Reproductive response of crossbred Bos taurus × Bos indicus cows to biostimulation by pre-pubertal and pubertal teasers.

Although the beneficial effect of biostimulation on reproduction has been reported, the influence of selectivity and social factors on the response to biostimulation has not received sufficient research attention in both Bos indicus and Bos indicus influenced cattle. Furthermore, 'green and cheap' strategies to improve cattle reproduction are currently in demand while Bos indicus influenced cattle with inferior reproductive performance, and farmers with economic limitations are common in tropical zones. Hence, to assess the reproductive response of crossbred taurus × indicus cows to biostimulation by pre-pubertal (PPM) or pubertal (PM) teasers males, two trials of 2 years each were conducted. Trial 1 n = 187 cows (Year 1:85 cows exposed to PPM and Year 2:102 cows exposed to PM). Trial 2 n = 196 cows (Year 1:101 cows exposed to PPM and Year 2:95 cows exposed to PM). The effect of exposing cows to PPM and PM on the intervals calving to first service (ICFS), calving to conception (ICC) and economic cost of days open (ECDO) was analysed using Kruskal-Wallis ANOVA and the effect of exposing cows to PPM and to PM on reproductive status at 90 days (RS90) and proportion of cows requiring hormonal protocols (PRH) was compared using χ2 analysis. Both ICFS and ICC were shorter (p < .0001) for PM-exposed females (96.12 ± 4.1 and 110.93 ± 2.9 days; respectively) compared with those PPM-exposed (134.41 ± 3.3 and 135.64 ± 2.4 days; respectively). With RS90, more (p < .0001) PM-exposed cows (50.7%) were pregnant compared with PPM-exposed cows (16.1%). The PRH was greater (p < .0001) in PPM-exposed cows (79.0%) compared with PM-exposed (27.9%). The ECDO was less (p < .0001) in PM-exposed cows (US$ 142.9 ± 3.8) compared with PPM-exposed (US$ 176.3 ± 2.9). In conclusion, cows exposed to PM had shorter ICFS and ICC compared with cows exposed to PPM. More cows exposed to PM were pregnant after 90 days, and PRH was less than cows exposed to PPM. Cows exposed to PM had a reduced ECDO than those exposed to PPM.

Food insecurity among graduate students: prevalence and association with depression, anxiety and stress.

OBJECTIVE: The impact of food insecurity on mental health has not yet been examined in graduate students, a population widely considered at elevated risk for financial strain and negative mental health outcomes. This study aimed to derive initial prevalence estimates of food insecurity in a sample of current graduate students at a large state university and to elucidate the relationship between food insecurity and depression, anxiety and stress in this sample. DESIGN: Cross-sectional online survey including the US Household Food Security Survey Module: Six-Item Short Form and the Depression, Anxiety, and Stress Scales (DASS-21). SETTING: University in the northeastern region of the USA. PARTICIPANTS: Two hundred sixty-three graduate students. RESULTS: In the present sample, 59·7 % of participants reported high/marginal food security, 18·5 % reported low food security and 21·8 % reported very low food security. Graduate students with very low food security reported significantly greater depression (η2 = 0·09), anxiety (η2 = 0·10) and stress (η2 = 0·10), compared with those with low food security and high food security (all P's < 0·001). CONCLUSIONS: Food insecurity occurred in nearly half of the graduate students surveyed, and very low food security was associated with elevated levels of depression, anxiety and stress. Findings highlight the need to address food insecurity and associated elevated mental health problems present among graduate students.

About the inconvenience of handling mixed-breed herds; aspects of social behavior as a potential source of stress and economic losses.

The objective of this study was to assess aspects of the social behavior of a mixed-breed herd of beef cows as a potential source for stress and economic losses. Angus (AN; N = 10), Brahman (BR; N = 10), and Senepol (SE; N = 10) cows were assigned to two groups (N = 15 each containing equal breed numbers) on separate pastures. Agonistic interactions (win/loss) during feeding were recorded daily for 45 days. Dominance values were estimated as the proportion of individuals dominated to total herdmates. From this, individuals were placed into social categories based upon linear ranking as follows: dominants (D), intermediate (I), and subordinates (S). Breed influenced (P < 0.01) social category, with SE cows being dominants (P < 0.05) over AN and BR cows. Interactions between AN and BR cows were less (P < 0.0005) than interactions between AN and SE (53 vs 140, respectively). Within breeds, BR (152) and SE (182) cows had more (P < 0.0005) agonistic interactions than AN (107) cows. Although apparently influenced by breed, agonistic interactions occurred more frequently (P < 0.005) between social categories than within social categories (814 vs 310, respectively). Dominant cows were involved in more agonistic interactions with cows from different social categories than were intermediate and subordinate cows (P < 0.0005). However, intermediate (100) and subordinate (157) cows generated more (P < 0.0005) agonistic interactions within their own social category than dominant cows (53). It was concluded that, in mixed-breed herds, breed influences both social organization and agonistic interactions which could be considered as potential sources of stress and economic losses.

Mnemonic convergence in social networks: The emergent properties of cognition at a collective level.

The development of shared memories, beliefs, and norms is a fundamental characteristic of human communities. These emergent outcomes are thought to occur owing to a dynamic system of information sharing and memory updating, which fundamentally depends on communication. Here we report results on the formation of collective memories in laboratory-created communities. We manipulated conversational network structure in a series of real-time, computer-mediated interactions in fourteen 10-member communities. The results show that mnemonic convergence, measured as the degree of overlap among community members' memories, is influenced by both individual-level information-processing phenomena and by the conversational social network structure created during conversational recall. By studying laboratory-created social networks, we show how large-scale social phenomena (i.e., collective memory) can emerge out of microlevel local dynamics (i.e., mnemonic reinforcement and suppression effects). The social-interactionist approach proposed herein points to optimal strategies for spreading information in social networks and provides a framework for measuring and forging collective memories in communities of individuals.

Foamy viral vector integration sites in SCID-repopulating cells after MGMTP140K-mediated in vivo selection.

Foamy virus (FV) vectors are promising for hematopoietic stem cell (HSC) gene therapy but preclinical data on the clonal composition of FV vector-transduced human repopulating cells is needed. Human CD34(+) human cord blood cells were transduced with an FV vector encoding a methylguanine methyltransferase (MGMT)P140K transgene, transplanted into immunodeficient NOD/SCID IL2Rγ(null) mice, and selected in vivo for gene-modified cells. The retroviral insertion site profile of repopulating clones was examined using modified genomic sequencing PCR. We observed polyclonal repopulation with no evidence of clonal dominance even with the use of a strong internal spleen focus forming virus promoter known to be genotoxic. Our data supports the use of FV vectors with MGMTP140K for HSC gene therapy but also suggests additional safety features should be developed and evaluated.

Consequences of gene editing of PRLR on thermotolerance, growth, and male reproduction in cattle.

Global warming is a major challenge to the sustainable and humane production of food because of the increased risk of livestock to heat stress. Here, the example of the prolactin receptor (PRLR) gene is used to demonstrate how gene editing can increase the resistance of cattle to heat stress by the introduction of mutations conferring thermotolerance. Several cattle populations in South and Central America possess natural mutations in PRLR that result in affected animals having short hair and being thermotolerant. CRISPR/Cas9 technology was used to introduce variants of PRLR in two thermosensitive breeds of cattle - Angus and Jersey. Gene-edited animals exhibited superior ability to regulate vaginal temperature (heifers) and rectal temperature (bulls) compared to animals that were not gene-edited. Moreover, gene-edited animals exhibited superior growth characteristics and had larger scrotal circumference. There was no evidence for deleterious effects of the mutation on carcass characteristics or male reproductive function. These results indicate the potential for reducing heat stress in relevant environments to enhance cattle productivity.

Investigation into sampling strategies in response to potential outbreaks of low pathogenicity notifiable avian influenza initiated in commercial duck holdings in Great Britain.

The aim of this study was to evaluate potential sampling strategies for detection of infected flocks that could be applied during an outbreak of low pathogenicity notifiable avian influenza (LPNAI) initiated in duck holdings, following initial detection. A simulation model of avian influenza virus transmission and spread within and between holdings, respectively, was used to predict the impact on the size and duration of an outbreak of (i) changing the tracing window within which premises that might be the source of infection or that may have been infected by the index premises were sampled and (ii) changing the number of birds sampled in the flock being tested. It has shown that there is potential benefit in increasing the tracing window in terms of reducing the likelihood of a large outbreak. It has also shown that there is comparatively little benefit from increasing the number of birds sampled per flock.

N-terminal pro-B-type natriuretic peptide concentrations and long-term outcome after cardiac surgery: a prospective cohort study.

BACKGROUND: N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations predict cardiovascular outcome in many settings. There are very few data assessing the utility of NT-proBNP concentrations in the prediction of long-term outcome after cardiac surgery. We assessed the ability of NT-proBNP to predict 3 yr mortality compared with validated clinical risk prediction tools. METHODS: A secondary analysis of a prospectively recruited patient cohort of 1010 patients undergoing cardiac surgery. Baseline clinical details were obtained including EuroSCORE. Multi-variable modelling, area under the receiver operating characteristic curves (AUCs), and net reclassification improvement were utilized. RESULTS: NT-proBNP was a univariable predictor of 3 yr mortality but was no longer a significant predictor in a multivariable model (hazard ratio 1.00 per 250 ng litre(-1), 95% confidence interval 0.98-1.02, P=0.80). The relative and additive predictive values of the preoperative EuroSCORE (both additive and logistic versions) and NT-proBNP concentrations were compared. All were predictive of 3 yr mortality (P<0.001) with almost identical AUCs (0.71 for EuroSCORE, 0.70 for NT-proBNP). When either the EuroSCORE or NT-proBNP concentrations are known, the addition of the other does not improve the ability to predict 3 yr mortality. CONCLUSIONS: Preoperative NT-proBNP concentrations and the EuroSCORE have equivalent, and moderate, predictive accuracy for mortality 3 yr after cardiac surgery. EuroSCORE uses clinical data but is not routinely used for individual clinical risk prediction. NT-proBNP measurement would incur additional costs but can be measured quickly and objectively. With such similar predictive accuracy, factors such as the ease of calculation and cost will likely determine their use in clinical practice.

Health gains from home energy efficiency measures: The missing evidence in the UK net-zero policy debate.

Objectives: This study examined the health gains from a programme of external wall insulation works to homes in south-west Scotland, and in particular the impact upon hospitalisations for respiratory and cardiovascular conditions. Furthermore, to consider how evidence on health outcomes could form part of the debate around actions to meet net-zero goals in the UK. Study design: This was a two-part study. Part one involved before-and-after interviews with 229 recipient households. The second part comprised an observational study of hospital admissions in 184 postcode areas. Methods: Across three years, interviews collected thermal comfort and self-reported health data(Sf-36) in the winter months prior to installation, and again in follow-up interviews the next winter. Standarised monthly data on non-elective admissions for each set of conditions were compared between the intervention postcodes and the wider health board area over a ten year period. Results: Following receipt of wall insulation, inability to achieve thermal comfort in winter reduced by two-thirds. Improvements in thermal comfort were associated with gains in physical health scores. Relative standardised admissions fell in the treatment areas, remaining lower than the district-wide standardised rate for the majority of a five year period, this effect ending during the Covid-19 pandemic. The impact on admissions was greater for respiratory conditions than for cardiovascular conditions. Conclusion: A weak policy commitment to energy efficiency could be strengthened with further evidence of the cost-savings and reduced hospital bed demand resulting from insulations works. The potential health gain may also encourage more home owners to participate.

Academic and Wellness Outcomes Associated with use of Anki Spaced Repetition Software in Medical School.

OBJECTIVES: Medical students are increasingly using a spaced repetition software called Anki to study. There are limited studies evaluating the relationship between Anki and learner outcomes. In this study, we describe the history of Anki use in medical school and assess the potential relationships between use of Anki and medical student academic, extracurricular, and wellness outcomes. METHODS: We used cross-sectional data from a 50-item online survey and retrospective academic performance data from our institution's outcomes database. Participants were medical students. The survey assessed the frequency and timing of Anki use, student perceived stress, sleep quality, burnout risk, and involvement in extracurricular activities. Academic success was measured by USMLE Step 1 and Step 2 scores. RESULTS: 165 students responded survey. 92 (56%) identified as daily Anki users. Daily Anki use was correlated with increased Step 1 score (P = .039), but not Step 2 scores. There was an association between Anki use and increased sleep quality (P = .01), but no difference for other measurements of wellness or extracurricular involvement. CONCLUSION: The study demonstrates potential benefits of daily use of Anki but also confirms that a variety of study methods can be used to achieve similar medical school outcomes.

Lack of immunogenicity of xenogeneic DNA from porcine biomaterials.

Background: Clinically useful biomaterials are derived from xenogeneic extracellular matrices, but extensive processes often used to remove all residual DNA are detrimental to their proper biological function. We hypothesized that deliberate and repeated injection of DNA extracted from clinically implantable, xenogeneic extracellular matrices might elicit an immune response in a well-established murine model that could ultimately lead to altered extracellular matrix remodeling. Methods: DNA was purified from unprocessed porcine extracellular matrices and processed extracellular matrices before sterilization (aseptic) and after sterilization. Groups of 10 mice were injected with these 3 purified DNAs and 3 controls: (1) DNA from E. coli; (2) DNA from unprocessed porcine extracellular matrices combined with interleukin-12 and methylated bovine serum albumin and emulsified in incomplete Freund's adjuvant; and (3) buffered saline. Immunizations occurred every 2 weeks for a total of 3 injections. Local cytokines and systemic anti-DNA antibodies were quantified 3 and 7 days after final injection. Results: The DNA extracted from unprocessed, aseptic, or sterilized porcine extracellular matrices failed to elicit a rejection response, and only with significant, proinflammatory adjuvant activation could such a response be seen. Without the adjuvants, biomaterial-derived DNA resulted in a mild accommodation cytokine response locally and no systemic anti-DNA antibody expression even at doses approximately 100-fold larger than would be clinically likely via extracellular matrix implantation. Conclusion: The immunological safety of porcine extracellular matrix biomaterials appears not to be related to DNA residues present. Such biomaterials need not be extensively processed, likely leading to detrimental changes in their bioactivity, solely in an effort to remove the mammalian DNA.

Effects of the SLICK1 mutation in PRLR on regulation of core body temperature and global gene expression in liver in cattle.

The SLICK1 mutation in bovine PRLR (c.1382del; rs517047387) is a deletion mutation resulting in a protein with a truncated intracellular domain. Cattle carrying at least one allele have a phenotype characterized by a short hair coat (slick phenotype) and increased resistance to heat stress. Given the pleiotropic nature of prolactin, the mutation may affect other physiological characteristics. The liver is one organ that could potentially be affected because of the expression of PRLR. The mutation is a dominant allele, and heterozygous animals have a similar hair coat to that of animals homozygous for the mutation. Present objectives were to determine whether inheritance of the SLICK1 mutation affects liver gene expression and if animals homozygous for the SLICK1 allele differ from heterozygotes in liver gene expression and regulation of body temperature during heat stress. In one experiment, rectal and ruminal temperatures were less for Holstein heifers that were heterozygous for the SLICK1 allele compared with wildtype heifers. There were 71 differentially expressed genes in liver, with 13 upregulated and 58 downregulated in SLICK1 heterozygotes. Among the ontologies characteristic of differentially expressed genes were those related to immune function and fatty acid and amino acid metabolism. In a prospective cohort study conducted with adult Senepol cattle, body temperature and hepatic gene expression were compared between animals heterozygous or homozygous for the SLICK1 mutation. There were no differences in ruminal temperatures between genotypes, rectal temperature was higher in animals homozygous for the SLICK1 mutation, and there was only one gene in liver that was differentially expressed. It was concluded that inheritance of the SLICK1 allele can exert functional changes beyond those related to hair growth although changes in liver gene expression were not extensive. Results are also consistent with the SLICK1 allele being dominant because there were few differences in phenotype between animals inheriting one or two copies of the allele.

Massive blood transfusion following older adult trauma: The effect of blood ratios on mortality.

BACKGROUND: Massive blood transfusion (MBT) following older adult trauma poses unique challenges. Despite extensive evidence on optimal resuscitative strategies in the younger adult patients, there is limited research in the older adult population. METHODS: We used the Trauma Quality Improvement Program (TQIP) database from 2013 to 2017 to identify all patients over 65 years old who received a MBT. We stratified our population into six fresh-frozen plasma:packed red blood cell (FFP:pRBC) ratio cohorts (1:1, 1:2, 1:3, 1:4, 1:5, 1:6+). Our primary outcomes were 24-h and 30-day mortality. We constructed multivariable regression models with 1:1 group as the baseline and adjusted for confounders to estimate the independent effect of blood ratios on mortality. RESULTS: A total of 3134 patients met our inclusion criteria (median age 73 ± 7.6 years, 65% male). On risk-adjusted multivariable analysis, 1:1 FFP:pRBC ratio was independently associated with lowest 24-h mortality (1:2 odds ratio [OR] 1.60, 95% confidence interval [CI] 1.25-2.06, p < 0.001) and 30-day mortality (1:2 OR 1.44, 95% CI 1.15-1.80, p = 0.002). CONCLUSIONS: Compared to all other ratios, the 1:1 FFP:pRBC ratio had the lowest 24-h and 30-day mortality following older adult trauma consistent with findings in the younger adult population.

Genome-wide scan reveals important additive and non-additive genetic effects associated with resistance to Haemonchus contortus in Florida Native sheep.

Florida Native sheep is among the sheep breeds best adapted to humid and hot climatic conditions such as those of Florida, USA, and have shown a superior ability to regulate nematode burdens. This is one of the oldest sheep breeds in North America and is an endangered species. To ensure genetic diversity and long-term survival of the breed, protection of the current genetic stock is critical and conservation efforts are required to promote its breeding and production. The objective of the present study was to investigate the importance of additive and non-additive genetic effects on resistance to natural Haemonchus contortus infections in Florida Native sheep using a whole genome scan. A total of 200 sheep were evaluated in the present study. Phenotypic records included faecal egg count (FEC, eggs/gram), FAMACHA® score, packed cell volume (PCV, %), body condition score and average daily gain (ADG, kg). Sheep were genotyped using the GGP Ovine 50K SNP chip and 45.2 k single nucleotide polymorphism (SNP) markers spanning the entire genome were available for quality control procedures. Mixed models were used to analyse the response variables and included the identity by state matrix to control for population structure. Bonferroni correction was used to control for multiple testing and a second arbitrary threshold (0.1 × 10-3) was used. Fifteen SNPs with additive and non-additive genetic effects and located in Ovis aries chromosome OAR1, 2, 3, 6, 8, 10, 11, 12, 13 and 21 were associated with FEC, FAMACHA® score, PCV and ADG. These SNPs could be potential genetic markers for resistance to natural H. contortus exposure in Florida Native sheep.

The emotion regulatory function of online social networking: Preliminary experimental evidence.

Correlational research suggests that emotion regulation deficits, which are known risk factors for substance addictions, may also play a role in the development of problem behaviors such as excessive or maladaptive use of social networking sites (SNS). This study sought to experimentally assess the hypothesized emotion regulatory function of SNS use. 139 undergraduates (53.2% female) were randomized to view brief movie clips known to reliably induce positive (37.4%), negative (29.5%), or neutral mood (33.1%) and then to browse a SNS (46.8%) or control website (53.2%). Mood and subjective urge to access SNS and the Internet were assessed before and after viewing the movie clips and browsing the websites. Participants meeting criteria for "moderate" levels of disordered SNS use self-reported significantly greater deficits in emotion regulation (p = .02, ηp2 = 0.14). Increases in positive and negative affect following the mood induction were associated with a decrease in subjective urge to access SNS (r = -0.22, p = .02, r = -0.28, p = .002, respectively). Time spent browsing SNS resulted in significantly greater increases in self-reported positive affect, compared to the control website (p = .001, ηp2 = 0.09). We replicate previous findings of greater emotion regulation deficits in individuals endorsing problematic SNS use. Increased positive and negative affect resulted in decreased urge to access SNS, suggesting that social networking may primarily serve to counter low-arousal emotions like boredom. Data provide initial experimental evidence to support the hypothesized emotion regulatory function of SNS, with SNS exposure resulting in increased positive affect. Findings suggest that interventions targeting problematic SNS use should incorporate strategies for improved emotion regulation.

The impact of sleep, physical activity and sedentary behaviour on symptoms of depression and anxiety before and during the COVID-19 pandemic in a sample of South African participants.

During lockdowns associated with the COVID-19 pandemic, individuals have experienced poor sleep quality and sleep regularity, changes in lifestyle behaviours, and heightened depression and anxiety. However, the inter-relationship and relative strength of those behaviours on mental health outcomes is still unknown. We collected data between 12 May and 15 June 2020 from 1048 South African adults (age: 32.76 ± 14.43 years; n = 767 female; n = 473 students) using an online questionnaire. Using structural equation modelling, we investigated how insomnia symptoms, sleep regularity, exercise intensity/frequency and sitting/screen-use (sedentary screen-use) interacted to predict depressive and anxiety-related symptoms before and during lockdown. We also controlled for the effects of sex and student status. Irrespective of lockdown, (a) more severe symptoms of insomnia and greater sedentary screen-use predicted greater symptoms of depression and anxiety and (b) the effects of sedentary screen-use on mental health outcomes were mediated by insomnia. The effects of physical activity on mental health outcomes, however, were only significant during lockdown. Low physical activity predicted greater insomnia symptom severity, which in turn predicted increased depressive and anxiety-related symptoms. Overall, relationships between the study variables and mental health outcomes were amplified during lockdown. The findings highlight the importance of maintaining physical activity and reducing sedentary screen-use to promote better sleep and mental health.

Diagnostic accuracy of methods for detecting Anaplasma marginale infection in lactating dairy cattle of Puerto Rico.

Bovine anaplasmosis (BA) is a hemoparasitic disease of great importance in cattle within the tropical and subtropical regions of the world. Control programs for BA require accurate diagnostic assays but validation can be challenging because the true disease status of all animals is frequently not known with certainty. The objective of this study was to estimate the accuracy of assays for detection of Anaplasma marginale infection in lactating dairy cattle of Puerto Rico using Bayesian methods without a perfect reference test. There were 2,331 cattle with complete diagnostic results sampled from 79 herds, and the prevalence of BA was estimated as 22% (95% probability interval [PI]: 19-25%). The sensitivity (Se) and specificity (Sp) of a major surface protein 5 competitive enzyme-linked immunosorbent assay (MSP-5 cELISA) were estimated as 99% (95% PI: 96-100%) and 89% (95% PI: 87-92%), respectively. The Se and Sp of a quantitative polymerase chain reaction (qPCR) were 67% (95% PI: 60-74%) and 99% (95% PI: 99-100%). The Se and Sp of a card agglutination test were 34% (95% PI: 29-39%) and 99% (95% PI: 99-100%). Area under the receiver-operating characteristic curve for the MSP-5 cELISA was 0.748 (95% PI: 0.71-0.79). The MSP-5 cELISA appears to be the test of choice for screening cattle for subclinical BA based on the high estimated Se, rapidity of results, relative low cost, and ease of standardization.

Brace yourselves: esports is coming.

Background: Competitive gaming (or esports) is an emerging phenomenon with a field of over 454 million fans globally. Despite its tremendous popularity and commercial support, esports is not widely understood. It is also disregarded as a reputable or credible form of competition. The International Olympic Committee (IOC) contends that esports may be considered a sporting activity, but this is limited to the basis of its sedentary nature and poor governance. Discussion: These authors present evidence to inform and clarify misconceptions surrounding esports among the broader scientific community. They also encourage researchers to engage in further work into the phenomenon of competitive gaming with regard to health and performance, resulting in a better understanding of esports and guiding its development as a credible, competitive entity.

The Association Between Physiological Sources of Pain and Sleep Quality in Older Adults With and Without Dementia.

The association of musculoskeletal pain, respiratory distress, gastrointestinal discomfort, and genitourinary pain to sleep quality in 89 persons with and without dementia was examined in the current exploratory, cross-sectional, observational quantitative design. Sources of pain were recorded, with 37.1% of the sample reporting urinary retention, 30.3% reporting genitourinary discomfort, and 53.9% reporting gastrointestinal discomfort. Mild scores of musculoskeletal pain and respiratory discomfort were elicited in >75% of the sample. An actigraph was used to measure sleep variables. Findings from this research illustrated dementia, gender, pillow use, respiratory distress, and urinary retention were statistically significantly associated with nighttime sleep quality. Results suggest comprehensive assessments of pain and sleep for older adults with and without dementia are needed. Developing and testing interventions that address factors contributing to sleep quality may improve outcomes. [Research in Gerontological Nursing, 13(6), 297-308.].

Effect of season and genotype on values for bull semen variables under tropical conditions.

To assess the effects of season and genotype on fresh semen quality for freezing and subsequent use for AI, 32 healthy, mature (>4 to <6 years old) and habituated bulls (Bos indicus n = 14, Bos taurus n = 5, Crossbred taurus x indicus n = 6, and tropically adapted Bos taurus composites n = 7) were evaluated at a Venezuelan AI center for 12 months in which four distinct seasons (Hot-dry, Transition, Hot-humid, Cool-rainy) occur. Ejaculates were collected weekly from Bos taurus (n = 260), Bos indicus (n = 669), tropically adapted Bos taurus composites (n = 389), and crossbred Bos taurus x Bos indicus (n = 340) bulls. Routine AI Center assessments were conducted i.e., ejaculate volume (EV), sperm mass-motility (MM), total sperm number/ejaculate (TSE), sperm concentration/mL (SC), pre-freezing (PREF), and post-freezing minimum criteria rate for AI use (POSTF). Genotype affected EV (P < 0.0001), TSE (P < 0.0001), and SC (P < 0.0001) but not MM (P>0.05). Season affected EV (P < 0.001), TSE (P < 0.0001), SC (P < 0.01), and MM (P < 0.05). There were genotype x season interactions for EV, MM, TSE, and SC. The PREF averaged 74.0% during the study, although was less (P < 0.0001) during the hot-humid season than the other seasons. Even though, percent ejaculates considered unsuitable for freezing differed (P < 0.03) among the Hot-dry (20.2%), transition (30.9%), Hot-humid (32.4%), and Cool-rainy (24%) seasons. For POSTF, there were no seasonal differences (P>0.05). It is concluded that in tropical regions, season and genotype can affect bull semen variables, particularly those which affect the success of semen freezing and AI.