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付記する学位プログラム名: 霊長類学・ワイルドライフサイエンス・リーディング大学院 / 京都大学 / 新制・課程博士 / 博士(理学) / 甲第24780号 / 理博第4974号 / 新制||理||1710(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 明里 宏文, 准教授 足立 幾磨, 教授 平田 聡 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

<p>Dairy calves in the preweaning period are exposed to a variety of stressors (e.g. disbudding, castration, etc.) and management practices that have the potential to influence their health and productivity later in life. Proper colostrum management at birth is the first step in ensuring calves can reach their full potential in terms of health, growth, and development, while improper management increases a calf’s risk of failed transfer of passive immunity <strong>(FTPI)</strong> which puts the calf at an increased risk of morbidity and mortality. Previous research has indicated there is a difference in colostrum management practices between dairy bull and heifer calves. Due to the marketing of dairy-beef crossbred calves as surplus animals along with dairy bull calves, there is growing interest in the treatment of these calves on farms. The first study presented here (Chapter 2) investigated the relationship between colostrum management practices on 15 farms and the prevalence of FTPI between purebred dairy and dairy-beef crossbred calves on those farms. The results of this study found no influence of calf breed (purebred dairy or dairy-beef crossbred) on the prevalence of FTPI. However, farm tended to influence FTPI. There was also a significant influence of the reported timing of the first colostrum feeding on FTPI, with calves on farms reporting feeding colostrum within 1 hour of birth having decreased odds of experiencing FTPI. In addition to colostrum management at birth, calves are exposed to several management factors during the preweaning period that can cause stressful experiences and result in negative behavioral and physiological outcomes. Early life stress, especially chronic stress, can negatively impact calves later in life. Short term stress load in calves can be quantified by measuring cortisol in the blood serum or saliva; however, these measures are not reflective of chronic stress load because they only measure circulating cortisol. The second study (Chapter 3) considered the efficacy of utilizing hair cortisol concentration <strong>(HCC)</strong> as a measure of stress load in 27 dairy calves exposed to a weekly saline injection or a weekly or biweekly repeated acute stressor (Cosyntropin injection) during the preweaning period. The results revealed no difference in HCC between the treatment groups, though salivary cortisol was increased in calves injected with Cosyntropin. Additionally, calf behavior and growth were not influenced by the treatments in this study. Overall, these studies provided insights into two areas that have not been extensively researched. First, considering dairy-beef crossbred calf management, and second investigating a method to assess chronic stress that has not been extensively researched in calves.</p>

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<p>  Broiler chickens are routinely exposed to various conditions, such as heat stress and stocking density, which may negatively influence their welfare status. This study examined the influence of a commercially available proprietary phytogenic feed additive (Probiotech International, Inc.) on welfare measures, environmental measures, productivity, body temperature, and behavior of commercial broiler chickens. Two flocks (Trials 1 & 2) utilized a total of 1,650 Ross 708 broilers housed in two separate rooms with floor pens at Purdue University’s ASREC Poultry Unit. </p> <p>  Trial 1 birds (n = 750) were divided into 20 separate pens (5 pens/treatment): PHD: phytogenic supplementation and raised at standard industry stocking density (37 kg/m²), PLD: phytogenic supplementation and raised at a lowered stocking density (27 kg/m²), CHD: control diet and raised at standard industry stocking density, and CLD: control diet and raised at a lowered stocking density. Due to the aromatic properties of the phytogenic additive, PHD and PLD birds were housed in one room and CHD and CLD birds were housed in another room. The feed supplement was mixed in at an inclusion rate of 0.25 g/kg. Phytogenic supplementation began at 15 d, coinciding with feeding the grower diet, and continued until 42 d when the study concluded. Heat stress was applied to all birds from 30 to 32 d, where the peak temperature did not exceed 34.4ºC. Welfare measures (gait, footpad dermatitis, hock burn, and feather cleanliness) and litter quality were assessed at 27 d and 39 d. Ammonia concentrations were measured at 35 d and 39 d. Productivity (body weight, feed intake, and feed conversion ratio) was measured weekly. Body temperature via thermography of the eye surface was collected at 29, 32, and 34 d. Behavior data were collected at the following periods for 2 continuous days: 23-24 d (Period 1), 31-32 d (Period 2), and 36-37 d (Period 3). </p> <p>  Trial 2 birds (n = 900) were assigned to 25 separate pens (5 pens/treatment) with the same groups as Trial 1, with an additional group (MHD): control diet, housed in the same room as PHD and PLD birds, and raised at standard industry stocking density. Phytogenic supplementation was provided as in Trial 1. Heat stress was again applied to all treatments from 30 to 32 d, where the peak temperature did not exceed 31ºC. Welfare measures and litter quality were collected at 27 d and 38 d. Ammonia concentrations were measured at 27, 31, and 38 d. Productivity was measured from 15 d to 27 d (grower phase), and 27 d to 38 d (finisher phase). Body temperature via cloacal temperature recording occurred at 29, 31, and 33 d. </p> <p>  Welfare data and litter quality were analyzed using PROC LOGISTIC (SAS 9.4); productivity data were analyzed using PROC MIXED (SAS 9.4); behavior data were analyzed using PROC GLIMMIX (SAS 9.4); and eye surface temperature, cloacal temperature, and ammonia concentration were analyzed using a nested mixed model found in the afex package using R (version 4.2.1) and R Studio (R Foundation for Statistical Computing). All statistical differences were considered significant when P < 0.05. Results of Trial 1 indicated that phytogenic supplementation significantly influenced hock burn and feather cleanliness, body weight and feed conversion ratio, ammonia concentration, as well as Period 1 sitting, Period 2 drinking, preening, standing, and wing spreading, and Period 3 drinking, preening, sitting, standing, and walking behaviors. Results of Trial 2 indicated that diet had no effect on any measured parameter. The variation in results suggests that factors such as stocking density or management strategies influenced the measured parameters, rather than diet alone. More research is needed to understand the specific effects of phytogenic feed additives, social and environmental stressors and whether phytogenic feed additives can improve bird performance and welfare under longer heat stress periods.</p>

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Surgical castration of young male piglets is an extremely common husbandry procedure in the United States swine industry, with nearly 100% of males castrated. The procedure is performed primarily to prevent the occurrence of boar taint in the meat and to reduce aggression as the animals age. No research has investigated the impact of surgical castration on the long-term mood states – also known as the affective state – of piglets, but it has been proven to cause both acute and chronic pain that can last up to 4 days, modify piglet behavior, and reduce weight gain. Because of this, feasible approaches for pain alleviation are needed. A hinderance to this is that currently no analgesics are approved for piglets. In addition, we need validated, practical methods to recognize pain in piglets in order to help researchers, veterinarians, and caretakers to identify the need for analgesics. One useful tool for this could be the Piglet Grimace Scale, which has previously been validated in this context, but is not widely applied. The current lack of analgesic use during castration may be cause for concern for consumers, however little is known about the public's knowledge on the industry's practices. Therefore, the thesis' objectives are to (1) assess the impact of surgical castration on pain and affective states, (2) determine people's ability to recognize pain expression after surgical castration, and (3) get insights into public perception of swine industry practices. In Chapter 3, we assessed the impact of surgical castration and practical pain alleviation methods during and after castration on piglets' short and long-term affective states and activity levels. Piglets were surgically castrated, castrated with analgesics, or sham-handled at 3 days of age. Data on piglets' activity (using accelerometers), tails (affective states), and grimaces (pain expression) were collected for 1, 6, and 24 hours after castration treatments while piglets were in their home pens. An attention bias test was then performed in week 1 and 12 to assess anxiety (an affective state). Home pen activity after castration treatments suggested that there was a positive impact of using analgesics. The piglets' behavior (eating) and activity during the attention bias test at week 1 suggest a negative impact of castration on affective states. The differences observed in week 1 were no longer found in week 12, suggesting that any impact of surgical castration at 3 days of age on affective states are no longer detectable at 12 weeks of age. In Chapter 4, through an online survey we investigated the validity and reliability of Piglet Grimace Scale ratings applied by swine industry professionals and the general public, to assess its potential utility in non-research settings. The survey contained a training, followed by 9 piglet images showing facial expressions immediately after castration or sham-handling. Both response groups were able to recognize pain in castrated piglets. However, both response groups overestimated pain experience compared to trained experts, suggesting more training may be necessary. Nevertheless, overall, the scale can be widely applied by veterinarians, industry professionals and even members of the public. In Chapter 5, a survey provided initial insights into public knowledge and perceptions on castration and analgesia use and compared this to industry stakeholders. The results show that knowledge on industry practices was especially lacking for public respondents, but also for a minority of industry respondents, indicating opportunities for education and further research on the topic. / Master of Science / Surgical castration is performed on nearly every male piglet in the United States swine industry. Males are castrated to prevent the occurrence of boar taint and to reduce aggression. Boar taint is the unpleasant odor produced by the skatole and androsterone in the fat when the meat is prepared. It is unclear how this practice impacts piglet's long-term mood states (affective states), but we do know it causes pain, changes in behavior, and reduced productivity. Thus, we need feasible approaches for pain relief. However, there are currently no pain relievers approved for piglets. In addition, we need validated, practical methods to quantify pain in piglets in order to identify the need for pain relief. One useful tool is the Piglet Grimace Scale, which is validated but is not widely applied. The current lack of pain relief use during castration may concern consumers, yet no data is collected on this. Therefore, the thesis' objectives are to (1) assess the impact of surgical castration on pain and affective states, (2) determine people's ability to recognize pain expression after surgical castration, and (3) get insights into public perception of swine industry practices. In Chapter 3, we assessed the impact of surgical castration and practical pain alleviation methods during and after castration on piglets' short and long-term affective states and activity levels. Piglets were surgically castrated, castrated with analgesics, or sham-handled at 3 days of age. Home pen activity after castration treatments showed a positive impact of using analgesics. The piglets' behavior and activity during an attention bias test at week 1 suggest that piglets were experiencing a negative emotional state after castration. The differences seen in week 1 were no longer found in week 12. This suggests that any potential impact of surgical castration on affective states are no longer detectable at 12 weeks of age. In Chapter 4, an online survey was used to investigate the Piglet Grimace Scale ratings applied by swine industry professionals and the general public. After training, respondents scored 9 images showing facial expressions of piglets after castration or sham-handling. Both public and industry people were able to recognize pain in castrated piglets. However, both response groups overestimated the pain experience compared to trained experts, suggesting more training may be necessary. Nevertheless, overall findings suggest that the scale can be widely applied. In Chapter 5, a survey provided insights into public knowledge and perceptions on castration and pain relief use in the industry, and compared this to industry stakeholders. The results showed that knowledge on industry practices was especially lacking for public respondents, but also for a minority of industry respondents, indicating opportunities for education and further research on the topic.