A comprehensive MRI investigation to identify potential biomarkers of Osgood Schlatter disease in adolescents: A cross sectional study comparing Osgood Schlatter disease with controls.

BACKGROUND: Osgood-Schlatter disease (OSD) is the most common knee pain complaint among adolescents playing sports. Despite this, there remains controversy over the pathophysiology and whether specific anatomical characteristics are associated with OSD. PURPOSE: This study aimed to systematically and comprehensively characterize adolescents with OSD using magnetic resonance imaging (MRI) compared to pain-free controls, including both tissue abnormalities that may be associated with OSD, as well as anatomical characteristics. A secondary objective was to identify potential imaging biomarkers associated with pain. STUDY DESIGN: Cross-sectional study. METHODS: Adolescents with OSD and controls were recruited from 2020 to 2022. Following a clinical exam, demographics, pain, sports participation, and Tanner stage were collected. Knee MRI was conducted on the participants' most symptomatic knee (OSD) or the dominant leg (controls). RESULTS: Sixty-seven adolescents (46 with OSD and 30 controls) were included. 80% of participants with OSD had at least one tissue alteration compared to 54% of controls. Compared to controls, OSD had 36.3 (95%CI 4.5 to 289.7) higher odds of bony oedema at the tibial tuberosity, and 32.7 (95%CI 4.1 to 260.6) and 5.3 (95%CI 0.6 to 46.2) higher odds of bony oedema at the  tibial epiphysis and metaphysis respectively. Participants with OSD also had higher odds of fluid/oedema at the patellar tendon (12.3 95%CI 3.3 to 46.6), and superficial infrapatellar bursitis (7.2).  Participants with OSD had a more proximal tendon attachment (mean tibial attachment portion difference, -0.05, 95% CI: -0.1 to 0.0, p = 0.02), tendon thickness (proximal mean difference, -0.09, 95% CI: -0.4 to 0.2, p = 0.04; distal mean difference, -0.6, 95% CI: -0.9 to -0.2, p = 0.01). Those with bony/tendon oedema had 1.8 points (95% CI: 0.3 to 3.2) higher pain on palpation than those without (t = -2.5, df = 26.6, p = 0.019), but there was no difference between these groups in a functional single leg pain provocation. CONCLUSION: Adolescents with OSD present with tissue and structural abnormalities on MRI that differed from age-matched controls. The majority had findings in the patellar tendon and bone, which often co-occurred. However, a small proportion of OSD also presents without alterations. It appears these findings may be associated with clinical OSD-related pain on palpation of the tibial tuberosity. CLINICAL RELEVANCE: Our highlight the pathophysiology on imaging, which has implications for understanding the mechanism and treatment of OSD.

Geriatric assessment and medical preoperative screening (GrAMPS) program for older hernia patients.

PURPOSE: The incidence of older adults undergoing inguinal and ventral hernia repairs is increasing. Older adults are disproportionately affected by age-related risk factors, which are often under-recognized and may adversely affect surgical outcomes. These age-related risk factors often termed "geriatric syndromes," include multimorbidity, frailty, cognitive impairment, depression, obesity, functional impairment, polypharmacy, and poor subjective health. The aim of this study was to identify the prevalence of age-related risk factors in older patients undergoing elective hernia repair. METHODS: Patients aged 60 years or older with a planned elective surgical repair of a ventral or inguinal hernia were prospectively enrolled in a clinic. Subjects completed several validated screening tools for geriatric syndromes. RESULTS: Seventy patients completed preoperative assessments (mean age: 68.5 years). In total, 24 (34.3%) screened positive for previously unrecognized objective cognitive impairment (Mini-Cog) and 33 (47.1%) for a subjective memory concern. Sixty patients (85.7%) met criteria for polypharmacy. Additionally, 48 (68.6%) screened positive for either pre-frailty (37, 52.9%) or frailty (11, 15.7%), and 66 (94.3%) had multimorbidity. Twenty-five (35.7%) patients self-rated their health as "poor" or "fair," and 18 (25.7%) patients endorsed some functional impairment. CONCLUSIONS: There is a high prevalence of age-related risk factors in older patients undergoing elective hernia repair. Further, these factors are often unrecognized and underappreciated despite their potential to significantly impact informed consent and shared decision making. Additional study is required to define the impact of these age-related risk factors on surgical outcomes, which will inform preoperative risk assessment and optimization through modifiable risk reduction.

Randomized control trial evaluating the use of a shared decision-making aid for older ventral hernia patients in the Geriatric Assessment and Medical Preoperative Screening (GrAMPS) Program.

PURPOSE: Shared decision making (SDM) is ideally suited to abdominal wall surgery in older adults given the breadth of decision making required by the hernia surgeon and the impact on quality of life (QOL) by various treatment options. Given the paucity of literature surrounding SDM in hernia patients, the feasibility of a novel, formalized SDM aid/tool was evaluated in a pilot randomized trial. METHODS: Patients 60 years or older with a diagnosed ventral hernia were prospectively randomized at an academic hernia center. In the experimental arm, a novel SDM tool, based on the SHARE Approach, guided the consultation. Previously validated SDM assessments and patient's hernia knowledge retention was measured. RESULTS: Eighteen (18) patients were randomized (9 control and 9 experimental). Cohorts were well matched in age (p = 0.51), comorbidities (Charlson Comorbidity Score: p = 0.43) and frailty (mFI-11: p = 0.19; Risk Analysis Index: p = 0.33). Consultation time was 11 min longer in the experimental cohort (p < 0.01). There was a trend towards better Decisional Conflict Scores in the experimental group (p = 0.25) and the experimental cohort had improved post-visit retained hernia knowledge (p < 0.01). All patients in the experimental arm (100%) enjoyed working through the SDM aid/tool and felt it was a worthwhile exercise. CONCLUSION: Incorporating a formalized SDM tool into a busy hernia surgical practice is feasible and well received by patients. In addition, early results suggest it improves retention of basic hernia knowledge and may reduce patient's decisional conflict. Next steps include condensing the SDM tool to enhance efficiency within the clinic and beginning a large, randomized control trial.

Many physiotherapists lack preparedness to prescribe physical activity and exercise to people with musculoskeletal pain: A multi-national survey.

OBJECTIVES: Determine physiotherapists' (i) awareness of physical activity, and exercise prescription guidelines; (ii) perceived role, knowledge, confidence, skills and training in prescribing and progressing aerobic exercise and resistance training to people with musculoskeletal pain; (iii) professional development preferences; and (iv) perceived influences of external factors on exercise prescription for people with musculoskeletal pain. DESIGN: Multi-national cross-sectional survey. METHODS: An open online survey was developed specifically for this study. RESULTS: 1,352 physiotherapists from 56 countries participated. The majority of respondents correctly stated physical activity guidelines for adults (60%) and children (53%), but only 37% correctly stated guidelines for older adults. Eleven percent and 16% could name an accepted guideline for aerobic exercise and resistance training, respectively. Most agreed their role included prescribing aerobic exercise (75%) and resistance training (89%). Fewer reported they had the confidence, training or skills to prescribe aerobic exercise (38-50%) and resistance training (49-70%). Workshops were the most preferred (44%) professional development option. Most respondents believed appointment scheduling and access to equipment and professional development (62-79%) affected their ability to prescribe effective exercise. CONCLUSION: Many physiotherapists lack knowledge and training to provide physical activity advice, and to prescribe aerobic exercise and resistance training to people with musculoskeletal pain.

Early drain removal does not increase the rate of surgical site infections following an open transversus abdominis release.

PURPOSE: Intraoperative drain placement during an open transversus abdominis release (TAR) is common practice. However, evidence detailing the optimal timing of drain removal is lacking. Surgical dogma teaches that drains should remain in place until output is minimal. This practice increases the risk of drain-associated complications (infection, pain, and skin irritation) and prolongs the burden of surgical drain maintenance. The objective of this study is to review infectious outcomes following TAR with early or late drain removal. METHODS: Patients who underwent an open bilateral TAR from 1/2018 to 1/2020 were eligible for the study. Prior to 2019, one of the two intraoperative drains was left in place at discharge. In 2019, clinical practice shifted to remove both drains at hospital discharge irrespective of output. The rate of infectious morbidity was compared between the two cohorts. RESULTS: A total of 184 patients were included: 89 late and 95 early drain removal. No differences in wound complications existed between the two cohorts: surgical site occurrence (SSO): 21.3% vs. 18.9% (p = 0.68); surgical site infection (SSI): 14.6% vs. 10.5% (p = 0.40); abscess: 8.9% vs. 4.2% (p = 0.20); seroma: 6.7% vs. 10.5% (p = 0.36); cellulitis: 14.6% vs. 8.4% (p = 0.19%); or SSO requiring procedural intervention (SSOPI): 5.6% vs. 5.2% (p = 0.92). Rates of antibiotic prescription and 30-day readmission were also similar (p = 0.69 and p = 0.89). CONCLUSIONS: Early removal of abdominal wall surgical drains at discharge irrespective of drain output does not increase the prevalence of infectious morbidity following TAR. It is likely safe to remove all drains at discharge regardless of drain output.

Surgical "error traps" of open posterior component separation-transversus abdominis release.

PURPOSE: Past techniques for the repair of complex incisional hernias have been met with unacceptably high recurrence rates and postoperative complications. The transversus abdominis release (TAR) is a versatile and durable solution gaining popularity amongst both abdominal wall specialists and general surgeons. However, several preoperative factors and specific intraoperative pitfalls can have a major impact on patient outcomes. METHODS: The authors review the current literature and draw upon their own practice experience to highlight key preoperative and perioperative steps for avoiding common pitfalls or "error traps" often performed by a surgeon new to this surgical technique. RESULTS: We discuss preoperative factors that influence the outcomes of patients undergoing incisional hernia repair. We show how a TAR that preserves the neurovascular bundles supplying the rectus complex and dissection in the correct plane prevents the formation of new, challenging unintended hernia defects and provides for wide prosthetic overlap offering the patient a sustainable repair. Lastly, we highlight key postoperative factors that affect a patient's recovery. CONCLUSIONS: Avoidance of surgical error traps combined with technique mastery can lead to the successful repair of challenging abdominal wall defects using the TAR approach.

Evaluation of delayed timing of artificial insemination with sex-sorted sperm on pregnancy per artificial insemination in seasonal-calving, pasture-based lactating dairy cows.

The objective was to use ovulation synchronization with timed artificial insemination (TAI) to evaluate the effect of timing of artificial insemination (AI) with frozen sex-sorted sperm on fertility performance in pasture-based compact calving herds. Ejaculates from 3 Holstein-Friesian bulls were split and processed to provide frozen sex-sorted sperm (SS) at 4 × 106 sperm per straw, and frozen conventional sperm at 15 × 106 sperm per straw (CONV). A modified Progesterone-Ovsynch protocol was used for estrous synchronization, with TAI occurring 16 h after the second GnRH injection for cows assigned to CONV, and either 16 h (SS-16) or 22 h (SS-22) for cows assigned to SS. Pregnancy diagnosis was conducted by transrectal ultrasound scanning of the uterus 35 to 40 d after TAI (n = 2,175 records available for analysis). Generalized linear mixed models were used to examine the effects of treatment on pregnancy per artificial insemination (P/AI). Fixed effects included treatment (n = 3), bull (n = 3), treatment by bull interaction, parity (n = 4), days-in-milk category (n = 3), and treatment by days-in-milk category, with herd (n = 24) included as a random effect. Pregnancy per AI was greater for CONV compared with both SS-16 and SS-22 (61.1%, 49.0%, and 51.3%, respectively), and the SS treatments did not differ from each other (relative P/AI for SS-16 and SS-22 vs. CONV were 80.2% and 84.0%, respectively). There were significant bull and treatment by bull interaction effects. Additional analysis was undertaken using a model that included herd as a fixed effect. This analysis identified marked herd-to-herd variation (within-herd relative P/AI for the combined SS treatments vs. CONV ranged from 48-121%). The tertile of herds with the best performance achieved a mean relative P/AI of 100% (range = 91-121%), indicating that P/AI equivalent to CONV is achievable with SS. Conversely, the tertile of herds with the poorest performance achieved a mean relative P/AI of 67% (range = 48-77%). We found that SS resulted in poorer overall P/AI compared with CONV sperm regardless of timing of AI. Marked variation existed between herds; however, one-third of herds achieved P/AI results equal to CONV. Identification of factors responsible for the large herd-to-herd variation in P/AI with SS, and development of strategies to reduce this variation, warrant further research.

Fertility of frozen sex-sorted sperm at 4 × 106 sperm per dose in lactating dairy cows in seasonal-calving pasture-based herds.

The objective was to evaluate the reproductive performance of frozen sex-sorted sperm at 4 × 106 sperm per dose (SexedULTRA 4M, Sexing Technologies, Navasota, TX) relative to frozen conventional sperm in seasonal-calving pasture-based dairy cows. Semen from Holstein-Friesian (n = 8) and Jersey (n = 2) bulls was used. Four of the Holstein bulls used were resident at or near a sex-sorting laboratory (Cogent, UK, or ST Benelux, the Netherlands). The remaining 6 bulls were located at studs in Ireland. For these 6 bulls, ejaculates were collected, diluted with transport medium, and couriered to Cogent in parcel shippers. Transit time from ejaculation to arrival at the sorting laboratory was 6 to 7 h. For all bulls, ejaculates were split and processed to provide frozen conventional sperm (CONV) at 15 × 106 sperm per straw and frozen sex-sorted (SS) sperm at 4 × 106 sperm per straw and used to inseminate lactating dairy cows after spontaneous estrus. Pregnancy diagnosis was performed by ultrasound scanning (n = 7,246 records available for analysis). Generalized linear mixed models were used to examine effects on pregnancy per AI (P/AI) at first artificial insemination, with sperm treatment (CONV vs. SS), bull (n = 10), and treatment × bull interaction as the fixed effects, and herd (n = 142) as a random effect. Overall, P/AI was greater for cows inseminated with CONV than for those inseminated with SS (59.9% vs. 45.5%; 76.0% relative to CONV). This study was not designed to compare resident bulls vs. shipped ejaculates, but the magnitude of the difference between P/AI achieved by CONV and SS was apparently less for resident bulls (60.3% vs. 50.2%) than for shipped ejaculates (58.6% vs. 40.7%). We discovered a treatment × bull interaction for shipped ejaculates (P/AI ranged from 45 to 86% relative to CONV) but not for the resident bulls (P/AI ranged from 81 to 87% relative to CONV). Relative P/AI of SS compared with CONV was greater in cows with high or average fertility potential (76.1% and 78.3%, respectively) than in cows with low fertility potential (58.1%). In 33.1% of the enrolled herds, the P/AI achieved with SS was 90% or more of the P/AI achieved with CONV; this was mainly explained by herds in which SS performed exceptionally well but CONV performed poorly. In conclusion, SS had lower overall P/AI compared with CONV; however, P/AI achieved with SS was dependent on the bull, fertility potential of the cow, and herd. Strategies to improve the P/AI with SS in seasonal-calving pasture-based lactating dairy cows require further research.

Transparency in the eye region of an ostracod carapace ( Macrocypridina castanea, Myodocopida).

Many myodocopid ostracods are unusual in that they have well-developed compound eyes yet must view their environment through a shell. The cypridinid Macrocypridina castanea is relatively large among ostracods (about 5-10 mm) and is a pelagic predator. This species possess highly pigmented shells with a transparent region lying just above the eye. Here we examine the ultrastructure and transparency of this window using electron microscopy, serial-block face scanning electron microscopy and X-ray diffraction analysis and optical modelling. An internal, laminar stack was identified within the window region of the shell that formed a more regular half-wave reflector than in non-window regions, and where the distance between molecules in the chitin-protein fibrils decreases as compared to the non-window area. This results in excellent transmission properties-at around 99% transmission-for wavelengths between 350 and 630 nm due to its half-wave reflector organization. Therefore, blue light, common in the mid and deep sea, where this species inhabits, would be near-optimally transmitted as a consequence of the sub-micrometre structuring of the shell, thus optimizing the ostracod's vision. Further, pore canals were identified in the shell that may secrete substances to prevent microbial growth, and subsequently maintain transparency, on the shell surface. This article is part of the theme issue 'Bioinspired materials and surfaces for green science and technology'.

The relationship between anogenital distance and fertility, and genome-wide associations for anogenital distance in Irish Holstein-Friesian cows.

The evaluation of anogenital distance (AGD), the distance from the center of the anus to base of the clitoris, as a potential fertility trait for genetic selection in dairy cows has generated recent interest. The objectives of this cross-sectional observational study were to (1) characterize the distribution and variability of AGD, (2) determine factors associated with AGD, (3) estimate heritability for AGD, (4) identify single nucleotide polymorphisms (SNP) associated with phenotypic variation of AGD, and (5) validate the relationship between categories of AGD and fertility in Irish Holstein-Friesian cows. Anogenital distance was measured using digital calipers in 1,180 Holstein cows (mean ± standard deviation: 225 ± 79 d in milk) from 10 dairy herds located in Munster, Ireland. In addition, age (yr), weight (kg), height at hip (cm), and body condition score (BCS) at the time of AGD measurement were determined in a subset of 281 cows. Genotype information available from 908 cows was subsequently imputed to the Illumina Bovine High Density BeadChip (Illumina Inc., San Diego, CA) for genome-wide association analysis of phenotypic variation in AGD. Overall, AGD had a normal distribution and high variability (mean ± standard deviation; 119.2 ± 11.6 mm). Anogenital distance was weakly but positively associated with cow age, hip height, and body weight, and negatively associated with BCS; the phenotypic variation in AGD that was explainable by these variables was small (coefficient of determination; R2 = 0.09, 0.06, 0.10, and 0.02, respectively). The estimated heritability for AGD was 0.37 (standard error of mean ± 0.08). Six SNP of suggestive significance were identified on Bos taurus autosomes 6, 15, 20, and 26; however, none of these SNP was related to previously identified candidate genes for fertility. Cows were categorized into quartiles (Q1; 86 to 111 mm; n = 311, Q2; 112 to 120 mm; n = 330; Q3; 121 to 127 mm; n = 265, and Q4; 128 to 160 mm; n = 274) based on AGD and the association with reproductive outcomes examined (21-d submission rate, pregnancy to first AI, pregnancy rate within 21, 42 and 84-d after the farm mating start date, and number of times bred). None of the reproductive variables differed significantly between AGD categories. In summary, despite identification of high variability and moderate heritability for AGD in Irish Holstein-Friesian cows, reproductive outcomes did not differ between categories of AGD. This latter result differs from our previous finding of an inverse relationship between AGD and pregnancy outcomes in first- and second-parity Canadian Holstein cows, emphasizing the need to test and validate this new phenotype in diverse cow populations.

Review: Applications and benefits of sexed semen in dairy and beef herds.

The use of sexed semen in dairy and beef cattle production provides a number of benefits at both farm and industry levels. There is an increasing demand for dairy and beef products across the globe, which will necessitate a greater focus on improving production efficiency. In dairy farming, there is surplus production of unwanted male calves. Male dairy calves increase the risk of dystocia compared with heifer calves, and as an unwanted by-product of breeding with conventional semen, they have a low economic value. Incorporating sexed semen into the breeding programme can minimise the number of unwanted male dairy calves and reduce dystocia. Sexed semen can be used to generate herd replacements and additional heifers for herd expansion at a faster rate from within the herd, thereby minimising biosecurity risks associated with bringing in animals from different herds. Furthermore, the use of sexed semen can increase herd genetic gain compared with use of non-sorted semen. In dairy herds, a sustainable breeding strategy could combine usage of sexed semen to generate replacements only, and usage of beef semen on all dams that are not suitable for generating replacements. This results in increased genetic gain in dairy herd, increased value of beef output from the dairy herd, and reduced greenhouse gas emissions from beef. It is important to note, however, that even a small decrease in fertility of sexed semen relative to conventional semen can negate much of the economic benefit. A high fertility sexed semen product has the potential to accelerate herd expansion, minimise waste production, improve animal welfare and increase profitability compared with non-sorted conventional semen.

Pain patterns during adolescence can be grouped into four pain classes with distinct profiles: A study on a population based cohort of 2953 adolescents.

INTRODUCTION: Although multi-site pain is common in adolescents, pain conditions are frequently diagnosed and treated in isolation. Little is known about whether there are specific sites in which pain commonly co-occurs. This study examines the patterns of pain in adolescents, and whether these are associated with sports participation, health-related quality of life (HRQoL), and sex. METHODS: In previously collected cohort data ('Adolescent Pain in Aalborg-2011'), adolescents (aged 12-19) completed an online questionnaire, including demographic data, current pain sites, sports participation and HRQoL (assessed by Euro-QoL 5D-3L). Latent class analysis was used to classify spatial pain patterns, based on the pain sites. The analysis included 2953 adolescents. RESULTS: Four classes were identified as follows: (1) little or no pain (63% of adolescents), (2) majority lower extremity pain (10%), (3) multi-site bodily pain (22%) and (4) head and stomach pain (3%). The lower extremity multi-site pain group reported highest weekly sports participation (p < 0.001; mean: 2.9 days/week; 95% CI 2.7 to 3.2), while the multi-site bodily pain and the multi-site head and stomach pain groups had lowest EQ-5D scores (p < 0.001). Males were more likely to belong to the little or no pain class, whereas females were more likely to belong to the multi-site bodily pain class. CONCLUSIONS: Latent class analysis identified distinct classes of pain patterns in adolescents, characterized by sex, differences in HRQoL and sports participation. The class with multi-site bodily pain and reduced quality of life was the largest among adolescents reporting pain, and future research on treatment strategies should consider targeting this group.

Effect of seminal plasma from high- and low-fertility bulls on cauda epididymal sperm function.

The aim of this study was to characterise the effect of seminal plasma (SP) from bulls of high or low fertility on sperm function. First, the effect of SP on the motility of fresh cauda epididymal spermatozoa (CES) and frozen-thawed ejaculated spermatozoa was assessed (Experiment 1a). Seminal plasma was then collected from bulls of known high and low fertility. Pooled CES were incubated in the SP from each bull, diluted and assessed for motility and viability on Days 1, 2, 3 and 5 after packaging as fresh semen (Experiment 1b). Also assessed were motility, kinematics, viability and mitochondrial membrane potential after thawing (Experiment 1c) as well as hypotonic resistance (Experiment 2) and fertilisation potential using in vitro fertilisation (Experiment 3). Seminal plasma increased the motility of CES (P<0.05); however, there was no effect of SP on the motility and viability of fresh CES or on CES post-thaw motility, viability and mitochondrial membrane potential (P>0.05). The hypotonic resistance of CES was reduced by SP (P<0.05), irrespective of whether the SP was from high- or low-fertility bulls. Seminal plasma from high- or low-fertility bulls had no effect on cleavage or blastocyst rates (P>0.05). In conclusion, SP affects the physiological function of CES but there is no difference between SP from high- or low-fertility bulls.

Dietary polyunsaturated fatty acid supplementation of young post-pubertal dairy bulls alters the fatty acid composition of seminal plasma and spermatozoa but has no effect on semen volume or sperm quality.

The aim of this study was to examine the effects of dietary supplementation with rumen protected n-6 or n-3 polyunsaturated fatty acids (PUFA) on the quantity and quality of semen from young post-pubertal dairy bulls. Pubertal Holstein-Friesian (n = 43) and Jersey (n = 7) bulls with a mean ± s.e.m. age and bodyweight of 420.1 ± 5.86 days and 382 ± 8.94 kg, respectively, were blocked on breed, weight, age and semen quality (based on the outcomes of two pre-trial ejaculates) and randomly assigned to one of three treatments: (i) a non-supplemented control (CTL, n = 15), (ii) rumen-protected safflower (SO, n = 15), (iii) rumen-protected n-3 PUFA-enriched fish oil (FO, n = 20). Bulls were fed their respective diets, ad libitum for 12 weeks; individual intakes were recorded using an electronic feeding system for the initial 6 weeks of the feeding period. Semen was collected via electro-ejaculation at weeks -2, -1, 0, 7, 10, 11 and 12 relative to the beginning of the trial period (week 0). On collection, semen volume, sperm concentration and progressive linear motility (PLM) were assessed. On weeks -2, -1, 0, 10, 11, 12, semen was packaged into 0.25 mL straws and frozen using a programmable freezer. On weeks -1, 7 and 11; a sub-sample of semen was separated into sperm and seminal plasma, by centrifugation and stored at - 20 °C until analysis of lipid composition. Semen from 10 bulls per treatment were used for post-thaw analysis at weeks 10, 11 and 12 (3 straws per ejaculate). Sperm motility was analysed by computer assisted semen analysis (CASA). In addition, membrane fluidity, acrosome reaction and oxidative stress were assessed using flow cytometry. Sperm from bulls fed SO had a 1.2 fold higher total n-6 PUFA content at week 11 compared to week -1 (P < 0.01) while bulls fed FO had a 1.3 fold higher total n-3 PUFA content, in sperm by week 11 (P < 0.01). There was no effect of diet on semen volume, concentration or PLM of sperm when assessed either immediately following collection or post-thawing. Membrane fluidity and oxidative stress of sperm were also not affected by diet. The percentage of sperm with intact-acrosomes was lower in CTL bulls compared to those fed SO (P < 0.01). In conclusion, while the lipid composition of semen was altered following dietary supplementation with either n-6 or n-3 based PUFA, this did not lead to measurable improvements in the quantity or quality of semen produced by young post-pubertal dairy bulls.