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Background: Identifying molecular mechanisms responsible for the response to heat stress is essential to increase production, reproduction, health, and welfare. This study aimed to identify early biological responses and potential biomarkers involved in the response to heat stress and animal's recovery in tropically adapted beef cattle through proteomic analysis of blood plasma. Methods: Blood samples were collected from 14 Caracu males during the heat stress peak (HSP) and 16 h after it (heat stress recovery-HSR) assessed based on wet bulb globe temperature index and rectal temperature. Proteome was investigated by liquid chromatography-tandem mass spectrometry from plasma samples, and the differentially regulated proteins were evaluated by functional enrichment analysis using DAVID tool. The protein-protein interaction network was evaluated by STRING tool. Results: A total of 1,550 proteins were detected in both time points, of which 84 and 65 were downregulated and upregulated during HSR, respectively. Among the differentially regulated proteins with the highest absolute log-fold change values, those encoded by the GABBR1, EPHA2, DUSP5, MUC2, DGCR8, MAP2K7, ADRA1A, CXADR, TOPBP1, and NEB genes were highlighted as potential biomarkers because of their roles in response to heat stress. The functional enrichment analysis revealed that 65 Gene Ontology terms and 34 pathways were significant (P < 0.05). We highlighted those that could be associated with the response to heat stress, such as those related to the immune system, complement system, hemostasis, calcium, ECM-receptor interaction, and PI3K-Akt and MAPK signaling pathways. In addition, the protein-protein interaction network analysis revealed several complement and coagulation proteins and acute-phase proteins as important nodes based on their centrality and edges. Conclusion: Identifying differentially regulated proteins and their relationship, as well as their roles in key pathways contribute to improve the knowledge of the mechanisms behind the response to heat stress in naturally adapted cattle breeds. In addition, proteins highlighted herein are potential biomarkers involved in the early response and recovery from heat stress in tropically adapted beef cattle.

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Cattle tick control poses a significant challenge for livestock in tropical and subtropical regions. The objective of this study was to determine the most suitable timing to initiate a strategic tick control program and to identify the ideal number of acaricide treatments for adult taurine cattle (Bos taurus taurus) in a tropical region throughout the year. Three groups with 10 bovines each were performed: T01 (strategic treatment in late autumn/winter/late spring, every 28 days), T02 (strategic treatment to act in the "first tick generation" - early spring/summer/early autumn, every 28 days) and T03 (control). Tick counts (females 4-8 mm) were conducted every 14 days. If the tick burden in any group reached 30 or more during these counts, we applied an additional treatment. Over the course of a year, T02 required significantly fewer (p < 0.05) acaricide treatments than T01, with nine treatments for T02 and eleven for T01. Furthermore, during the tick counts, animals in T02 showed a lower tick burden compared to those in T01. Initiating the strategic tick control program in early spring, corresponding to the first tick generation, proved more effective than starting in autumn. This approach not only required fewer acaricide treatments but also resulted in a reduced tick burden. These benefits are particularly valuable in terms of animal welfare and managing acaricide resistance issues.

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This study aimed to verify the reproductive efficiency of beef cows treated with recombinant bovine somatotropin (rbST). Study 1, Bos indicus cows were distributed (three groups). The control group (CG) was subjected: on day zero (d0), the animals received a CIDR and oestradiol benzoate (EB); on (d8, CIDR was removed, and PGF2α and oestradiol cypionate (EC) were administered; on d10, timed Artificial Insemination (TAI) was performed; on d45, pregnancy diagnosis was made. The rbST on d0 group (bST0G) was subjected to an identical protocol as CG, except for the addition of 250 mg rbST on d0. The rbST on d8 group (bST8G) was subjected to the same protocol as bST0G, except that the rbST was administered on d8 rather. In study 2, the animals followed the same design which was used in Bos taurus cows. The follicular growth rate (FGR) was calculated between d8 and d10. In study 1, pregnancy/artificial insemination (P/AI) did not differ among the treatments. FGR in bST8G was higher than in other groups. In study 2, bST0G showed higher Pregnancy/Artificial Insemination (P/AI) (p < .05) when compared with other groups. bST0G showed a different FGR (p < .0001) than the other groups. In conclusion, rbST (Bos indicus cows) did not increase P/AI, but it did promote follicular growth when administered on d8; the rbST administered on d0 improved P/AI (p < .05) and the FGR in Bos taurus cows.

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A exposição de bovinos a temperaturas elevadas pode causar hipertermia e alterações fisiológicas denominadas de estresse térmico. Este fenômeno tem sido caracterizado em várias espécies, sendo exacerbado em vacas leiteiras de alta produção. Apesar de estas alterações serem observadas em diversos órgãos e tipos celulares, oócitos e embriões pré-implantacionais são mais susceptíveis ao estresse térmico, resultando em reduções na fertilidade das vacas lactantes durante os meses mais quentes do ano. Os oócitos bovinos expostos ao estresse térmico apresentam alterações celulares e moleculares que reduzem a competência oocitária sendo carreados ao embrião pré-implantacional. A maturação in vitro de oócitos bovinos em condições de temperatura elevada (choque térmico) recapitula as principais alterações observadas in vivo, permitindo investigar em mais detalhes a susceptibilidade e os mecanismos de sobrevivência. O entendimento dos processos mediados pelo estresse térmico na fisiologia do oócito permitirá o desenvolvimento de estratégias para mitigar os efeitos negativos mantendo a competência oocitária

The exposure of cattle to high environmental temperatures may lead to hyperthermia and physiological changes known as heat stress. This phenomenon has been characterized in several species, albeit is a more profound problem in high-yielding dairy cows. Although these alterations are observed in several organs and cell types, oocytes and preimplantation embryos are more susceptible to heat stress, resulting in reductions in the fertility of lactating cows during the hottest months of the year. Bovine oocytes exposed to heat stress undergo cellular and molecular changes reducing oocyte competence which is carried out to the preimplantation embryo. In vitro maturation of bovine oocytes under conditions of high temperature (heat shock) recapitulates the main changes observed in vivo, allowing us to investigate the susceptibilities and survival mechanisms. Understanding the processes mediated by heat stress in oocyte physiology will allow the development of strategies to mitigate the negative effects while maintaining oocyte competence.

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BACKGROUND: The cattle introduced by European conquerors during the Brazilian colonization period were exposed to a process of natural selection in different types of biomes throughout the country, leading to the development of locally adapted cattle breeds. In this study, whole-genome re-sequencing data from indicine and Brazilian locally adapted taurine cattle breeds were used to detect genomic regions under selective pressure. Within-population and cross-population statistics were combined separately in a single score using the de-correlated composite of multiple signals (DCMS) method. Putative sweep regions were revealed by assessing the top 1% of the empirical distribution generated by the DCMS statistics. RESULTS: A total of 33,328,447 biallelic SNPs with an average read depth of 12.4X passed the hard filtering process and were used to access putative sweep regions. Admixture has occurred in some locally adapted taurine populations due to the introgression of exotic breeds. The genomic inbreeding coefficient based on runs of homozygosity (ROH) concurred with the populations' historical background. Signatures of selection retrieved from the DCMS statistics provided a comprehensive set of putative candidate genes and revealed QTLs disclosing cattle production traits and adaptation to the challenging environments. Additionally, several candidate regions overlapped with previous regions under selection described in the literature for other cattle breeds. CONCLUSION: The current study reported putative sweep regions that can provide important insights to better understand the selective forces shaping the genome of the indicine and Brazilian locally adapted taurine cattle breeds. Such regions likely harbor traces of natural selection pressures by which these populations have been exposed and may elucidate footprints for adaptation to the challenging climatic conditions.

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This study aimed to evaluate the effect of recombinant bovine somatotropin (bST) in combination with progesterone (P4) and estradiol benzoate (EB) on ovarian follicular dynamics using a protocol for estrus and ovulation synchronization in crossbred Bos taurus taurus cows. Twenty-four non-lactating multiparous cows were randomly assigned to two groups: the recombinant bovine somatotropin group (GbST; n = 11) received an intravaginal P4 device (1.5 g), estradiol benzoate (EB = 1.0 mg IM), bST (500 mg SC), and an ovarian ultrasonography (US) on day zero (d0 = beginning of the study); d-cloprostenol (150 µg, IM), US, and P4 removal on d8; 1.0 mg of EB (IM) on d9; and US on d10 and d15. On the other hand, to the control group (GC; n = 13), the same protocol as the GbST was applied, except for the non-receipt of bST on d0. The follicles were measured and evaluated on d0, d8, and d10, as were the corpora lutea (CL) on d15 (using ultrasonography). The effect of the two treatments (GbST vs. GC) on the follicle size, CL (F-test), and ovulation rate (logistic regression) were evaluated. The GbST showed a greater follicle diameter on d10 (14.5 mm) than the GC (12.1 mm; P < 0.03), as well as a greater diameter of CL on d15 (19.7 vs. 16.9 mm, P < 0.01). In addition, in the former, the ovulation rate (90.9 vs. 69.2%, P = 0.09) was observed to be greater. It was concluded that the combination of bST, P4, and EB in synchronization for estrus and ovulation protocols significantly increased the diameter of the preovulatory follicle, produced a higher follicular growth rate, and a greater diameter of the corpus luteum. Additionally, there was a higher percentage of cows with ovulation compared to the group that did not receive bST.

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This study aimed to evaluate the effect of recombinant bovine somatotropin (bST) in combination with progesterone (P4) and estradiol benzoate (EB) on ovarian follicular dynamics using a protocol for estrus and ovulation synchronization in crossbred Bos taurus taurus cows. Twenty-four non-lactating multiparous cows were randomly assigned to two groups: the recombinant bovine somatotropin group (GbST; n = 11) received an intravaginal P4 device (1.5 g), estradiol benzoate (EB = 1.0 mg IM), bST (500 mg SC), and an ovarian ultrasonography (US) on day zero (d0 = beginning of the study); d-cloprostenol (150 µg, IM), US, and P4 removal on d8; 1.0 mg of EB (IM) on d9; and US on d10 and d15. On the other hand, to the control group (GC; n = 13), the same protocol as the GbST was applied, except for the non-receipt of bST on d0. The follicles were measured and evaluated on d0, d8, and d10, as were the corpora lutea (CL) on d15 (using ultrasonography). The effect of the two treatments (GbST vs. GC) on the follicle size, CL (F-test), and ovulation rate (logistic regression) were evaluated. The GbST showed a greater follicle diameter on d10 (14.5 mm) than the GC (12.1 mm; P < 0.03), as well as a greater diameter of CL on d15 (19.7 vs. 16.9 mm, P < 0.01). In addition, in the former, the ovulation rate (90.9 vs. 69.2%, P = 0.09) was observed to be greater. It was concluded that the combination of bST, P4, and EB in synchronization for estrus and ovulation protocols significantly increased the diameter of the preovulatory follicle, produced a higher follicular growth rate, and a greater diameter of the corpus luteum. Additionally, there was a higher percentage of cows with ovulation compared to the group that did not receive bST.

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We evaluated blood parameters of Angus and Nellore bulls fed diets with and without forage. Forty animals with initial body weight (BW) of 380±16.2 kg were housed in individual stalls. Eight bulls of each breed were fed a whole shelled corn (WSC) diet [850 g kg−1 of WCS and 150 g kg−1 of a pellet based on soybean meal, dry mater (DM) basis] or a ground corn with silage (GC) diet (300 g kg−1 of silage and 700 g kg−1 of a concentrate based on corn and soybean meal, DM basis), ad libitum, and four animals of each breed were limited-fed the GC diet [feed restriction (FR), 55% of the DM intake of bulls fed ad libitum, adjusted for the metabolic BW]. Intake was measured daily, and a metabolism trial was conducted with total collection of feces and urine to estimate the ruminally degraded and undegraded protein (intake and nitrogen balance). Blood samples for determination of hormones and metabolites were collected. The data were analyzed using the GLM procedure of SAS adopting a significance level of 0.05. The diet affected only the serum concentrations of triglycerides, HDL, and VLDL, with limited-fed animals presenting smaller concentrations than ad libitum-fed bulls. No difference in blood parameters was observed between animals fed WSC or GC diets. Nellore bulls presented greater T4, cholesterol, HDL, LDL, and serum urea nitrogen concentrations than Angus. Feeding finishing beef cattle with no-roughage diets does not alter their blood parameters. Also, our results support that Zebu cattle might have lower serum removal of nutrients due to a lesser demand for fat and protein deposition than Bos taurus taurus.(AU)

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O objetivo do estudo foi avaliar perímetro escrotal e características seminais de touros da raça Senepol, de acordo com a idade e as correlações entre elas. Foram avaliados 397 touros na raça Senepol, com idade entre 12 e 30 meses, puros de origem, do estado de Minas Gerais. O método de coleta foi massagem das ampolas e eletroejaculação. Foram avaliados motilidade e vigor do sêmen e os defeitos espermáticos. Os dados foram analisados pelo teste de Kruskal-Wallis e pelo método de Spearman. Os testículos apresentaram um crescimento linear com a idade. Houve maior diferença na motilidade espermática em animais com 18 e 20 meses de idade e o vigor espermático apresentou maior diferença em animais com 20 meses. Houve correlação significativa entre todas as características analisadas. O perímetro escrotal em touros Senepol apresentou crescimento linear dos 12 aos 30 meses e mesmo os animais mais jovens, com menor perímetro escrotal, já apresentaram boa qualidade de sêmen, o que mostra a precocidade reprodutiva dos machos dessa raça. Conclui-se que o perímetro escrotal em touros Senepol apresenta crescimento linear dos 12 aos 30 meses e mesmo os animais mais jovens, já apresentam boa qualidade de sêmen, indicando uma precocidade reprodutiva dos machos dessa raça.(AU)

The objective of this study was evaluate scrotal perimeter and seminal characteteristics of Senepol bulls acording to age and correlations between them. 397 Senepol bulls were avaliable, with ages between 12 and 30 months, pure breed, in the state of Minas Gerais. The collect method were massage of ampoules and electro-ejaculation. Motility and vigor of semen and sperm defects were avaliable. Data were analyzed by the Kruskal-Wallis test and the Spearman method. The tests had a linear growth with age. The biggest difference of motility were in animals with 18 and 20 months of age and the biggest difference of vigor were in animals with 20 months. There was a significant correlation between all analyzed characteristics. Concludes that the scrotal perimeter in Senepol bulls have a linear growth from 12 to 30 months and even the youngest animals, it is a already a good semen quality, indicating a reproductive precocity in males of this breed.(AU)

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O objetivo do estudo foi avaliar perímetro escrotal e características seminais de touros da raça Senepol, de acordo com a idade e as correlações entre elas. Foram avaliados 397 touros na raça Senepol, com idade entre 12 e 30 meses, puros de origem, do estado de Minas Gerais. O método de coleta foi massagem das ampolas e eletroejaculação. Foram avaliados motilidade e vigor do sêmen e os defeitos espermáticos. Os dados foram analisados pelo teste de Kruskal-Wallis e pelo método de Spearman. Os testículos apresentaram um crescimento linear com a idade. Houve maior diferença na motilidade espermática em animais com 18 e 20 meses de idade e o vigor espermático apresentou maior diferença em animais com 20 meses. Houve correlação significativa entre todas as características analisadas. O perímetro escrotal em touros Senepol apresentou crescimento linear dos 12 aos 30 meses e mesmo os animais mais jovens, com menor perímetro escrotal, já apresentaram boa qualidade de sêmen, o que mostra a precocidade reprodutiva dos machos dessa raça. Conclui-se que o perímetro escrotal em touros Senepol apresenta crescimento linear dos 12 aos 30 meses e mesmo os animais mais jovens, já apresentam boa qualidade de sêmen, indicando uma precocidade reprodutiva dos machos dessa raça.

The objective of this study was evaluate scrotal perimeter and seminal characteteristics of Senepol bulls acording to age and correlations between them. 397 Senepol bulls were avaliable, with ages between 12 and 30 months, pure breed, in the state of Minas Gerais. The collect method were massage of ampoules and electro-ejaculation. Motility and vigor of semen and sperm defects were avaliable. Data were analyzed by the Kruskal-Wallis test and the Spearman method. The tests had a linear growth with age. The biggest difference of motility were in animals with 18 and 20 months of age and the biggest difference of vigor were in animals with 20 months. There was a significant correlation between all analyzed characteristics. Concludes that the scrotal perimeter in Senepol bulls have a linear growth from 12 to 30 months and even the youngest animals, it is a already a good semen quality, indicating a reproductive precocity in males of this breed.

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