Determination deviation method for evaluating negative emotions of laying hens

Abstract

The invention discloses a deviation judgment method for evaluating negative emotions of laying hens, belongs to the technical field of animal husbandry, and provides the deviation judgment method for evaluating the negative emotions of the laying hens in order to judge the negative emotions of the laying hens, the laying hens are placed in a site provided with a starting area and a test area, and the negative emotions of the laying hens are evaluated by changing the color of a pecking trough cover plate. And observing the pecking time of the laying hens in the test area to judge the emotions of the laying hens. According to the method, the emotional change of the laying hen is evaluated by rapidly and accurately judging the deviation test result, and a theoretical basis is provided for the laying hen production practice process.

Description

Technical Field

[0001] The invention belongs to the technical field of animal husbandry, and in particular relates to a judgment bias method for evaluating negative emotions of laying hens. Background Art

[0002] As global attention to sustainable food production continues to grow, the welfare of commercially farmed laying hens has gradually become a hot topic of discussion in academia and the public. The commercial laying hen farming model often pursues maximum production, often ignoring the living conditions and psychological needs of laying hens. Laying hens may experience a variety of stressors during the farming process, such as crowded environments, improper feeding and management, or changes in social structure. These factors have led to the emergence of many welfare issues and induced negative emotions in laying hens. Negative emotions not only affect the health and production performance of laying hens, but may also have a profound impact on their behavioral performance. Therefore, accurately evaluating and testing the negative emotions of laying hens has become a key link in animal welfare research.

[0003] Since birds cannot make facial expressions or communicate verbally, we cannot directly perceive the emotional changes of laying hens. The emotional state of laying hens is usually assessed through physiological index detection, behavioral video observation, and behavioral testing. The present invention aims to provide a behavioral testing method for accurately judging the negative emotions of laying hens, and to evaluate the emotional changes of laying hens by judging the deviation test results, in order to provide a theoretical basis for the practical process of laying hen production. Summary of the invention

[0004] The purpose of the present invention is to provide a judgment bias method for evaluating negative emotions of laying hens.

[0005] The present invention provides a method for evaluating the judgment bias of negative emotions in laying hens, and the specific steps of the method are as follows:

[0006] Step 1: Site design: The site is divided into two parts. The first part is the test area 6, which is set as a double right-angled symmetrical hexagon;

[0007] The second part is a starting area 12 in the long direction. The test area 6 and the starting area 12 are separated by a movable baffle 11. The dividing part is on one side of the short side of the first part. A square decision area 10 is divided at the long side of the test area. A feeding trough 9 and a cover are provided in the center of the decision area. The food that the laying hens like is placed in the feeding trough, and a blowing device 8 is provided above it.

[0008] Step 2: Judgment bias test:

[0009] Step 2.1: Adaptation phase: Select laying hens and place them from the starting area into the arena for 5 minutes two days before the experiment to adapt to the arena. During the adaptation phase, the partitions are removed and the laying hens move freely in the arena.

[0010] Step 2.2: Training phase: In the association training phase, mealworms are added to the trough 9 in the decision area 10 in the test area, and a white cover is put on it. The laying hens are transported into the starting area 12 of the test site in a black plastic basket, and the baffle 11 is covered;

[0011] At the beginning of the training, there was a white cover on the trough. The baffle was removed and the laying hens entered the experimental area 6. The laying hens were observed to see if they pecked at the mealworms in the white-covered trough. The latency of the laying hens to peck was recorded. If they did not peck, the longest time was 30 seconds, which was recorded as failure. Each laying hen was trained 8 times a day. Each laying hen that achieved a success rate of more than 75% per day was recorded as completing the training. The laying hens that completed the training for 3 consecutive days were recorded as passing the training. If the laying hens did not achieve a success rate of more than 75%, they were considered to have failed. They were judged as the negative emotion group and did not enter the visual discrimination training stage.

[0012] During the visual discrimination training phase, the mealworms in the trough were removed, a black cover was put on, and the laying hens were placed in the starting area. The baffle was removed and the timing was started. The latency of the laying hens pecking at the trough with the black cover was recorded. The laying hens would be punished by the blowing device if they pecking at the black cover. Pecking at the black cover was recorded as failure, and not pecking at the black cover within 30 seconds was recorded as success. Each laying hen was trained 8 times a day. A success rate of more than 75% per day was recorded as completed training. A laying hen that completed the training for 3 consecutive days was recorded as passing the training. If the laying hen failed to achieve a success rate of more than 75%, it would be considered a failure and the laying hen would be judged as a laying hen with positive emotions.

[0013] Step 2.3: Experimental stage: add fuzzy stimulation, which are 25% gray and 50% gray lids, respectively. No mealworms are placed in the trough under the lid. Place the laying hen in the starting area, remove the baffle and start timing. During the test, each laying hen conducts 16 trials, which are four positive stimulations of white lids, four aversive stimulations of black lids and four fuzzy stimulations of two gray lids, which appear randomly but not repeatedly. Record the latency of the laying hen approaching and pecking the gray lid. The latency is the latency of the laying hen pecking the gray lid from the removal of the baffle until the laying hen finishes pecking the lid. If there is no pecking, the longest time is 30s.

[0014] Step 3: Take the average of the latency of each tested laying hen to the fuzzy stimulus during the test phase in step 2.3. If the average test latency of the laying hen is less than 20 seconds, it is defined as a laying hen with positive emotions; if it is greater than or equal to 20 seconds, it is defined as a laying hen with negative emotions.

[0015] It is further defined that in step 1, a square one-way mirror 7 with a side length of 5 cm is provided next to the feeding trough 9. The one-way mirror (7) is for the convenience of the operator to observe the movement of the laying hens, while the laying hens cannot perceive the operator.

[0016] It is further defined that the decision line in the middle of the site described in step 1 is drawn with a paint pen.

[0017] Further defined, the formula for the success rate of the daily training of laying hens in step 2.2 is: the number of successful tests of laying hens on that day / the total number of tests of laying hens on that day×100%.

[0018] It is further defined that the latency period of the laying hens pecking at the beginning of the training in step 2.2 is from the time when the baffle is removed until the laying hens finish pecking at the mealworms.

[0019] It is further defined that the latency period for the laying hen to peck at the trough with the black lid during the visual discrimination training phase in step 2.2 is from the time when the baffle is removed until the laying hen finishes pecking at the lid.

[0020] It is further defined that the order of the cover plate colors that appear randomly but non-repeatingly in 2.3 of step 3 is white, 25% gray, black, 50% gray, black, 25% gray, white, 50% gray, 25% gray, white, 50% gray, black, white, 50% gray, black, 25% gray.

[0021] Further defined, laying hens were acclimatized to medium-sized enrichment cages for one week prior to the judgment bias test.

[0022] It is further defined that an egg-laying box 1, a sand bath tray 3, two perches 2, a feeding trough 5 and a water line 4 equipped with two nipple waterers are provided in a medium-sized enrichment cage. The medium-sized enrichment cage is rectangular, and an egg-laying box 1 is provided on one side of the short side of the medium-sized enrichment cage, and a sand bath tray 3 is provided on the other side. The two perches 2 are located above the egg-laying box 1, one side of the perch 2 is connected to one side of the short side of the medium-sized enrichment cage, and the other side of the perch 2 is connected to the other short side of the medium-sized enrichment cage. The feeding trough 5 is located on one side of the long side of the medium-sized enrichment cage, and the water line 4 is located above the feeding trough 5, one side of the water line 4 is connected to one side of the short side of the medium-sized enrichment cage, and the other side of the water line 4 is connected to the other short side of the medium-sized enrichment cage. During the experiment, the laying hens are free to eat and drink, with 16 hours of light and 8 hours of darkness every day.

[0023] It is further defined that the medium-sized enrichment cage is 180 cm long and 90 cm wide, and the two perches 2 are 30 cm and 50 cm above the ground respectively.

[0024] Beneficial effects: The present invention uses a judgment bias test to judge the negative emotions of laying hens, explores whether various stress factors affect the emotions of laying hens in the process of commercial breeding, and causes the welfare of laying hens to decline, and provides a theoretical basis for improving the welfare and health indicators of laying hens in the commercial production process. The number of training times is 8 times, which is the normal number. The probability of success of the laying hen test will be very low if it is less than eight times. For laying hens that fail the test, the purpose of training cannot be achieved even if they are trained more than 8 times. After more than 8 times, laying hens will not learn to associate colors with rewards and punishments. This test site is set according to the size of the animal. The size of the site will also be adjusted for different species or different ages. This size is just suitable for the size of laying hens.

[0025] Decision-making area: This is also determined according to the body shape of the laying hen. It is the distance between the head and the paw of the laying hen when feeding. When the laying hen's paw steps into the decision-making area, it has already started to peck at the food in the trough. However, due to individual differences, some laying hens cannot open the cover on the trough in time to obtain food rewards. If calculated based on the time it takes for the laying hen to eat the mealworms, there will be errors in the experiment. Therefore, this decision line is set, and the laying hen is considered successfully completed when it steps into this area.

[0026] The egg-laying box, sand bath tray, and perch are all indispensable devices for laying hens to express natural behaviors, and are also common facilities in enrichment cages. The sand bath tray is mainly used to allow laying hens to express sand bathing behaviors. The red cone represents the nipple drinker, the water line is the water supply device for laying hens, and the cylinder is used to fix the water line and has no other function. The medium-sized enrichment cage is 180cm long and 90cm wide in order to meet the density requirements of welfare breeding and the environmental adaptation of laying hens' emotional evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of a chicken cage, 1 is the egg-laying box, 2 is the perch, 3 is the sand bath, 4 is the water line, and 5 is the feeding trough;

[0028] Figure 2 Schematic diagram of the site for judging deviations, 6 is the test area, 7 is the one-way mirror, 8 is the blowing port, 9 is the feeding trough, 10 is the decision area, 11 is the baffle, and 12 is the starting area;

[0029] Figure 3 for Figure 3 Bar graph of mean latency for the judgment bias test for each laying hen;

[0030] Figure 4 The bar graphs of the two-factor analysis of the latency period of the laying hen test during the judgment bias training phase are shown in Figure 1. A is the bar graph of the association training phase, and B is the bar graph of the visual discrimination phase.

[0031] Figure 5 Survival analysis of the latency period of the laying hen test for the judgment of the deviation test; A is the survival analysis curve of the latency period of the laying hen pecking at 25% of the gray lid in the high latency group (H) and the low latency group (L), and B is the survival analysis curve of the latency period of the laying hen pecking at 50% of the gray lid in the high latency group (H) and the low latency group (L);

[0032] Figure 6 This is a bar graph comparing the concentrations of brain-derived neurotrophic factor (BDNF) and dopamine (DA) in the hippocampus of laying hens in group H and group L; A is a graph showing the results of brain-derived neurotrophic factor concentration in the hippocampus; and B is a graph showing the results of dopamine concentration. DETAILED DESCRIPTION

[0033] Example 1. A method for evaluating the bias of negative emotions in laying hens

[0034] Figure 1 This is a schematic diagram of a chicken cage. The length × width × height of the chicken house is 180 cm × 90 cm × 90 cm, the two perches are 50 cm and 30 cm above the ground respectively, the sand bathing tray area is 90 × 45 cm, and the egg-laying box is a rectangular parallelepiped with a length × width × height = 90 cm × 45 cm × 50 cm; Layer treatment: 240 laying hens were randomly selected from the farm and raised in a medium-sized enrichment cage, which was equipped with an egg-laying box, a sand bathing tray, and two perches (30 cm and 50 cm above the ground respectively). During the experiment, the laying hens had free access to food and water, 16 h of light and 8 h of darkness per day, and the laying hens were raised for one week to adapt to the new environment.

[0035] Step 1: Site design, Figure 2 Schematic diagram of the site for judging deviations. Covers of different colors were placed on the troughs so that the laying hens could not see whether there were mealworms in the troughs. The site was divided into two parts. The first part was the experimental area 6, which was set up as a double right-angled hexagon with a long side length of 120 cm, a short side of 25 cm, and two right-angled sides of 50 cm;

[0036] The second part is the starting area 12, which is set as a rectangle with a length × width of 60 cm × 25 cm. The test area 6 and the starting area 12 are separated by a movable baffle 11, and the dividing part is on the short side of the first part. The test area is marked with a 25 cm × 25 cm decision area 10 on the long side (the decision line in the middle of the venue is drawn with an oil pen to prevent fading. It also prevents the laying hens from pecking with tape). A trough 9 and a cover are provided in the center of the decision area. A one-way mirror 7 is provided next to the trough 9 (it is convenient for the operator to observe the movements of the laying hens, while the laying hens cannot perceive the operator, provided that the room is well lit, otherwise the one-way mirror effect is affected. The laying hens were fully adapted before the test. During the test, almost no laying hens were attracted by the mirror, that is, its effect on the laying hens can be ignored. The square is 5 cm in length). The laying hens' favorite food is placed in the trough, and a blowing device 8 is provided above it;

[0037] Step 2: Judgment bias test:

[0038] Step 2.1: Adaptation phase: Select laying hens and place them in the arena for 5 minutes two days before the experiment to adapt to the arena;

[0039] Step 2.2: Training phase: In the association training phase, mealworms are added to the trough 9 in the decision area 10 in the test area, and a white cover is put on it. The laying hens are transported into the starting area 12 of the test site in a black plastic basket, and the baffle 11 is covered;

[0040] At the beginning of the training, the cover was removed, and the laying hens started timing from then on. The laying hens pecking at the mealworms under the white cover was recorded as successfully completing the training and recording the latency (the latency of the laying hens pecking was from the removal of the baffle plate to the end of the laying hens pecking at the mealworms). If they did not peck, the longest time was recorded as 30 seconds and recorded as failure. Each laying hen was trained 8 times a day, and each laying hen achieved a success rate of more than 75% per day and was recorded as completing the training. Laying hens that completed 3 consecutive days were recorded as passing this training; if the laying hens did not achieve a success rate of more than 75%, they were directly returned to the negative emotion group and did not enter the next experiment;

[0041] During the visual discrimination training phase, the mealworms in the trough were removed, a black cover was put on, and the laying hens were placed in the starting area. The baffle was removed and the timing was started. The latency of the laying hens pecking at the trough with the black cover was recorded (the latency of the laying hens pecking at the trough with the black cover was from the removal of the baffle until the laying hens finished pecking at the cover). When the laying hens pecked at the black cover, they were punished by using an air blowing device. Pecking at the black cover was recorded as failure, and failure to peck at the black cover within 30 seconds was recorded as success. Each laying hen was trained 8 times a day. A success rate of more than 75% per day was recorded as completing the training. Laying hens that completed the training for 3 consecutive days were recorded as passing the training. If the laying hens failed to achieve a success rate of more than 75%, they were directly returned to the positive emotion group and did not enter the next experiment.

[0042] Step 2.3: Experimental stage: add fuzzy stimulation, which are 25% gray and 50% gray covers (using color hexadecimal code, gray is made by adding 25% or 50% dark color to white in power point, 25% gray code is #BFBFBF and 50% gray code is #7F7F7F), no mealworms are placed in the trough under the cover, the laying hens are placed in the starting area, the baffle is removed and the timing is started. During the experiment, each laying hen conducts 16 trials, positive stimulation of the white cover, aversive stimulation of the black cover and two fuzzy stimulations four times each (white, 25% gray, black, 50% gray, black, 25% gray, white, 50% gray, 25% gray, white, 50% gray, black, white, 50% gray, black, 25% gray), record the latency of the laying hen approaching and pecking the gray cover, if it does not peck, record the longest time of 30s, and take the average of 8 times;

[0043] Step 3: Data statistics and analysis: The average value of the latency (s) of each laying hen approaching the fuzzy stimulus during the test phase was taken, and the hen was divided into two groups based on 20 seconds. The group with a latency greater than or equal to 20 seconds was set as the high latency group (H), and the group with a latency less than 20 seconds was set as the low latency group (L). The groups are shown in Figure (3). A two-way ANOVA was performed with the number of training days and grouping as independent variables and the pecking latency as the dependent variable, and a curve was drawn. The success rate of training for each laying hen per day was calculated (formula: number of successful tests of laying hens on that day / total number of tests of laying hens on that day × 100%).

[0044] Enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of brain-derived neurotrophic factor (BDNF) and dopamine (DA) in the hippocampus of the two groups of laying hens to determine the emotional state of the laying hens.

[0045] Figure 3 The bar graph of the average latency of the judgment bias test for each laying hen is shown. With 20 s as the boundary, groups with latency greater than or equal to 20 s are marked as group H, and groups with latency less than 20 s are marked as group L.

[0046] Figure 4 The two-way analysis bar chart was drawn using the latency data of laying hens approaching the covered trough during training obtained in step 2.2. The results showed that the latency of the laying hens in group L for associative training was lower than that in group H for laying hens (P<0.01), and there was no difference in the latency of visual discrimination training (P>0.05).

[0047] Figure 5 This is a survival analysis chart of the latency period of the laying hens in the bias test. The results showed that the latency period of the laying hens in the L group to peck at the gray lid was significantly lower than that in the H group (P<0.01).

[0048] Figure 6 This is a bar chart comparing the concentrations of brain neurotrophic factor (BDNF) and dopamine (DA) in the hippocampus of laying hens in group H and group L. The results show that the concentrations of BDNF and DA in the hippocampus of laying hens in group L are higher than those in group H. Brain-derived neurotrophic factor (BDNF) plays a key role in neuroplasticity, learning and memory. Studies have shown that changes in BDNF levels are associated with mood disorders such as depression and anxiety. BDNF promotes the survival and growth of neurons and helps improve emotional states. Dopamine is an important neurotransmitter associated with reward mechanisms, motivation and pleasure. Dopamine disorders are closely related to emotional problems such as depression and anxiety. The reduction of the two indicators indicates that the animals are in a negative emotional state, that is, the experiment proves that the laying hens in group H are more negative.

[0049] Conclusion: In the judgment bias test, the laying hens in group H showed a longer pecking latency than those in group L. In psychology, the relationship between judgment bias and emotion is reflected in how emotional state affects individual cognitive processing and information processing. When individuals are in a negative mood, they are more likely to make negative judgments and selectively focus on information consistent with their emotions. In addition, emotional state also affects the attribution style of individuals, making them tend to attribute failure to their own factors, thereby exacerbating negative emotions. The interaction between these emotional reactions and judgment bias may form a cycle, further affecting decision-making ability and judgment of reality. In the judgment bias test, the gray lid is an ambiguous stimulus for laying hens. Laying hens with more negative emotions are more inclined to believe that it is a punishment stimulus and are unwilling to approach it, indicating that the laying hens in group H tend to have a more negative understanding of ambiguous stimuli and have more negative emotions.

[0050] The latency grouping was set to a fixed value of 20s. Laying hens with an average test latency of less than 20s were defined as laying hens with positive emotions, and those with an average test latency of greater than or equal to 20s were defined as laying hens with negative emotions.

Claims

1. A method for evaluating the judgment bias of negative emotions in laying hens, characterized in that: The specific steps of the method are as follows: Step 1: Site design: The site is divided into two parts. The first part is the test area (6), which is set as a double right-angled symmetrical hexagon; The second part is a starting area (12) in the long direction. The test area (6) and the starting area (12) are separated by a movable baffle (11). The separation is on the short side of the first part. A square decision area (10) is divided on the long side of the test area. A feeding trough (9) and a cover are provided in the center of the decision area. The food that the laying hens like is placed in the feeding trough. An air blowing device (8) is provided above. Step 2: Judgment bias test: Step 2.1: Adaptation phase: Select laying hens and place them from the starting area into the arena for 5 minutes two days before the experiment to adapt to the arena. During the adaptation phase, the partitions are removed and the laying hens move freely in the arena. Step 2.2: Training phase: During the association training phase, mealworms are added to the feeding trough (9) in the decision area (10) in the test area and covered with a white cover. The laying hens are transported into the starting area (12) of the test area in a black plastic basket and the baffle (11) is covered. At the beginning of the training, there is a white cover on the trough. The baffle is removed and the laying hens enter the test area (6). The laying hens are observed to see if they peck at the mealworms in the white-covered trough. The latency of the laying hens to peck at the mealworms is recorded. If they do not peck at the mealworms, the longest time is 30 seconds, which is considered a failure. Each laying hen is trained 8 times a day. Each laying hen that achieves a success rate of more than 75% per day is considered to have completed the training. A laying hen that completes the training for three consecutive days is considered to have passed the training. If a laying hen fails to achieve a success rate of more than 75% even once within three days, it is judged to be in the negative emotion group and does not enter the visual discrimination training stage. During the visual discrimination training phase, the mealworms in the trough were removed, a black cover was put on, and the laying hens were placed in the starting area. The baffle was removed and the timing was started. The latency of the laying hens pecking at the trough with the black cover was recorded. The laying hens would be punished by the blowing device if they pecking at the black cover. Pecking at the black cover was recorded as failure, and failure to peck at the black cover within 30 seconds was recorded as success. Each laying hen was trained 8 times a day. Each laying hen was considered to have completed the training if it achieved a success rate of more than 75% per day. The laying hens that completed the training for three consecutive days were considered to have passed the training. If the laying hen failed to achieve a success rate of more than 75% even once within three days, it was judged to be a laying hen with positive emotions. Step 2.3: Experimental stage: add fuzzy stimulation, which are 25% gray and 50% gray lids, respectively. No mealworms are placed in the trough under the lid. Place the laying hen in the starting area, remove the baffle and start timing. During the experiment, each laying hen conducts 16 trials, which are four positive stimulations of white lids, four aversive stimulations of black lids and four fuzzy stimulations of two gray lids. The 16 trials are random but not repeated. The latency of the laying hen approaching and pecking the gray lid is recorded. The latency is the latency of the laying hen pecking the gray lid from the removal of the baffle until the laying hen finishes pecking the lid. If there is no pecking, the longest time is recorded as 30s. Step 3: Take the average of the latency of each tested laying hen to the fuzzy stimulus during the test phase in step 2.

3. If the average test latency of the laying hen is less than 20 seconds, it is defined as a laying hen with positive emotions; if it is greater than or equal to 20 seconds, it is defined as a laying hen with negative emotions.

2. The method according to claim 1, characterized in that In step 1, a square one-way mirror (7) with a side length of 5 cm is provided next to the feeding trough (9). The one-way mirror (7) is used to facilitate the operator to observe the movement of the laying hens, while the laying hens cannot perceive the operator.

3. The method according to claim 1, characterized in that: The decision line in the middle of the site described in step 1 is drawn with a pencil.

4. The method according to claim 1, characterized in that: The formula for the success rate of laying hen training every day in step 2.2 is: the number of successful tests of laying hen on that day / the total number of tests of laying hen on that day × 100%.

5. The method according to claim 1, characterized in that The latency period of the laying hens pecking at the beginning of the training in step 2.2 is from the time when the baffle is removed until the laying hens finish pecking at the mealworms.

6. The method according to claim 1, characterized in that According to the visual discrimination training phase in step 2.2, the latency period for the laying hen to peck at the trough with the black lid is from the time the baffle is removed until the laying hen finishes pecking at the lid.

7. The method according to claim 1, characterized in that In step 3, the order of the cover colors that appear randomly but not repeatedly in 2.3 is white, 25% gray, black, 50% gray, black, 25% gray, white, 50% gray, 25% gray, white, 50% gray, black, white, 50% gray, black and 25% gray.

8. The method according to claim 1, characterized in that Laying hens were acclimatized to the new environment in medium-sized enrichment cages for one week before the judgment bias test.

9. The method according to claim 8, characterized in that The medium-sized enrichment cage is provided with an egg-laying box (1), a sand bath tray (3), two perches (2), a food trough (5) and a water line (4) equipped with two nipple waterers. The medium-sized enrichment cage is rectangular. The egg-laying box (1) is arranged on one side of the short side of the medium-sized enrichment cage, and the sand bath tray (3) is arranged on the other side. The two perches (2) are located above the egg-laying box (1). One side of the perch (2) is connected to one side of the short side of the medium-sized enrichment cage, and the other side of the perch (2) is connected to the other short side of the medium-sized enrichment cage. The food trough (5) is located on one side of the long side of the medium-sized enrichment cage. The water line (4) is located above the food trough (5). One side of the water line (4) is connected to one side of the short side of the medium-sized enrichment cage, and the other side of the water line (4) is connected to the other short side of the medium-sized enrichment cage. During the experiment, the laying hens can freely eat and drink water, and the light is on for 16 hours and the dark is on for 8 hours every day.

10. The method according to claim 9, characterized in that The medium-sized enrichment cage is 180 cm long and 90 cm wide, and the two perches (2) are 30 cm and 50 cm above the ground respectively.

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