Maria Marina Unanian

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.

Associação do polimorfismo do gene do hormônio de crescimento com a caraterística peso em bovinos da raça Nelore

The polymorphism of the growth hormone gene (bGH) was studied in 211 Nellore pure breed bovine males to estimate the genotype and allelic frequencies and possible associations of the gene with weight traits. For this study, body weight data were collected at birth, weaning and monthly from 10 to 16 months of age. Additionally, weight gains from birth to weaning and weaning to 16 months of age were calculated. DNA was extracted from blood samples and the animals genotyped for Msp I (bGH/Msp I, 891 bp), Hae III (bGH/Hae III, 441 bp) and Alu I (bGH/Alu I, 427 bp) polymorphic sites. Every polymorphism presented two alleles. The predominant alleles were D, F and A, respectively. The effect of the bGH/Alu I AA genotype was observed on the weight gain from weaning to 15 months of age, and of the bGH/Msp I DD genotype from weaning to 14 and 15 months. The results suggest that bGH/Alu I and bGH/Msp I polymorphisms may be potential markers for the weight gain trait in young bulls.

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.

Possible Associations between Bovine Growth Hormone Gene Polymorphism and Reproductive Traits

The polymorphism of the bovine growth hormone gene (bGH) was studied in 211 Nellore pure breed males for association with reproductive traits. Scrotal circumference and testosterone concentrations were collected monthly from 10 until 16 months of age. Additionally, testicular growth rates were calculated. DNA was amplified by PCR and digested using Msp I and Hae III restriction enzymes. Every polymorphism presented two alleles. The predominant alleles were D (0.85) and F (0.98), respectively, and genotype EE - bGH/Hae III was missing. Significant association (P<0.05) between bGH/Msp I polymorphism, scrotal circumference and testicular growth after puberty, as well as between bGH/Hae III and testosterone concentrations at puberty were detected. The results suggested that these association could be useful for selection, since bGH/Msp I and bGH/Hae III polymorphisms could be considered as markers for testicular development after puberty and onset of puberty, respectively.

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.