Antonio Emidio Dias Feliciano Silva

Testicular thermoregulation in Bos indicus, crossbred and Bos taurus bulls: relationship with scrotal, testicular vascular cone and testicular morphology, and effects on semen quality and sperm production.

Mechanisms of testicular thermoregulation, the relationship of scrotal, testicular vascular cone (TVC), and testicular morphology with thermoregulatory capability, and their effects on semen quality and sperm production were studied in 20 Bos indicus, 28 crossbred, and 26 Bos taurus bulls. The ratio of testicular artery length and volume to testicular volume were larger (P<0.05) in B. indicus and crossbred bulls than in B. taurus bulls (1.03 and 0.94 cm/cm3 versus 0.48 cm/cm3; 0.034 and 0.047 ml/cm3 versus 0.017 ml/cm3, respectively). Testicular artery wall thickness (average 192.5, 229.0, and 290.0 microm, respectively) and arterial-venous blood distance in the TVC (average 330.5, 373.7, and 609.4 microm, respectively) were smallest in B. indicus, intermediary in crossbred, and greatest in B. taurus bulls (P<0.05); the proximity between arterial and venous blood was consistent with the estimated decrease in arterial blood temperature after passage through the TVC (5.9, 5.0, and 2.9 degrees C, in B. indicus, crossbred, and B. taurus bulls, respectively). In crossbred and B. taurus bulls, there was a positive top-to-bottom scrotal temperature gradient and a negative testicular subtunic temperature gradient. However, in B. indicus bulls, both scrotal and testicular subtunic temperatures gradients were positive. Differences in the vascular arrangement, characteristics of the artery (e.g. wall thickness) or thickness of the tunica albuginea may have affected the testicular arterial blood and subtunic temperatures in B. indicus bulls. Better testicular thermoregulatory capability was associated with increased scrotal shape (pendulosity), testicular artery length and volume, and top-to-bottom gradient of the distance between the artery wall and the veins in the TVC. Increased semen quality was associated with increased testicular volume and scrotal subcutaneous (SQT) temperature gradient, and with decreased scrotal surface and testicular temperatures. Increased sperm production was associated with increased testicular artery volume, testicular volume, and SQT temperature gradient, and with decreased testicular artery wall thickness, scrotal circumference (SC), and scrotal surface, testicular subtunic, and epididymal temperatures. In conclusion, morphology of the TVC may contribute to the greater resistance of B. indicus bulls to high ambient temperatures by conferring a better testicular blood supply and by facilitating heat transfer between the testicular artery and veins. Testicular thermoregulation was associated with opposing scrotal and testicular subtunic temperatures gradients only in crossbred and B. taurus bulls. Scrotal, TVC, and testicular morphology influence testicular thermoregulatory capability and were associated with differences in semen quality and sperm production.

Effect of age and genetic group on characteristics of the scrotum, testes and testicular vascular cones, and on sperm production and semen quality in AI bulls in Brazil

The objectives were to determine the effects of age and genetic group on characteristics of the scrotum, testes and testicular vascular cones (TVC), and on sperm production and semen quality in 107 Bos indicus, B. taurus and cross-bred bulls at three artificial insemination (AI) centers in Brazil. In addition, predictors of sperm production and semen quality were identified. In general, scrotal circumference (SC), scrotal shape score, scrotal neck perimeter, and testicular size (length, width and volume) increased (P < 0.05) with age. Although there were no significant differences among genetic groups for SC or testicular size, B. indicus bulls had the least pendulous scrotal shape, the shortest scrotal neck length, and the greatest scrotal neck perimeter (P < 0.05). Fat covering the TVC was thinner (P < 0.05) in bulls < or = 36 months of age and in B. taurus bulls than in older bulls and B. indicus bulls, respectively. Age and genetic group did not affect testicular ultrasonic echotexture. B. indicus bulls tended (P < 0.1) to have the lowest average scrotal surface temperature (SST). In general, ejaculate volume, total number of spermatozoa and number of viable spermatozoa increased (P < 0.05) with age. However, there was no significant effect of age on sperm concentration, motility, major and total defects. The proportion of spermatozoa with minor defects was highest (P < 0.05) in bulls 37-60 months of age. B. indicus bulls had higher (P < 0.01) sperm concentration, total number of spermatozoa and number of viable spermatozoa than B. taurus bulls, with intermediate values for cross-bred bulls. Increased sperm production was associated with increased testicular volume, SC, TVC fat cover, and SST top-to-bottom gradient. Decreased semen quality was associated with increased SC and bottom SST, and decreased scrotal shape, scrotal neck perimeter and vascular cone diameter. In summary, age and genetic group affected the characteristics of the scrotum, testes, and TVC, sperm production and semen quality. In addition, characteristics of the scrotum, testes and TVC were associated with sperm production and semen quality in bulls and could be assessed for breeding soundness evaluation.

Effects of environmental factors, age and genotype on sperm production and semen quality in Bos indicus and Bos taurus AI bulls in Brazil

The effects of ambient temperature and humidity, month, age and genotype on sperm production and semen quality in AI bulls in Brazil were evaluated. Data from two consecutive years were analyzed separately. Seven Bos indicus and 11 Bos taurus bulls from one artificial insemination (AI) center were evaluated in Year 1 and 24 B. indicus and 16 B. taurus bulls from three AI centers were evaluated in Year 2. Ambient temperature and humidity did not significantly affect sperm production and semen quality, probably because there was little variation in these variables. Month accounted for less than 2% of the variation in sperm production and semen quality. Increased bull age was associated with decreased sperm motility (P<0.10) and increased minor sperm defects (P<0.001) in Year 1. B. indicus bulls had greater (P<0.005) sperm concentration than B. taurus bulls in both years (1.7 x 10(9)/ml versus 1.2 x 10(9)/ml in Year 1 and 1.6 x 10(9)/ml versus 1.2 x 10(9)/ml in Year 2, respectively). Ejaculate volume was not significantly affected by genotype in Year 1 (6.6 ml versus 6.9 ml in B. indicus and B. taurus bulls, respectively), but B. indicus bulls had greater (P<0.05) total (11.4x10(9) versus 8.2 x 10(9)) and viable (6.7 x 10(9) versus 4.9 x 10(9)) numbers of spermatozoa in the ejaculate than B. taurus bulls. In Year 2, B. taurus bulls had greater (P<0.05) ejaculate volume than B. indicus bulls (8.2ml versus 6.7 ml, respectively) and total and viable number of spermatozoa in the ejaculate were not significantly different between genotypes (10.3 x 10(9) versus 9.1 x 10(9) and 6.1 x 10(9) versus 5.4 x 10(9) in B. indicus and B. taurus bulls, respectively). Sperm motility was not significantly affected by genotype (mean, 59%). In Year 1, B. indicus bulls tended (P<0.10) to have more major sperm defects and had more (P<0.05) total sperm defects than B. taurus bulls (11.8% versus 8.7% and 13.6% versus 10.0%, respectively). In Year 2, B. indicus bulls tended (P<0.10) to have more total sperm defects than B. taurus bulls (16.2% versus 13.3%, respectively). In conclusion, neither ambient temperature and humidity nor month (season) significantly affected sperm production and semen quality. B. indicus bulls had significantly greater sperm concentration and B. taurus bulls had significantly fewer morphologically defective spermatozoa.

Effects of scrotal insulation on sperm production, semen quality, and testicular echotexture in Bos indicus and Bos indicus × Bos taurus bulls

The objectives of the present study were to evaluate the effects of scrotal insulation on sperm production, semen quality, and testicular echotexture in Bos indicus and Bos indicus x Bos taurus crossbred bulls. In one experiment, B. indicus bulls (n=12) were allocated to control and whole-scrotum insulation groups, while in a second experiment, crossbred bulls (n=21) were allocated into control, whole-scrotum, and scrotal-neck insulation groups. Insulation was applied for 4 days (start of insulation = Day 0) and semen collection and testicular ultrasonographic examinations were performed twice weekly until Day 35. Sperm concentration and total sperm output during the post-insulation period were greater in control groups, but significant differences were observed only in B. indicus bulls. Overall, sperm motility in scrotal-insulated B. indicus bulls was lower (P<0.05) than in the control group. After whole-scrotum insulation in crossbred bulls, sperm motility was lower (P<0.05) than pre-insulation levels between Days 21 and 31, and lower than control levels on Day 24. The proportion of normal sperm after whole-scrotum insulation was lower than pre-insulation and control values from Day 11 to the end of the experiment in B. indicus bulls (P<0.05 from Days 14 to 21 and on Day 27), and from Days 14 to 25 in crossbred bulls (P<0.05 on Days 14 and 18). Insulation of the scrotal neck in crossbred bulls did not significantly affect semen quality. Loose sperm heads (Day 11), midpiece defects (Days 11 and 14), and acrosome defects (Days 27 and 31) increased (P<0.05) in insulated B. indicus bulls, while proximal cytoplasmic droplets (Days 14, 18 and 27 in B. indicus; Days 24 and 27 in crossbred bulls) and sperm vacuoles (Days 18 and 21 in B. indicus; Day 18 in crossbred bulls) increased (P<0.05) in whole-scrotum insulation groups in both experiments. There was considerable variation among bulls in the incidence of specific sperm defects. The timing of appearance of sperm defects after insulation provided insights into the pathogenesis of specific abnormalities. Neither whole-scrotum nor scrotal-neck insulation affected testicular echotexture in either experiment. In conclusion, whole-scrotum insulation resulted in decreased sperm production and semen quality in B. indicus and B. indicus x B. taurus bulls, but those changes were not associated with changes in testicular echotexture.

Características biométricas testiculares para avaliação de touros zebuínos da raça Nelore

ABSTRACT - The objective of this study was to analyze the testicular volume and shape in young males of Nellore Zebu breed and their importance for the evaluation and selection of sires. Four hundred and forty two males, from 12 to 18 month of age, were examined for scrotal circumference (CE), length (COMP), width (LARG) and testicular volume (VOL). The animals were divided in two groups (G1 and G2) according to their date of birth. The VOL was calculated by the formula: VOL = 2[(r2) x P x h], where r, h and P are LARG/2, length and 3.14, respectively. The mean values of CE, COMP, LARG and VOL at 12 month of age were 184.89±15.79 mm, 65.96±6.48 mm, 2.58±4.63 mm and 113.80±42.03 cm3, and at 18 months of age were 236.81±mm, 79.31±11.16 mm, 42.92±5.83 mm and 239.26±90.56 cm3, respectively. The parameters at 12 and 18 months of age were influenced by contemporary groups, being highly correlated. The testicular shape was considered as a length to width ratio, being recorded five forms: long (ratio £ .5), long moderate (.51 to .626 ratio), long/ovoid (.626 to .750 ratio), ovoid/spheroid (.751 to .875 ratio) and spheroid (> .875 ratio). 87% of the animals presented the long shape and, in 74%, the testicular shape changed with the age. All the parameters were influenced by testicular shape, and the testis grew in width. The results suggest that the selection of young bulls should consider the testicular volume besides the possible change in the testicular shape.

Relação da Circunferência Escrotal e Parâmetros da Qualidade do Sêmen em Touros da Raça Nelore, PO

In 960 Nellore purebred bulls, of 11.4 to 135 months of age, belonging to farms located in the Sao Paulo, Goias and Para states, was studied the possible association among the size of the scrotal circumference (CE) and sperm quality parameters, progressive motility (MOT) and sperm pathologies: the major (DEFMAI), minor (DEFMIN) and total (DEFTOT) defects. The bulls were divided by age in groups: minor than 18, from 18 to 24, from 24 to 30, from 30 to 36 and major than 36 months of age. This study was accomplished with the purpose of obtaining sizes of CE that may indicate the functional status of the testicles through the quality of the semen that can be used to predict the reproductive potential of the animals destined to the selection of bulls. Of the correlation of CE with MOT, by age group, resulted an association (R = 0,60; P<0.0001) of these parameters in the bulls up to 18 months of age, which CE above 26 cm indicated semen of high MOT (60 to 80%). The correlation between CE and sperm pathologies was very low and negatives. It was concluded that in the young bulls the size of CE indicates the quality of the semen, therefore it can be used as a criteria for the selection of animals of high reproductive potential.

Conteúdo de peptídeos e avaliação morfofisiológica dos espermatozóides do epidídimo e ejaculado de bovinos

The objective of the study was to identify some protein factors involved in bovine epididymis (SPZEP) and ejaculated (SPZEJ) sperm functional quality. With this propose, epididymis and ejaculated sperm of 11 Nellore crossbreed animals, 24 to 30 month of age, was evaluated for morphophisyological characteristics and analyzed for the peptides content. The morphophisyological characteristics consisted of progressive motility (MOT, %), velocity, sperm pathologies, and acrosome and chromatin integrity. These evaluations showed that the mean values of the SPZEJ were higher than of SPZEP, 72.3 and 46.4%, respectively. The considered sperm pathologies were the major, minor and total abnormalities. It was observed a significant difference between the means values of the minor and total abnormalities of epididymis and ejaculated sperm, 91.1 and 8.5% and 95.4 and 11.8%, respectively. These differences were caused by the presence of sperm with distal citoplasmatic droplets. The analysis of the protein of epididymis and ejaculated sperm was realized by mass spectrometer, MALDI-TOF method (matrix-assisted laser desorption/ionization-time of flight). The method identified low molecular mass proteins, i.e. peptides. The analysis of SPZEJ showed peptides ranging from 1.1 to 26.3 kDa and SPZEP from 1.1 to 11.6 kDa. Some peptides, such as 10.6 and 13.4 kDa, were found only in ejaculated sperm, and the other, such as 6.8 kDa, only in epididymis. A relationship was observed between the 7.4 kDa SPZEP and 4.7 kDa SPZEJ peptides and sperm with E 80% motility. These last results suggested the participation of these peptides in the functional processes of spermatic cells. This study used for the first time in this country the MALDI/TOF mass spectrometer method to identify peptides in bovine epididimal sperm.

Efeitos da pentoxifilina sobre a viabilidade in vitro dos espermatozóides de eqüinos, após o resfriamento a 5ºC

The objective of this work was to evaluate the in vitro effect of the addition of 1 mg pentoxifylline per ml of seminal samples from normospermic stallions, which were first diluted in Kenney extender and cooled at 5oC. The evaluation was carried out using the following parameters: total and progressive motility rate, track speed, straightness and linearity rate, progressive velocity, viability rate and plasmatic membrane integrity rate. For this experiment, 20 ejaculates from four stallions were examined using Hamilton Thorn Research (Animal Version 12.0 L, EUA) with a Makler camera. The viability rates were obtained using eosin dyes under a light microscope and membrane integrity was obtained by fluorochrom, propidium iodine and carboxyfluorescein diacetat dyes under a fluorescence microscope. The semen examination occurred at 30, 60 and 120 minutes of incubation at 37o C, after 12, 24 and 48 hours of cooling at 5oC. The pentoxifylline significantly increased the sperm parameter rates of motility and plasmatic membrane integrity for all incubation times, when compared with the control group. The rates were: +8.2% total motility, +4.7% progressive motility, +23.1 mm/s track speed, +7.4% progressive velocity, +4.7% viability and +3.5% plasma membrane integrity. The straightness and linearity rates were not significantly different between the control and treated groups. The experimental data confirm that pentoxifylline addition to stallion-cooled sperm, up to 48 hours after cooling, could preserve sperm quality for artificial insemination.

Aspectos relacionados à precocidade sexual em bovinos machos da raça Nelore, PO

The sexual precocity was studied on 79 Nelore pure breed bovine males ten to 16 month of age. All animals were avaluated for scrotal circumference (CE), testosterone concentration (Testo) and onset of the first spermatozoa in the ejaculate. The results indicate that 18,5% of males exhibit the first spermatozoa at 306,17 ± 2,42 days, 19,75± 0,9 cm of scrotal circunference and a testosterone concentration of 1,57± 0,9ng/ml. According to the onset of the first spermatozoa in ejaculate, these males showed puberty at 365,39± 1,13 days and the maturity at 487,38± 3,08 days. The results indicate the existence of Nelore pure breed males presenting sexual activity at ages bellow that described in the literature, therefore beeing considered precocious.

Estudo de parâmetros bioquímicos de éguas gestantes, Puro Sangue Árabe

Metabolic rates were determined during the first and last gestation periods in Arab mares raised on Coast-cross(Cynodon dactylon) pasture. For this study, blood, urine and stool samples were collected and body measures were taken. The mares had a weight gain, from the beginning till the end of the gestation, of 69,4 kg. Total protein values in the blood had shown a significant increase (P<0,05) from the first to the last gestation month, while the albumin values decreased. The ratio of albumin : protein was constant during the gestation, reflecting balance in the protein feeding. The levels of calcium, phosphorus, magnesium, copper and zinc in the blood serum did not suffer any alteration during pregnancy. The same could be observed with total protein, glucose, creatinin and urea in the urine. The calcium and magnesium levels in the urine had an increase (P<0,05) of the beginning to the end of gestation. Conversely, the phosphorus and potassium decreased (P<0,05) due to increased mobilization of these elements in the final period, as result of fetal growth. In the stools, the protein, calcium, phosphorus and potassium levels decreased (P<0,05) at the beginning and end of pregnancy, probably due to greater mobilization and an increase of nutritional needs. Analysis of the data allowed to conclude that most of the analyzed elements were eliminated in the urine, with the exception of the microminerals, which were eliminated in the stools. Considering the development of the animals during pregnancy the biochemical parameters obtained in this study can be considered as reference values for Arab pregnant mares raised exclusively on Coast-cross pasture.