Trever G. Crowe

Effect of light intensity on broiler production, processing characteristics, and welfare

Manipulation of light intensity is an important management tool affecting broiler production and well being. Despite considerable research on light intensity, there is still a debate on the optimum level to be used for intensively housed broilers. Two trials were conducted with the objective of investigating the effect of light intensity, within the practical levels at confinement barns (1, 10, 20, and 40 lx), on production, processing characteristics, and welfare of broilers raised to 35 d of age. Each light intensity treatment was replicated in 2 environmentally controlled rooms in each trial with 950 Ross × Ross 308 chicks per room. Data were analyzed as a randomized complete block design with trial serving as a block. All chicks were exposed to 40 lx of light intensity and 23 h of light for the first 7 d followed by treatment light intensity and 17 h of day length thereafter. Body weight and feed consumption were determined at 7, 14, and 35 d of age. At the end of each trial, 60 birds per treatment were processed to determine the detailed meat yield. Skeletal and footpad and ocular health were monitored at 31 and 32 d of age, respectively. Body weight, feed consumption, feed:gain ratio, and mortality were unaffected by light intensity. Carcass, thigh, and drum yield as a percentage of live weight decreased linearly with increasing light intensity. The 1 lx treatment resulted in heavier wings as a percentage of live weight. Light intensity had no effect on skeletal health, but ulcerative footpad lesions decreased linearly with increasing light intensity. Birds exposed to the 1 lx treatment had heavier and larger eyes. In conclusion, light intensity did not affect broiler production and mortality but did affect carcass characteristics. The 1 lx light intensity treatment had a negative effect on broiler welfare as demonstrated by increased ulcerative footpad lesions and eye size.

The Saskatchewan Farm Injury Cohort: rationale and methodology.

The Saskatchewan Farm Injury Cohort (SFIC) is a major new Canadian study that was developed to evaluate potential causes of injury among farmers and their family members. The cohort involves 2,390 farms and 5,492 farm people being followed over a two-year period. The article describes the rationale and methodology for the baseline and longitudinal components of this study. The SFIC is one of the first studies to apply population health theory to the modeling of risks for injury in a defined Canadian population. In doing so, the relative influence of several potential causes of farm injury, including physical, socioeconomic, and cultural factors, will be estimated. Study findings will inform the content and targeting of injury prevention initiatives specific to the farm occupational environment.

Effect of microclimate temperature during transportation of broiler chickens on quality of the pectoralis major muscle

This study investigated the effect of microclimate temperature during preslaughter transportation on chicken meat quality. Ninety broilers per load of 2,900 were monitored individually during 3 to 4 h of preslaughter transport in an actively ventilated trailer. Six transport test runs were conducted at average ambient temperatures of -27, -22, -17, -5, +4, and +11 degrees C. Birds were classified into 4 groups based upon the temperatures recorded in their immediate surroundings as follows: -16 to 0, 0 to 10, 10 to 20, and 20 to 30 degrees C. Internal body temperatures of the birds were recorded using Thermocron DS1922L iButtons. Birds were slaughtered in a commercial facility and meat quality of the chilled carcasses was evaluated by determination of pH, color, drip loss, thaw loss, cook loss, shear force, water-binding capacity, and pellet cook yield of the pectoralis major muscle. The breast meat from birds exposed to temperatures below 0 degrees C showed a significantly higher (P < 0.05) ultimate pH. Breast meat from birds exposed to temperatures below 0 degrees C showed significantly higher (P < 0.05) ultimate pH, a* value, water-binding capacity, and pellet cook yield and a significantly lower L* compared with breast meat of birds exposed to temperatures above 0 degrees C. The average core body temperatures were significantly lower (P < 0.05) during transport for birds exposed to temperatures below 0 degrees C compared with those exposed to temperatures between 0 and 10 degrees C. The latter birds had significantly lower (P < 0.05) core body temperatures compared with those exposed to temperatures above 10 degrees C. Thaw loss was significantly higher (P < 0.05) for breast meat of birds exposed to temperatures above 20 degrees C during transportation. There was no significant trend for b* value, drip loss, cook loss, or shear values based on environment temperature immediately surrounding the birds. Exposure to temperatures below 0 degrees C increased the incidence of dark, firm, and dry breast meat and decreased the incidence of pale, soft, and exudative breast meat. These results demonstrate that preslaughter transport may influence breast meat quality characteristics of broiler chicken.

Effect of acute cold exposure, age, sex, and lairage on broiler breast meat quality

The effect of acute cold exposure on bird physiology, muscle metabolites, and meat quality was assessed in 360 male and female broilers at 5 and 6 wk of age, exposed for 3 h to temperature ranges of -18 to -4°C and a control of +20°C, by using a simulated transport system followed by 0 or 2 h of lairage. Core body temperature (CBT) was recorded, and the microclimate temperature and RH surrounding individual birds were monitored. Birds were classified based on the temperature in their immediate surroundings. Exposure to temperatures below 0°C resulted in a decrease (P < 0.05) in blood glucose and an increase in live shrink. During the 3 h of exposure to -8°C or lower, CBT dropped substantially. Temperatures below -14°C caused lower glycolytic potential and lactate concentrations. Five-week-old birds showed darker and redder breast meat with higher ultimate pH (pH(u)), less cook loss, and higher processing cook yield at temperatures below -8°C compared with warmer temperatures and with 6-wk-old birds exposed to similar temperatures. No difference in meat quality was observed between the 2 ages at temperatures below -14°C. Males had a greater decrease in CBT and had breast meat with higher pH(u) compared with females. The 2-h lairage resulted in darker breast meat with higher pH(u) at exposure temperatures below -14°C and with higher water-binding capacity and processing cook yield at temperatures below -11°C. A high (>57%) incidence of dark, firm, and dry breast meat [pH >6.1 and L* (lightness) <46] was observed at temperatures below -14°C. A 2-h lairage resulted in an additional 20% increase in the incidence of dark, firm, and dry meat at temperatures below -8°C. Results of this study showed that older birds coped better with extreme cold conditions compared with younger birds. Furthermore, it would be beneficial to limit the length of lairage before processing after exposure to acute cold to improve bird welfare and reduce meat quality defects.

Milk Thistle, Silybum marianum (L.) Gaertn., Flower Head Development and Associated Marker Compound Profile

ABSTRACT Flower head development and marker compound changes were examined for milk thistle grown under dryland conditions during the 1998 and 1999 growing seasons. Flower heads harvested at the early flowering, mid-flowering, late flowering, and dehiscing (seed development) growth stages had average seed/ovule weights of 5 mg, 13 mg, 21 mg, and 26 mg, respectively. At the time of harvest, the plants contained flower heads at all stages of development. During the 1999 harvest, the average plant produced 2.0 g, 2.9 g, and 3.4 g of dry seeds per flower head, corresponding to mid-flowering, late flowering, and dehiscing development stages of the flower. The silymarin and fixed-oil content for the 1999 seeds were 1 mg, 14 mg, and 24 mg of silymarin and 15 mg, 168 mg, and 252 mg of lipid/g dry weight for mid-flowering, late flowering, and dehiscing development stages, respectively. The highest silymarin yield was obtained from late flowering and dehiscing flower heads in early September of both test years.

Operational safety practices as determinants of machinery-related injury on Saskatchewan farms

Agricultural machinery is a major source of injury on farms. The importance of machinery safety practices as potential determinants of injury remains incompletely understood. We examined two such safety practices as risk factors for injury: (1) the presence of safety devices on machinery and (2) low levels of routine machinery maintenance. Our data source was the Saskatchewan Farm Injury Cohort baseline survey (n=2390 farms). Factor analysis was used to create measures of the two operational safety practices. The farm was the unit for all analyses and associations were evaluated using multiple Poisson regression models. Limited presence of safety devices on machinery during farm operations was associated with higher risks for injury (RR 1.94; 95% CI 1.13-3.33; p(trend)=0.02). Lower routine maintenance scores were associated with significantly reduced risks for injury (RR 0.54; 95% CI 0.29-0.98; p(trend)=0.05). The first finding implies that injury prevention programs require continued focus on the use of safety devices on machinery. The second finding could indicate that maintenance itself is a risk factor or that more modern equipment that requires less maintenance places the operator at lower risk. These findings provide etiological data that confirms the practical importance of operational safety practices as components of injury control strategies on farms.

Prevention of agricultural injuries: an evaluation of an education-based intervention

Objective: To evaluate the effectiveness of an agricultural health and safety program in reducing risks of injury. Design: Cross-sectional survey. Setting: 50 rural municipalities in the Province of Saskatchewan, Canada. Intervention: The Agricultural Health and Safety Network (AHSN), a mainly educational program that administered 112 farm safety interventions over 19 years. Subjects: 5292 farm people associated with 2392 Saskatchewan farms. Farms and associated farm people were categorized into three groups according to years of participation in the AHSN. Main measures: Impact: self-reported prevalence of: (1) farm safety practices; (2) physical farm hazards. Outcome: (1) self-reported agricultural injuries. Results: After adjustment for group imbalances and clustering at the rural municipality level, the prevalence of all impact and outcome measures was not significantly different on farms grouped according to years of AHSN participation. To illustrate, the adjusted relative risk of reporting no rollover protection on tractors among farms with none (0 years) versus high (>8 years) levels of AHSN participation was 0.95 (95% CI 0.69 to 1.30). The adjusted relative risk for agricultural injuries (all types) reported for the year before the survey was 0.99 (95% CI 0.74 to 1.32). Conclusions: Educational interventions delivered via the AHSN program were not associated with observable differences in farm safety practices, physical farm hazards, or farm-related injury outcomes. There is a need for the agricultural sector to extend the scope of its injury prevention initiatives to include the full public health model of education, engineering, and regulation.

Determinants of agricultural injury: a novel application of population health theory

Objectives (1) To apply novel population health theory to the modelling of injury experiences in one particular research context. (2) To enhance understanding of the conditions and practices that lead to farm injury. Design Prospective, cohort study conducted over 2 years (2007–09). Setting 50 rural municipalities in the Province of Saskatchewan, Canada. Subjects 5038 participants from 2169 Saskatchewan farms, contributing 10 092 person-years of follow-up. Main measures Individual exposure: self-reported times involved in farm work. Contextual factors: scaled measures describe socioeconomic, physical, and cultural farm environments. Outcome: time to first self-reported farm injury. Results 450 farm injuries were reported for 370 individuals on 338 farms over 2 years of follow-up. Times involved in farm work were strongly and consistently related to time to first injury event, with strong monotonic increases in risk observed between none, part-time, and full-time work hour categories. Relationships between farm work hours and time to first injury were not modified by the contextual factors. Respondents reporting high versus low levels of physical farm hazards at baseline experienced increased risks for farm injury on follow-up (HR 1.54; 95% CI 1.16 to 1.47). Conclusions Based on study findings, firm conclusions cannot be drawn about the application of population health theory to the study of farm injury aetiology. Injury prevention efforts should continue to focus on: (1) sound occupational health and safety practices associated with long work hours; (2) physical risks and hazards on farms.

Endotoxin as a determinant of asthma and wheeze among rural dwelling children and adolescents: A case–control study

BackgroundThe association between endotoxin exposure and asthma is complex and has been associated with rural living. We examined the relationship between domestic endotoxin and asthma or wheeze among rural school-aged children (6–18 years) and assessed the interaction between endotoxin and other characteristics with these outcomes.MethodsBetween 2005 and 2007 we conducted a case–control study of children 6–18 years in the rural region of Humboldt, Canada. Cases (n = 102) reported doctor-diagnosed asthma or wheeze in the past year. Controls (n = 208) were randomly selected from children without asthma or wheeze. Data were collected to ascertain symptoms, asthma history and indoor environmental exposures (questionnaire), endotoxin (dust collection from the play area floor and child’s mattress), and tobacco smoke exposure (saliva collection). Statistical testing was completed using multiple logistic regression to account for potential confounders and to assess interaction between risk factors. A stratified analysis was also completed to examine the effect of personal history of allergy.ResultsAmong children aged 6–12 years, mattress endotoxin concentration (EU/mg) and load (EU/m2) were inversely associated with being a case [odds ratio (OR) = 0.44, 95% confidence interval (CI) = 0.20-0.98; and OR = 0.38, 95% CI = 0.20-0.75, respectively]. These associations were not observed in older children or with play area endotoxin.ConclusionsOur results suggest that endotoxin exposure might be protective for asthma or wheeze. The protective effect is found in younger school-aged, non-allergic children. These results may help explain the inconsistencies in previous studies and suggest that the protective effects of endotoxin in the prevention of atopy and asthma or wheeze are most effective earlier in life.

Endotoxin and Dust at Respirable and Nonrespirable Particle Sizes are not Consistent Between Cage- and Floor-Housed Poultry Operations

BACKGROUND Individuals engaged in work in intensive animal houses experience some of the highest rates of occupationally related respiratory symptoms. Organic dust and in particular endotoxin has been most closely associated with respiratory symptoms and lung function changes in workers. It has previously been shown that for intensive poultry operations, type of poultry housing [cage-housed (CH) versus floor-housed (FH)] can influence the levels of environmental contaminants. The goal of the study was to determine the differences in endotoxin and dust levels at different size fractions between CH and FH poultry operations. METHODS Fifteen CH and 15 FH poultry operations were sampled for stationary measurements (area) of dust and associated endotoxin. Fractioned samples were collected utilizing Marple cascade impactors. Gravimetric and endotoxin analysis were conducted on each of the filters. RESULTS When assessed by individual Marple stage, there was significantly greater airborne endotoxin concentration (endotoxin units per cubic meter) in the size fraction >9.8 μm for the FH operations whereas at the size fraction 1.6-3.5 μm, the CH operations had significantly greater airborne endotoxin concentration than the FH operations. Endotoxin concentration in the dust mass (endotoxin units per milligram) was significantly greater in the CH operations as compared to the FH operations for all size fractions >1.6 μm. As such, endotoxin in the respirable fraction accounted for 24% of the total endotoxin in the CH operations whereas it accounted for only 11% in the FH operations. There was significantly more dust in all size fractions in the FH operations as compared to the CH poultry operations. CONCLUSIONS There is more endotoxin in the presence of significantly lower dust levels in the respirable particle size fractions in CH poultry operations as compared to the FH poultry operations. This difference in respirable endotoxin may be important in relation to the differential respiratory response experienced by CH and FH poultry operation workers.