Espermiogênese alterada em um touro doador de sêmen: relato de caso / Altered spermiogenesis in a semen donor bull: case report

A espermiogênese é o processo final da espermatogênese no qual a espermátide se transforma em espermatozoide. Durante esse processo podem ocorrer alterações espermáticas, especialmente no acrossoma, na morfologia da cabeça, na condensação da cromatina e na formação dos vacúolos nucleares. A diferenciação entre os quadros clínicos é feita com repetições dos exames andrológicos. A avaliação morfológica indica a situação da espermiogênese nas 4 semanas anteriores a coleta do sêmen. Com os resultados do exame andrológico é possível identificar a qualidade seminal naquele período. O presente artigo é o relato de caso de um touro jovem doador de sêmen com 26 meses de idade, no início do regime de coletas de sêmen em um Centro de Coleta e Processamento de Sêmen no Sul do Brasil. A produção espermática deste animal foi avaliada durante 12 meses de coleta, apresentando sempre morfologia espermática muito alterada e motilidade média de 54% no exame imediato. Em 13 coletas seminais, o ejaculado deste animal apresentou em média 86% de defeitos maiores, 10% de defeitos menores e 96% de defeitos totais. Os defeitos maiores, que são os que possuem maior efeito na fertilidade, estão diretamente ligados a espermiogênese e os defeitos menores, que possuem menor efeito na fertilidade, são ocasionados principalmente durante o trânsito pelo epidídimo. O quadro clínico desse animal demonstrou a importância do exame morfológico para avaliar a espermatogênese e principalmente o processo de diferenciação final da espermátide em espermatozoide. Casos como este devem ser descritos como espermiogênese alterada e o reprodutor deve ser afastado da reprodução, após descartar alterações morfológicas devido a degeneração testicular grave.(AU)

Spermiogenesis is the final process of spermatogenesis in which the spermatid transforms into sperm. During this process, sperm alterations may occur, especially in the acrosome, head morphology, chromatin condensation and formation of nuclear vacuoles. Differentiation between clinical conditions is made with repetitions of andrological exams. The morphological evaluation indicates the status of spermiogenesis in the 4 weeks prior to semen collection. With the results of the breeding soundness examination, it is possible to identify the seminal quality in that period. The present article is a case report of a young 26-month-old semen donor bull, that started semen collection routines at a Semen Collection and Processing Center in southern Brazil. The sperm production of this animal was evaluated during 12 months of collection, always showing very altered sperm morphology and average motility of 54% in the immediate examination. In 13 seminal collections, the ejaculate of this animal presented an average of 86% of major defects, 10% of minor defects and 96% of total defects. Major defects, which have the greatest impact on fertility, are directly linked to spermiogenesis and minor defects, which have less effect on fertility, are mainly caused during transit through the epididymis. The clinical conditions of this animal demonstrated the importance of the morphological examination to evaluate spermatogenesis and especially the process of final differentiation of the spermatid into spermatozoa. Cases like this should be described as altered spermiogenesis and the bull should be withdrawn from breeding, after ruling out morphological changes due to severe testicular degeneration.(AU)

Impact of quercetin, carnosine, and ozone in the cryopreservation on Nellore (Bos indicus) semen

The objective of this study was to reduce the effects of cryoinjury caused in bovine semen by cryopreservation. Ejaculates were collected from Nellore bulls and subjected to freezing in C (control), ozone (15, 30, and 60 µg mL-1 of ozone), quercetin (25, 50, and 100 µg mL-1 of quercetin), and carnosine groups (100, 200, and 300 ng mL-1 of carnosine). Samples were evaluated post-thaw (M0) and post-rapid thermoresistance test (M30) for sperm kinetics (total motility, progressive motility, curvilinear speed, linearity and amplitude of lateral head displacement) and cell structure viability (plasma membrane integrity, acrosomal integrity, mitochondrial potential, membrane fluidity, and lipid peroxidation). There were no differences (P > 0.05) between the control, quercetin, and carnosine-treated groups for the parameters evaluated at M0 and M30. In turn, supplementation with ozone resulted in lower values for sperm kinetics (P < 0.05) and lower mitochondrial potential at M30 (P < 0.05). Quercetin and carnosine at the concentrations used did not promote significant gains in frozen semen, nor did they demonstrate cytotoxicity. We expected to obtain positive results with the use of ozone. Nonetheless, the addition was harmful to the parameters of sperm kinetics, and its effect was not observed as a possible pro-antioxidant. We believe that the fact that the gas did not harm the sperm structure opens avenues for tests with lower dosages, since, by reducing its concentration, we could minimize the damage to sperm kinetics.(AU0

Relação entre a capacitação espermática e a fertilidade de sêmen criopreservado de bovinos / Relationship between sperm capacitation and fertility in bovine cryopreserved semen

A qualidade do sêmen criopreservado, utilizado na inseminação artificial em tempo fixo (IATF) em bovinos, é um dos principais fatores que impactam sobre a fertilidade, e está relacionada à capacidade de produção espermática dos touros, à criotolerância dos espermatozoides e aos critérios técnicos do processo de criopreservação adotados. Neste sentido, devemos destacar a importância do controle de qualidade das partidas de sêmen antes de serem liberadas para uso na IATF. Nos últimos anos várias técnicas vêm sendo desenvolvidas para avaliar com mais acurácia as partidas de sêmen e evitar o uso daquelas que possam resultar em prejuízos na fertilidade, mas mesmo assim, tem se notado alta variabilidade na taxa de prenhez entre touros e entre partidas de sêmen. Esta divergência se deve ao fato da habilidade fértil do espermatozoide ser multifatorial, ou seja, dependente de diversas características estruturais, morfofuncionais e moleculares. Ademais, os eventos que permitem os espermatozoides passarem por capacitação espermática, um pré-requisito para a fertilidade, têm intrigado os pesquisadores em vista da complexidade dos processos envolvidos e dos efeitos deletérios da criopreservação espermática. Esta revisão tem por objetivo compilar estudos que mostrem a relação entre a capacitação espermática e a fertilidade do sêmen bovino criopreservado, levando em consideração as técnicas de avaliação e os resultados até o momento.(AU)

The quality of cryopreserved semen, used in fixed-time artificial insemination (FTAI) in cattle, is one of the main factors that impact fertility and is related to the sperm production capacity of bulls, sperm cryotolerance, and the technical criteria for cryopreservation. In this sense, we must highlight the importance of quality control of semen batches before commercialization for the FTAI. In recent years, several techniques have progressed to more accurately evaluate semen batches and avoid using those that may result in impaired fertility. However, we still notice a high variability in the pregnancy rate between bulls and between semen batches. This divergence is due to the multifactorial sperm-fertilizing ability, i.e., it depends on several structural, morphofunctional, and molecular characteristics. In addition, the events that allow sperm to undergo sperm capacitation, a prerequisite for fertility, have intrigued researchers due to the complexity of the processes involved and the adverse effects of sperm cryopreservation. This review aims to compile studies that show the relationship between sperm capacitation and fertility in cryopreserved bovine semen, considering the evaluation techniques and results to date.(AU)

Sêmen refrigerado ­ estado da arte em diferentes espécies / Chilled semen ­ state of the art in different species

Na atual conjuntura da criação artificial de bovinos e bubalinos, o material genético masculino de qualidade superior de reprodutores é explorado ao máximo possível através da inseminação artificial em tempo fixo de um grande número de fêmeas com apenas um único ejaculado. Para isso, é necessário um sêmen de boa qualidade que desempenhe um papel indispensável na melhoria das taxas de fertilidade, independente de qual tipo seja utilizado (fresco, refrigerado e congelado). Porém, o processo de congelação/descongelação causa uma série de injúrias aos espermatozoides, ocasionando resultados inferiores para percentuais de viabilidade espermática, motilidade, membrana plasmática e integridade acrossomal, potencial de membrana mitocondrial, cinemática do esperma, quando comparado ao sêmen refrigerado. Assim, o objetivo desta revisão é disseminar o conhecimento sobre o uso sêmen refrigerado na preservação de germoplasma de reprodutores bovinos e bubalinos para melhorar as taxas de concepção em propriedades. Para isso, serão abordados comentários sobre o armazenamento do sêmen refrigerado, com ênfase nas diferenças entre curvas de refrigeração, suas vantagens e desvantagens relativas para procedimentos de uso na IATF, identificando o método mais indicado por diversos autores, o estado atual da biotécnica, seus méritos e possibilidades futuras.(AU)

In the current conjuncture of the artificial creation of bovines and buffaloes, the male genetic material of superior quality of sires is exploited to the maximum possible through the fixed-time artificial insemination of a large number of females with only a single ejaculate. For this, a good quality semen is needed that plays an indispensable role in improving fertility rates, regardless of which type is used (fresh, chilled and frozen). However, the freezing/thawing process causes a series of injuries to spermatozoa, causing lower results for percentages of sperm viability, motility, plasma membrane and acrosomal integrity, mitochondrial membrane potential, sperm kinematics, when compared to refrigerated semen. Thus, the objective of this review is to disseminate knowledge about the use of chilled semen in the preservation of germplasm of bovine and buffalo breeders to improve conception rates in properties. For this, comments on the storage of refrigerated semen will be addressed, with emphasis on the differences between refrigeration curves, their relative advantages and disadvantages for procedures for use in FTAI, identifying the method most indicated by several authors, the current state of biotechnics, its future merits and possibilities.(AU)

Leptospirosis, bovine viral diarrhea and infectious bovine rhinotracheitis: prevalence in Colombian cattle and buffaloes

One of the limiting factors of productive efficiency in cattle and buffalo herds is related to the high prevalence of infectious diseases which affect reproduction. The aim of this study was to determine the prevalence of anti-Leptospiraantibodies for bovine viral diarrhea virus (BVDV) and bovine herpesvirus type 1 (BoHV-1) in bovine and buffalo herds in Colombia. Blood serum samples were collected from 1100 buffaloes and 1000 cattle. The ELISA technique was used to detect antibodies against BVDV and BoHV-1, and the microscopic agglutination technique to detect anti-Leptospiraantibodies. The prevalence of anti-Leptospiraantibodies and of BVDV and BoHV-1 in bovine samples was observed in 16, 39.7, and 65% of animals, respectively, while the positivity in samples for the same antibodies in buffalos was detected in 18.7, 27.5 and 51.5%, respectively. Exposure of cattle and buffaloes to BoHV-1 was positively associated with age, higher prevalence rates were observed in older ages. Seropositivity of cattle for BVDV and BoHV-1 was higher in male animals. Activities such as embryo transfer, milking, and needle reuses, as well as the presence of cats and rodents are factors which favor positivity of the herd for BVDV and BoHV-1.(AU)

Occurrence of foot diseases in cattle attended at the Clínica de Bovinos de Garanhuns: Epidemiological, clinical, therapeutic and economic aspects / Ocorrência de afecções podais em bovinos atendidos pela Clínica de Bovinos de Garanhuns: aspectos epidemiológicos, clínicos, terapêuticos e econômicos

The objective was to study the occurrence of foot disorders in cattle treated at the Clínica de Bovinos de Garanhuns, campus of the Universidade Federal Rural de Pernambuco from 1999 to 2021. A retrospective study of the medical records was carried out, with a total of 334 cases, in which 613 lesions were diagnosed. A frequency distribution, with simple mean and standard deviation was performed to evaluate the data. Interdigital dermatitis was more frequent in 12.4% (76/613), double sole in 9.79% (60/613), chronic laminitis in 8.81% (54/613), sole ulcer in 7.83% (48 /613), and interdigital hyperplasia in 7.24% (45/613). Laminitis and its consequences accounted for 45% of the total injuries identified, followed by 36% of injuries of secondary or uncertain cause, and 19% from infectious diseases. The distribution of lesions between the limbs was 68% in the pelvic and 32% in the thoracic limbs. Females, raised in a semi-intensive system, Holstein, with a body score of III, and large size were more affected. Lameness was present in 78% (260/334), while 10% (33/334) did not present lameness. The case fatality and recovery rates were 9% (31/334) and 73% (243/334), respectively. In total, 51% of cases occurred in the rainy season and 49% in the dry season. The main cities of origin were Bom Conselho 22.75% (76/334), Garanhuns 18.86% (63/334), and Brejão 12.57% (42/334). The estimated cost of treatment was US$ 150.13/case. Diseases are probably directly linked to management failure on the property due to the nature of the diagnosed diseases, in addition to the significant cost of the treatment of these animals, with the need for prophylactic measures in order to avoid the economic losses associated with foot diseases.

Objetivou-se estudar a ocorrência das afecções podais em bovinos atendidos na Clínica de Bovinos de Garanhuns, Campus da Universidade Federal Rural de Pernambuco, no intervalo de 1999 a 2021. Realizou-se estudo retrospectivo dos prontuários, com total 334 casos, dos quais foram diagnosticadas 613 lesões digitais. Foi realizada a distribuição de frequência, média simples e desvio padrão para avaliação dos dados. A dermatite interdigital foi a mais frequente, sendo observada em 12,4% (76/613) dos casos, seguida por sola dupla 9,79% (60/613), laminite crônica 8,81% (54/613), úlcera de sola 7,83% (48/613) e a hiperplasia interdigital 7,24% (45/613). A laminite e suas consequências representaram 45% do total de lesões identificadas, acompanhadas por 36% das injúrias de causa secundárias ou incertas e de doenças infecciosas com 19%. A distribuição das lesões entre os membros foi de 68% nos pélvicos e 32% nos torácicos. As fêmeas criadas em sistema semi-intensivo, holandesas, com escore corporal III e porte grande eram mais acometidas. A claudicação estava presente em 78% dos animais, enquanto 10% não claudicavam. As taxas de letalidade e recuperação foram de 9% (31/334) e 73 % (243/334), respectivamente. No período chuvoso foram 51% dos casos e 49% na época seca. Os principais municípios de origem foram Bom Conselho 22,75% (76/334), Garanhuns 18, 86% (63/334) e Brejão 12,57% (42/334). O custo estimado com tratamento foi de US$ 150,13/caso. Provavelmente falhas de manejo nas propriedades foram importantes fatores de risco para as doenças. Sugere-se a implementação de medidas profiláticas para evitar as perdas econômicas associadas às enfermidades podais.

Morphological and morphometric characterization of the preputial ostium, internal preputial leaflet, and free part of the penises of Aberdeen Angus and Nellore bulls / [Caracterização morfológica e morfométrica do óstio prepucial, do folheto prepucial interno e da parte livre do pênis de touros Aberdeen Angus e Nelore]

The morphological characteristics of the external genitalia of the bull may contribute to the etiopathogenesis of preputial diseases that trigger the impotence coeundi and losses in farms. The goal of this study was to establish morphometric parameters of the preputial ostium, the internal preputial leaflet (IPL), the free part and glans of the penis; describe the histological characteristics of the IPL; perform a count of the preputial sebaceous glands and compare these variables between 24-month-old Aberdeen Angus and Nellore bulls. At the slaughterhouse, 20 preputial pieces were collected from each breed. A device composed of base, rod, ring, and funnel was designed to hold each suspended and distended part. The IPL, the free part of the penis and the glans were measured. The ostium diameter was measured, and the radius, perimeter, and area of the preputial ostium were calculated. Samples were collected from the dorsal and ventral regions and from the cranial, medial, and caudal portions of the IPL. By electronic and optical microscopy, IPL characterization and sebaceous gland counts were performed. Analysis of variance was performed using the F test at 5%. It was concluded that Nellore bulls have a more extensive IPL and free part of the penis and more preputial sebaceous glands than Aberdeen Angus bulls. In both breeds, there are more glands in the ventral region of the ostium.

As características morfológicas da genitália externa do touro podem contribuir para a etiopatogenia de enfermidades prepuciais que desencadeiam a impotência coeundi e prejuízos nos criatórios. O objetivo deste estudo foi estabelecer parâmetros morfométricos do óstio prepucial, do folheto prepucial interno (FPI), da parte livre e da glande do pênis; descrever as características histológicas do FPI; realizar contagem de glândulas sebáceas prepuciais; e comparar essas variáveis entre touros Aberdeen Angus e Nelore, com 24 meses de idade. No abatedouro, colheram-se 20 peças prepuciais de cada raça. Elaborou-se um dispositivo composto por base, haste, anel e funil para sustentar cada peça suspensa e distendida. Realizou-se medição do FPI, da parte livre do pênis e da glande. Aferiu-se diâmetro do óstio, e calculou-se o raio, o perímetro e a área do óstio prepucial. Colheram-se amostras nas regiões dorsal e ventral e das porções cranial, medial e caudal do FPI. Por microscopia eletrônica e óptica, fez-se a caracterização do FPI e a contagem de glândulas sebáceas. Realizou-se análise de variância pelo teste F a 5%. Concluiu-se que touros Nelore possuem o FPI e a parte livre do pênis mais extensos e mais glândulas sebáceas prepuciais que touros Aberdeen Angus. Nas duas raças, há mais glândulas na região ventral do óstio.

Larvoscopic study on Dictyocaulus sp. in the faeces of beef cattle in northeastern Brazil / Estudo larvoscópico de Dictyocaulus sp. em fezes de bovinos de corte do nordeste do Brasil

Abstract The lungworm Dictyocaulus viviparus has an important role in cattle health and productivity worldwide, since infections can lead to substantial economic losses. Despite its importance, few studies investigating the epidemiological aspects of infection by this parasite have been conducted. The aim of this study was to report the occurrence of lungworm infection in beef cattle herds reared in an area of livestock production in the northeastern region of Brazil. From September 2020 to August 2021, monthly fecal samples (n = 493) were collected from 46 beef cattle. Among all the animals assessed, lungworm larvae were detected in 8.7% (4/46). None of them presented any clinical sign suggestive of infection by lungworm parasites. Twenty larvae were retrieved, with the minimum number (n = 1) detected in October and December, and the maximum number (n = 13) in November. These presented a mean length of 363 μm (± 28.65 μm) and mean width of 19 μm (± 1.03 μm), and were morphologically similar to Dictyocaulus sp.. This study reports the occurrence of this parasite in this livestock production area. Lastly, local veterinarians need to be aware of inclusion of this parasite in the differential diagnosis of other respiratory infections in beef cattle.

Resumo O parasito pulmonar Dictyocaulus viviparus tem um papel importante na saúde e produtividade bovina em todo o mundo, uma vez que infecções podem levar a perdas econômicas. Além de sua importância, poucos estudos que investigam aspectos epidemiológicos das infecções por esse parasito têm sido realizados. Objetivou-se, nesta pesquisa, relatar a ocorrência de infecção por nematódeos pulmonares em rebanhos bovinos de corte, criados em uma importante área de produção pecuária, na região Nordeste do Brasil. De setembro de 2020 a agosto de 2021, foram coletadas, mensalmente, amostras fecais (n = 493) de 46 bovinos de corte. De todos os animais avaliados, larvas de nematódeos pulmonares foram detectadas em 8,7% (4/46). Os animais não apresentaram nenhum sinal clínico sugestivo de infecção por parasitos pulmonares. Vinte larvas foram recuperadas, com o número mínimo (n = 1) detectado em outubro e dezembro, e o número máximo (n = 13) em novembro. Apresentavam comprimento médio de 363 μm (± 28,65 μm), largura média de 19 μm (±1,03 μm) e eram morfologicamente semelhantes a Dictyocaulus sp.. Este estudo relata a ocorrência desse parasito nesta área. Logo, os veterinários locais devem estar atentos à inclusão desse parasito no diagnóstico diferencial de outras infecções respiratórias em bovinos de corte.

Antimicrobial resistance profile of Staphylococcus spp. isolates in cattle herds from Western Amazon / Perfil de resistência antimicrobiana de Staphylococcus spp. isolados em rebanhos leiteiros da Amazônia Ocidental

Staphylococcus is one of the most frequent etiological agents of bovine mastitis, causing economic losses to milk farming. This study aimed to describe the milk production and management practices in 15 herds located in three microregions of the State of Rondônia and to identify the antimicrobial resistance profile of 97 isolates of the genus Staphylococcus from these herds. The isolates were subjected to antimicrobial susceptibility tests using the agar diffusion method. Twenty-nine S. aureus isolates were selected to determine their minimum inhibitory concentration (MIC). In the farms studied, the breeding system was semi-intensive, with the Girolando breed being predominant. Milking was performed predominantly using a mechanical milking system (86.7%), twice a day (66.7%), in the presence of the calf (53.8%). The average number of lactating cows in the farms was 24, with an average milk production of 204.9 L d-1 and a milk productivity of 10.2 L animal-1 d-1. The use of antimicrobials for the treatment and prevention of bovine mastitis was reported for all properties, and therapy for dry cows was adopted in 80% of the herds. The percent susceptibility to antimicrobials ranged from 85.5% to 100% for S. aureus, 22.2% to 88.9% for coagulase-positive staphylococci (CPS), and 69.2% to 100% for coagulase-negative staphylococci (CNS), with the highest resistance frequencies for penicillin, ampicillin, and tetracycline. Among the S. aureus isolates, 100% susceptibility to oxacillin, cefalexin, and gentamicin was observed, and among the CNS isolates, 100% susceptibility to gentamicin was observed. None of the antimicrobials tested showed 100% in vitro effectiveness for CPS. CPS and CNS presented lower percentages of susceptibility to penicillin, ampicillin, and tetracycline than the S. aureus isolates. Twelve resistance patterns were detected, six of which were multiresistance patterns. The most prevalent resistance patterns were penicillin and ampicillin (PEN-AMP) and penicillin, ampicillin, and tetracycline (PEN-AMP-TET). Results of the MIC assay revealed that all 29 S. aureus isolates were susceptible to cephalothin, cefoxitin, tetracycline, and erythromycin, whereas 25 (86.2%) were susceptible to penicillin.(AU)

O gênero Staphylococcus destaca-se como um dos agentes etiológicos mais frequentes da mastite bovina, causando prejuízos econômicos à pecuária de leite. Este estudo teve o objetivo de descrever a produção de leite e práticas de manejo de 15 rebanhos localizados em três microrregiões do Estado de Rondônia, e identificar o perfil de resistência aos antimicrobianos de 97 isolados do gênero Staphylococcus provenientes destes rebanhos. Os isolados foram submetidos a testes de suscetibilidade a antimicrobianos, utilizandose a técnica de difusão em ágar. Foram selecionados 29 isolados de Staphylococcus aureus (S. aureus) para determinação da concentração inibitória mínima (CIM). Nas propriedades estudadas, o sistema de criação era semi-intensivo, com predomínio da raça Girolando. A ordenha era realizada predominantemente em sistema de ordenha mecânica (86,7%), duas vezes ao dia (66,7%) e com a presença do bezerro (53,8%). A média do número de vacas em lactação das propriedades era de 24 animais, com média de produção de leite de 204,9 L d-1 e produtividade de leite de 10,2 L animal-1 d-1. O uso de antimicrobianos para o tratamento e prevenção da mastite bovina foi relatado em todas as propriedades, sendo adotada a terapia da vaca seca em 80% dos rebanhos. A percentagem de susceptibilidade aos antimicrobianos variou de 85,5 a 100% para S. aureus, 22,2 a 88,9% para Staphylococcus coagulase positivos (SCP) e 69,2 a 100% para Staphylococcus coagulase negativos (SCN), sendo as maiores frequências de resistência para penicilina, ampicilina e tetraciclina. Entre os isolados de S. aureus foi observada 100% de susceptibilidade aos antimicrobianos oxacilina, cefalexina e gentamicina, e entre os isolados de SCN, 100% de susceptibilidade à gentamicina. Nenhum dos antimicrobianos testados apresentou 100% de efetividade in vitro para SCP. SCP e SCN apresentaram menores percentagens de susceptibilidade à penicilina, ampicilina e tetraciclina do que os isolados de S. aureus. Foram observados 12 padrões de resistência, sendo seis padrões de multirresistência. Os padrões de resistência mais prevalentes foram resistência à penicilina e ampicilina (PEN-AMP) e à penicilina, ampicilina e tetraciclina (PEN-AMP-TET). A determinação da CIM dos 29 isolados de S. aureus mostraram que todos foram susceptíveis à cefalotina, cefoxitina, tetraciclina e eritromicina, e 25 (86,2%) foram susceptíveis à penicilina.(AU)

The effect of adjusting settings within a ComputerAssisted Sperm Analysis (CASA) system on bovine sperm motility and morphology results

Semen motility is the most widely recognized semen quality parameter used by Artificial Insemination (AI) centers. With the increasing worldwide export of semen between AI centers there is an increasing need for standardized motility assessment methods. Computer-Assisted Sperm Analysis (CASA) technology is thought to provide an objective motility evaluation; however, results can still vary between laboratories. The aim of present study was to verify the impact of different setting values of the CASA IVOS II on motility, concentration, and morphology of bovine semen samples frozen in an extender with or without egg yolk and then decide on optimal settings for a further validation step across AI centers. Semen straws from 30 different bulls were analyzed using IVOS II with twelve modified settings. No significant changes were observed in semen concentration, percentage of motile sperm or kinetic results for either extender type. However, increasing settings for both STR and VAP progressive (%) from Low, Medium, and High cut-off values significantly (p<0.05) reduced the percentage of detected progressive spermatozoa, in egg yolk extender from 49.5±15.2, 37.2±11.9 to 11.9±5.3%, and in clear extender from 51.9±9.1, 35.8±7.3 to 10.0±2.4%, respectively. In clear extender only, the modification of droplet proximal head length significantly affected the detection of normal sperm percentages (88.0± 4.7 to 95.0±0.6 and 96.0±0.6%) and of the percentage of detected proximal droplets (12.2±4.7, 2.5±2.7 to 0.6±0.2%) for Low, Medium and High values respectively (p<0.05). The identification of sensitivity within the CASA system to changes in set parameters then led to the determination of an optimal IVOS II setting. The existing variability among centers for these phenotypes was reduced when the standardized settings were applied across different CASA units. The results clearly show the importance of applied settings for the final CASA results and emphasize the need for standardized settings to obtain comparable data.(AU)

Water intake and feeding with whole milk accentuate metabolic acidosis in calves with induced osmotic diarrhea / Ingestão de água e alimentação com leite integral acentuam a acidose metabólica em bezerros com diarreia osmótica induzida

Sucrose- and diuretics-based protocols are widely used to induce osmotic diarrhea and dehydration in calves, but they fail to cause metabolic acidosis. In previous studies, calves were fed milk replacers and deprived of water. In this study, we assessed the water, electrolyte, and acid-base imbalances in calves that were fed whole milk and were not completely deprived of water during the induction period. Healthy, male Holstein calves aged 10-12 days were assigned to two groups: free access to water (FWG; n=17) and water deprivation at night (DWG; n=21); and osmotic diarrhea was induced with sucrose added to milk, spironolactone (2mg kg-1) and hydrochlorothiazide (2mg kg-1) orally every 8h for 48h. pH, pCO2, HCO3-, BE, Na+, K+, Cl-, SID3, TPP, AG, Atot, glucose, L-lactate, D-lactate, SIG, and percentage change in plasma volume were measured in venous blood samples taken at 0, 24, and 48h. Data were analyzed using two-way repeated measures ANOVA. Calves showed diarrhea, mild (FWG) to moderate (DWG) dehydration, hyponatremia, and moderate (FWG) to severe (DWG) metabolic acidosis. AG and D-lactate levels were higher and SIG was lower in the DWG, and there was no hyper-L- or D-lactatemia. The magnitude of metabolic acidosis was similar to that observed in natural cases of diarrhea. The protocol for inducing osmotic diarrhea and dehydration should be applied to calves that are fed whole milk and are not completely deprived of water.

Protocolos baseados em sacarose e diuréticos são amplamente usados para induzir diarreia osmótica e desidratação em bezerros, porém não provocam acidose metabólica. Em estudos anteriores, os bezerros foram alimentados com substitutos de leite e privados de água. Neste estudo, avaliaram-se os desequilíbrios hídrico, eletrolítico e ácido base em bezerros que foram alimentados com leite integral e não foram completamente privados de água durante o período de indução. Bezerros HPB machos sadios com 10 a 12 dias de idade foram distribuídos por dois grupos: acesso livre à água (FWG; n=17) e privação de água durante a noite (DWG; n=21); e a diarreia osmótica foi induzida com sacarose adicionada ao leite, espironolactona (2mg kg-1) e hidroclorotiazida (2mg kg-1) por via oral a cada 8h durante 48h. pH, pCO2, HCO3-, BE, Na+, K+, Cl-, SID3, PPT, AG, Atot, glicose, lactato L, lactato D, SIG e alteração percentual no volume plasmático foram medidos em amostras de sangue venoso colhidas em 0, 24 e 48h. Os dados foram analisados usando ANOVA de medidas repetidas bifatorial. Os bezerros apresentaram diarreia, desidratação leve (FWG) a moderada (DWG), hiponatremia e acidose metabólica moderada (FWG) a grave (DWG). Os valores de AG e de lactato D foram maiores e o de SIG foi menor no DWG, e não houve hiperlactatemia L ou D. A magnitude da acidose metabólica foi semelhante à observada em casos naturais de diarreia. O protocolo para induzir diarreia osmótica e desidratação deve ser aplicado a bezerros alimentados com leite integral e não totalmente privados de água.

Evaluation of fertilization capability of frozen-thawed completely immotile spermatozoa collected from a white bengal tiger after interspecific ICSI with bovine oocytes

The objective of this study was to evaluate the fertilization capability of White Bengal Tiger frozen-thawed completely immotile spermatozoa after interspecific intracytoplasmic sperm injection (ICSI) with bovine oocytes. The fertilization status of presumptive zygotes was assessed 18 h after ICSI by immunofluorescence staining and confocal microscopy. The fertilization rate was 34.8% (8/23), as confirmed by the extrusion of two polar bodies, or male and female pronuclei formation. For unfertilized oocytes (65.2%, 15/23), one activated oocyte had an activated spermatozoon but most were unactivated oocytes with unactivated spermatozoa (1/15, 6.7% vs 10/15, 66.7%, respectively, p < 0.05). These results showed that White Bengal Tiger frozen-thawed completely immotile spermatozoa retained the capacity to fertilize bovine oocytes after interspecific ICSI. This is the first report of in vitro produced zygotes using tiger immotile sperm with bovine oocytes by interspecific ICSI technique, which provides an efficient and feasible method for preservation and utilization of endangered feline animals.(AU)

The macroscopic and microscopic description of ruminal lesions in feedlot bovine / Descrição macroscópica e microscópica das lesões ruminais em bovinos confinados

Administration of diets rich in highly fermentable carbohydrates and low fiber content can cause an imbalance between the microorganisms in the rumen with consequent ruminal acidosis. This problem can cause lesions in the rumen wall, often progressing to rumenitis. The purpose of the present was to characterize macroscopic and microscopic ruminal lesions observed in confined feedlot cattle with claw lesions or liver abscess. A total of 1060 bovines were evaluated via postmortem examination. Claw lesions were identified in 88, liver abscess in 10, and macroscopic rumen lesions in 230 bovines; furthermore, 178 rumens were characterized with hyperkeratosis, 41 with hyperemia, 9 with ulcer, and 2 with neoplasia. The 98 bovines with claw lesions and liver abscess were selected for histopathological examination. Of these, macroscopic lesions were noted in 23 and microscopic lesions in 23 animals. Of the 23 animals that presented macroscopic lesions, 10 showed the same changes observed under microscopy. Seven cases of hyperkeratosis were diagnosed in the macro and microscopic evaluation. Of the 5 cases of hyperemia verified on macroscopy, 2 cases were identified via microscopy, and 1 case of ulcer identified through macroscopy and microscopy. The microscopic evaluation of the rumens allowed the identification of lesions in animals with claw lesions that did not present macroscopic rumen alterations.

O uso de dietas ricas em carboidratos altamente fermentáveis e com baixos teores de fibras pode ocasionar desequilíbrio entre os microrganismos do rúmen com consequente acidose ruminal. Esse problema pode resultar em lesões na parede do rúmen, evoluindo com frequência para formação de ruminite. O presente estudo objetivou caracterizar lesões ruminais macroscópicas e microscópicas, observadas em bovinos confinados que apresentavam lesões podais ou abscesso hepático. Avaliou-se 1060 bovinos pelo exame post mortem. Foram encontradas lesões podais em 88 animais, abscesso hepático em 10 e lesões ruminais macroscópicas em 230 bovinos, sendo caracterizado 178 rumens com hiperqueratose, 41 com hiperemia, 9 com úlcera e 2 com neoplasia. Os 98 bovinos com lesões podais e abscesso hepático foram selecionados para realização de exame histopatológico. Desses, foram encontradas lesões macroscópicas em 23 e, microscópicas, em 23 animais. Dos 23 animais que apresentaram lesões macroscópicas, 10 tiveram as mesmas alterações verificadas na microscopia. Foram diagnosticados 7 casos de hiperqueratose na avaliação macro e microscópica. Dos 5 casos de hiperemia verificados na macroscopia, 2 casos foram identificados na microscopia e um caso de úlcera identificado na macroscopia também foi identificado na microscopia. A avaliação microscópica dos rumens permitiu identificar lesões em animais com lesões podais que não apresentam alterações macroscópicas ruminais.

Productive and reproductive performance of crossbred dairy heifers with induced lactation and efficacy of antimicrobial therapy associated with internal teat sealants / Desempenho produtivo e reprodutivo de novilhas com lactação induzida e eficácia da terapia antimicrobiana associada com selante interno de tetos

This study evaluated (a) the efficacy of an association between injectable antibiotic therapy and sealant (ATBS) on milk yield (MY), somatic cell count (SCC), and prevalence of intramammary infections (IMI); and (b) the efficacy of gonadotropin-releasing hormone (GnRH) on follicular cyst (FCs) resolution (cyclicity at the 45th day in milk; DIM) and cumulative pregnancy rate (CPR) in heifers submitted to a lactation induction protocol (LIP). A total of 114 crossbred (Holstein × Jersey) heifers, with 34.7 ± 4.8 months and 439 ± 56.35 kg were submitted to LIP. On the 5th day of the LIP, the heifers were assigned to (i) ATBS (n = 57) with 7 mg/kg of norfloxacin associated with sealant and (ii) Control 1 (n = 57; CONT1) with no treatments. Lactation began on the 21st day of LIP and the 15th DIM, FCs were diagnosed and 106 heifers were randomized into two treatment groups with 53 heifers each: (i) GnRH (5 mL injectable GnRH) and (ii) Control 2 (CONT2; no treatment). Of the 114 heifers initially induced, 83.33% (n = 95) responded to LIP with an average MY of 15.19 kg/milk/day during 22 weeks of lactation. In the first 14 DIM, the IMI prevalence was 18% and 28% for heifers ATBS and CONT1 treated, respectively. Additionally, coagulase-negative Staphylococcus was the most frequently isolated group of pathogens. Mammary quarters that received ATBS treatment had a lower risk of IMI and SCC than CONT1. The cyclicity at 45 DIM was 68% (ATBS) and 35% (CONT1), and 57% and 46% for animals in the GnRH and CONT2. CPR was 60% in the ATBS group and 89% in CONT1, but GnRH treatment did not affect the CPR. In conclusion, LIP was effective in stimulating MY in heifers, and the IMI prevalence decreased with ATBS treatment. Also, the use of GnRH did not affect the FC regression, cyclicity at 45 DIM, and CPR.(AU)

Este estudo avaliou a (i) eficácia da associação entre antibioticoterapia injetável e selante interno de tetos (ATBS) na produção de leite (PL), contagem de células somáticas (CCS), e prevalência de infecções intramamárias (IIM); e (ii) eficácia do hormônio liberador de gonadotrofina (GnRH) na resolução de cistos foliculares (CFs), ciclicidade ao 45º dia em lactação (DEL) e taxa de prenhez cumulativa (TPC) em novilhas submetidas a um protocolo de indução de lactação (PIL). Um total de 114 novilhas mestiças (Holandês × Jersey), com 34,7 ± 4,8 meses e 439 ± 56,35 kg foram submetidas ao PIL. No 5º dia do PIL, as novilhas receberam: (i) ATBS (n = 57) com 7 mg/kg de norfloxacina associada ao selante interno de tetos e (ii) Controle 1 (n = 57; CONT1) sem tratamento. A lactação teve início no 21º dia do PIL e no 15º DEL, foram diagnosticados CFs e 106 novilhas foram agrupadas em dois grupos de tratamento com 53 novilhas em cada: (i) GnRH (5 mL de GnRH injetável) e (ii) Controle 2 (CONT2; sem tratamento). Das 114 novilhas inicialmente induzidas, 83,33% (n = 95) responderam ao PIL com PL média de 15,19 kg/leite/d durante 22 semanas de lactação. Nos primeiros 14 DEL a prevalência de IIM foi de 18% e 28% para as novilhas tratadas com ATBS e CONT1, respectivamente. Além disso, estafilococos coagulase negativa foram o grupo de patógenos mais frequentemente isolados. Quartos mamários tratados com ATBS tiveram menor risco (0,56) de IIM e menor CCS do que CONT1. A ciclicidade a 45 DEL foi de 68% (ATBS) e 35% (CONT1), e 57% e 46% para os animais no GnRH e CONT2. A TPC foi de 60% no grupo ATBS e 89% no CONT1, porém o tratamento com GnRH não afetou a TPC. Em conclusão, o PIL foi eficaz em estimular a PL em novilhas tardias e a prevalência de IIM diminiuiu com o tratamento ATBS. Além disso, o uso de GnRH não afetou a regressão de CF, ciclicidade em 45 DEL e a TPC.(AU)

Identification of Pentatrichomonas hominis in preputial washes of bulls in Brazil / Identificação de Pentatrichomonas hominis em lavado prepucial de touros no Brasil

The parabasalid Pentatrichomonas hominis is generally considered to represent a symbiotic component of the gastrointestinal microbiota in a wide variety of vertebrate hosts including humans. Nevertheless, a limited number of studies have raised the possibility that it may act as a pathogen of humans, dogs, and pigs and that some human infections may have a zoonotic origin. Data from North America revealed an association between P. hominis and the bovine urogenital tract, principally in bulls and rarely in cows. The importance of this observation is linked to possible interference in the accurate diagnosis of the economically important venereal pathogen Tritrichomonas foetus. The current study employed culture-based and molecular methods to examine the preputial cavities of four breeding bulls, raised in open pasture in southeastern Brazil, for the presence of trichomonads. Motile protozoa were isolated from three of the bulls and were definitively identified as P. hominis based on nucleotide sequencing of polymerase chain reaction (PCR) amplicons derived from the ribosomal RNA operon (ITS1-5.8S rDNA-ITS2) of the parasite. The potential implications of these findings for bovine and human health are discussed.(AU)

O parabasalídeo Pentatrichomonas hominis é geralmente considerado um componente simbiótico da microbiota gastrointestinal em uma ampla variedade de hospedeiros vertebrados, incluindo os humanos. No entanto, um número limitado de estudos levantou a possibilidade de que possa atuar como patógeno de humanos, cães e suínos, e que algumas infecções humanas possam ter origem zoonótica. Dados da América do Norte revelaram uma associação entre P. hominis e o trato urogenital bovino, principalmente, em touros e raramente em vacas. A importância dessa observação está ligada a uma possível interferência no diagnóstico preciso do patógeno venéreo de importância econômica Tritrichomonas foetus. O presente estudo empregou métodos baseados em cultura em combinação com técnicas moleculares, para examinar as cavidades prepuciais de quatro touros, criados em pastagem aberta no sudeste do Brasil, quanto à presença de tricomonas. Protozoários móveis foram isolados de três dos touros e foram definitivamente identificados como P. hominis com base no sequenciamento de nucleotídeos de amplicons geradas pela reação em cadeia da polimerase (PCR), empregando a região RNA ribossômico (ITS1-5.8S rDNA-ITS2) do parasita como alvo. Os potenciais implicações desses achados para a saúde bovina e humana são discutidas.(AU)

Penile fractures in young bulls raised in feedlots in Southern Brazil

Background: Penile fracture is a pathology of young cattle that perform precocious and disordered breeding. The incompatibility of height between males and females and sodomy between males cause a great pressure on the sigmoid flexure and retractor muscle of the penis, which are the main causes and sites of organ injury. This study aimed to describe the epidemiological and pathological aspects of penile fractures observed in young bulls raised in pre-export feedlots (PEFs) in southern Brazil. Cases: In 2 PEFs located in the municipalities of Pelotas (property 1) and Capão do Leão (property 2), 3 male cattle [1 from property 1 and 2 from property 2] presented subcutaneous edema in the foreskin and perineum, associated with dysuria. The evolution of the clinical picture was approximately 20 days in all cases, with evolution to death. The bovine necropsied on property 1 had an increased volume and inguinal edema, involving the penis and scrotal sac. Necrosis of the subcutaneous tissue and local musculature was also observed. The testicles were surrounded by the necrotic tissue, and the right testis was swollen, with flaccid parenchyma adhering to the tunica albuginea. In the necropsy of 1 bull from property 2, an increase in the inguinal volume was observed, with an extensive area of necrosis and edema extending from the prepuce to the caudal musculature of the scrotal sac. There were also marked varicosis in the sigmoid flexure and necrosis of the adjacent region, without the involvement of the corpus cavernosum. During the necropsy of the 2 young bulls, fragments of organs from the abdominal, thoracic, and brain cavities were collected and fixed in 10% buffered formalin. From the bull of the property 2, an anatomical piece consisting of the penis, prepuce, and testicles was also collected and fixed in 10% buffered formalin. After 48 h, the tissue samples were cleaved, embedded in paraffin, cut into 3-µm-thick sections, and stained using hematoxylin and eosin (HE). A histological evaluation of the penile lesions in both cattle revealed intense hemorrhage, congestion, and necrosis of the muscles and tissues adjacent to the corpus cavernosum. In addition to areas of dystrophic calcification, neutrophil and macrophage infiltration was also observed. In the bull from the property 1, an intense edema and proliferation of fibrous tissue surrounding the urethra were noted. There were also marked tubular degeneration and intense infiltration of neutrophils, lymphocytes, and macrophages in the inner portion of the tunica albuginea. Discussion: In the present cases, the diagnosis was based on epidemiological data associated with clinical signs and pathology. The macroscopic lesions observed were probably due to the involvement of blood vessels adjacent to the penis, which suffered trauma during sodomy mating among cattle. These lesions have been described in other reports of this pathology and in diseases, such as acropostitis-phimosis, fibropapilloma of the glans, preputial abscess, and urolithiasis, and the differential diagnosis of these diseases must be carried out, as they have different etiologies. In the bulls of the present study, no lesions were observed in the corpus cavernosum, and this condition was attributed to the presence of varicosis and accumulation of urine in the prepuce, due to the difficulty in exposing the penis. Histologically, there were intense hemorrhage, congestion, and necrosis of the muscles and tissues adjacent to the corpus cavernosum, with the infiltration of neutrophils and macrophages, and areas of dystrophic calcification. The presence of necrotic lesions in tissues adjacent to the penis may be related to hypoxia, vascular lesions, or the action of chemical elements present in the urine. In both cases, vascular lesions were present, which were attributed to the main triggering factor for the disease.

Erythrogram and oxidative stress in confined cattle fed with Brachiaria sp hay and supplemented with antioxidants / Eritrograma e estresse oxidativo em bovinos confinados alimentados com feno de Brachiaria sp. e suplementados com antioxidantes

Brachiaria sp contains sporidesmin that can be oxidized by lipoperoxidation and cause oxidative stress. In the present study we evaluated the effects of different antioxidants on lipoperoxidation of erythrocytes from Nelore cattle fed with Brachiaria sp hay. The experimental design was entirely randomized, in which 40 whole male cattle were divided into five treatments (G1: control - no supplementation; G2: selenium and vitamin E supplementation; G3: zinc supplementation; G4: selenium supplementation and G5: vitamin E supplementation) and allocated in feedlot pens for 105 days. The samples heparinized and withethylenediaminetetraacetic acid (EDTA) were obtained every 28 days for hematological and oxidative stress evaluation (0, 28 56, 84 and 105 days). In the erythrogram total erythrocyte count, hemoglobin, and hematocrit (Ht) were measured. For the evaluation of oxidative stress, in order to analyze the characteristics of the erythrocyte membrane, the thiobarbituric acid reactive substances (TBARS), total glutathione (GSH-T), glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD) were determined. The results showed that regardless of the treatment there was no oxidative stress during the experimental confinement period and that the joint association of selenium and vitamin E in the bovine diet provided a lower incidence of deleterious alterations on erythrocytes.

As Brachiaria sp contêm esporidesminas que podem ser oxidadas por lipoperoxidação e ocasionar estresse oxidativo. No presente estudo foram avaliados os efeitos de diferentes antioxidantes na lipoperoxidação dos eritrócitos de bovinos da raça Nelore, alimentados com feno de Brachiaria sp. O delineamento experimental foi inteiramente casualizado, em que 40 bovinos machos, inteiros, foram divididos, em cinco tratamentos (G1: controle - sem suplementação; G2: suplementação de selênio e vitamina E; G3: suplementação de zinco; G4: suplementação de selênio e G5: suplementação de vitamina E) e alocados em baias de confinamento, por 105 dias. As amostras de plasma heparinizado ou com ácido etilenodiamino tetra-acético (EDTA) foram obtidas a cada 28 dias para avaliação hematológica e de estresse oxidativo (0, 28 56, 84 e 105 dias). No eritrograma foi mensurado a contagem total de eritrócitos, a hemoglobina e o volume globular (VG). Para a avaliação do estresse oxidativo, com o objetivo de analisar as características da membrana do eritrócito foram determinadas as substâncias reativas ao ácido tiobarbitúrico (TBARS), glutationa total (GSH-T), glutationa peroxidase (GSH-Px), catalase (CAT) e superóxido dismutase (SOD). Os resultados demonstraram que independente do tratamento não houve estresse oxidativo durante o período do confinamento experimental e que a associação conjunta de selênio e vitamina E na dieta dos bovinos proporcionaram menor incidência de alterações deletérias sobre os eritrócitos.

Growth performance, reproductive parameters and fertility measures in young Nellore bulls with divergent feed efficiency

The growth, sexual maturity and fertility-related parameters related of young Nellore bulls with divergent residual feed intake (RFI) raised on pasture were evaluated. After classification of 48 young males as low and high RFI (more and less efficient, respectively), the animals were evaluated for growth and reproductive parameters at 28-day intervals from 14.3 to 24.6 months of age. The semen was cryopreserved in the last sampling and fresh and post-thaw semen samples were evaluated. Low RFI bulls exhibited higher initial and final body weight (P < 0.05), but feed intake, body condition score and growth measures evaluated by carcass ultrasound were unaffected by RFI (P > 0.05). The scrotal circumference, sperm concentration, defects, and quality of fresh semen, and ultrasonographic testicular characteristics were unaffected by RFI (P > 0.05). However, velocity parameters such as average path and curvilinear velocities determined by computer-assisted sperm analysis of thawed semen submitted to the rapid thermoresistance test were improved (P < 0.05) in low RFI bulls, but this improvement in quality did not enhance in vitro sperm fertilizing ability. Our results demonstrated significant differences in metabolism and growth performance between bulls of divergent RFI. In addition, there was slight improvement in the semen quality of bulls with low RFI bulls, but this did not enhance in vitro fertilizing ability. Selection of beef bulls for RFI can be performed, which will result in economic benefits by improving the growth performance of the animals without affecting reproductive parameters.(AU)

Quais são as dúvidas no momento do exame clínico andrológico bovino? / What are the doubts at the time of the bovine andrological clinical examination?

O exame clínico andrológico é a ferramenta de eleição utilizada para avaliar a fertilidade de um reprodutor. Normalmente utilizado em tourinhos jovens na pré-comercialização, como uma forma de garantia reprodutiva; no período pré-estação de monta; quando existem falhas ou desordens reprodutivas nos rebanhos; prévio ao ingresso nas centrais de inseminação; na determinação da puberdade, dentre outras. O exame clínico andrológico deve ser realizado por profissional com experiência suficiente para tomada de decisões sobre o real potencial reprodutivo dos animais, porém, em muitas ocasiões mesmo um profissional capacitado defronta-se com dúvidas, entre elas destacam-se as questões relacionadas ao valor cobrado e "tipo de exame"; a biometria testicular; exigências relacionadas a impotencia coeundi; e o que é necessário no certificado do exame. Buscou-se elencar, explanar e discutir essas questões em vista de diminuí-las e/ou encontrar possíveis soluções. O exame clínico andrológico é uma etapa fundamental e complexa para a seleção de reprodutores, e apesar de constantemente debatida, ainda permanecem lacunas a serem respondidas, visto que os profissionais necessitam de constante atualização.(AU)

The clinical andrological examination is the tool of choice used to assess the fertility of a sire. Usually used in young bulls in pre-marketing, as a form of reproductive guarantee; in the pre-mounting season period; when there are reproductive failures/disorders in herds; before entering insemination centers, in determining puberty, among others. The clinical andrological examination must be carried out by a professional with sufficient expertise to make decisions about the real reproductive potential of these animals, however, on many occasions even a trained professional is faced with doubts, among them the issues related to the amount charged and "type of exam"; testicular biometry; requirements related to impotencia coeundi; and what is required in the exam certificate. Based on the above context, we sought to list some possible doubts, explaining them and discussing them among veterinarians, so that such issues could be reduced and/or possible alternative solutions could be defined. The clinical andrological examination is a fundamental and complex step for the selection of sires, and despite being constantly debated, there are still gaps to be answered, since professionals need constant updating.(AU)

Perspectives of gene editing for cattle farming in tropical and subtropical regions

Cattle productivity in tropical and subtropical regions can be severely affected by the environment. Reproductive performance, milk and meat production are compromised by the heat stress imposed by the elevated temperature and humidity. The resulting low productivity contributes to reduce the farmer's income and to increase the methane emissions per unit of animal protein produced and the pressure on land usage. The introduction of highly productive European cattle breeds as well as crossbreeding with local breeds have been adopted as strategies to increase productivity but the positive effects have been limited by the low adaptation of European animals to hot climates and by the reduction of the heterosis effect in the following generations. Gene editing tools allow precise modifications in the animal genome and can be an ally to the cattle industry in tropical and subtropical regions. Alleles associated with production or heat tolerance can be shifted between breeds without the need of crossbreeding. Alongside assisted reproductive biotechnologies and genome selection, gene editing can accelerate the genetic gain of indigenous breeds such as zebu cattle. This review focuses on some of the potential applications of gene editing for cattle farming in tropical and subtropical regions, bringing aspects related to heat stress, milk yield, bull reproduction and methane emissions.(AU)