*, and C*. CONCLUSION: The bruises probably caused by stress-inducing situations triggered DFD meat. Appropriate changes in handling routines in operating conditions should be made to minimize stress to animals during the slaughter process to improve animal welfare and meat quality.

Embryo production after superovulation of bovine donors with a reduced number of FSH applications and an increased eCG dose.

This study evaluated embryo production after superovulation (SO) with a reduced number of FSH applications and increased eCG dose in 26 Bos taurus × Bos indicus donors. On Day 0, donors received an intravaginal device (CIDR) with 1.9 g of progesterone plus 2.5 mg of estradiol benzoate and 50 mg of progesterone via IM. On Day 4, donors were randomly allotted to one of three SO treatments: 1) 455 IU of Folltropin +400 IU of eCG (n = 9), 2) 350 IU of Folltropin +600 IU of eCG (n = 9), and 3) 500 IU of Pluset + 600 IU of eCG (n = 8). In treatment 455 IU of Folltropin +400 IU of eCG, donors received eight IM Folltropin injections in decreasing dose 12 h apart from Day 4 to Day 7. On Day 6, at the same time as the Folltropin, donors received via IM 25 mg of dinoprost tromethamine (PGF2a). On Day 7, the CIDR was removed, and together with the Folltropin, donors received 200 IU of eCG via IM. In treatment 350 IU of Folltropin +600 IU of eCG, donors received four IM Folltropin injections in decreasing dose 12 h apart on Days 4 and 5. On Day 6, donors received via IM 600 IU of eCG in the morning and two doses of 25 mg of PGF2a 12 h apart. On Day 7, the CIDR was removed. Donors from treatment 500 IU of Pluset +600 IU of eCG received four IM Pluset injections in decreasing dose 12 h apart on Days 4 and 5. On Day 6, donors received via IM 600 IU of eCG in the morning and two doses of 25 mg of PGF2a 12 h apart. On Day 7, the CIDR was removed. In the morning of Day 8, donors from the three treatments received 0.25 mg of GnRH via IM. Artificial insemination was performed on Day 8 (pm) and Day 9 (am). Embryos were collected on Day 15. Variables evaluated were number of CL before embryo collection, number of structures recovered, transferable embryos, degenerate embryos and unfertilized oocytes, recovery rate, and viability rate. There was no difference in any variable among treatments (P > 0.05). In conclusion, replacement of four Folltropin or Pluset injections from a conventional eight FSH-injection SO protocol, by a single injection of 600 IU of eCG, is a good alternative to reduce donor handling without decreasing yield of transferable embryos.

Embryo production in middle-aged and mature Bos taurus × Bos indicus cows induced to multiple ovulation in a tropical environment.

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.

Progesterone and estradiol profiles in different reproductive stages of captive collared peccary (Pecari tajacu) females assessed by fecal metabolites.

The study determined the fecal progesterone and estradiol profiles in different reproductive stages of captive collared peccary (Pecari tajacu) females from eastern Mexico. Fifteen adult females were included. At the start of the study the females were either pregnant (early, mid, or late pregnancy), lactating, or non-lactating of unknown pregnancy status. Feces from each female were collected once a week during nine consecutive months to determine concentrations of fecal progesterone and estradiol metabolites using ELISA. Progesterone was similar in early (2048±285ng/g), mid (2254±274ng/g), and late pregnancy (2491±374ng/g), and in early-pregnant and non-lactating females (1154±274ng/g). Progesterone in lactating females (442±255ng/g) was lower than in females at any stage of pregnancy, but was similar to non-lactating females. Overall progesterone in pregnant females (2229±173ng/g) was higher than in lactating and non-lactating females together (772±189ng/g). Estradiol was similar in early (66±8ng/g), mid (83±9ng/g), late pregnant (109±15ng/g), and non-lactating females (64±9ng/g). Estradiol in lactating females (34±8ng/g) was similar to estradiol in early-pregnant and non-lactating females, but was lower than in females in late and mid pregnancy. Overall estradiol in pregnant females (79±6ng/g) was similar to non-lactating females, but higher than in lactating females. The progesterone and estradiol profiles of captive collared peccary females at different reproductive stages were determined by assessing concentrations of fecal hormone metabolites.

EARLY ONSET OF THE REPRODUCTIVE SEASON IN CAPTIVE WHITE-TAILED DEER ( ODOCOILEUS VIRGINIANUS VERAECRUCIS) IN EASTERN MEXICO.

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.

Faecal cortisol concentrations as indicator of stress during intensive fattening of beef cattle in a humid tropical environment.

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.

High prevalence of Toxoplasma gondii antibodies in dogs in Veracruz, Mexico.

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.