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This study evaluated the plasma membrane integrity, acrosomal membrane integrity, and mitochondrial membrane potential of Nelore bull sperm from early puberty to early sexual maturity and their associations with sperm motility and vigor, the mass motility of the spermatozoa (wave motion), scrotal circumference, and testosterone. Sixty Nelore bulls aged 18 to 19 months were divided into four lots (n=15 bulls/lot) and evaluated over 280 days. Semen samples, collected every 56 days by electroejaculation, were evaluated soon after collection for motility, vigor and wave motion under an optical microscope. Sperm membrane integrity, acrosomal integrity, and mitochondrial activity were evaluated under a fluorescent microscope using probe association (FITC-PSA, PI, JC-1, H342). The sperm were classified into eight integrity categories depending on whether they exhibited intact or damaged membranes, an intact or damaged acrosomal membrane, and high or low mitochondrial potential. The results show that bulls have a low amount of sperm with intact membranes at puberty, and the sperm show low motility, vigor, and wave motion; however, in bulls at early sexual maturity, the integrity of the sperm membrane increased significantly. The rate of sperm membrane damage was negatively correlated with motility, vigor, wave motion, and testosterone in the bulls, and a positive correlation existed between sperm plasma membrane integrity and scrotal circumference. The integrity of the acrosomal membrane was not influenced by puberty. During puberty and into early sexual maturity, bulls show low sperm mitochondrial potential, but when bulls reached sexual maturity, high membrane integrity with high mitochondrial potential was evident.Keywords: sexual development, sperm motility, sperm vigor, testosterone, cattle RESUMO

The objective of this study was to evaluate the effect of one or two doses of the anti-rabies vaccination on the serum concentration of cortisol and the humoral immune response in cattle as well as the correlation between serum cortisol concentrations and the titers of rabies-neutralizing antibodies. Nelore cattle were randomly assigned to one of three groups, which were vaccinated with one dose of rabies vaccine (group GVSR, N = 15), two doses of rabies vaccine (group GVR, N = 15) or were not vaccinated (group Gc, N = 15). A commercial liquid inactivated rabies vaccine was used. The stressors imposed on the cattle were vaccination, corral handling and the presence of people. Blood samples were collected on days 0, 30 and 60 post-vaccination. Serum cortisol concentrations were determined using a solid-phase radioimmunoassay, and rabies antibody titers were determined using a serum neutralization test with BHK 21 cells (RFFIT). Both serum cortisol concentrations and antibody titers increased after the second (booster) vaccination (P < 0.05). In all the groups, the serum cortisol concentrations increased after the cattle were handled in the corral (P < 0.05). No correlation was observed between the serum cortisol concentrations and the antibody titers with any treatment or on any observation day. In conclusion, booster vaccination is indispensable for primovaccinated cattle in achieving high and protective levels of rabies antibodies. Although booster vaccination and frequent cattle handling in corrals are stressors, the response is not strong enough to cause immunosuppression in cattle.

The mastite, inflammation process of mammary gland, characterized by a decrease in production and changes in milk composition, is considered the disease of major impact for dairy cattle in Brazil. Normally, this disease is resultant of the action of infectious agents, and may be involved different species of virus, fungi, and mainly, bacteria. It is important to remember, that the mastite, of any form and effect, reduces milk production and, in severe cases, may occur loss of one or more teats. Thus, the control of bovine mastite is important for the milk production of high quality. The aim of study is develop a study about this pathology that affects the dairy cattle and their effects in production and quality milk, and consequently, farmers, dairy industry and their products.

Mastitis is an inflammatory reaction of the mammary gland to some microorganism, chemical substance, thermal variations and / or lesion of the mammary gland. This inflammatory process can cause several disorders in the mammary gland, with different forms of presentation and degrees of severity, where the main symptoms are the decrease in milk production and changes in chemical and sensorial composition. This work aims to review what is mastitis and all factors associated with this disease of great importance for dairy cattle.

The aim of the present study was to analyze live weight and growth data of live weight at birth to 24.5-25.5 kg in weaned Dorper crossbred lambs. A total of 93 Dorper crossbred born lambs (½ Dorper + ½ Santa Inês) were evaluated, with percentage of 17.7 double (twin couple = 21%, twin with only females = 50%, twin with only males 29%). The sex of the lamb influenced (P < 0.05) the live weight at birth total (LWB total) and live weight at birth average (LWB average) , the male lambs had in both characteristics superior values. No differences (P > 0.05) were found for the age at weaning (AW), live weight at birth total (LWW total ) and live weight at weaning average (LWW average ) . For the type of birth all characteristics were significant (P < 0.05). For doubling birth the characteristics LWB total , AW and LWW total had higher values

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The present study investigated the hormonal profile and expression of prostaglandin F 2α (PGF 2α ), oxytocin and estrogen receptors in uterine tissues of postpartum cows treated with cloprostenol. Twenty HolsteinZebu crossbred cows were treated with saline solution (treatment CONT) or cloprostenol (treatment CLO), both administered two and five days postpartum. Blood samples were collected on days two, seven, 14, 21 and 28 postpartum for progesterone, PGF 2α metabolite (PGFM) and estradiol determination, and endometrial biopsy was performed in order to quantify the expression of oxytocin receptor (OXTR), prostaglandin F receptor (PTGFR) and estrogen receptor 1 (ERS1) genes. In the CLO treatment, expression of OXTR was reduced (P<0.05) but no difference (P>0.05) between treatments was found for PTGFR and ERS1 expression. Estrogen concentrations increased progressively until day 14 (P<0.05) and the highest OXTR expression and lowest PTGFR expression were observed on day 14 (P<0.05) in both treatments. Serum PGFM concentrations were high throughout the experiment. In conclusion, cloprostenol administration at days two and five of postpartum seems to reduce OXTR expression in the endometrium in crossbred cows.