Analysis of risk factors for dermatitis and cellulitis in turkeys using abattoir post mortem data.

1. Cellulitis and dermatitis are often seen in turkeys at slaughter and are, in many cases, reasons for rejection at meat inspection. Using the results of meat inspections and information about the housing conditions of the animals may provide information on causative factors in the development of cellulitis and dermatitis. 2. A census of two years of turkey production in a company including both fattening farms and an abattoir in the north of England was used to study the relationship between the prevalence of cellulitis/dermatitis and mechanical versus natural ventilation in the poultry house, litter type (long straw, short straw and wood shavings) and stocking density. 3. The overall prevalence of cellulitis and dermatitis in this population was 0.12 %, which was extremely low compared to reports in the literature. In mechanically ventilated houses, the odds of developing cellulitis and/or dermatitis was significantly higher than in naturally ventilated houses (Odds Ratio 3.18). Long straw had a protective effect compared to wood shavings (Odds Ratio 0.18). 4. The study showed that using slaughter data can be helpful in studying on-farm risk factors for disease development.

Lifelong exercise and locally produced insulin-like growth factor-1 (IGF-1) have a modest influence on reducing age-related muscle wasting in mice.

The age-related loss of skeletal muscle mass and function is termed sarcopenia and has been attributed to a decline in concentrations of insulin-like growth factor-1 (IGF-1). We hypothesized that constitutively expressed IGF-1 within skeletal muscles with or without exercise would prevent sarcopenia. Male transgenic mice that overexpress IGF-1 Ea in skeletal muscles were compared with wild-type littermates. Four-month-old mice were assigned to be sedentary, or had access to free-running wheels, until 18 or 28 months of age. In wild-type mice, the mass of the quadriceps muscles was reduced at 28 months and exercise prevented such loss, without affecting the diameter of myofibers. Conversely, increased IGF-1 alone was ineffective, whereas the combination of exercise and IGF-1 was additive in maintaining the diameter of myofibers in the quadriceps muscles. For other muscles, the combination of IGF-1 and exercise was variable and either increased or decreased the mass at 18 months of age, but was ineffective thereafter. Despite an increase in the diameter of myofibers, grip strength was not improved. In conclusion, our data show that exercise and IGF-1 have a modest effect on reducing aged-related wasting of skeletal muscle, but that there is no improvement in muscle function when assessed by grip strength.

Changes to insulin sensitivity in glucose clearance systems and redox following dietary supplementation with a novel cysteine-rich protein: A pilot randomized controlled trial in humans with type-2 diabetes.

We recently developed a novel keratin-derived protein (KDP) rich in cysteine, glycine, and arginine, with the potential to alter tissue redox status and insulin sensitivity. The KDP was tested in 35 human adults with type-2 diabetes mellitus (T2DM) in a 14-wk randomised controlled pilot trial comprising three 2×20 g supplemental protein/day arms: KDP-whey (KDPWHE), whey (WHEY), non-protein isocaloric control (CON), with standardised exercise. Outcomes were measured morning fasted and following insulin-stimulation (80 mU/m2/min hyperinsulinaemic-isoglycaemic clamp). With KDPWHE supplementation there was good and very-good evidence for moderate-sized increases in insulin-stimulated glucose clearance rate (GCR; 26%; 90% confidence limits, CL 2%, 49%) and skeletal-muscle microvascular blood flow (46%; 16%, 83%), respectively, and good evidence for increased insulin-stimulated sarcoplasmic GLUT4 translocation (18%; 0%, 39%) vs CON. In contrast, WHEY did not effect GCR (-2%; -25%, 21%) and attenuated HbA1c lowering (14%; 5%, 24%) vs CON. KDPWHE effects on basal glutathione in erythrocytes and skeletal muscle were unclear, but in muscle there was very-good evidence for large increases in oxidised peroxiredoxin isoform 2 (oxiPRX2) (19%; 2.2%, 35%) and good evidence for lower GPx1 concentrations (-40%; -4.3%, -63%) vs CON; insulin stimulation, however, attenuated the basal oxiPRX2 response (4%; -16%, 24%), and increased GPx1 (39%; -5%, 101%) and SOD1 (26%; -3%, 60%) protein expression. Effects of KDPWHE on oxiPRX3 and NRF2 content, phosphorylation of capillary eNOS and insulin-signalling proteins upstream of GLUT4 translocation AktSer437 and AS160Thr642 were inconclusive, but there was good evidence for increased IRSSer312 (41%; 3%, 95%), insulin-stimulated NFκB-DNA binding (46%; 3.4%, 105%), and basal PAK-1Thr423/2Thr402 phosphorylation (143%; 66%, 257%) vs WHEY. Our findings provide good evidence to suggest that dietary supplementation with a novel edible keratin protein in humans with T2DM may increase glucose clearance and modify skeletal-muscle tissue redox and insulin sensitivity within systems involving peroxiredoxins, antioxidant expression, and glucose uptake.

Colour, pH and weight changes of PSE, normal and DFD breast fillets from British broilers treated with a phosphate-free, low salt marinade.

1. Colour (L*, a*, b*), pH and weight changes during tumbling, overnight holding and cooking were measured in pale, soft and exudative (PSE, L* > 58); normal; and dark, firm and dry (DFD, L* < 52) broiler breast fillets (n = 180) subject to tumbling in a low salt (4%), phosphate-free marinade at three target addition levels: 0, 10 and 20%. 2. The mean L* values for PSE, normal and DFD fillets were 60·1, 56·0 and 51·7 respectively, with corresponding mean pH values of 5·73, 5·85 and 6·07. 3. There were no significant differences in marinade uptake during tumbling for the three groups of fillets. Losses during overnight holding were highest for the PSE fillets, but losses for all three colour groups were relatively small (<2%). 4. Cooking losses for fillets of normal colour were 19·7, 24·1 and 26·2% at 0, 10 and 20% addition levels respectively, with corresponding yields of 80·3, 82·8 and 84·8%. 5. PSE fillets had higher cooking losses and lower yields than normal fillets (and DFD fillets had lower cooking losses and higher yields than normal fillets) but the differences were small and not always significant (P < 0·05). 6. There was a strong negative correlation between pH and L* (r = -0·82) in the raw fillets, but weaker correlations of yield with L* (r = -0·53) and pH (r = 0·38) in the cooked fillets.

Effect of racing on cardiac troponin I concentration and associations with cardiac rhythm disturbances in Standardbred racehorses.

INTRODUCTION/OBJECTIVES: Accumulating evidence indicates intense exercise can be associated with myocardial damage. Investigating the impact of maximal effort on myocardium and exploring possible association of injury with rhythm disturbance requires a high-sensitivity cardiac troponin assay. The objectives of this study were: (1) to determine the effect of racing on serum cardiac troponin I (cTnI) in Standardbred horses using a high-sensitivity assay; (2) to determine the 99th percentile of cTnI in healthy horses and investigate the effect of demographic variables on cTnI prevailing pre-race in Standardbred horses using a validated high-sensitivity assay and a contemporary assay, and; (3) to explore associations between exercise-associated arrhythmia and cTnI concentration. ANIMALS: Racehorses (n = 145). MATERIALS AND METHODS: ≤ 2 h pre-race, cTnI concentrations were measured in 158 race starts. Electrocardiogram (ECG) monitoring was applied during racing and race recovery and screened for complex ventricular arrhythmia. Associations between cTnI prevailing before racing concentration, age, sex, and gait were investigated. Demographic and performance variables were evaluated for associations with cTnI concentration post-race and rhythm disturbance. RESULTS: Incidence of arrhythmia was 11.6% (16 horses). A significant increase in median (interquartile range) cTnI concentration of 1.36 (0.49-2.81) ng/L was found post-race (p < 0.0001). Serum cardiac troponin I (cTnI) concentration prevailing pre-race was positively associated with increasing age, and gait. Serum cardiac troponin I prevailing post-race was positively associated with concentration prevailing pre-race. Interaction between arrhythmia and finishing distanced revealed horses finishing distanced and experiencing arrhythmia displayed higher cTnI release than with the presence of either alone. CONCLUSIONS: Racing increased cTnI concentration. Horses finishing distanced and also exhibiting arrhythmia may be experiencing myocardial compromise.

Ventricular arrhythmias during race recovery in Standardbred Racehorses and associations with autonomic activity.

BACKGROUND: A lack of information on normal heart rhythm at maximal effort hampers investigation of poor performance and sudden death in Standardbred racing. HYPOTHESIS/OBJECTIVE: To characterize rhythm variations during scheduled racing in clinically normal Standardbred horses. ANIMALS: Two hundred and eighty-eight Standardbred horses competing in 40 scheduled races at a Southern Ontario racetrack. METHODS: Observational study, convenience sampling: Heart rhythm was monitored by ECG from harnessing to postrace recovery and assessed visually and by examining heart rate intervals. Rhythm variations were used as response variables in multivariate analysis of race records detailing signalment, race, and race outcome. RESULTS: Monitoring involved 345 individual horse or race events. Occasional, isolated premature cycles, only, occurred during the race. Postrace, sudden cardiac slowing (punctuated deceleration [PD]) appeared in 42 events (12.2%). Only premature ventricular complexes were exhibited in 40 events postrace (11.6%), whereas 55 (15.9%) exhibited complex ventricular arrhythmias (CVA) including torsades-like polymorphic ventricular tachycardia, 34.5% of these being closely associated with PD (odds ratio = 8). Predispositions to CVA were found for horses parked at the 1/2 mile (odds ratio = 3), and trotters breaking in the stretch (odds ratio = 38). Horses spontaneously reverted to sinus rhythm and no sudden death events were encountered. CONCLUSIONS AND CLINICAL IMPORTANCE: Arrhythmias occur frequently in racing Standardbreds during cardiac deceleration, often associated with sudden, rapid increases in vagal tone. Circumstances imposing unusual demand and racing at the trot appear to predispose. Findings provide insight into possible mechanisms of sudden death.

Clonal restriction boundaries in Xenopus embryos shown with two intracellular lineage tracers.

It has been proposed that clonal restriction boundaries develop in Xenopus embryos between clones initiated at the 512-cell stage, and that these boundaries result in formation of morphological compartments, each populated by progeny of a group of ancestral cells. Although this hypothesis has gained some acceptance, it has also been criticized because the use of only one cell lineage tracer was not a conclusive test of the hypothesis. However, the critical experiment, an assessment of the extent of mingling between two labeled clones in the same embryo, has now been performed. A model of the proposed arrangement of the ancestral cell groups in the 512-cell embryo predicted that the two clones would remain separate in 49% of cases and intermingle in 51% of cases. In fact, there was a bimodal distribution, in which separation of the clones occurred in 46% of embryos and extensive interclonal mingling was observed in 54%. These results are not compatible with hypotheses in which a unimodal distribution of mingling would be predicted but are consistent with the compartment hypothesis.

Ontario Racehorse Death Registry, 2003-2015: Descriptive analysis and rates of mortality.

BACKGROUND: The Province of Ontario maintains a registry of racehorse deaths occurring within 60 days of a race or trial entry that provides insight into mortality rates and costs of competition. OBJECTIVES: To characterise and quantify mortality and identify breed differences. STUDY DESIGN: Retrospective annualised cohort study. METHODS: The Ontario Death Registry for 2003-2015, containing 1713 cases, was audited and information on the relationship between death and official work added. Race and trial data from industry performance databases were used to determine mortality rates according to breed, year, age, sex and circumstances of death. RESULTS: Breed differences in mortality rate and individual risk were found. Thoroughbreds (Tb) had the greatest exercise-associated mortality (EAM) rate and risk by all measures (2.27 deaths/1000 race starts, 0.95-1.0% annual individual risk), followed by Quarter horses (Qh, 1.49, 0.60-0.69%). Rate and risk were lowest for Standardbreds (Sb, 0.28, 0.23-0.24%). Nonexercise annual individual risk was highest for the Sb (0.45%, vs. Tb 0.33%, and Qh 0.32%). Pattern and type of EAM mirrored the characteristics of competitive activity in each industry, with high Tb and Qh mortality being associated with exercise and involving musculoskeletal injuries, dying suddenly and accidents. Low Sb EAM reflected the more extensive nature of training preparation and racing for this breed. MAIN LIMITATIONS: Available data provided no information on morbidity, mortality beyond the 60-day horizon or for horses not racing. Numbers for the Qh were low. CONCLUSIONS: Race-intensity exercise is clearly hazardous for horses, with hazards varying widely between breeds and showing parallels with industry cultural and management norms. Breed differences provide insights concerning strategies that could reduce mortality, while improving welfare and reducing costs of participation. For all breeds, musculoskeletal injury was the major contributing cause of mortality.

Post-exercise cardiac troponin I release and clearance in normal Standardbred racehorses.

BACKGROUND: There are currently no studies detailing cardiac troponin I (cTnI) release in normal horses post-exercise using an analytically validated assay. These data are essential for selecting appropriate sampling times in equine athletes with suspected myocardial injury. OBJECTIVE: To plot the magnitude and time course of cTnI release after maximal effort, using validated cTnI assays. STUDY DESIGN: Descriptive longitudinal study. METHODS: Five clinically normal Standardbred racehorses in race training were included in the study. Horses were exercised in harness at near-race intensity. Blood samples were taken immediately pre- and post-exercise and then hourly for 24 h. Samples were analysed using the validated high-sensitivity cTnI assay and a contemporary sensitivity cTnI assay. RESULTS: Mean resting cTnI was 1.33 ± 0.6 s.d. ng/L (range, 0.82-2.33 ng/L) using assay A. All horses were below the detection limit at rest using assay B. Peak elevation occurred 2-6 h post-exercise with both assays (mean, 4.6 ± 1.7 and 4.0 ± 2 h, respectively). Mean peak increase in cTnI was 11.96 ± 9.41 ng/L (range, 1.72-23.76 ng/L) using assay A. Peak concentrations were detectable in three of the horses using assay B and were between 0.039 and 0.051 µg/L (mean: 0.043 ± 0.006 µg/L). All horses returned to baseline within 24 h. MAIN LIMITATIONS: A small (n = 5) convenience sample was used as random sampling was not logistically possible. CONCLUSIONS: All horses experienced an increase in cTnI post-exercise, with peak occurring 2-6 h post-exercise. Cardiac troponin I elevation was detected earlier using the high-sensitivity assay, which may convey a diagnostic advantage. Targeted studies are needed to determine the significance of these increases.

Transvenous electrical cardioversion of equine atrial fibrillation: patient factors and clinical results in 72 treatment episodes.

BACKGROUND: Transvenous electrical cardioversion (TVEC) has been developed for treatment of atrial fibrillation (AF) in horses. The relationship among patient variables, treatment response, and outcome in a typical referral population has not been evaluated. HYPOTHESIS: Patient variables such as age, sex, weight, and duration of arrhythmia affect prognosis for response to treatment and the energy level at which cardioversion occurs. ANIMALS: TVEC was applied to 72 episodes of lone AF in 63 client-owned performance horses, with the majority (54) being Standardbred racehorses. METHODS: Catheterization of the right atrium (RA) and pulmonary artery (PA) through the jugular vein was used for electrode placement before horses were placed under general anesthesia. Biphasic, truncated exponential shock waves were delivered at incremental energy levels until cardioversion was achieved or a maximum single-energy level of 300 J was reached (cumulative energy 50-1,960 J). A multivariate model was constructed to evaluate influence of patient factors on cardioversion energy. RESULTS: Cardioversion was achieved in 71 of 72 episodes (62 of 63 horses) at a mean energy of 165.43 +/- 8.75 J. Cardioversion energy was higher for females than for males, and for interaction terms, weight was negatively related to energy in females and positively related in males. Age was positively related to cardioversion energy in females. No relationship was identified between duration of arrhythmia before treatment and prognosis for response or cardioversion energy. CONCLUSIONS AND CLINICAL IMPORTANCE: TVEC is highly effective in the treatment of lone AF in horses. Although age and sex influence cardioversion energy level, duration of arrhythmia does not.

A comparison of organic and conventionally-produced lamb purchased from three major UK supermarkets: Price, eating quality and fatty acid composition.

Organic and conventional lamb loin chops, labelled as British lamb, were bought from three major UK supermarket chains (designated A, B and C) in the Bristol area on 10 occasions over a six week period. Samples (n=360) were from unknown production systems but representative of what is available to UK consumers. The nutritional quality of muscle was assessed in terms of its fatty acid composition and eating quality was assessed by a trained sensory panel. Lamb prices varied between £9 and £12.50 per kg, with a relatively modest price differential between organic and conventional lamb chops of £1.10, £1.88 and £1.16 £/kg for supermarkets A, B and C, respectively. On average, organic chops were 20g heavier than conventional chops. Chops were relatively lean, having just 14% of subcutaneous fat, approximately half that of a similar survey 10 years ago. Organic lamb had a better eating quality than conventional lamb in terms of juiciness (p<0.05), flavour (p<0.05) and overall liking (p<0.05) thus providing some evidence for the perception among consumers that organic products 'taste better'. Differences in juiciness were attributed to the higher intramuscular fat content of organic meat whilst differences in flavour were attributed to differences in fatty acid composition, in particular, the higher level of linolenic acid (18:3) and total n-3 PUFA in organic chops. Conventional chops had a higher percentage of linoleic acid (18:2). Chops from both productions systems had a favourable n-6:n-3 ratio. The most important difference between the three supermarkets was that lamb flavour was significantly lower in chops from supermarket A, probably due to differences in their 'display until' dates. Chops from supermarket A were also the cheapest.

Fat deposition, fatty acid composition and meat quality: A review.

This paper reviews the factors affecting the fatty acid composition of adipose tissue and muscle in pigs, sheep and cattle and shows that a major factor is the total amount of fat. The effects of fatty acid composition on meat quality are also reviewed. Pigs have high levels of polyunsaturated fatty acids (PUFA), including the long chain (C20-22) PUFA in adipose tissue and muscle. The full range of PUFA are also found in sheep adipose tissue and muscle whereas cattle 'conserve' long chain PUFA in muscle phospholipid. Linoleic acid (18:2n-6) is a major ingredient of feeds for all species. Its incorporation into adipose tissue and muscle in relation to the amount in the diet is greater than for other fatty acids. It is deposited in muscle phospholipid at a high level where it and its long chain products eg aracidonic acid (20:4n-6) compete well for insertion into phospholipid molecules. Its proportion in pig adipose tissue declines as fat deposition proceeds and is an index of fatness. The same inverse relationships are not seen in ruminant adipose tissue but in all species the proportion of 18:2n-6 declines in muscle as fat deposition increases. The main reason is that phospholipid, where 18:2n-6 is located, declines as a proportion of muscle lipid and the proportion of neutral lipid, with its higher content of saturated and monounsaturated fatty acids, increases. Oleic acid (18:1cis-9), formed from stearic acid (18:0) by the enzyme stearoyl Co-A desaturase, is a major component of neutral lipid and in ruminants the same enzyme forms conjugated linoleic acid (CLA), an important nutrient in human nutrition. Like 18:2n-6, α-linolenic acid (18:3n-3) is an essential fatty acid and is important to ruminants since it is the major fatty acid in grass. However it does not compete well for insertion into phospholipid compared with 18:2n-6 and its incorporation into adipose tissue and muscle is less efficient. Greater biohydrogenation of 18:3n-3 and a long rumen transit time for forage diets also limits the amount available for tissue uptake compared with 18:2n-6 from concentrate diets. A positive feature of grass feeding is that levels of the nutritionally important long chain n-3 PUFA are increased ie EPA (20:5n-3) and DHA (22:6n-3). Future research should focus on increasing n-3 PUFA proportions in lean carcasses and the use of biodiverse pastures and conservation processes which retain the benefits of fresh leafy grass offer opportunities to achieve this. The varying fatty acid compositions of adipose tissue and muscle have profound effects on meat quality. Fatty acid composition determines the firmness/oiliness of adipose tissue and the oxidative stability of muscle, which in turn affects flavour and muscle colour. Vitamin E is an essential nutrient, which stabilises PUFA and has a central role in meat quality, particularly in ruminants.

Ocular tear film bubble formation after breath-hold diving.

Bubbles in the ocular tear film have been observed following both dry-chamber, simulated compressed air dives and in-water, recreational compressed air dives. The current paper reports on the formation of tear film bubbles in a breath-hold diver following repeated, extended breath-hold excursions to a maximum depth of -28.5 m. It is believed that this is the first time that ocular tear film bubbles have been reported in breath-hold divers.

Developing neurites from mouse basal forebrain gonadotropin-releasing hormone neurons use Sonic hedgehog to modulate their growth.

Hypothalamic gonadotropin-releasing hormone (GnRH) neurons are required for fertility in all mammalian species studied to date. GnRH neuron cell bodies reside in the basal forebrain, and most extend long neurites in the caudal direction to terminate at the median eminence (ME), the site of hormone secretion. Using in vitro neurite growth assays, histological methods, and genetic deletion strategies in mice we have analysed the role of the morphogen and neurite growth and guidance molecule, Sonic hedgehog (Shh), in the growth of GnRH neurites to their target. Immunohistochemistry revealed that Shh was present in the basal forebrain, the preoptic area (POA) and mediobasal hypothalamus (MBH) at gestational day 14.5 (GD 14.5), a time when GnRH neurites grow towards the ME. Furthermore, in situ hybridization revealed that mRNA encoding the Shh receptor, Smoothened (Smo), was present in GnRH neurons from GD 15.5, when the first GnRH neurites are extending towards the MBH. In vitro neurite growth assays using hypothalamic explants from GD 15.5 fetuses in 3-D collagen gels showed that Shh was able to significantly stimulate GnRH neurite outgrowth. Finally, genetic deletion of Smo specifically from GnRH neurons in vivo, using Cre-loxP technology, resulted in a significant decrease in GnRH neurites innervating the ME. These experiments demonstrate that GnRH neurites use Shh for their neurite development, provide further understanding of the mechanisms by which GnRH nerve terminals arrive at their site of hormone secretion, and identify an additional hypothalamic neuronal population for which Shh/Smo signaling is developmentally important.

Effects of sodium bicarbonate on voluntary face immersion breath-hold times.

The purpose of this study was to examine the effects of orally ingested sodium bicarbonate (NaHCO3) on voluntary breath-hold time with facial immersion. Eight non-elite breath-hold divers aged 20-41 (26.75 +/- 7.83 years) were recruited to undertake two bouts of three monitored, facial-immersion breath-holds, one week apart. Subjects were randomly allocated to double-blind sessions of ingesting an experimental (0.3 g x kg(-1) NaHCO3) or placebo (8 g NaCl) solution. Heart rate, pre- and post-breath-hold end-tidal gases, peripheral oxygen saturation (SpO2) at right index finger and maximum breath-hold times (Max-BHT) were recorded. Max-BHT was established during the third breath-hold in both trials. Max-BHT of 168.2 (+/- 20.7) sec and 145.7 (+/- 21.4) see were recorded for the experimental and placebo conditions, respectively (P = 0.019). Average bradycardic response did not differ between the experimental and placebo trials (P = 0.166). Whilst there was a significant difference in post-breath-hold end-tidal oxygen (P(ET) O2), one was not noted in end-tidal carbon dioxide (P(ET) CO2) measures (P = 0.048, and; P = 0.530, respectively). There was significant difference in lowest recorded SpO2 (P = 0.008) between the trials. It is suggested that ingestion of NaHCO3, prior to facially immersed breath-holds, has an ergogenic effect, prolonging Max-BHT by approximately 8.6%.

Estimates of heritability of atrial fibrillation in the Standardbred racehorse.

BACKGROUND: The number of Standardbred racehorses admitted to the Ontario Veterinary College Teaching Hospital (Guelph, Canada) for treatment of atrial fibrillation (AF) has been on the rise since the early 1990s. A small number of sires have been contributing to a large proportion of cases, indicating there may be a genetic predisposition to the arrhythmia in this breed. OBJECTIVES: The objectives of this study were to determine the heritability of AF in Standardbred horses and whether heritability of the arrhythmia differs across gaits and/or sexes. STUDY DESIGN: Heritability study based on retrospective review of clinical records and publicly available pedigree and racing records. METHODS: Standardbred horses admitted to hospital for treatment of AF that were born between 1978 and 2007 comprised the affected case population (n = 204). Five randomly selected racing contemporaries for each case, assumed to not suffer from the arrhythmia, comprised the control population (n = 1017). Racing contemporaries were identified by examining the race records of affected horses within the 6 months prior to their admission, and randomly selecting sex- and gait-matched horses from these races. Heritability was estimated from the sampled horses as a whole (n = 1221), as well as for both sexes and gaits, using a generalised linear mixed model. RESULTS: Heritability of AF on the underlying liability scale was estimated to be (±s.e.) 0.30±0.04 in the entire data set; 0.30±0.06 in males; 0.24±0.08 in females; and 0.32±0.05 in pacers. After conversion to the observed scale, heritability estimates were 0.14, 0.15, 0.09 and 0.15, respectively. MAIN LIMITATIONS: There were insufficient data to estimate heritability of AF for trotters. CONCLUSIONS: Modest heritability estimates were found for AF in the Standardbred horse, particularly in males and pacers, which support the hypothesis that there is a genetic contribution to the arrhythmia in this breed. The Summary is available in Chinese - See Supporting Information.

Associations of acute stress and overnight heart rate with feed efficiency in beef heifers.

Proxies have the potential to accelerate feed efficiency (residual feed intake (RFI); kg dry matter/day) improvement, assisting with the reduction of beef cattle feed costs and environmental impact. Heart rate (HR) (beats per minute (BPM)) is associated with feed efficiency and influenced by autonomic activity and peripheral metabolism, suggesting HR could be used as a proxy for feed efficiency. Objectives were to assess associations between overnight HR, lying patterns and RFI, and between acute stress HR and RFI. Heifer calves (n=107; 408±28 days of age, 341±42.2 kg) and yearling heifers (n=36; 604±92 days of age, 539±52.2 kg) were exposed to a performance test to determine productive performance. Overnight HR (electrode based) and lying patterns (accelerometer based) were monitored on a subgroup of heifer calves (n=40; 20 lowest RFI; 20 highest RFI). In the 10-min acute stress assessment, all heifers were individually exposed to the opening and closing of an umbrella and HR before (HRBEF), in response to (HRMAX), after (HRAFT) and change (HRCHG; HRAFT-HRBEF) as a result of exposure were determined. Using polynomial regression, rate of HR decrease pre-exposure (ß 1) and rates of HR increase (ß 2) and decrease (ß 3, ß 4) post-exposure were determined. Heifer calves in the overnight assessment were classified into equal RFI groups (low RFI; high RFI) and HR means were treated as repeated measures and compared using multiple regression. In the acute stress assessment, heifers were classified within cattle category into equal RFI groups (low RFI; high RFI) and means and polynomial regression parameters were compared using multiple regression. Low-RFI heifer calves had a lower overnight HR (69.2 v. 72.6 BPM), similar HR change from lying to standing intervals (8.9 v. 9.2 BPM) and similar time lying (61.1% v. 64.5%) compared with high-RFI heifer calves. Low-RFI heifer calves had a higher absolute HRMAX (162.9 v. 145.7 BPM) and ß 2 (-0.34 v. -0.20) than high-RFI heifer calves. Low-RFI yearling heifers had similar acute stress HR means and a lower ß 1 (0.003 v. 0.006) than high-RFI yearling heifers. Overnight HR and acute stress HR are potential indicators of RFI in heifer calves. However, acute stress HR results varied in yearling heifers, suggesting previous handling experience and/or age influence stress response. Pending further development (predictive ability, repeatability), the acute stress assessment could have potential for on-farm application as a feed efficiency proxy in young heifers with minimal handling experience.

Influence of dietary oils and protein level on pork quality. 2. Effects on properties of fat and processing characteristics of bacon and frankfurter-style sausages.

Palm kernel oil (PKO) and palm oil (PO) are used in tropical countries as cheaper substitutes for conventional feed sources such as soya bean oil (SBO) but little is known about their effects on meat quality. This study, therefore, evaluated the effects of these three dietary oils on the fatty acid composition (FA) of pork fat and the qualities of belly bacon and frankfurter sausage. The 3×2 factorial design also included high and low dietary protein. Total cooking loss, water loss and fat losses were determined in frankfurter sausages at chopping temperatures from 2 to 24°C. PKO resulted in a poor P:S ratio (0.34) and a relatively hard fat (slip point 32.8°C), but resulted in bacon with a higher tensile cohesive force and more high quality slices, judged subjectively. PO had a fatty acid composition closer to the SBO control, a better P:S ratio than PKO (0.48) and softer fat. There was a trend for total cooking losses and fat losses to be higher in PKO compared with PO and SBO at all chopping temperatures, suggesting that the firmest, most saturated fat (PKO) was least suitable for frankfurter production. The low protein diet increased the concentration of saturated fatty acids and increased fat firmness but its effect on fatty acid composition and other properties were less marked than those of oil type.

Influence of dietary oils and protein level on pork quality. 1. Effects on muscle fatty acid composition, carcass, meat and eating quality.

This study evaluated the effects of three dietary oils - palm kernel (PKO), palm (PO) and soyabean (SBO) - and two protein levels - high (HP) and low (LP) in a 3×2 factorial design involving 60 pigs on growth performance, muscle fatty acid composition and content, carcass, meat and eating qualities. Oil type did not have a significant effect on growth and carcass quality. PKO significantly reduced the polyunsaturated (PUFA) to saturated (SFA) fatty acid (P:S) ratio in longissimus muscle (P<0.001). PKO increased the concentrations of lauric (12:0), myristic (14:0), palmitic (16:0) and stearic (18:0) fatty acids and decreased linoleic acid (18:2). The LP diet increased intramuscular fat (IMF) from 1.7g/100g muscle in HP to 2.9g/100g (P<0.001), increased tenderness by 0.6 units (P<0.01) and juiciness by 0.5 units (P<0.01) on the 1-8 scale, but at the expense of lower daily weight gain (P<0.01), lower feed conversion efficiency (P<0.01), reduced P:S ratio (P<0.001) and increased lipid oxidation (P<0.01). The results suggest that PKO and PO could be used in tropical developing countries as cheaper alternatives to SBO for the production of good quality and healthy pork, but their limits of inclusion need to be determined.

Effects of breed and marination on the sensory attributes of pork from Large White and Hampshire-sired pigs.

The effects of breed and marination were tested for their effects on meat pH, water holding (marinade uptake and losses) and eating quality (tenderness, juiciness and flavour). Loins were removed from one side of 20 Large White-sired and 20 Hampshire-sired pigs after slaughter, cut into four pieces and injected to 112% of their initial weight with water, a polyphosphate-containing marinade (pH 7.7) or a high pH marinade (pH 10.3). An uninjected piece of loin served as control. Samples were left overnight and then frozen before being thawed, cooked and assessed by a trained ten member sensory panel using 1-8 category scales. Hampshires had higher intramuscular fat (0.95%) than Large Whites (0.62%) but otherwise the effects of breed were small compared with marination. Both marinades significantly increased meat pH from 5.5 (control) by 0.2U, significantly reduced the cooking loss and increased the meat yield from about 80% to 90%. Water-injected samples lost large amounts of added water as drip after thawing and had a yield (76%) similar to the control. Marinaded samples retained more water post-cooking. Both marinades significantly increased tenderness (p<0.001) and juiciness (p<0.001) by about 1.0U compared with the control (4.4 for tenderness and 4.2 for juiciness). Pork flavour, however, was significantly reduced (p<0.001) and abnormal flavour was significantly increased (p<0.001) by marination. Tenderness was positively correlated with pH after injection (0.83) and yield (0.75); juiciness was also positively correlated with pH after injection (0.78) and yield (0.87). The absence of any significant difference in eating quality between control and water-injected samples, and the relatively large effects of marination, suggest that retained water (after cooking) is crucial in determining perceived tenderness and juiciness in pork.