Month: December 2024

For Wichman and Norman et al. , the detour apparatus consisted of an arena with a starting compartment in the center, across from a holding compartment. The starting compartment consisted of three walls, two opaque and one of wire mesh, so that the holding compartment was visible through the wire mesh. Opposite the wire mesh screen was an opening in the back of the compartment allowing access to the rest of the arena. The holding compartment consisting of a screen so that its contents could be seen by the individual in the starting compartment. The test chick was placed in the central starting compartment and two of its companions from it home pen were placed in the holding compartment. To solve this task, the chicks had to walk away from the familiar chicks, out of the central staring compartment, and around this compartment to reach their companions. Wichman tested ninety 3 day old chicks on a detour test to evaluate their spatial ability. The young chicks had not yet developed perching behavior at the time they were tested. As with the radial arm experiment, all birds were raised in three different rearing environments: control, floor enrichment, and hanging enrichment. The time it took chicks to reach their companions was recorded or, if the chick was unable to successfully complete the task, square pot the trial elapsed at 10 minutes.Forty out of the ninety chicks successfully solved the detour task, however, no relationship was found between onset of perching behavior and the performance of the chicks on the detour test.

This result suggests that the detour test is not a good predictor of early perching behavior in pullets. Additionally, there was no significant effect of rearing environment complexity on the success of chicks in the detour task. Norman et al. also employed a detour task in order to assess if early access to elevated structures affects spatial working memory and route planning in laying hens. They raised chicks from one day of age in either a control or enriched treatment. The control treatment had no elevated structures and the enriched treatment had eight wooden perches arranged in an A-frame structure. In addition to the perches the enriched treatment also had a ramp leading up a platform placed on the second rung of perches. Norman et al tested 48 chicks from both rearing treatments on a detour task at either 14-15 days of age or 28-29 days of age. The test chick was placed in the starting compartment and two of its companions from their home pen were placed in the holding compartment. If the chick left the start box and began walking around the compartment, but then reentered the center of the arena, this was considered an orientation error. Chicks were given a maximum of 5 minutes to complete the task. Out of the 96 birds tested, 67 completed the detour task. There was no significant difference between treatment groups for the number of orientation errors, however the latency to complete the task was significantly shorter for the enriched as compared to the control chicks.

Morris also used a detour task to assess birds from two different rearing treatments on their spatial reasoning . For this study, the unenriched condition included shavings, a hanging feeder, and a nipple line drinker. The enriched treatment included two perches, three live plants for cover, a dust bathing box, two hanging party decorations, and hidden meal worms. At 10 weeks of age 42 birds were tested on a detour task. The target consisted of three familiar birds from their home pen. A barrier was located at the other end of the arena and was made of a mesh screen with an opening on the far-left side, across from the target. The test bird was placed in a starting location behind the barrier and was given 3 to 5 minutes to acclimate in a mesh enclosure. Once the enclosure was lifted, the birds were given 5 minutes to reach their companions. The latency of each test bird to navigate around the barrier and come within 0.5 m of the target was recorded. No significant differences between treatment groups in time taken to reach companions were found. These results contradict the finding from Norman et al. that birds with accesses to vertical structures at a young age did have a shorter latency to complete the detour task than birds without access to vertical structures. It is possible that the difference in these results could be due to the different rearing environments and detour design of these two experiments. The design of the detour task in Morris differed from the design of Norman et al. and Wichman . Instead of the chick walking away from the companion chicks to reach the goal, the Morris design required the chicks to walk towards the companions with them in view at all times through a mesh screen.

The birds were unable to take the most direct route, a diagonal path across the arena, but were not required to walk away from the target at any point to successfully solve the task. Due to this, the Morris detour task does differ from the classic detour task used by Wichman and Norman et al. . However, the inconsistent results between Wichman and Norman et al. should be taken into account when interpreting the impact of rearing environment on performance in a detour task. Due to the varying results across these studies, it is difficult to make definitive conclusions. However, the lack of relationship found by Wichman between early success on the detour task and onset of perching behavior suggests this task may not be relevant to use of vertical space.There is growing evidence in the literature that vertical complexity of the rearing environment of pullets can impact spatial abilities of domestic laying hens. However, tasks such as the hole board test, radial maze, and detour task only test spatial navigation and memory and this is done on a single geometric plane, the ground. Adult hens utilize three dimensional space and therefore their spatial cognitive abilities should also be investigated in relation to depth. While these tasks evaluate spatial memory in hens, a useful skill for finding resources in the aviary, they are not appropriate for assessing visual perception as it relates to navigating around structures in the aviary. In contrast, the jump test does use three-dimensional space and does not directly test spatial memory, making it more relevant to the use of vertical space in commercial aviaries. However, due to the increasing physical difficulty of this test, visual perception and physical skill cannot be separated. There is a great need to study the depth perception of laying hens in relation to complexity of rearing treatment by using both a floor test and a test that utilizes three dimensional space. This methodology would allow for the comparison of performance on both two-dimensional and a three-dimensional test, square plastic plant pots providing greater evidence for the translation of floor tests of spatial cognition to the use of vertical space. It is also important to investigate depth perception as this aspect of spatial cognition has not been specifically evaluated in relation to rearing environment. Adequate perception of depth seems to be vital for gauging the distance to fly or jump between perches and platforms in an aviary. Without proper depth perception, collisions and falls would be likely to occur due to misjudgment of distances.The aim of this study is to gain a better understanding of how rearing environment impacts the cognitive and spatial development of laying hens by examining the development of depth perception. Laying hens reared in three environments of differing vertical complexity were tested on a Y-maze and visual cliff task to evaluate depth perception acuity. Both tasks utilize hens’ motivation to escape after being caught and handled, by offering them the option to exit the experimental apparatuses. Previous studies have used food or social rewards in spatial cognition tasks. In this study, variance in responses due to appetite or sociality was removed by utilizing the hens’ motivation to escape. The Y-maze uses arms of varying lengths to determine if the bird can assess distance and choose the shortest path to escape. The visual cliff was used to evaluate perception of depth as well as method of crossing the visual cliff. In order to account for the disadvantages associated with the traditional visual cliff test, the plexiglass was illuminated and the table was covered with a canopy to reduce reflection.

Additionally, a perch was added in the center of the table, 15 cm above the plexiglass. This prevented tactile information from pecking the glass and the birds’ feet, further concealing the plexiglass. These tests offer greater insight into the topic of spatial cognitive development by examining a previously overlooked, yet relevant aspect of spatial cognition: depth perception.Data Collection At each of three time points a sample of 150 Dekalb White hens were tested . Due to camera malfunctions, video data from three birds were excluded from the visual cliff data set. An equal number of birds were randomly selected from each of three rearing treatments. All birds were tested on the Y-maze task the first week and the visual cliff the second week of testing. Birds were caught from their home pen just prior to testing by corralling them with a metal catch pen. All trials were recorded using a Sony Action Camera and specific behaviors were coded from the video data using Noldus Observer XT . Y-Maze The Y-maze was constructed out of 1 m high wooden boards and included a starting chamber and two arms . The starting chamber was 40 cm long and 60 cm wide, with a guillotine door. The two arms of the maze were 60 cm wide and were joined at a 50o vertex. The arms were adjustable in length so that each arm could be either 30 cm or 90 cm long. The maze was covered by soft, plastic black mesh, preventing the birds from flying out. Both arms were open at the end, allowing the bird the choice to escape into an arena via one of the arms. Chalk lines were drawn where the entrance met each arm of the maze to indicate that the bird had entered an arm of the maze. Additional lines were also drawn at 30 cm from the entrance to mark the point the bird had chosen that side of the maze. Birds were tested with two consecutive trials where the length of each arm varied so that the birds are presented with a 1:3 ratio and a 1:1 ratio .The Y-maze was randomly configured into one of three different orientations: equal length arms or unequal with either the right or left arm being shorter in length. The equal configuration had a 1:1 ratio , while the unequal configuration consisted of a 1:3 ratio . A bird was randomly selected, caught using a catch pen, and assigned an ID number. The bird was then placed into the entrance of the maze facing the vertex of the two arms of the maze. When the bird was placed, a timer was started and the guillotine door of the entrance was closed behind them. If the subject had not exited the maze after two minutes had elapsed, the guillotine door was lifted and then immediately closed to encourage movement of the bird out of the maze. Trials ended after the bird had successfully crossed one of the 30 cm lines or after 2.5 minutes had elapsed. Trials were then repeated once more with the same individual so that each bird was presented with both the equal and the unequal configuration. Time spent in each arm, exit choice, and frequency of flying within or out of maze was recorded . The exit choice was considered correct if, when presented with arms of different lengths, the bird chose the shortest path to the arena . Visual Cliff Two visual cliff tables were used. A small table was used for the 8-week-old pullets while a larger table was used for the 16 and 30-week-old birds . This allowed for the proportions of the table to remain consistent as the birds grew.

The price premium is significant for almond and alfalfa . However, organic almonds suffer from an average 20% of yield loss, which hinders the transition . For alfalfa, the price depends on the organic status as well as quality, which is hard to control for organic growers due to weed and pest pressures . The z-test results in Table 1.3 and Table 1.4 show that the coefficients of Organicare similar to or larger, in absolute value, than those in the full sample estimation, which implies that the difference between two production systems are larger in the sub-sample than full sample.Differences in environmental impacts between organic and conventional production vary across crops. The full-sample regression is estimated for selected crops individually, except for lettuce where an additional time dummy is added to split the sample in half, to highlight important patterns of pesticide use in conventional and organic production. The specifications without grower or field fixed effects provide similar results and therefore results are not presented here for individual crops. The PURE index values are plotted for conventional and organic lettuce fields in Figure 1.4. The risk index from pesticides used in conventional lettuce fields decreased since growers have gradually transitioned from organophosphates to pyrethroid and neonicotinoid insecticides over the past twenty years and organophosphate insecticides are more toxic than their pyrethroid and neonicotinoid alternatives . Prior to 2005, diazinon was the most used insecticide in conventional lettuce production while the usage of lambda-cyhalothrin , was limited in lettuce.

However, by 2015, blueberry grow bag size lambda-cyhalothrin was the most used insecticide in conventional lettuce fields while fewer than 30 acres of lettuce were treated with diazinon. Consistent with these changes, in Table 1.5, the coefficients for Organic × 06_15 are significant and positive showing that the difference in the environmental impacts from pes-ticides use between conventional and organic lettuce production decreased in the second half of the study period. In Table 1.6, differences in environmental impacts between conventional and organic strawberries are largely driven by the environmental impacts of pre-plant soil fumigation, which is used by conventional but not organic strawberry growers. Soil fumigation is a common practice for managing pathogens, nematodes, and weeds in conventional strawberry fields. While soil fumigants are most commonly regulated because of their negative effects on human health via the impact on air quality and ozone layer, most soil fumigants are also highly toxic to earthworms . Accordingly, the PUREindex for soil is large. Consequently organic strawberry production achieves a 78% reduction in the environmental impact on soil. Conventional strawberry production also poses higher impacts on surface water because several AIs are highly toxic to fish and aquatic invertebrates , including abamectin for controlling spider mites , malathion for white flies , and pyraclostrobin for gray mold . As a result, the coefficient of Organic for surface water is larger than average. The difference in the PURE index for air is smaller because azadirachtin and clarified neem oil, two primary AIs contributing to VOC emissions in the nonattainment area of Ventura , a major strawberry producing county, together accounted for 18% of treated acreage for organic strawberries.

Comparing the results in Table 1.7 with other tables in this section, organic processing tomato production reduces the environmental impact on air by a larger percentage than all organic production on average. The key difference between processing tomatoes and other crops is that processing tomatoes are more threatened by diseases than by insects or nematodes . The two most common diseases are powdery mildew and bacterial speck, which are treated with sulfur and copper hydroxide respectively in organic production . In 2015, the acreage treated with these two AIs accounted for 42% of total acreage treated for organic processing tomatoes. In comparison, the share of sulfur-and copper hydroxide-treated acreage is below 10% for production of lettuce and strawberries and 25% for all organic crops. These two AIs have lower VOC emissions than other AIs used in organic production such as pyrethrins, azadirachtin, and clarified neem oil, which together accounted for nearly 30% of treated acreage for organic lettuce and strawberries, 18% for organic processing tomatoes, and 18% for all crops. However, the impact is increasing as indicated by the positive coefficient for the variable Organic × Year. Wine grape production occurs in many regions in California, and pest and disease pressures vary across production regions due to different climate and soil conditions. In the North Coast production region, which includes Napa and Sonoma counties among others, powdery mildew is a common disease because the fungus prefers a cooler temperatures, ideally around 21◦C, to grow . Measured by treated acreage, 9 out of the 10 most used AIs are fungicides targeting powdery mildew in this area. In the San Joaquin Valley, in contrast, powdery mildew is rarely seen because of high temperatures. Due in part to the large number of frost-free days per growing season, insects are the primary concern .

For wine grapes, the most used AIs beside sulfur are abamectin targeting spider mites, imidacloprid targeting vine mealybugs, and methoxyfenozide targeting lepidoptera . These insecticide AIs aremore toxic for humans, earthworms, and honeybees and have larger VOC emissions than the fungicides used for powdery mildew , so the estimated intercept in Table 1.8 is larger in the San Joaquin Valley than in Napa and Sonoma counties and the state as a whole for groundwater, soil air, and pollinators. Powdery mildews in grapes are often treated with sulfur . In 2015, table, wine, and raisin grapes accounted for 77% of acreage treated with sulfur among all crops. To control powdery mildew, organic growers also rely on bio-ingredients such as Bacillus pumilus and Bacillus subtilis, which have larger VOC emissions than sulfur and mineral oils. Thus, organic wine grapes growers in Napa and Sonoma counties only achieve a 38% reduction in the PURE index for air while the reduction in the San Joaquin Valley is 45%.Using a consistent index, this essay quantifies the environmental impacts of pesticide use in conventional and organic fields and how they have changed over time. Information from this analysis could benefit organic crop production worldwide because California is an important production region with a diverse set of crops and environmental conditions. Previous studies rarely focused on the use of specific AIs or the change in the structure of pesticide use when evaluating the environmental impact of organic agriculture. To the best of my knowledge, the PUR database has never been used to compare pesticide use for conventional and organic production. The U.S. organic agriculture sector has grown significantly over the past two decades, after the launch of the NOP in 2002. Organic farming has the potential to continue to ex-pand in the future. Pesticides are essential for both conventional and organic crop production. However, pesticide use is not static. The pesticide portfolio changed dramatically for both farming systems in the study period. Based on field-level pesticide application information, this essay shows that the environmental impact of pesticide use on air increased in organic fields due to the adoption of new chemicals and the reduction in the use of sulfur, which has zero VOC emissions. Pesticides used in organic agriculture had lower environmental impacts per acre on surface water, groundwater, soil, air, blueberry box and pollinators depending on the pesticide portfolios for conventional and organic growers. However, the difference between two systems is decreasing over time for all five dimensions. Notably, they had almost the same level of VOC emissions in 2015. In both production systems, increases in growers’ total acreage were associated with increases in the environmental impacts of pesticide use in all dimensions. Increases in grower experience were associated with increases in the environmental impacts of pesticide use to surface water and groundwater, and decreases in the impacts on soil, air, and pollinators. The magnitude of effects of these two variables is smaller than the effect of the organic status of the field. Pesticide use in organic agriculture has evolved to have greater environmental impacts over time. This is consistent with findings in Läpple and Van Rensburg , who showed that late adopters, those who adopted organic farming after the launch of government supporting program, are more likely to be profit-driven and less likely to be environmentally concerned than early adopters. New policy instruments could alter the current situation.

When reviewing pesticide and fertilizer AIs used in organic agriculture, the NOSB could focus on environmental criteria such as VOC emissions, which has not been considered previously. Such policy instruments could partially offset the negative environmental impacts of pesticide used in organic fields. Whether organic farming is the most cost-effective way to reduce the environmental impacts of agriculture remains unclear because the changes in PURE index values does not directly translate to a one-dimensional environmental or food safety benefit that is comparable across commodities or farming methods. An alternative approach to reducing environmental impacts is to regulate pesticide use directly, which could have a significant cost. For example, the ban of methyl bromide was estimated to result in an annual revenue loss of $234 million and a 10% revenue loss for the strawberry industry in California . However, as the result shows, the PURE air index for strawberry did not decrease in conventional production after the ban. In addition, the groundwater index value increased because alternatives to methyl bromide have a greater impact on groundwater. In previous studies, demographic variables, such as gender and education, were shown to be determinants of the adoption of organic farming . Here, these characteristics are addressed by using time-invariant grower fixed effects. More information regarding the determinants of pesticide use decisions might be revealed if those characteristics data were available. Future research could focus on impacts on human health rather then the environment and cal-culate the monetary value of reduced mortality and morbidity of converting to organic production. And, estimating the value of improved environmental quality associated with organic agriculture, identified in this essay, is another research direction. While pesticide use remains important for both farming systems, another caveat is that this essay does not investigate the environmental impacts of non-chemical pest management practices, such as biological, cultural, and mechanical/physical controls. However, if one were to pursue that direction by collecting data on non-chemical practices, the analysis would necessarily be done on a relatively small scale, unlike the comprehensive data used here.Organic agriculture has been proposed as an essential part of sustainable food systems . In 2016, over 5 million acres of land were certified organic in the United States, which generated over $7.5 billion worth of agricultural products. California is the leading state as a producer of organic crops in the United States, accounting for 12% of organic cropland and 51% of crop sales value in 2016 . According to Willer and Lernoud , the United States is the largest market for organic products and accounted for 43% of global organic retail sales in 2017. Organic land use data for California have been collected for a limited number of years by two government agencies, the United States Department of Agriculture and the California Department of Food and Agriculture . Farm-level acreage and location information are not publicly available from either source. Detailed crop acreage data would facilitate further investigation of key topics such as the spatial distribution of organic fields, which previously could be studied only at a very small geographic scale using other data sources . In this context, California’s unique Pesticide Use Report database serves as an alternative source of very detailed and long-term data, which allows the identification of individual organic fields based on their historical pesticide use records. The PUR database contains information on all commercial agricultural pesticide use in California since 1990, including information on the chemicals used, crops and acreages for millions of individual applications. Pesticide use patterns for organic fields and their environmental impacts have not been studied previously. Existing studies often evaluate the environmental performance of organic agriculture as a system, rather than focusing on specific farming practices . To the best of my knowledge, no study has quantitatively described pesticide use in organic agriculture or assessed its environmental impacts for ecosystems on a large scale across numerous crops and over a long time period .