Improved cattle behaviour monitoring by combining Ultra-Wideband location and accelerometer data.

Cattle behaviour is fundamentally linked to the cows' health, (re)production, and welfare. The aim of this study was to present an efficient method to incorporate Ultra-Wideband (UWB) indoor location and accelerometer data for improved cattle behaviour monitoring systems. In total, 30 dairy cows were fitted with UWB Pozyx wearable tracking tags (Pozyx, Ghent, Belgium) on the upper (dorsal) side of the cow's neck. In addition to the location data, the Pozyx tag reports accelerometer data as well. The combination of both sensor data was performed in two steps. In the first step, the actual time spent in the different barn areas was calculated using location data. In the second step, accelerometer data were used to classify cow behaviour using the location information of step 1 (e.g., a cow located in the cubicles cannot be classified as feeding, or drinking). A total of 156 hours of video recordings were used for the validation. For each hour of data, the total time each cow spent in each area and performing which behaviours (feeding, drinking, ruminating, resting, and eating concentrates) were computed using the sensors and compared against annotated video recordings. Bland-Altman plots for the correlation and difference between the sensors and the video recording were then computed for the performance analysis. The overall performance of locating the animals into the correct functional areas was very high. The R2 was 0.99 (P < 0.001), and the root-mean-square error (RMSE) was 1.4 min (7.5% of the total time). The best performance was obtained for the feeding and lying areas (R2 = 0.99, P < 0.001). Performance was lower in the drinking area (R2 = 0.90, P < 0.01) and the concentrate feeder (R2 = 0.85, P < 0.05). For the combined location + accelerometer data, high overall performance (all behaviours) was obtained with an R2 of 0.99 (P < 0.001) and a RMSE of 1.6 min (12% of the total time). The combination of location and accelerometer data improved the RMSE of the feeding time and ruminating time compared to the accelerometer data alone (2.6-1.4 min). Moreover, the combination of location and accelerometer enabled accurate classification of additional behaviours that are difficult to detect using the accelerometer alone, such as eating concentrates and drinking (R2 = 0.85 and 0.90, respectively). This study demonstrates the potential of combining accelerometer and UWB location data for the design of a robust monitoring system for dairy cattle.

Environmental and cow-related factors affect cow locomotion and can cause misclassification in lameness detection systems.

To tackle the high prevalence of lameness, techniques to monitor cow locomotion are being developed in order to detect changes in cows' locomotion due to lameness. Obviously, in such lameness detection systems, alerts should only respond to locomotion changes that are related to lameness. However, other environmental or cow factors can contribute to locomotion changes not related to lameness and hence, might cause false alerts. In this study the effects of wet surfaces, dark environment, age, production level, lactation and gestation stage on cow locomotion were investigated. Data was collected at Institute for Agricultural and Fisheries Research research farm (Melle, Belgium) during a 5-month period. The gait variables of 30 non-lame and healthy Holstein cows were automatically measured every day. In dark environments and on wet walking surfaces cows took shorter, more asymmetrical strides with less step overlap. In general, older cows had a more asymmetrical gait and they walked slower with more abduction. Lactation stage or gestation stage also showed significant association with asymmetrical and shorter gait and less step overlap probably due to the heavy calf in the uterus. Next, two lameness detection algorithms were developed to investigate the added value of environmental and cow data into detection models. One algorithm solely used locomotion variables and a second algorithm used the same locomotion variables and additional environmental and cow data. In the latter algorithm only age and lactation stage together with the locomotion variables were withheld during model building. When comparing the sensitivity for the detection of non-lame cows, sensitivity increased by 10% when the cow data was added in the algorithm (sensitivity was 70% and 80% for the first and second algorithm, respectively). Hence, the number of false alerts for lame cows that were actually non-lame, decreased. This pilot study shows that using knowledge on influencing factors on cow locomotion will help in reducing the number of false alerts for lameness detection systems under development. However, further research is necessary in order to better understand these and many other possible influencing factors (e.g. trimming, conformation) of non-lame and hence 'normal' locomotion in cows.

Effect of summer conditions and shade on the production and metabolism of Holstein dairy cows on pasture in temperate climate.

For dairy cattle on pasture in temperate regions, it is largely unknown to what degree hot summer conditions impact energy metabolism, milk yield and milk composition and how effective shade is in reducing these negative effects. During the summer of 2012, a herd of Holstein cows was kept on pasture without access to shade (treatment NS). During the summers of 2011 and 2013, the herd was divided into a group with (treatment S) and a group without (treatment NS) access to shade. Shade was provided by young trees combined with shade cloths (80% reduction in solar radiation). A weather station registered the local climatic conditions on open pasture, from which we calculated daily average Heat Load Index (HLI) values. The effects of HLI and shade on rectal temperature (RT), blood plasma indicators of hyperventilation and metabolic changes due to heat stress, milk yield and milk composition were investigated. RT increased with increasing HLI, but was less for S cows than for NS cows (by 0.02°C and 0.03°C increase per unit increase of HLI, respectively). Hyperchloraemia (an increased blood plasma concentration of Cl-), a sign of hyperventilation, increased for NS cows but not for S cows. The plasma concentration of alkaline phosphatase, a regulator of energy metabolism in the liver, decreased with increasing HLI for NS cows only. Access to shade, thus, reduced the effect of HLI on RT, hyperchloraemia and the regulation of metabolism by the liver. As HLI increased, the plasma concentration of cholesterol decreased (indicating increased lipolysis) and the plasma concentration of creatinine increased (indicating increased protein catabolism). These effects did not differ between S and NS cows. For NS cows, after a lag-time of 2 days, the milk yield decreased with increasing HLI. For S cows, the milk yield was unaffected by HLI and its quadratic factor. The milk concentrations of lactose, protein and fat decreased as HLI increased, but only the effect on milk protein content was remediated by shade. In conclusion, access to shade tempered the negative effects of high HLI on RT, hyperchloraemia and a blood plasma indicator of changing energy metabolism (generally) as well as prevented the decrease in milk yield observed in cows without access to shade.

Effect of summer conditions and shade on behavioural indicators of thermal discomfort in Holstein dairy and Belgian Blue beef cattle on pasture.

Using behavioural indicators of thermal discomfort, that is, shade seeking, panting scores (PS) and respiration rate (RR), we evaluated the effect of hot summer conditions and shade, for a herd of adult Holstein dairy cows and a herd of Belgian Blue beef cows kept on pasture in a temperate area (Belgium). During the summer of 2012, both herds were kept on pasture without access to shade (NS). During the summers of 2011 and 2013 each herd was divided into one group with (S) and one without (NS) access to shade. Shade was provided by young trees with shade cloth (80% reduction in solar radiation) hung between them. For S cows, we investigated how shade use was related to hot conditions as quantified by six climatic indices. The heat load index (HLI), which incorporates air temperature and humidity, solar radiation and wind speed, was the best predictor of the six indices tested. In 2011, there was a relatively high threshold for use of shade. When HLI=90, shade use probability reached 17% for dairy cows and 27% for beef cows. In 2013, however, at HLI=90, shade use probability reached 48% for dairy cows and 41% for beef cows. For animals from the NS treatment we determined the effect of hot summer conditions on RR and PS (with 0=no panting and 4.5=extreme panting). In both types of cattle, an increase in black globe temperature was the best predictor for increasing RR and PS. Furthermore, we determined how the effect of hot summer conditions on RR and PS was affected by the use of shade. Under hot conditions (black globe temperature ⩾ 30°C), >50% of the animals under shade retained normal PS and RR (PS<1 and RR<90 breaths per minute), whereas normal RR and PS were significantly less prevalent for animals outside shade. Our findings suggest that, even in temperate summers, heat can induce thermal discomfort in cattle, as evidenced by increases in shade use, RR and PS, and that shade increases thermal comfort.

Survey of egg producers on the introduction of alternative housing systems for laying hens in Flanders, Belgium.

In the context of the European Union ban on battery cages by 2012, a survey was conducted among Flemish egg producers (60% response rate, 140 completed questionnaires) about the introduction and opinion of alternative housing systems. Belgium appears to be among the countries in the European Union that are slower to adopt alternative housing. Belgium's egg industry is thus likely to undergo drastic changes to comply with the 2012 deadline. As of 2010, the battery cage was the dominant housing system (56% housing units, 67% hens), followed by floor housing (33% housing units, 15% hens) and aviary (10% housing units, 15% hens), whereas colony cages and furnished cages were extremely rare. Future- and market-oriented production was the most important reason for choosing a certain type of alternative system, although the importance of hen performance and amount of labor seemed to increase. A quarter of the producers with battery cages had detailed plans to convert to an alternative system (most planned to install aviaries, followed by colony cages, furnished cages, and floor housing) by 2012. Many older farmers indicated that they would stop farming, whereas others found it more profitable to delay the conversion as long as possible. Apart from hen welfare, producers expressed a negative opinion (relative to battery cages) about noncage systems and, to a lesser extent, furnished cages. However, users of alternative systems reported being quite satisfied, except for the amount of labor and hen health. The housing system had several effects on user satisfaction: positive effect of flock size, negative effect of experience with battery cages, and negative effect of outdoor area on hen health. Although not all opinions were supported by evidence, such surveys provide feedback about the success of alternative systems in practice. This information is valuable to further improve these systems and to producers who have yet to convert. Moreover, producer attitude may determine the extent to which legally imposed changes in husbandry environment result in the desired improvement of hen welfare in practice.

Bacteriological contamination, dirt, and cracks of eggshells in furnished cages and noncage systems for laying hens: an international on-farm comparison.

For laying hens, the effects of housing system on bacterial eggshell contamination and eggshell quality is almost exclusively studied in experimental hen houses. The aim of this study was to compare eggshell hygiene and quality under commercial conditions. Six flocks of laying hens in furnished cages and 7 flocks in noncage systems were visited when hens were about 60 wk of age. Farms from Belgium, the Netherlands, and Germany were included in the study. The following parameters were determined on eggs sampled at the egg belts: 1) bacterial eggshell contamination, as expressed by total count of aerobic bacteria and number of Enterobacteriaceae; 2) proportion of dirty eggs; and 3) proportion of cracked eggs and eggs with microcracks. Considerable within-flock differences were found in eggshell contamination with total count of aerobic bacteria, both for furnished cages (P < or = 0.001, range 4.24 to 5.22 log cfu/eggshell) and noncage systems (P < or = 0.001, range 4.35 to 5.51 log cfu/eggshell). On average, lower levels of contamination with total count of aerobic bacteria (4.75 vs. 4.98 log cfu/eggshell; P < or = 0.001) were found on eggshells from furnished cages compared with noncage systems. Concerning Enterobacteriaceae, no significant difference in average eggshell contamination between both systems could be shown. The total percentage of cracked eggs was higher (P < or = 0.01) in furnished cages (7.8%) compared with noncage systems (4.1%). This was, however, due to the high percentage of cracked eggs (24%) observed on one of the furnished cage farms. We conclude that bacteriological eggshell contamination and percentage of cracked eggs differed substantially between individual farms using the same housing system. This may also explain some discrepancies between the findings of the present study versus some findings of previous experimental studies or studies on a small number of farms. Although statistically significant, the average differences in bacteriological contamination of nest eggs between both housing systems have limited microbiological relevancy.

Perch width preferences of laying hens.

1. In order to investigate the effect of perch width on perching behaviour of laying hens, two experiments in which hens could choose between 7 different perch widths (1.5, 3.0, 4.5, 6.0, 7.5, 9.0 and 10.5 cm) were conducted. In one experiment (EXP-2P) test cages contained two long perches gradually broadening and narrowing stepwise, in the other experiment (EXP-7P) 7 separate short perches differing in width were placed in the test cages. In each experiment 12 groups of 4 hens were filmed during day and night. The behaviour and location of the hens were recorded and whether the nest box affected hen distribution over the perches was investigated. 2. During daytime, in EXP-2P, there was an increase in perch use with increasing perch width. Hens spent less time on perches of 1.5 cm wide compared to perches of 9.0 and 10.5 cm wide. In EXP-7P, the 1.5-cm wide perch was also used the least (but only the difference with 4.5-cm wide perches was statistically significant) but perch use did not increase linearly with perch width. During the night, there were no significant perch width preferences in either experiment. 3. The percentage of active behaviours (preening, walking, drinking, pecking at hen) versus passive behaviours (standing, sitting, sleeping) did not differ significantly according to perch width. 4. In EXP-7P, there was a trend for perch use to decrease with greater distances to the nest box in the morning. 5. A perch width of 1.5 cm is not recommended for laying hens. For wider perch widths, results were equivocal: they tend to support rather than challenge the widespread use of 4.5-cm wide perches in commercial units.

Perching behaviour and perch height preference of laying hens in furnished cages varying in height.

1. The objective was to investigate the effect of cage height on perch height preference and perching behaviour in laying hens. Twelve groups of two hens and 12 groups of 14 hens were tested in furnished cages equipped with two wooden perches. These stepwise perches were designed such that hens could choose between 7 different heights (6, 11, 16, 21, 26, 31 and 36 cm). Day- and night-time perching behaviour was observed on 4 consecutive days with a different cage height each day: 150, 55, 50 and 45 cm. 2. Given that a minimum perch-roof distance of 19 to 24 cm was available, hens preferred to roost on the highest perches at night. 3. Lowering cage height not only forced hens to use lower perches, but also reduced time spent on the perches during the day (two-hen and 14-hen test) and night (14-hen test). Moreover, it affected daytime behavioural activities (more standing and less preening) on the perches in the two-hen tests (but not in the 14-hen tests). 4. During the day lower perches were used more for standing and walking, higher perches more for sitting and sleeping. This behavioural differentiation was most pronounced in the highest cages. 5. Perch preference and perching behaviour depend on both the floor-perch distance and the perch-roof distance. Higher cages provide more opportunity for higher perches (which hens prefer), for better three-dimensional spacing (and consequently reduced density at floor level) and for behavioural differentiation according to perch height.

Effect of cross-wise perch designs on perch use in laying hens.

1. The use of cross-wise perches by laying hens was investigated in 8 groups of 6 hens. During a period of 5 weeks each group was exposed to 4 different perch arrangements: a single straight perch of 60 cm (P60), a 30-cm perch crossing the middle of another 30-cm perch (P30 + 30), crossing a 45-cm (P45 + 30) or crossing a 60-cm perch (P60 + 30). 2. Perch arrangement influenced perch use. Perch occupancy (the mean number of hens using the perches) was lowest in the P30 + 30 treatment during daytime, evening and night. Perch occupancy was lower for P45 + 30 than for P60 + 30 during daytime and for P60 during evening and night. Perch occupancy did not differ between P60 and P60 + 30. 3. Perch utilisation (perch use per unit of total perch length provided) was lower for the three cross-wise perch arrangements than for P60, indicating that the area near the crossing was not used optimally. 4. There were indications that the process of taking roosting positions was more disturbed with cross-wise perches. 5. Legislation and guidelines about the minimal perch length per hen should be refined to take into account the arrangement of the perches. A perch of 30 cm cross-wise to another perch should not be included in the total amount of perch length provided to the hens. For longer cross-wise perches, the precise distance near the cross that should be excluded remains to be determined.

Direct and indirect drift assessment means. Part 1: PDPA laser based droplet characterisation.

The spray quality generated by agricultural nozzles is important considering the efficiency of the pesticide application process because it affects spray deposits, biological efficacy and driftability. That is why a measuring set-up for the characterisation of spray nozzles was developed. This set-up is composed of a controlled climate room, a spray unit, a three-dimensional automated positioning system and an Aerometrics PDPA laser system which measures droplet size and velocity characteristics based on light scattering principles. Using this set-up and a well defined measuring protocol, droplet size and velocity characteristics of 15 different nozzle-pressure combinations were measured. It was found that at a nozzle distance of 0.50 m, droplet sizes vary from a few up to some hundreds of micrometres and droplet velocities from about 0 m.s(-1) up to 16 m.s(-1). From the results, the importance of the nozzle type and size on the droplet size and velocity spectra is clear. Standard flat fan nozzles produced the finest droplet size spectrum followed by low-drift and the air injection nozzles which results in significant differences in the proportion of small droplets. The larger the ISO nozzle size, the coarser is the droplet size spectrum and the lower is the proportion of small droplets. This effect is most pronounced for the standard flat fan followed by the low-drift nozzles and is less important for the air inclusion nozzles. Comparing the PDPA measuring results with other studies confirmed the need for reference nozzles to classify sprays because of the considerable variation of absolute results depending on variations in reference sprays, measuring protocol, measuring equipment and settings. As described in part 4, these results will be linked with the drift potential of different nozzle-pressure combinations.

Direct and indirect drift assessment means. Part 2: wind tunnel experiments.

Wind tunnel measurements, performed in Silsoe Research Institute (SRI), were used to measure airborne and fallout spray volumes under directly comparable and repeatable conditions for single and static nozzles. Based on these measurements, drift potential reduction percentages (DPRP), expressing the percentage reduction of the drift potential compared with the reference spraying, were calculated following three approaches. The first approach was based on the calculation of the first moment of the airborne spray profile (DPRPv1). In the second and third approach, the surface under the measured airborne (DPRPv2) and fallout (DPRP(H)) deposit curve were used. These DPRP values express the percentage reduction of the drift potential compared with the reference spraying. Ten different spray nozzles were tested. The results showed the expected fallout profiles with the highest deposits closest to the nozzle and a systematic decrease with distance from the nozzle. For the airborne deposit profiles, the highest deposits were found at the Lowest collectors with an important systematic decrease with increasing heights. For the same nozzle size and spray pressure, DPRP values are generally higher for the air inclusion nozzles followed by the low-drift nozzles and the standard flat fan nozzles and the effect of nozzle type is most important for smaller nozzle sizes. In general, the bigger the ISO nozzle size, the higher the DPRP values. Comparing results from the three different approaches namely, DPRPv1, DPRPv2 and DPRP(H), some interesting conclusions can be drawn. For the standard flat fan nozzles, DPRPv1, values were the highest followed by DPRPv2 and DPRP(H) while for the low-drift nozzles opposite results were found. For the air inclusion nozzles, there was a relatively good agreement between DPRPv1, DPRPv1 and DPRP(H) values. All of this is important in the interpretation of wind tunnel data for different nozzle types and sampling methodologies.

Direct and indirect drift assessment means. Part 4: a comparative study.

Three contrasting drift risk assessment means were evaluated when predicting absolute losses of sedimenting pesticide drift from field crop sprayers namely PDPA laser measurements, wind tunnel measurements (both indirect drift risk assessment means) and field drift experiments (direct drift risk assessment means). In total, 90 PDPA laser measurements, 45 wind tunnel experiments and 61 field drift experiments were performed with 10 different spray nozzles at a pressure of 3.0 bar. The effect of nozzle size (ISO 02, 03 04 and 06) and nozzle type (standard flat fan, low-drift flat fan, air inclusion) on the amount of near-field sedimenting spray drift was studied. The reference spray application was defined as a Hardi ISO F 110 03 standard flat fan nozzle at a pressure of 3.0 bar with a nozzle or boom height of 0.50 m and a driving speed of 8 km.h(-1) for the field measurements; conditions that were always used for the comparative assessment of the different investigated nozzle-pressure combinations. A comparison is made between the results obtained with the indirect drift assessment means and the direct drift assessment method to evaluate the potential of these three different drift assessment means. Droplet size as well as droplet velocity characteristics are related with DRPt (field experiments) and DPRP (wind tunnel experiments). Because of the strong intercorrelation between droplet size and velocity characteristics for the nozzle-pressure combinations investigated in this study, simple first-order linear regressions with one of the droplet characteristics as a predictor variable, were the best choice to predict DRPt and DPRP. Results showed that with the indirect risk assessment means (wind tunnel and PDPA laser measurement), driftability experiments can be made with different spraying systems under directly comparable and repeatable conditions and both methods are suited to permit relative studies of drift risk. Moreover, based on these indirect drift measurements and a statistical drift prediction equation for the reference spraying, it is possible to come to a realistic estimate of field drift data at a driving speed of 8 km.h(-1) and a boom height of 0.50 m.

Direct and indirect drift assessment means. Part 3: field drift experiments.

A whole series of field drift experiments were performed to investigate the effect of nozzle type (flat fan, low-drift, air inclusion) and size (ISO 02, 03, 04 and 06) on sedimenting spray drift. Sedimenting spray drift was determined by sampling in a downwind area at 24 different positions using horizontal drift collectors in combination with a fluorescent tracer with measurements up to 20 m from the directly sprayed zone. Meteorological conditions were continuously monitored. Based on 27 drift experiments with the reference spraying at various environmental conditions, the important effect of atmospheric conditions on the amount of near-field sedimenting spray drift was demonstrated and quantified. A non-linear drift prediction equation was set up and validated. This equation was used to compare the drift results of the different spraying techniques under various weather conditions with the reference spraying by calculating their total drift reduction potential (DRPt). Air inclusion nozzles have the highest drift reduction potential followed by the low-drift nozzles and the standard flat fan nozzles and the effect on drift deposits is high with DRPt values varying from -136.5 up to 89.8%. The effect of nozzle type is most important for smaller nozzle sizes A large database with (absolute) near-field drift results is made available to enlarge the international drift database with information about the effect of climatological conditions and spray application technology. The results are generally in good agreement with the results from different other studies although drift studies are difficult to compare due to differences in weather conditions, spray application techniques, methodologies and crop conditions.

Fluctuating asymmetry in broiler chickens: a decision protocol for trait selection in seven measuring methods.

Nonidentical development of bilateral traits due to disturbing genetic or developmental factors is called fluctuating asymmetry (FA) if such deviations are continuously distributed. Fluctuating asymmetry is believed to be a reliable indicator of the fitness and welfare of an animal. Despite an increasing body of research, the link between FA and animal performance or welfare is reported to be inconsistent, possibly, among other reasons, due to inaccurate measuring protocols or incorrect statistical analyses. This paper reviews problems of interpreting FA results in poultry and provides guidelines for the measurement and analysis of FA, applied to broilers. A wide range of morphological traits were measured by 7 different techniques (ranging from measurements on living broilers or intact carcasses to X-rays, bones, and digital images) and evaluated for their applicability to estimate FA. Following 4 selection criteria (significant FA, absence of directional asymmetry or antisymmetry, absence of between-trait correlation in signed FA values, and high signal-to-noise ratio), from 3 to 14 measurements per method were found suitable for estimating the degree of FA. The accuracy of FA estimates was positively related to the complexity and time investment of the measuring method. In addition, our study clearly shows the importance of securing adequate statistical power when designing FA studies. Repeatability analyses of FA estimates indicated the need for larger sample sizes, more repeated measurements, or both, than are commonly used in FA studies.

Experimental stress does not increase fluctuating asymmetry of broiler chickens at slaughter age.

Fluctuating asymmetry (FA) is increasingly applied as a putative indicator of animal welfare. Yet its sensitivity to measure welfare of ad libitum-fed farm animals (that presumably have little or no energy allocation constraints) remains largely untested. This study was conducted to examine whether FA is sensitive to experimentally induced stress in broiler chickens and whether effect sizes differ between emotional and physical stressors. Broiler chickens were randomly assigned to emotional stress treatments (pain or frustration), physical stress treatments (wet litter or high temperature and density), or no stress treatment (control). Both physical stressors, unlike the emotional stressors, were known to affect a number of conventional welfare indicators measured at slaughter age. Left-right asymmetry of 14 bilateral traits was measured at slaughter age and compared between treatments. Seven of the 14 bilateral traits proved unsuitable for the study of FA, either due to the presence of directional asymmetry or high measurement error. Fluctuating asymmetry tended to be lowest in the control group and highest in the high temperature and density treatment. However, either when modeling traits as repeated measures at individual broiler level or when performing trait-by-trait analysis, no significant differences between treatments were detected. This negative result may indicate that FA is not a suitable indicator to detect variations of welfare status in fast-growing broiler chickens because of strong past selection for increased BW and improved feed efficiency, which can mask additional stress effects on developmental processes. Alternatively, FA is not a sensitive indicator of welfare in ad libitum-fed animals because of absence of energy allocation constraints. Finally, FA may still be a suitable indicator of welfare under such conditions, but differences between treatments may remain undetected due to insufficient statistical power, which was estimated at 35% for our study.

The effect of air support on droplet characteristics and spray drift.

Air assistance on field sprayers creates a forced airstream under the spray boom which blows the spray droplets into the crop. The advantages of this relative new technique are less drift of spray droplets and the possibility to reduce the amount of pesticides and spray Liquid. The purpose of this work was to investigate the effect of air assistance on the characteristics of spray droplets and their driftability. Based on air velocity measurements on an air assisted field sprayer, a system of air assistance was developed in addition to a laser-based measuring set-up for the characterisation of spray droplets. With this set-up, the effect of air support on the droplet characteristics was investigated for different settings of the air assistance. The effect on spray drift was quantified based on field drift measurements. A reducing effect on the total amount of spray drift was demonstrated for the Hardi ISO F 110 02, F 110 03 and LD 110 02 nozzles with drift reduction factors a(d) of, respectively, 2.08, 1.77 and 1.53. The use of air support had no significant effect for the LD 110 03 nozzles on the total amount of spray drift. Comparing droplet size and drift results, it was found that air support has the highest impact on the amount of spray drift for the finer sprays by increasing droplet velocities. The effect of air support on droplet sizes is rather limited.

Optimizing the application of entomopathogenic nematodes: experimental set-up.

The complex issue concerning the spray application of Entomopathogenic Nematodes (EPNs) with a hydraulic sprayer is still not solved. This research project focuses on the effect of spray application technique on the viability and deposition of EPNs. In this paper the experimental set-up used for this evaluation is described. A modular spray application system has been developed and is currently used to evaluate the effect of different parts of a sprayer on the viability of the EPNs. Based on the results of experiments using this modular spray application system, recommendations regarding pump type, mixing system, nozzle type and filter size will be formulated. Because of the large number of experiments in this research project, an image analysis system for the determination of the viability of the nematodes is developed. This paper describes two experiments comparing the new developed image processing technique with the standard microscopic counting technique.

Optimizing the application of entomopathogenic nematodes.

A wide range of susceptible insect species encourages the wider use of Entomopathogenic Nematodes (EPNs) as biological insecticides in plant production. So far, the complex expertise concerning the application of EPNs with a hydraulic sprayer is far from complete. At present there are a few guidelines on how biopesticides should be applied to optimize their performance in the field or in the glasshouse. Such guidelines are essential to obtain a good efficacy of the EPN products and to encourage the acceptance and use of biopesticides by growers. This article is a description of the first part of a recently started Ph.D.-research. This research will focus on the effect of spray application technique on the viability and deposition of EPNs (first part). Also the effect of different formulation types and the interaction of formulation and application technique on the viability of EPNs will be investigated (second part). Based on the results of experiments using a modular spray application system, recommendations regarding pump type, mixing system, nozzle type and formulation will be made.