Progress 09/01/20 to 08/31/23
Outputs
Target Audience:This project targets scientists, health professionals, animal nutritionists, swine producers and undergraduate students for presentations of our results at regional and national meetings. Information gathered from our initial efforts on this project has been disseminated among the target audiences through Wisconsin Pork Association newsletters, UW Extension seminars and regional feed industry conferences. Future presentations are planned for producer and feed industry groups, research presentations to regional and national scientific audiences, and peer-reviewed publications. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Over the entire project, training and professional development has been provided for one post-doctorate student (Mariola Grez Capdeville); a research assistant (Brittney Kokinos, also enrolled as a graduate student), 2 graduate students (Kadence Walsh and Brittney Kokinos), and 9 undergraduate student workers (Erik Ohman, Madeline Zutz, Johanna Hutchinson, Natalie Tyley, Lori Drake, Caley Haas, Connor Smith, Allison Vandenberg, and Emily Banks). Dr. Grez Capdeville trained Brittney Kokinos in laboratory assays required for the project. In turn, Brittney has trained and supervised the undergraduate students as they assisted with laboratory assays and with data collection for the animal trials. Brittney Kokinos completed her Master's Degree in November, 2022. How have the results been disseminated to communities of interest?Initial results and updates on experiments in progress were publicized in four news releases through the Wisconsin Pork Association bimonthly newsletter and two presentations to the Annual Wisconsin Pork Expo meetings. Oral presentations were also made to two national audiences via NIFA sponsored project reports. An additional presentation to a regional feed manufacturers conference (Deklab/Huber) stimulated considerable discussion on the current project with suggestions of additional opportunities for additional applications of using ammonium chloride as a nutritional strategy to control animal growth. Abstracts were presented at the Mid-West American Society of Animal Science (n=2), the National American Society of Animal Science society meetings (n=2), and the Agricultural Applied Economics Association Annual meeting (n=1). A podcast (Swine-IT Podcast. released May 17, 2022) that included discussions on our research efforts for this project was released in May. An oral presentation was made to the July 19, 2022, USDA-NIFA: AFRI A1711- 2022. Project Director's Meeting. Rapid Response to Novel Coronavirus (SARS-CoV-2) Impacts Across Food and Agricultural Systems. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Over this project we were successful in our efforts to "hold" pigs by slowing growth using ammonium chloride (NH4Cl) additions to feed. The overall objectives for this project were to "develop nutritional strategies to hold pigs for 2 to 6 weeks atessentially no growth, so that housing issues are reduced if access to markets are suddenly stopped". We concluded that 2% ammonium chloride additions to a reduced nutrient diet would stop growth and allow recovery to market. The economic analysis of these strategies produced surprising outcomes as economic advantages were predicted by implementing an attenuated growth for designated intervals. Experimental Objectives. Over the duration of this project, 6 separate pig experiments were completed to accomplish the primary goals outlined for Objective 1 involving feed supplements and 2 experiments for Objective 2 involving water supplements with ammonium chloride. The goals outlined in Objective 1 were to identify an effective ammonium chloride supplement to feed that safely attenuates pig growth and allows recovery before market weight. An effective supplement of ammonium chloride (2%) to feed was established and validated in growth trials. Over the last year we have developed a dynamic economic model as described in Objective 3. In subsequent paragraphs, we provide a summary of the overall accomplishments for each objective. Feed supplements. Uniquely formulated diets supplemented with 2% ammonium chloride were developed to create an electrolyte imbalance between Cl and K as a nutritional strategy to attenuate pig growth for 2 to 6 weeks. A reduction in growth and feed intake was realized within two days after implementation. The selected nutritional mitigation strategy successfully reduced growth by 80% compared to that of control pigs. Of critical importance, a dramatic 2-fold increase in compensatory growth was observed after the ammonium chloride diets were withdrawn. No negative consequences on animal welfare were observed. Expected reductions in skeletal bone mineral (measure by whole body DXA scans) were not of concern for market pigs, however bone mineral depletions should be further evaluated if pigs were retained in the breeding herd. As only a dietary electrolyte imbalance was involved in the responses, the animal products were safe for consumption. Further assessment of the compensatory growth responses revealed unexpected benefits of economic significance. Protein accretion increased and fat accretion decreased during the compensatory recovery phase. Initially, several experiments designed to quickly arrive at a diet formulation to meet the qualifying objectives were completed. Supplements with 2% ammonium chloride in feed for growing pigs at various "hold" periods from 20 to 75 kg allowed a 70 to 80% growth attenuation for 2 to 6 weeks (Kokinos et al., 2022). Diets with 2.5% ammonium chloride reduced growth by 90%. However, based on visual appraisals the growth restriction was deemed too severe, although all pigs recovered from the restrictions. Diets formulated with 2% ammonium chloride were fed to pigs at 25, 50 or 75 kg body weight for a 4-week attenuation phase then allowed to recover. As predicted by the earlier experiments, growth was restricted to greater than a 70% reduction over the 4 week "hold" phase and pigs recovered with only a 2-week delay in age of pigs at market weight. No adverse effects were observed in animal behavior during the restriction phase in groups of animals housed within the same pens. Based on standard carcass traits (fat depth, loin depth, percentage of lean) collected from the slaughter plant data, no differences were detected in carcass quality between control and pigs that previously subjected to a growth-attenuated strategy. However, differences were detected based on a limited number of pigs submitted to more sensitive DXA scans at market weight (Walsh et al., 2022). The growth data were used for development of an economic model (Stevens et al., 2023), which predicted economic advantages for growth-attenuated pigs compared to control pigs. To confirm the imbalance between excess Cl and minimal K in diets fed to attenuate growth with ammonium chloride, Hutchinson et al., 2022 showed that growth responses of pigs fed diets with 2% ammonium chloride could be rescued by addition of potassium carbonate. Over the last year efforts were focused on the compensatory recovery phase after a 6-week attenuated growth phase. Pigs fed diets with additional (150% of requirements) potassium, lysine, and phosphorus gained more body weight and lean, but less fat tissue than pigs fed standard control diets during the compensatory growth phase (Kokinos et al., 2023). The experiment was not designed to assess separate benefits of potassium, lysine, or phosphorus, nor did the experimental design allow determination of the duration of compensatory responses. Lean gain increased and fat gained decreased as pigs grew from 25 to 45 kg, but the magnitude of responses appeared to diminish with the duration of the compensatory growth phase. More frequent measures of protein and fat accretion are needed. Relative to control pigs, bone gain increased during the compensatory phase for pigs feed diets with additional potassium, lysine, and phosphorus. These results have confirmed the physiological basis for use of ammonium chloride as a method to attenuate growth in pigs. Economic analysis Objective 3. Using "bench-mark" standards collected from producers and lenders to establish model constraints, a dynamic economic model was developed to allow producers to make wise decisions about the consequences and opportunities that arise from use of 2.0% ammonium chloride to "hold" pigs during a crisis management strategy. The model developed allowed analysis of experimental responses by pigs on fed ammonium chloride diets for various intervals and assessed the economic implications over the entire growth cycle to market. As pigs displayed compensatory growth during recovery. The results of this economic analysis infer for growth to market weight that (1) a "control" pig (no attenuated growth) would take 101 days and cost $47.74 (shortest duration), (2) a pig fed an ammonium chloride diet beginning in week 1 would take 109 days and cost $44.03 (lowest cost), and (3) a pig fed an ammonium chloride diet beginning in week 11 would take 116 days and cost $49.38 (highest cost and longest duration). Conclusions from the economic optimum infer that intentional attenuation of pig growth at a young age, even if the strategy required an additional week longer for housing than normal feeding would improve profitability. This potential profit is based solely on growth and feed efficiency responses. Future efforts to optimize compensatory protein accretion during recovery from feeding ammonium chloride must be included in the economic assessment to realize the full benefits. To further elucidate the current outcomes, we have submitted an Agriculture and Food Research Initiative Competitive Grant entitled, "Nutritional strategies to optimize compensatory protein accretion in pigs after growth attenuation imposed by feeding ammonium chloride". Submission Title: 08-10-AnSci-Crenshaw-NIFA-pigs, (Opportunity ID: USDA-NIFA-AFRI-009755). Water supplements. A treated water delivery system was developed to allow estimates of fluid consumption of individual animals. Two experiments were initiated. As described in previous annual reports in the Changes/Problems section, a specific dosage of ammonium chloride additions to drinking water could not be identified. Animal health concerns were identified that preclude our recommendation for use of this approach for growing pigs.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Kokinos, B. P., R. A. Budde, M. Grez-Capdeville, L.A. Amundson, A.W. Stevens, J. P. Chavas, and T.D. Crenshaw. 2023. Recovery of growth and body composition in 10-kg pigs after a 6-week growth attenuation by ammonium chloride additions to feed. J Anim Sci 101 (2):57-58. https://doi.org/10.1093/jas/skad341.062
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Stevens, Andrew W., Jean-Paul Chavas, and Thomas D. Crenshaw. 2023. Compensatory growth, capacity constraints, and market timing: optimizing pork production. Agric. Appl. Economics Assoc. Annual Meeting, July 25, 2023. https://ageconsearch.umn.edu/record/335758?ln=en
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Thomas D. Crenshaw, Laura A. Amundson, Jean-Paul Chavas, Andrew W. Stevens Kadence M. Walsh, Brittney P. Kokinos, and Mariola Grez Capdeville. Efficacy of using ammonium chloride supplements during crisis management to stop growth in various ages of pigs Wisconsin Pork, Soy, Corn Expo. 2/03/2023. Wisconsin Dells, WI.
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Progress 09/01/21 to 08/31/22
Outputs
Target Audience:In 2022, one abstract was presented at the Mid-West American Society of Animal Science (March, 2022) and a second abstract was presented at the National American Society of Animal Science society meetings (June, 2022). A podcast (Swine-IT Podcast. released May 17, 2022) that included discussions on our research efforts for this project was released in May. An oral presentation was made to the July 19, 2022, USDA-NIFA: AFRI A1711- 2022. Project Director's Meeting. Rapid Response to Novel Coronavirus (SARS-CoV-2) Impacts Across Food and Agricultural Systems. Changes/Problems:As described in last years' report, attempts to refine the amount of ammonium chloride additions to drinking water were not successful. This year (2022) a follow-up trial was conducted. The trial was designed with intentions to initially stop pig growth by water-supplements of ammonium chloride for one week. This brief interval would allow producers, under a crisis, stop-shipment order, to empty feed bins and replenish feed supplies with an ammonium chloride-supplemented feed. The initial design involved a strategy to treat pigs with 1.5% ammonium chloride treated water for one week. However, within the first 4 days of the trial, four pigs were euthanized with apparent salt toxicity related to an over consumption of the ammonium chloride. Additional problems in other pigs were identified (loose stools and staggered gait in other treated pigs). Modifications to ammonium chloride water treatments were made and the remaining pigs were transferred to fresh-water treatments and ammonium chloride supplemented feed. The 6-week trial provided additional data on protein accretion during recovery from an ammonium chloride-attenuated growth phase. Conclusions from the current year results infer that the approach to attenuate pig growth by treatments of the water supply with ammonium chloride is not a practice that should be recommended for applications to stop pig growth under crisis management systems. Our attempts with feed additions have been effective. Pigs treated with ammonium chloride as a feed treatment and allowed free access to fresh water are able to effectively self-regulate electrolyte and osmotic balance. The pig-to-pig variation with ammonium chloride/water treatments has precluded the establishment of an effective dose even in tightly managed research trials. Recommendations of this approach for large numbers of animals housed in commercial production facilities cannot be recommended with results from the current experiments. What opportunities for training and professional development has the project provided?Over the past year (2022) training and professional development has continued for one post-doctorate student (Mariola Grez Capdeville); a research assistant (Brittney Kokinos, also enrolled as a graduate student), and 3 undergraduate student workers (Johanna Hutchinson, Natalie Tyley, and Emily Banks). Dr. Grez Capdeville has continued to provide oversight and training for Brittney Kokinos in laboratory assays required for the project. In turn, Brittney has trained and supervised the undergraduate students as they assisted with laboratory assays and with data collection for the animal trials. Brittney Kokinos will complete her Master's Degree in November, 2022. How have the results been disseminated to communities of interest?In 2022, one abstract was presented at the Mid-West American Society of Animal Science (March, 2022) and a second abstract was presented at the National American Society of Animal Science society meetings (June, 2022). A podcast (Swine-IT Podcast. released May 17, 2022) that included discussions on our research efforts for this project was released in May. An oral presentation was made to the July 19, 2022, USDA-NIFA: AFRI A1711- 2022. Project Director's Meeting. Rapid Response to Novel Coronavirus (SARS-CoV-2) Impacts Across Food and Agricultural Systems. What do you plan to do during the next reporting period to accomplish the goals?Over the next (and final year), we will complete development of a dynamic economic model to allow producers to make wise decisions about the consequences and opportunities that arise from the use of ammonium chloride to "hold" pigs during a crisis management strategy. Data from pig growth, feed consumption and enhanced protein accretion during recovery are compiled for model development. We have collected "bench-mark" standards from producers and lenders to establish constraints in the models. Final analysis of mineral contents of diets, urine and tissue samples are near completion. Our goals are to have the models developed and manuscripts submitted by June 2023 with presentations at Ag Economic meetings during the summer. A final management guide will be submitted to the National Pork Board for access from their on-line resource website in addition to submission to popular press swine resources.
Impacts
What was accomplished under these goals?
In 2022 we have continued projects as outlined in the 2021 report and added the following results and experiments. Feed supplements. We can now report success in our efforts to "hold" pigs by slowing growth using ammonium chloride (NH4Cl) additions to feed. The overall objectives for this project were to "develop nutritional strategies to hold pigs for 2 to 6 weeks atessentially no growth, so that housing issues are reduced if access to markets are suddenly stopped". In the previous year we completed several exploratory, short-term experiments, to fine-tune the amounts of ammonium chloride needed to effectively stop pig growth during crisis management and then to allow recovery of pigs before market. We concluded that 2% ammonium chloride additions to a reduced nutrient diet would stop growth and allow recovery to market. The growth curves of pigs that were fed "hold" diets with 2% ammonium chloride included 4 groups of pigs (20 each). One group was fed control diets throughout the experiment. In the other 3 groups, "hold" diets were fed for 4 weeks to different groups (20 in each group) of pigs at either 25, 50, or 75 kg body weight. After the 4-week hold, pigs were fed standard diets for pigs at each respective weight and allowed to recover to market weight 128 kg. During the "hold" phase, pig growth rate was reduced by approximately 80% in each weight group. Remarkedly, by market weight the pigs compensated for the reduced 4-week growth lag and required only 2 weeks longer to reach market weight. A subset of pigs in each treatment group were selected for DXA scans to determine if bone mineral content was altered by the ammonium chloride treatments. The percentage of bone mineral was reduced in pigs fed diets with ammonium chloride compared to that of control pigs. No evidence of lameness was observed, regardless of the treatment group. Differences were not detected in whole body lean and fat percentages using DXA scans. After shipment to market, pig carcass data were collected at the slaughter plant to assess carcass lean and fat composition. Again, no differences were detected between pigs fed control diets and the groups fed the "hold" diets for 4 weeks then allowed to recover. These results offer a nutritional strategy to hold pigs and successfully allow the pigs to recover with limited consequences. Current efforts to complete the feed strategy involve development of dynamic models to assess the economic consequences of delaying pig growth during a crisis management event. One aspect related to completion of the economic models involve potential changes in body composition during recovery. While differences were not detected in body composition based on slaughter plant assessments, observations of pigs during growth raised questions about potential improvements in body protein content. Two additional experiments were designed to better assess opportunities to enhance protein accretion during recovery from a period of ammonium chloride attenuated growth and whether additional nutrients (lysine and phosphorus) would accelerate protein accretion during recovery. In the first trial, body composition responses were assessed during recovery from HG diets with 2.0% NH4Cl (HGCL) by feeding control (Ctl) diets or Ctl diets fortified with 150% of lysine, P, and K requirements (+Lys+P+K). At 10 kg, 34 barrows were individually housed and randomly assigned to 1 of 4 dietary treatments with free access to assigned diets and water throughout the trial. During the HG phase pigs were fed either Ctl or HGCL diets until 25 kg; 6 weeks for pigs fed HGCl diets. An additional diet was included to validate K and Cl interactions (0.29:1 K:Cl ratio) in growth attenuation. Potassium bicarbonate was added to the HGCl diet (HGCl+K) to restore a 1.26:1 K:Cl ratio. At 25 kg BW pigs were fed either Ctl or +Lys+P+K diets until 45 kg BW. Pig, feed weights, and body composition derived from whole-body DXA scans during the hold (HG, 10 to 25 kg) and recovery (Rec, 25 to 45 kg) phases allowed calculations of weight gain, nutrient intake, and measurements of whole-body bone mineral, fat, and lean gain. Growth of pigs fed HGCl diets was reduced (P < 0.01) by approximately 50% compared to Ctl pigs during the HG phase. Pigs fed HGCl diets required 23 more days to grow from 10 to 25 kg. Similar reductions (P < 0.01) in bone mineral and lean gain, but not fat gain, were detected in pigs fed HGCl diets during the HG phase. Addition of K to the HGCl diet partially restored gain, bone, and lean gain (P < 0.01). Compensatory responses in weight, bone, fat, and lean gain were evident in HG pigs fed Ctl diets during Rec. Pigs previously fed HGCl diets compensated and only required 14 extra days to reach 45 kg compared with Ctl. Additions of lysine, P, and K allowed greater (P < 0.01) compensation in weight, bone, and lean, but not fat gain over a 20 kg recovery phase. These results confirm a successful strategy to hold pigs during crisis management with potential benefits of compensatory growth and improved body composition during recovery. Whether the improved lean gain was attributed to the additional lysine, P, or K was not determined in this experiment. A second trial was designed to assess body composition during recovery after pigs were held by NH4Cl additions to drinking water. Within the initial week, problems with the drinking water additions were identified and the experiment was modified. See adverse response comments is subsequent sections. The modifications allowed further validation of nutrients to enhance protein accretion during recovery from NH4Cl additions to feed for a 6 week hold phase. Laboratory assays are in-progress to further validate improvements in protein accretion. Independent additions of lysine and phosphorus both improved bone and lean accretion during the recovery phase.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Kokinos, B.P., M. Grez Capdeville, and T.D. Crenshaw. 2022. Addition of ammonium chloride to feed is an effective strategy to attenuate growth in 25-kg pigs. J Anim Sci 100: (Suppl. 2): 153-154. https://doi.org/10.1093/jas/skac064.260
Jo Hutchinson, Brittney Kokinos, Mariola Grez Capdeville, Laura Amundson, and Tom Crenshaw. 2022. Potassium carbonate rescues growth and bone attenuation responses to ammonium chloride in feed for growing pigs, supporting the importance of the K:Cl ratio in diet formulations. J Anim Sci 100: (Suppl. 3): 331-332. https://doi.org/10.1093/jas/skac247.606
Kadence M. Walsh, Brittney Kokinos, Mariola Grez Capdeville, Laura A. Amundson, Andrew W. Stevens, Jean-Paul Chavas, and Thomas D. Crenshaw. 2022. Efficacy of using ammonium chloride supplements during crisis management to stop growth in various ages of pigs. J Anim Sci 100 (Suppl. 3):94-95. https://doi.org/10.1093/jas/skac247.184
- Type:
Websites
Status:
Published
Year Published:
2022
Citation:
05/17/2022. Cation-Anion Balance by Dr. Tom Crenshaw. Swine-IT Podcast. released May 17, 2022.
https://www.swinecampus.com/blog/swineitpodcast-145?cid=cd3c344e-6056-463d-9a05-3b85ee9b3a84
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
07/19/2022. Efficacy of using ammonium chloride supplements during crisis management to stop growth in various ages of pigs. USDA-NIFA: AFRI A1711- 2022. Project Directors Meeting. Rapid Response to Novel Coronavirus (SARS-CoV-2) Impacts Across Food and Agricultural Systems. (via ZOOM).
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2023
Citation:
Kokinos, B. P., R. A. Budde, M. Grez-Capdeville1, L.A. Amundson, A.W. Stevens, J. P. Chavas, and T.D. Crenshaw. 2023. Recovery of growth and body composition in 10-kg pigs after a 6-week growth attenuation by ammonium chloride additions to feed. J Anim Sci 101 (accepted MidWest ASAS meetings March 2023).
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Progress 09/01/20 to 08/31/21
Outputs
Target Audience:This project targets scientists, health professionals, animal nutritionists, swine producers and undergraduate students for presentations of our results at regional and national meetings. Information gathered from our initial efforts on this project has been disseminated among the target audiences through Wisconsin Pork Association newsletters, UW Extension seminars and regional feed industry conferences. Future presentations are planned for producer and feed industry groups, research presentations to regional and national scientific audiences, and peer-reviewed publications. Changes/Problems:A trial was completed to assess responses of young pigs to various dosages of ammonium chloride to drinking water. Initial dosages included 0.50, 1.0 and 1.5% additions to drinking water supplies. Only minor effects in pig growth, feed consumption, serum and urine electrolytes were detected in pigs provided 0.50% ammonium chloride additions to drinking water, however after 7 days, dramatic differences were evident in pigs provided 1.50% as pigs lost weight and were not able to maintain serum electrolytes near homeostatic concentrations. Pigs provided the 1.50% dose were switched to a lower dose (1.25%). After switching to the lower dose, the pigs appeared to recover and displayed similar responses as that of pigs provided 1.0% ammonium chloride. Pig growth over the last week was only reduced by approximately 40%. Unfortunately, on the last day of the water treatment phase, one pig was euthanized with apparent salt toxicity related to an over consumption of the ammonium chloride additions to drinking water. Histological assessments of kidney tissues are currently under evaluation by veterinary pathologists. The observations have raised concerns about the potential applications of ammonium chloride to drinking water as a strategy to attenuate pig growth. Apparently, the pigs were not able to self-regulate electrolytes if ammonium chloride treated water was the only source of water. With ammonium chloride additions to feed, the pigs were apparently able to modify fresh-water consumption and maintain electrolyte concentrations, even under conditions of essentially "no growth". We propose to modify and refine the drinking water dosages in a future trial. We will limit the water treatments to 1 week, which would allow producers under a crisis, stop-shipment order, to empty feed bins and replenish feed supplies with ammonium chloride supplemented feed. If successful in our water treatments, an alternate approach for feed strategies will be available. What opportunities for training and professional development has the project provided?Over the past year, training and professional development has been provided for one post-doctorate student (Mariola Grez Capdeville); a research assistant (Brittney Kokinos, also enrolled as a graduate student), 2 graduate students (Kadence Walsh and Brittney Kokinos), and 9 undergraduate partime student workers (Erik Ohman, Madeline Zutz, Johanna Hutchinson, Natalie Tyley, Lori Drake, Caley Haas, Connor Smith, Allison Vandenberg, and Emily Banks). Dr. Grez Capdeville has trained Brittney Kokinos in laboratory assays required for the project. In turn, Brittney has trained and supervised the undergraduate students as they assisted with laboratory assays and with data collection for the animal trials. How have the results been disseminated to communities of interest?Initial results and updates on experiments in progress have been publicized in four news releases through the Wisconsin Pork Association bimonthly newsletter. Oral presentations have been made to two national audiences via NIFA sponsored project reports. An additional presentation at a regional feed manufacturers conference (Deklab/Huber) stimulated considerable discussion on the current project with suggestions of additional opportunities for additional applications of using ammonium chloride as a nutritional strategy to control animal growth. One abstract has been submitted for presentation at the Mid West American Society of Animal Science meeting next March, 2022. What do you plan to do during the next reporting period to accomplish the goals?Currently, we are compiling data from a growth trial that was just completed. The trial assessed addition of 2% ammonium chloride to feed as a strategy to attenuate growth for a 4-week "hold" period in pigs at 25, 50 and 75 kg followed by their subsequent recovery to market weight. Data from this trial will be used to generate the deterministic economic model for feed strategies. A modified approach will be used to further assess the use of ammonium chloride additions to drinking water as a strategy to attenuate growth in 10 kg pigs. If successful (see comments under Changes/Problems section), this modified approach will be extended to complete a trial based on ammonium chloride supplements to drinking water to attenuate growth in pigs at 25, 50 and 75 kg for a 4-week "hold" period followed by their subsequent recovery to market weight. We will complete an initial manuscript on the results generated under Aim 1 (a and b) by March, 2022, and submit abstracts for presentations at the national American Society of Animal Science meetings in July, 2022.
Impacts
What was accomplished under these goals?
Based on interactions with external stakeholders (swine producers and feed industry professionals) our research team has refined Four Qualifying Objectives to validate the additions of ammonium chloride to feed or water supplies as nutritional strategies to attenuate pig growth during CRISIS management. These Qualifying Objectives include: A. Pig growth must be reduced by more than 50% for 2 to 4 weeks with no adverse health or welfare effects on the pig. B. The cost of feed supplied during the "hold" phase must be reduced. C. After being released from the "hold", pigs must recover from the growth restriction with minimal negative consequences on carcass value. D. Ideally, the strategy should be possible to immediately implement if stop shipment orders were announced. Feed supplements. During the past year we have completed 3 separate pig experiments to accomplish the primary goals outlined for Objective 1 involving feed supplements and 1 experiment outlined for Objective 2. The goals outlined in Objective 1 are to identify an effective supplement of ammonium chloride to feed that will safely attenuate growth and allow recovery. An effective supplement of ammonium chloride (2%) to feed has been established and validated in a growth trial as described in Objective 2. In preliminary experiments, no growth suppression was observed in pigs fed standard diets with 2.5% ammonium chloride additions, however after diet modifications to reduce nutrient concentrations (HG diets), growth of 65 kg pigs was suppressed 90% over the first week if diets contained 2.5% ammonium chloride. Pigs became refractory after the first week and averaged 50% growth reduction over 3 weeks. The current objective was to evaluate use of ammonium chloride as a nutritional strategy to maintain pigs (3 to 6 weeks) at essentially no growth during crisis management. Nine F2 barrows (24.2 kg), were fed standard diets for a 9-d pre-trial phase to establish baseline traits. Afterwards, HG diets with 1.25, 2.00, or 2.75% ammonium chloride were fed for a 21-d treatment phase then fed control diets for an 11-d recovery phase. Pig weights and feed consumption were measured at various intervals. Additionally, whole-body bone mineral content (BMC), bone mineral density (BMD), and urine cation-anion profiles were determined to assess bone mineralization and physiological adaptation to ammonium chloride. Compared with gain during the pre-trial phase, gain was reduced by 0, 39, and 98% for pigs fed 1.25, 2.0 and 2.75% ammonium chloride. During an 11-d recovery, pigs gained 73.4, 118.5 and 154.1% more than baseline responses. Feed intake reflected similar responses as gain. Likewise, urine concentrations of Cl, NH4, K, and H responded to dietary treatments, however recovery to baseline values were not complete until day 3 of recovery. Based on limited observations for DXA scans, BMC appeared to be reduced by dietary treatment, but differences were not evident in BMD, likely a reflection of reduced growth. These results are consistent with the effectiveness of ammonium chloride as a strategy to attenuate pig growth during a crisis, "stop-shipment" event. In an additional experiment, we found that the effective dose of ammonium chloride additions to feed was affected by dietary potassium concentrations. Additions of 1.5 or 2.5% ammonium chloride did not attenuate growth in 40-kg pigs fed diets with 0.7% K, which is the typical K concentration in corn-soybean meal diets. By reducing the potassium concentration to 0.45%, growth was attenuated in 65-kg pigs by more than 70% during a 3-week treatment phase. Further support for the pivotal role of the dietary potassium concentration in establishing an effective dose of ammonium chloride additions to feed was provided in an experiment in which potassium carbonate was added to diets that also contained 2.0% ammonium chloride. The growth of pigs fed ammonium chloride supplemented diets with added potassium was essentially restored to growth of pigs fed control diets. Based on these observations, modifications were made in the formulation of the HG diets and a proof-of-concept experiment was initiated as described for Objective 2. The modified HG diets with 2.0% additions of ammonium chloride were fed to pigs at 25, 50 and 75 kg. Pigs were allowed to recover to market weight. Preliminary summary of the growth data are consistent with an 83.4, 77.1, and 82.95% reduction growth at 25, 50 and 75 kg phases of ammonium chloride treatments for 4 weeks. By market weight pigs recovered with only a 2-week lagged growth. No adverse effects were observed in the pigs. Thus, a 2.0% ammonium chloride supplement to feed, based on the HG formulated diets, provided a successful strategy to meet our qualifying objectives. Water supplements. A treated water delivery system was developed to allow estimates of fluid consumption of individual animals. One experiment as described in Objective 1 has been completed. As described in the Changes/Problems section, a specific dosage on ammonium chloride additions to drinking water has not been identified to progress to Objective 2 for the water treatments. Additional experiments are needed. Laboratory assays. In addition to the routine assays for serum and urine analysis, we have developed a rapid assay for quality control monitoring of feed and water treatments. The assay can be completed within 4 hours after mixing treatments to assure correct dosages are being provided to the animals.
Publications
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