By Diane DeWitte, UMN Extension swine educator
Originally printed in The LAND - as May 10, 2024, Swine & U column
As part of the University of Minnesota’s Agriculture Experiment Station network, 10 Research & Outreach Centers (ROCs) are strategically located across the state. The ROC network hosts scientists studying water quality, forest conservation, sustainable cropping systems, renewable energy, and livestock production.
The Southern Research and Outreach Center (SROC) at Waseca is home to the University’s 600-sow swine herd; sows are bred, farrow, and piglets weaned using the common industry production style. Breeding, nutrition, sow behavior, and market hog nutrition trials take place at SROC.
The West Central Research & Outreach Center (WCROC) at Morris is the site where alternative, niche, and organic production styles are investigated. In addition to typical nutrition, water consumption, and pig growth research projects, during the past two decades, WCROC has been the home of pig studies using alternative feedstuffs, trying out group gestation and farrowing, using different energy sources for heating and cooling, constructing alternative housing structures, and conducting an array of behavior studies overseen by Animal Science Department professors Yuzhi Li and Lee Johnston.
The hoop barn buildings used natural ventilation and were constructed with wooden walls and a polyvinyl tarp covering the hoop. Pigs were bedded in deep straw and provided ad lib feed and water.
The conventional pig barn was mechanically ventilated with slatted flooring. Pigs were provided ad lib feed and water.
Through the study pigs were observed for activity, social behavior, and fear responses; Postures were observed and scored, and a common stockperson walked and handled the pigs at intervals throughout the 13-week study to observe reaction and fear response. Saliva was collected randomly three times during the study to measure concentration of cortisol in the saliva. Cortisol in saliva is positively correlated with cortisol concentration in blood plasma and is an indicator of stress in the animal. Growth performance of the barrows was measured three times during the study by individually weighing the pigs and calculating feed consumption.
Meat quality was measured at the time of pig harvest. 80 focal pigs (40 from each treatment) were transported and harvested the same day. Carcass measurements of pH, meat color, firmness, marbling, drip loss, purge loss, and glucose in purge were collected at the abattoir. Following carcass processing, chops were grilled to 160 degrees and cut into equal size pieces for eight taste panelists. Panelists evaluated the pork for tenderness, juiciness, flavor, and overall like, using an eight-point scale.
In this study, hoop barn raised pigs were more active and exploratory day-to-day compared to the pigs housed conventionally. There was no significant difference in aggressive behavior among pigs in the two housing systems at the three collection times during the study. Pigs in the deep-bedded system consumed significantly more feed and as a result had a poorer feed-efficiency compared to pigs in conventional housing.
The data collected suggested that pigs raised in the deep-bedded, large group housing system might be easier to handle and adapt better to new environments, but this did not improve pork quality. Measures of stress physiology and aggressive behavior showed that over time there were no differences in the welfare of pigs between the two housing systems. (https://z.umn.edu/MorrisonStudyAppAnBehSci)
The project has completed the second year of the small-plot field experiment evaluating manure management strategies for organic hybrid rye production.
Stand count was conducted in November 2022 and May 2023. Rye grain was harvested in July 2023 and sampled for analysis of moisture content, test weight, and grain quality. In parallel to the small-plot study, organic hybrid rye was grown on 17 acres of an adjacent, organically certified land for the feeding trial.
Two replicates of the pig feeding trial have been completed. Within each replicate, 100 pigs that were born to 16 sows in a deep bedded farrowing hoop barn were selected for the trial. Pigs were managed organically from prenatal (third trimester) to market weight (270 lb) according to the organic standards set by the National Organic Program (NOP). From 10 weeks old until market weight, pigs were fed a control diet (organic corn soybean meal-based) or a treatment diet (replacing 50% corn in the control diet with organic hybrid rye).
Control pens were bedded with organic wheat straw and treatment pens were bedded with organic hybrid rye straw. Organic hybrid rye grain and straw produced in 2022 was used for the first two replicates of the feeding trial. In both replicates, growth performance (average daily gain, average daily feed intake, and gain to feed ratio) of pigs was monitored. The bedding, manure pad, and fecal samples were collected for analysis of N and P concentration.
At the end of the feeding trial, carcass traits (backfat thickness, loin area, and dressing percentage) and pork quality indicators (pH, shear force, water holding capacity, and color) were measured. Consumer acceptance of the pork was evaluated by a taste panel.
During the past year, the project team has been collecting cropping and livestock data for rye and rye-based swine diets for use in LCA modeling. In addition, new swine and rye production scenarios are being developed to add to the three crop rotations initially identified and the baseline organic swine diet. The added rotations include a broader array of cover crops and focus on enhanced environmental benefits. Specific cover crops that have been identified include forage radish, camelina, and oats. These are to be tested as both standalone cover crops and as inter-seeded crops.
Additionally, preliminary economic analysis was conducted using the data collected in 2022. The economic viability of growing winter hybrid rye for organic pigs as feed and bedding was discussed with organic farmers and their stakeholders at our first field day held in June 2023.
Originally printed in The LAND - as May 10, 2024, Swine & U column
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| Photo Source: Diane DeWitte, Organic Swine & Rye project Organically raised sows with litters at WCROC. |
The Southern Research and Outreach Center (SROC) at Waseca is home to the University’s 600-sow swine herd; sows are bred, farrow, and piglets weaned using the common industry production style. Breeding, nutrition, sow behavior, and market hog nutrition trials take place at SROC.
The West Central Research & Outreach Center (WCROC) at Morris is the site where alternative, niche, and organic production styles are investigated. In addition to typical nutrition, water consumption, and pig growth research projects, during the past two decades, WCROC has been the home of pig studies using alternative feedstuffs, trying out group gestation and farrowing, using different energy sources for heating and cooling, constructing alternative housing structures, and conducting an array of behavior studies overseen by Animal Science Department professors Yuzhi Li and Lee Johnston.
A LOOK BACK
Several years ago, researcher R.S. Morrison worked with Dr. Johnston in a comparison study of housing systems and their effect on growth performance, behavior, welfare, and meat quality of 450 genetically identical barrows. The pigs were all fed the same corn-soy diet. 90 pigs were housed in conventional Minnesota commercial type hog barns and split up, 15 pigs per pen. The other 360 were housed in deep-straw-bedded hoops barns, in pens of 90 pigs each.The hoop barn buildings used natural ventilation and were constructed with wooden walls and a polyvinyl tarp covering the hoop. Pigs were bedded in deep straw and provided ad lib feed and water.
The conventional pig barn was mechanically ventilated with slatted flooring. Pigs were provided ad lib feed and water.
Through the study pigs were observed for activity, social behavior, and fear responses; Postures were observed and scored, and a common stockperson walked and handled the pigs at intervals throughout the 13-week study to observe reaction and fear response. Saliva was collected randomly three times during the study to measure concentration of cortisol in the saliva. Cortisol in saliva is positively correlated with cortisol concentration in blood plasma and is an indicator of stress in the animal. Growth performance of the barrows was measured three times during the study by individually weighing the pigs and calculating feed consumption.
Meat quality was measured at the time of pig harvest. 80 focal pigs (40 from each treatment) were transported and harvested the same day. Carcass measurements of pH, meat color, firmness, marbling, drip loss, purge loss, and glucose in purge were collected at the abattoir. Following carcass processing, chops were grilled to 160 degrees and cut into equal size pieces for eight taste panelists. Panelists evaluated the pork for tenderness, juiciness, flavor, and overall like, using an eight-point scale.
In this study, hoop barn raised pigs were more active and exploratory day-to-day compared to the pigs housed conventionally. There was no significant difference in aggressive behavior among pigs in the two housing systems at the three collection times during the study. Pigs in the deep-bedded system consumed significantly more feed and as a result had a poorer feed-efficiency compared to pigs in conventional housing.
The data collected suggested that pigs raised in the deep-bedded, large group housing system might be easier to handle and adapt better to new environments, but this did not improve pork quality. Measures of stress physiology and aggressive behavior showed that over time there were no differences in the welfare of pigs between the two housing systems. (https://z.umn.edu/MorrisonStudyAppAnBehSci)
WHAT’S GOING ON TODAY?
WCROC has distinguished itself in the UMN ROC system as a center for energy, carbon & climate research in addition to housing an organic dairy herd and an organic sow herd. Since September 2021 a multidisciplinary team of faculty, Extension and graduate students has implemented a multi-year USDA grant to study organic hybrid rye and organic pigs. Piloted by professor Yuzhi Li, the grant explores substituting organic rye into the swine diet in place of organic corn and putting a numeric value to the practice.The project has completed the second year of the small-plot field experiment evaluating manure management strategies for organic hybrid rye production.
Stand count was conducted in November 2022 and May 2023. Rye grain was harvested in July 2023 and sampled for analysis of moisture content, test weight, and grain quality. In parallel to the small-plot study, organic hybrid rye was grown on 17 acres of an adjacent, organically certified land for the feeding trial.
Two replicates of the pig feeding trial have been completed. Within each replicate, 100 pigs that were born to 16 sows in a deep bedded farrowing hoop barn were selected for the trial. Pigs were managed organically from prenatal (third trimester) to market weight (270 lb) according to the organic standards set by the National Organic Program (NOP). From 10 weeks old until market weight, pigs were fed a control diet (organic corn soybean meal-based) or a treatment diet (replacing 50% corn in the control diet with organic hybrid rye).
Control pens were bedded with organic wheat straw and treatment pens were bedded with organic hybrid rye straw. Organic hybrid rye grain and straw produced in 2022 was used for the first two replicates of the feeding trial. In both replicates, growth performance (average daily gain, average daily feed intake, and gain to feed ratio) of pigs was monitored. The bedding, manure pad, and fecal samples were collected for analysis of N and P concentration.
At the end of the feeding trial, carcass traits (backfat thickness, loin area, and dressing percentage) and pork quality indicators (pH, shear force, water holding capacity, and color) were measured. Consumer acceptance of the pork was evaluated by a taste panel.
During the past year, the project team has been collecting cropping and livestock data for rye and rye-based swine diets for use in LCA modeling. In addition, new swine and rye production scenarios are being developed to add to the three crop rotations initially identified and the baseline organic swine diet. The added rotations include a broader array of cover crops and focus on enhanced environmental benefits. Specific cover crops that have been identified include forage radish, camelina, and oats. These are to be tested as both standalone cover crops and as inter-seeded crops.
Additionally, preliminary economic analysis was conducted using the data collected in 2022. The economic viability of growing winter hybrid rye for organic pigs as feed and bedding was discussed with organic farmers and their stakeholders at our first field day held in June 2023.
WHAT HAVE WE LEARNED?
Today’s organic pigs and rye grant project builds on some of the foundation from Morrison & Johnston’s hoop barn pig behavior research from decades ago. The hoop barns house the organic sow herd and market hogs, the pigs’ behavior and growth performance are carefully monitored, and a taste test panel has evaluated the loin from the rye-fed pigs vs. the corn-fed pigs. I’m not at liberty to share the results of our Organic Pigs & Rye project…yet! Diane DeWitte is a UMN Extension Educator focused on swine. She can be reached at stouf002@umn.edu or 507-384-1745.
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