Source: UNIV OF MINNESOTA submitted to NRP
IMPROVING PERFORMANCE AND WELFARE OF SWINE IN ALTERNATIVE HOUSING SYSTEMS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1006999
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Oct 1, 2015
Project End Date
Sep 30, 2020
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIV OF MINNESOTA
(N/A)
ST PAUL,MN 55108
Performing Department
West Central Research & Outreach Center
Non Technical Summary
With current regulations and market-driven bans on use of individual gestation stalls, pork producers are considering to switch from gestation stalls to group housing for pregnant sows. Sows in group housing usually require more floor space to maintain productivity and welfare compared with individual housing in gestation stalls. However, providing additional floor space for group-housed sows will reduce output from a given known footprint and will likely reduce profitability. Producers are interested in group housing sows using the least possible space that does not compromise welfare of sows so that sow inventory and total output from the barn can be maintained.A scientifically-defined recommendation for space allowance of large group-housed sows does not exist. The minimal space allowance applied in the swine industry in the U. S. is 16 ft2 for group-housed gestating sows (Miller, 2012), which is close to the minimal space allowance of 15 ft2 recommended several years ago in Australia (PISC, 2007), but lower than recommendations in other countries. The EU standard for floor space allowance for gestating sows is 24 ft2 for sows, and 18 ft2 for gilts (European Commission Council, 2001). This standard varies with group size. When the number of sows in a group is more than 40, floor space allowance can be reduced by 10%, while with group size less than 6, space allowance should be increased by 10%. The Canadian recommendation for the minimal space allowance is 19 to 24 ft2 for sows and 15 to 18 ft2 for gilts (Gonyou et al., 2013). However, these standards were not determined scientifically under production-like conditions.In this project, we investigate the effect of floor space allowance on performance and welfare of sows housed in large groups with electronic sow feeders (ESF), with the ultimate goal of scientifically determining the minimal space allowance for group-housed gestating sows. The unique features of this project include:A controlled study conducted under commercial settings at a Research and Outreach Center of the University of Minnesota, generating results that are reliable and applicable to commercial swine farms in the United States. Evaluating space allowance based on evidence of performance, health, stress, and behaviors of sows under near-production conditions, so that the minimal space allowance canbe determined scientifically.
Animal Health Component
100%
Research Effort Categories
Basic
0%
Applied
100%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
31501991060100%
Knowledge Area
315 - Animal Welfare/Well-Being and Protection;

Subject Of Investigation
0199 - Soil and land, general;

Field Of Science
1060 - Biology (whole systems);
Goals / Objectives
Currently there is no scientifically-established recommendation for the minimal floor space allowance for group-housed sows in the United States. When building new barns for group-housing sows or retrofitting existing barns with gestation stalls to pens, producers tend to keep as many sows as possible in a pen to maximize output of the barn and maintain profitibility. However, overcrowding can cause complications in both welfare and performance of sows. So the minimal floor space required by a sow to ensure good performance and welfare of the sow and simultaneously maintain output of the barn needs to be investigated.The major goal of this project is to determine the minimal floor space allowance that will ensure acceptable performance and welfare of gestating sows kept in large pens with electronic sow feeders (ESF). By investigating effects of floor space allowance on reproductive performance, behavior, health and stress of gestating sows under near-production conditions, we will be able to define the minimal space allowance scientifically.
Project Methods
The study will be conducted at the University of Minnesota's Southern Research and Outreach Center in Waseca, MN. All gestating sows are group-housed in pens with an ESF on totally slatted floors. About 50 two sows will be managed as a static group in each pen across all treatments. Sows will have continuous access to ESF stations, and the EFS feeding cycle will start at 4 pm daily.Treatments The treatment will be floor space allowance for sows. Five existing pens will be modified by using adjustable partitions to achieve five treatments of space allowances excluding areas occupied by the ESF station: 22 ft2 (control), 20 ft2, 18 ft2, 16 ft2 per sow, and 16 ft2 per sow with more space during mixing. This range of space allowances is determined according to the EU and Canadian recommendations for minimal space allowance for gestating sows, and producers' desire to maintain sow inventory in current building when moving from stalls to pens. The first four treatments will enable us to investigate effects of space allowance on performance and welfare of sows, with the ultimate goal of determining the minimal space allowance for gestating sows in an ESF system. The fifth treatment is to test whether providing more space during the mixing period benefit sows that will ultimately be housed in the most crowded pens. For the fifth treatment, we will provide 22 ft2 of floor space during the first week after mixing, and then reduce space allowance to 16 ft2 per sow. Sows will remain at 16 ft2 per sow of floor space for the rest of the gestation period. The extra space provided during the first week of mixing (22 ft2 per sow) is close to the EU's standard, and 16 ft2 per sow is about the same space that sows housed in a barn with gestation stalls will occupy. The study will be conducted in 4 blocks of 5 pens for 20 total pens. A block will include one pen for each treatment. A group of about 50 sows from the same breeding cohort will fill an experimental pen every 2 weeks, so a block will be filled within 20 weeks. The same procedure will be repeated four times over a period of 40 weeks, with about 200 sows allotted to each treatment for a total of 1,000 sows assigned for the entire study. All sows will be housed in pens with ESF during their previous gestation, and no gilts will be included in the study. Sows will be weaned at about 3wks after farrowing and moved to gestation stalls. Sows will be mated and remain in stalls for five weeks. Five weeks after mating, about 50 sows (parity 1 to 9) that are diagnosed pregnant will be introduced into an experimental pen. Once assigned, sows will remain in the pen for the remainder of gestation. Sows that experience any health or welfare issues during the study will be treated and the treatment recorded. If necessary, compromised sows will be removed or humanely euthanized according to the SOP of the Center. When 2 or more sows are removed from a gestation pen, the pen size will be adjusted to maintain the floor space allowance. Room temperature will be controlled by a heating system and exhaust fans as close as possible to thermoneutral conditions for sows both in the gestation and lactation rooms. Lights in each room will be on for 10 h starting at 0600h in both barns.The data of reproductive performance, behavior, injury and salivary cortisol will be collected to evaluate effects of floor space allowance on performance and welfare of sows. Data will be analyzed using the Glimmix model of SAS with Poission procedures for nonparametric variables and the Mixed model for continuous varibles. Within each model, floor space allowance will be the fixed effect, block will be the random effect, and pen will serve as the experimental unit. Repeated measurements will be used to analyze treatment effects on response variables measured over time.

Progress 10/01/15 to 09/30/20

Outputs
Target Audience:The primaryaudiences for this project are pork producers and swine scientists interested in swine behavior, well-being, and alternative housing systems.The other audiences are veterinarians, swine extension educators, andAg professional who look for management strategies to improve swine performance and well-being in different housing systems. We have disseminated outcomes from the project to audiences through presentations and publications, along withindividual communications. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project provided educational opportunities for undergraduate students, graduate students, and visiting scholars through participating in swine welfare research and swine production, and engaging with pork producers in extension activities. The project also provided the research team (PD, Co-PD and investigators) opportunities of exchanging research ideas and results with other scientists at regional and national conferences, which enhanced professional development of our research team. How have the results been disseminated to communities of interest?Results of the project have been disseminated to pork producers, swine scientists and extension educators, and Ag professionals via presentations and publications. Pork producers are encouraged to determine the minimal floor space allowance using allometric principles with consideration of variation in sow body weight. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We achieved the goal by fulfilling three objectives: 1) to determine effects of floor space allowance on performance and welfare of the sow; 2) to develop an allometric equation to estimate the optimal floor space allowance for gestating sows; 3) to measure body condition (a welfare indicator) of sows objectively using a Sow Caliper. To achieve the first objective, we tested a wide range of floor space allowance (1.5, 1.7, 1.9, and 2.1 m2/sow) and did not observe effects of floor space allowance on sow performance or welfare. While these results suggest that the minimal floor space allowance of 1.5 m2/sow appears to be acceptable for maintaining performance and welfare of gestating sows under conditions of this study, it (1.5 m2/sow) is lower than the minimal floor space allowance recommended in Canada and the European Union. When applying results of this study in swine production, producers are encouraged to consider other factors which may affect the floor space allowances, such as housing and feeding systems used, management protocols adopted, and experience and body size of sows. The second objective was complementary to the first objective by including body size of the sow in determining the minimal floor space allowance. The recommended allometric equation for estimating the minimal floor space allowance was: A = 0.044 BW0.66, where A represents the minimal floor space allowance in m2/sow, and BW represent bodyweight of the sow in kg. Using this equation to calculate the minimal floor space allowance, producers will be able to provide more floor space for larger sows than for small sows. In fulfilling the last objective, we demonstrated that body condition affects sow performance and longevity, and consequently, sow welfare. Sow Caliper can be used to measure sow condition because sow caliper measurements were correlated with backfat depth. The project provided not only scientifically-established recommendations for minimal floor space allowance, but also a tool to calculate the minimal floor space allowance based on body weight of the sow, along with an objective method to evaluate body condition, an indicator of sow welfare to pork producers.

Publications

  • Type: Other Status: Published Year Published: 2017 Citation: Li, Y.Z., H. Zhang, L. Johnston, S. Baidoo, and S. Cui. 2017. Determining the Minimal Floor Space Allowance for Gestating Sows Kept in Pens with Electronic Sow Feeders. National Pork Board Final Report. https://www.pork.org/research/determining-minimal-floor-space-allowance-gestating-sows-kept-pens-electronic-sow-feeders-2/
  • Type: Other Status: Published Year Published: 2017 Citation: Meersman, T. Swine Research at the University of Minnesota tackles animal welfare concerns. Star Tribune. Feb. 12, 2017. https://www.startribune.com/swine-research-at-the-university-of-minnesota-morris-tackles-animal-welfare-concerns/413464443/
  • Type: Journal Articles Status: Under Review Year Published: 2021 Citation: Li, Y.Z., S. Cui, S. Baidoo, and J. Johnston. Does sow caliper accurately measure backfat depth and visual condition score of sows? J. Swine Health and Production


Progress 10/01/18 to 09/30/19

Outputs
Target Audience:Pork producers, animal scientists, graduate students, extension educators, Ag professional, and veterinarians are audiences of this project. Audiences have been reached through presentations at conferences, publications on websites, newsletters, newspapers and journals, and individual communications. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project benefits professional development of the PI by providing opportunities of exchanging results with scientists at regional and national conferences. The project also provides educational opportunities for undergraduate students and graduate students through participating in swine welfare research and swine production. How have the results been disseminated to communities of interest?Results of the project have been disseminated to animal scientists, extension educators, graduate and undergraduate students, and Ag professionals through presentations and publications. Animal scientists are encouraged to evaluate floor space allowance using allometric principles with consideration of variation in sow body weight. What do you plan to do during the next reporting period to accomplish the goals?All animal trials and data analysis have been completed for this project. A final report will be submitted by the end date of the project.

Impacts
What was accomplished under these goals? When determining floor space allowances for pigs, body size (or weight) of pigs should be considered because large pigs would need more space than small pigs. However, floor space allowances recommended currently for breeding sows are expressed on per sow basis without consideration of variation in sow body weight. In this study, we evaluated floor space allowances using allometric principles which recognize changes in floor space allowance with changes in body size of pigs. According to allometric principles, floor space allowance can be estimated by an equation: A = k BW0.66, where A represents floor space allowance in m2, k is a constant, and BW represents body weight of the pig in kg. In young (growing-finishing) pigs, k-value varies between 0.033 and 0.047, depending on housing systems and floor types that pigs are housed. For gestating sows, no k-value has been documented. To determine k-values for gestating sows, we analyzed the data collected in this project retrospectively. During data collection, sows (n = 760, parity 1 to 9) were group-housed in pens with electronic sow feeders (ESF) from 5 weeks after mating until d 109 of gestation. Four floor space allowances (1.5, 1.7, 1.9, and 2.04 m2/sow) were evaluated in four pens (42 to 51 sows/pen) over a period of 18 months. The k-value was calculated for sows in each pen using individual body weight at entering pens. Average weight for sows in each pen across floor space treatments ranged from 196 to 223 kg at entering pens. The calculated k-value was 0.044 to 0.046, 0.047 to 0.051, 0.054 to 0.057, and 0.059 to 0.062 for 1.5 m2, 1.7 m2, 1.9 m2 and 2.04 m2 of floor space allowance, respectively, depending on body weight of sows in the pen. The following data were used to evaluate the k-value: total duration of fighting among sows immediately after mixing, day 2 and day 7 after mixing in pens; skin lesions and salivary cortisol concentrations day 2 after mixing and before moving for farrowing; lateral and sternal lying during week 3 and week 9 after entering pens; body weight change in pens; and farrowing performance. There was no correlation between the k-value and any variable of sows that were measured, suggesting that increasing k-value from 0.044 to 0.062 did not affect sow performance and welfare. Across floor space treatments, total duration of fighting at mixing was 32 sec/sow/2 h, farrowing rate 93.7%, litter size farrowed live 12.4 and weaned 10.4 piglets/litter. The minimal floor space allowance for gestating sows group-housed under conditions of the current study may be calculated using the equation: A (m2/sow) = 0.044 BW (kg)0.66. Although the k-value of 0.044 derived from this study needs further research for validation and it may change under different conditions from the current study, this study demonstrates a new method to estimate floor space allowance for gestating sows with consideration of sow body weight.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: 1. Li, Y. Z., M. Lou, M. Reese, E. Buchanan, and L. Johnston. 2019. Effects of cooled floor pads and cooled drinking water on behavior of lactating sows under heat stress. J. Anim. Sci. 97 (Supplement 2): 23.
  • Type: Other Status: Published Year Published: 2019 Citation: 2. Johnston, L., Y. Z. Li, A. Hibrands, R. Cox, W. Lazarus, W. Martin. F. Forcella, and R. Gesch. 2019. Feeding camelina meal to pigs. WCROC Newsletters. Mar. 2019. Available at: https://wcroc.cfans.umn.edu/news/feeding-camelina
  • Type: Websites Status: Published Year Published: 2019 Citation: 3. Camelina cover-crop use may support pig growth, soil health (an article in Feed navigator. com. Apr. 2019). Available at: https://www.feednavigator.com/Article/2019/04/18/Camelina-use-may-support-pig-growth-soil-health
  • Type: Other Status: Published Year Published: 2019 Citation: 4. Li, Y. Z., R. Carr, and A. Hernandez. 2019. Research on parasite control in organic swine production. WCROC Newsletters. Jun. 2019. Available at: https://wcroc.cfans.umn.edu/wcroc-news/parasite-control
  • Type: Other Status: Published Year Published: 2019 Citation: 5. Li, Y. Z., L. Johnston, C. Reese, J. Tallaksen, F. Forcella, R. Gesch, B. Lazarus, R. Cox, and W. Martin. 2019. Integrating winter camelina into organic pig production systems. The Stevens County Times. 2019 Farm Section. March 9, 2019.
  • Type: Other Status: Published Year Published: 2019 Citation: 6. Li, Y. Z., L. Johnston, B. Heins, J. Tallaksen, B. Lazarus, R. Cox, and W. Martin. 2019. Identifying challenges in organic swine production. The Stevens County Times. 2019 Farm Section. March 9, 2019.
  • Type: Websites Status: Published Year Published: 2019 Citation: 7. DeWitte, D. 2019. U of M currently conducting organic swine research. The land. Nov. 2019. Available at: https://www.thelandonline.com/news/u-of-m-currently-conducting-organic-swine-research/article.
  • Type: Other Status: Published Year Published: 2018 Citation: 8. Li, Y. Z. 2018. Organic swine research at the WCROC  Reducing feed cost by utilizing camelina cover crops. WCROC Newsletters. Dec. 2018. Available at: https://wcroc.cfans.umn.edu/wcroc-news/camelina


Progress 10/01/17 to 09/30/18

Outputs
Target Audience:Pig producers, animal scientists, graduate students, extension educators, Ag professional, and veterinarians are audiences of this project. The audiences have been reached through presentations at conferences, and publications on websites and in journals, and individual communications. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project benefited professional development of the PI by providing opportunities of exchanging results with scientists at regional and national conferences. The project also provided training opportunities for a post-doctoral fellow conduct research in animal welfare under near commercial production conditions. How have the results been disseminated to communities of interest?Results of the project have been disseminated to animal scientists, extension educators, Ag professionals, and pig producers world-wide through presentations at conferences, publications in peer-reviewed journals, and articles on websites. Pork producers are encouraged to valuate body condition objectively using sow calipers. Good body condition is important to welfare and performance of individual sows in group-housing systems. What do you plan to do during the next reporting period to accomplish the goals?All animal trials have been completed for this project. A final report will be submitted by the end date of the project.

Impacts
What was accomplished under these goals? Maintaining welfare and performance of individual sows in group-housing systemsis a challenge for pig farmers. Pork producers need science-based information about how to evaluate welfare of individual sows objectively. This project provides such information to pork producers. Body condition is one of the welfare indicators inbreeding sows. A study was conducted to evaluate an objective measurement of sow body condition using a Sow Caliper. Pregnant sows (n=928, Parity 1-9) were housed in pens (42-51 sows/pen) with an electronic sow feeder 5 weeks after mating and remained until day 109 of gestation. Sows farrowed in stalls and weaned their litters about 18 d after farrowing. Sows that were mated within one week after weaning were considered having completed the study. Sow caliper measurements were recorded at the P2 location and backfat depth using an ultrasonic scanner was recorded at the same location on both sides of the body. A scoring system of 1 (emaciated) to 5 (obese) was used for visual assessment of body condition. According to caliper measurement, 59% of sows were identified as Fit, 10% of sows as Fat, 21% of sows as Thin, and 10% of sows as Very-Thin. Caliper measurements were correlated with ultrasonic backfat depth measurements and visual scores. Fat sows had lower farrowing rate and completion rate than Fit sows. Very-Thin young sows (parity 1-2) farrowed lighter litters and Fat old sows (parity 7-9) weaned lighter litters than Fit sows within the same parity category. In general, caliper measurements did not affect litter size farrowed or weaned. These results indicate that caliper measurements correspond to backfat depth and visual condition scores, and can be used as a tool to evaluate body condition of gestating sows objectively. Results of this study also suggest that body condition affects sow performance and longevity, and consequently, sow welfare.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Li, Y. Z., S. Q. Cui, X. J. Yang, L. J. Johnston, and S. K. Baidoo. 2018. Minimal floor space allowance for gestating sows kept in pens with electronic sow feeders on fully slatted floors. J. Anim. Sci. 96: 4195-4208/doi: 10.1093/jas/sky282.
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: He, Y., J. Deen, G. C. Shurson, and Y. Z. Li. 2018. Behavioral indicators of slow growth in nursery pigs. J. Appl. Anim. Welfare Sci. 21(4): 389-399/ doi: 10.1080/ 10888705. 2018. 1438286.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Li, Y. Z., H. F. Zhang, L. Johnston, and M. Dawkins. 2018. Utilization of optical flow to monitor development of tail biting outbreaks in pigs. 12th World Conference of Animal Production, July 7, 2018 Vancouver, BC. Canada. Poster Session III-2. Available at: https://www.eventscribe.com/2018/ASAS-Annual/posteragenda.asp
  • Type: Websites Status: Published Year Published: 2018 Citation: Yuzhi Li, Wayne Martin, Brad Heins, Lee Johnston, Will Lazarus, and Joel Tallaksen. 2018. Improving health of organic pigs. Available at: https://extension.umn.edu/small-scale-swine-production/improving-health-organic-pigs
  • Type: Websites Status: Published Year Published: 2018 Citation: Yuzhi Li, Wayne Martin, Brad Heins, Lee Johnston, Will Lazarus, and Joel Tallaksen. 2018. Early detection of sick pigs in organic systems. Available at: https://extension.umn.edu/small-scale-swine-production/early-detection-sick-pigs-organic-systems
  • Type: Websites Status: Published Year Published: 2018 Citation: Yuzhi Li, Wayne Martin, Brad Heins, Lee Johnston, Will Lazarus, and Joel Tallaksen. 2018. Highlights - Organic Swine Production in the US. 2018. Available at: https://extension.umn.edu/swine/small-scale-swine-production#about-organic-swine-production-in-the-us-1311511
  • Type: Websites Status: Published Year Published: 2018 Citation: Yuzhi Li. 2018. Organic Swine Planning Project at the WCROC. WCROC Newsletters. June 2018. Available at: https://wcroc.cfans.umn.edu/wcroc-news/planning-organic-swine
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Li, Y. Z., H. Zhang, L. Johnston, and W. Martin. 2018. Understanding tail-biting in pigs through social network analysis. Anim. 8 (1)13: 1-13 /doi:10.3390.ani8010013.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Li, Y. Z., S. Q. Cui, L. J. Johnston, and S. K. Baidoo. 2018. Effect of body condition measured using a sow caliper on performance of group-housed gestating sows. ASAS Annual meeting, July 10, 2018 Vancouver, BC. Canada. Poster Session X  PSX-39. Available at: https://www.eventscribe.com/2018/ASAS-Annual/posteragenda.asp.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Li, Y. Z., S. Q. Cui, X. J. Yang, H. Zhang, L. J. Johnston, and S. K. Baidoo. 2018. Evaluation of floor space allowance for group-housed gestating sows: Application of Allometric Principles. J. Anim. Sci. 96 (Suppl. 2): p. 57 (Abstr. 108) / doi. 10.1093./jas/sky073.106.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Li, Y. Z., S. Q. Cui, X. J. Yang, L. J. Johnston, and S. K. Baidoo. 2018. Evaluating body condition of group-housed gestating sows: Sow caliper measurements vs. backfact thickness and visual scores. J. Anim. Sci. 96 (Suppl. 2): p. 47 (Abstr. 90) / doi: 10. 1093/jas/sky073.088.


Progress 10/01/16 to 09/30/17

Outputs
Target Audience:The target audiences for this project are swine producers, swine scientists, extension educators, veterinarians, graduate and undergraduate students who are interested in alternative swine production. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project has provided opportunities for the PI to collaborate with other faculty within the university and swine producers in the region, to attend and present results of the project at both national and international conferences which benefit the professional development of the PI. Furthermore, the project provided opportunities for two post-doctoral fellows and one undergraduate student to be trained for conducting researchand evaluating animal welfare. In return, the trainees contributed to the project through data collection and analysis. How have the results been disseminated to communities of interest?Results of this project have been disseminated toswine producers through publications in the National Hog Farmer magazine and the WCROC newsletters, presentations at conferences for farmers and producers,and personal communications. In addition, the results have been disseminated to swine scientists and extension educators world-wide through presentations at national and regional meetings and publications in peer-reviewed journals. The outcomes of this project contribute to our knowledge of animal welfare in alternative housing systems. Swine producers, animal scientists, and extension educators will use findings from this project to improve animal welfare through their production practices and teaching/extension programs. What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, we will continue our effort to understanding and improving the welfare of group-housed gestating sows. We will evaluate body condition as an welfare indicator of sowsin group-housing systems. Furthermore, we will evaluate effect of body weight (and size) of sows onfloor space allowance using allometric principles. Ultimately, we hope to definethe optimal floor space scientifically which will safeguard the well-being of sows, and will also allow producers to utilize floor space most efficiently.

Impacts
What was accomplished under these goals? Results of the project provided scientific evidence for the minimal floor space allowance for gestating sows. Swine producers would use findings from this project in managing pregnant sows. Policy makers and the general public could refer to the information from this project when making animal welfare regulations for swine production. We used 928 sows (parity 1 to 9) to evaluate four levels of floor space allowance: 22 ft2, 20 ft2, 18 ft2 and 16 ft2 per sow. To test whether providing more space during the initial mixing period will improve welfare and performance of sows with limited floor space (16 ft2), we imposed the fifth treatment which was to give sows more space (22 ft2) during the first week when mixing into pens, and allowed them 16 ft2 for the remaining gestation period. Each floor space allowance was tested in four pens (42 to 51 sows per pen) over a period of 18 months. Sows were moved to pens with an electronic sow feeder (ESF) after being tested pregnant at 5 weeks after mating. Sows remained in their pens until day 109 of gestation and moved to individual farrowing stalls. Sows weaned their piglets at about 18 days after farrowing. Sows that were rebred within one week after weaning a litter were considered to have completed the study. Results indicate that floor space treatments did not affect performance, skin lesions, stress hormones, fighting behavior or posturesof sows. In other words, increasing floor space allowance from 16 ft2 to 22 ft2 did not benefitwelfare orperformance of sows. These results suggest that the space allowance of 16 ft2 is acceptable as the minimal space allowance under conditions of the current study. When looking at these results closely, we noticed that sows used in the current study may need less floor space compared to sows housed and managed in other systems for several reasons. First of all, all sows used in the current study had been group-housed in the ESF system since they entered the breeding herd as gilts, and were managed as static groups. As a result, 50% to 70% of sows in a pen were housed as pen-mates during their previous gestation, and became familiarwith each other. Familiar sows may fight less compared to unfamiliar sows at mixing in pens, resulting in less injuries to sows in all treatment groups. So, familiar sows may need less floor space than unfamiliar sows. Secondly, in the current study, all sows had been allowed 16 ft2 floor space in the ESF systems before the study started. These sows probably had adapted to the minimal floor space allowance of 16 ft2. Thirdly, sows in the current study appear to be lighter than sows in previous studies. Lighter weight is associated with smaller body size which may contribute to less space requirement. Finally, in the current study, sows were moved into ESF pens after pregnant. Pregnant sows may be less aggressive compared to sows that hadjust beenmated or weaned. Again, sows that are less aggressive may need less floor space. As a result, the minimal floor space requirement obtained from this study might be lower than requirement of sows in other group-housing systems. When applying results of this study, producers should consider all factors that affect floor space requirement of sows, such as housing and feeding systems used, management protocols adopted, and genetics and experience of sows.

Publications

  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Li, Y. Z., L. H. Wang, and L. J. Johnston. 2017. Effects of social rank on welfare and performance of gestating sows housed in two group sizes. J. Swine Health Prod. 25: 290-289.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Li, Y. Z., S. Cui, X. Yang, B. A. Crooker, S. K. Baidoo, and L. J. Johnston. 2017. Salivary cortisol concentrations of group-housed gestating sows: individual vs. group samples. JAS. 95 (Suppl.1): 8 (Abstr. 18).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Li, Y. Z., S. Cui, H. Zhang, L. Johnston, and S. Baidoo. 2017. Minimal floor space allowance for gestating sows housed in pens with electronic sow feeders. Proceedings of the 2017 Pig Welfare Symposium. Des Moines, IA. Nov. 7-9, 2017. P. 35 (Abstr.).
  • Type: Other Status: Published Year Published: 2017 Citation: Li, Y. Z. 2017. How much floor space does a pregnant sow need in a group-hosing system with electronic sow feeders? West Central Research and Outreach Center Newsletter, Aug. 2017. Available at: https://wcroc.cfans.umn.edu/wcroc-news/floor-allowance-gestating-sows
  • Type: Other Status: Published Year Published: 2017 Citation: Li, Y. Z., S. Cui, H. Zhang, L. Johnston, S. Baidoo. 2017. How Much floor space do group-housed sows need? National Hog Farmer Dec. (2017 Research Review), p. 5-6.
  • Type: Other Status: Published Year Published: 2017 Citation: Li, Y. Z., S. Cui, H. Zhang, L. Johnston, S. Baidoo. 2017. Determining the Minimal Floor Space Allowance for Gestating Sows Kept in Pens with Electronic Sow Feeders. Final Report to National Pork Board (Project #14-041).


Progress 10/01/15 to 09/30/16

Outputs
Target Audience:The target audiences for this project are swine producers, swine scientists, extension educators, veterinarians, graduate and undergraduate students who are interested in alternative swine production. Changes/Problems:A study on tail biting in growing-finishing pigs was added to this project during this reporting period. What opportunities for training and professional development has the project provided?The project has provided opportunities for the PI to collaborate with renowned scientists from Europe, and other states of the U.S., as well as faculty within the university, which benefit the professional development of the PI. Furthermore, the project also provided opportunities for two post-doctoral fellows and oneundergraduate student to be trained for conducting research and evaluating animal welfare. In return, the trainees contributed to the project through data collection and analysis. How have the results been disseminated to communities of interest?The results of this project have reached swine producers through publications in the National Hog Farmer magazine and the WCROC newsletters, and presentations at meetings and seminars, and personal communications. In addition, the results have been disseminated to swine scientists and extension educators world-wide through presentations at national and regional meetings and publications in peer-reviewed journals. The outcomes of this project contribute to our knowledge of animal welfare in alternative housing systems. Swine producers, animal scientists, and extension educators would use findings from this project to improve animal welfare through their production practices and teaching/extension programs. What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, we will continue our effort to improving the welfare of group-housed gestating sows and understanding the the development of abnormal behaviors of pigs. For group-housed gestating sows, we will evaluate effects of floor space allowance on the welfare and performance of sows with an ultimate goal of identifying the optimal floor space allowance that will safeguard the well-being of group-housed sows, and will also allow producers to utilizefloor space most efficiently. Tounderstandabnormal behaviors of pigs, we will focus ontail biting behavior, using innovative approaches of social network and optical flow analysis to explore the development of this detrimentalbehavior.

Impacts
What was accomplished under these goals? Research effort has been devoted to evaluate salivary cortisol as a welfare indicator for gestating sows housed in group pens. Differences in salivary cortisol concentrations between individual and group samples collected from gestating sows were determined. Sows (n = 928, Parity 1 to 9) were moved from stalls and housed in pens at 5 weeks post-mating. Saliva samples were collected from focal sows in stalls before mixing, 2 d after mixing and about 109 d of gestation in pens. Once sows were moved to pens, group samples of saliva were collected on the same day that individual samples were collected. For individual focal sows, salivary cortisol concentrations were lower before mixing when sows were housed individually compared with 2 d after mixing and d 109 of gestation when sows were housed in groups (P < 0.001), suggesting that stress was induced by mixing and by physiological changes with the progress of pregnancy. Group cortisol concentrations were similar to individual concentrations on d 109 of gestation, but tended to be lower (P < 0.10) 2 d after mixing than individual concentrations which may be due to lower stress to animals during sample collection for groups of sows. These results suggestthat cortisol concentrations in group saliva samples may be a good indicator of animal welfare at the group level. Another study was conducted to investigate social structures of pigs. As social animals, pigs in a group may form certain social structures which could be important to their welfare. It is suspected that some abnormal behaviors, such as tail biting, are caused by disturbance of social structures of pigs. In this study, we used social network analysis to assess social structure and social position of pigs when grouped with littermates or non-littermates. Pigs (n = 96) weaned at 4 weeks of age were housed in 12 pens of 8 pigs for 5 weeks in a nursery barn. There were 6 pens of littermates and 6 pens of non-littermates. Behavior of pigs was video-recorded when pigs were 7 and 8 weeks of age. Videos were analyzed to register individual pigs that were lying together (1) or not (0) in binary matrices. Pigs that were lying together were considered to be socially connected. Degree centrality (DC) and closeness centrality (CC) measure direct and indirect connections, respectively, that a pig has with its pen-mates. Network density describes how frequently pigs in a pen were lying together. Larger values for DC, CC, and network density indicate a greater degree of social connection. No differences in average DC, CC, or network density were found between litter origin treatments, indicating that pigs in pens of littermates connected with each other in a similar way to pigs in pens of non-littermates. Standard deviation of CC tended to be higher (P = 0.06) for littermates than non-littermates. This suggests that some littermates may form more indirect connections than other littermates, while non-littermates form similar indirect connections among themselves. Furthermore, CC was correlated with bodyweight at 4 weeks (r = 0.242, P < 0.05) and 9 weeks (r = 0.233, P < 0.05) of age. Network density was correlated with bodyweight at 9 weeks (r = 0.629, P < 0.05), 4 weeks (r = 0.559, P < 0.10) of age, and ADG (r = 0.568, P < 0.10). These data suggest that heavy pigs had more indirect connections and connected with their pen-mates more frequently than lightweight pigs. These preliminary results suggest that social network analysis may be a useful tool to measure social structure among pigs.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Li, Y. Z., J. Anderson, A. Holten, A. M. Hilbrands, J. Holen, and L. J. Johnston. 2016. Understanding tail biters and victimized pigs during outbreaks of tail biting. J. Anim. Sci. 94: (Suppl. 2): 8 (Abstr. 018).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Li, Y. Z. 2016. Tail biting in growing-finishing pigs. Proceedings of 2016 AASV Annual Meeting, p. 46. New Orleans, LA, Feb. 27, 2016. https://www.aasv.org/annmtg/2016/program.php
  • Type: Other Status: Published Year Published: 2016 Citation: Li, Y. Z., L. Johnston, and W. Martin. 2016. Research reaffirms the necessity of tail docking for pigs. Natl. Hog Farmer, 2016 Research Review p. 18. http://viewer.zmags.com/publication/e8e2fcef#/e8e2fcef/18
  • Type: Other Status: Published Year Published: 2016 Citation: Li, Y. Z. 2016. Docking the tail or not: Effect on welfare and performance of growing-finishing pigs. WCROC Newsletters, Dec. 2016. http://wcroc.cfans.umn.edu/wcroc-news/docking-or-not
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Wang, L. H., and Y. Z. Li. 2016. Effect of continuous access to feeding stalls during mixing on behavior, welfare, and performance of group-housed gestating sows in different social ranks. Can. J. Anim. Sci. 96: 386-396.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: He, Y., J. Deen, G. C. Shurson, L. Wang, C. Chen. D. H. Keisler, and Y. Z. Li. 2016. Identifying factors contributing to slow growth in pigs. J. Anim. Sci. 94: 2103-2116.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Li, Y. Z., S. Cui, J. Anderson, A. Holten, A. Hilbrands, and L. Johnston. 2016. Docking the tail or not: Effect on tail damage, skin lesions and growth performance of pigs. Session 2.6. Precision Livestock Farming, Animal Production, Health, and Welfare; CIGR-Ag. Eng. conference Jun. 2629, 2016, Aarhus, Denmark. http://conferences.au.dk/cigr-2016/sessions-and-participants/#/programme?_k=k3rc9k
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Cui, S. Q., A. Holten, J. Anderson, and Y. Z. Li. 2016. Tail biting and tail damage in pigs: a comparison between pigs with and without the tail docked. ISAE 2016 Proceedings, p. 18. Jul. 12-16, Edinburgh, U.K. http://www.isae2016.co.uk/.