655 Southgate Drive Guelph, Ontario N1G 5G6. DATE: November 6, 2007 PROPOSAL # 07/135 ONTARIO PORK RESEARCH PROPOSAL FINAL REPORT

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1 655 Southgate Drive Guelph, Ontario N1G 5G6 DATE: November 6, 2007 PROPOSAL # 07/135 ONTARIO PORK RESEARCH PROPOSAL FINAL REPORT Project Leaders: C.F.M de Lange Project Title: Reducing the negative impact of high dietary potassium levels on growth performance and carcass characteristics of growing-finishing pigs fed large amounts of coproducts. PROVIDE THE FOLLOWING INFORMATION IN NON-TECHNICAL LANGUAGE: Objectives of the Research Proposal: The aim of the project was to (1) establish whether the negative impact of feeding high levels of co-product on growth performance and carcass characteristics of growing-finishing pigs can be attributed to high dietary potassium levels, and (2) reduce negative effects of high dietary potassium levels by increasing dietary chloride levels or adjusting the dietary electrolyte balance. Summary of Research Results: With the increased demand for corn for the production of bio-fuel, corn prices are increasing and alternative energy sources for use in pig feeds need to be explored. A concern with the use of co-products from the bio-fuel and food industry in pig diets is the large amount of potassium that is contained in these products. In preliminary studies the usage of large amounts of corn steep water (CSW) in diets for growing pigs was explored. However, largely due to the high mycotoxin content in CSW from the 2006 Ontario corn harvest, feed intake was reduced and this prevented us from assessing the impact of high dietary potassium levels. In a full-scale swine liquid feeding experiment, feeding diets that contained on a dry basis 20% whey permeate and either 4% of corn steep water (CSW) for growing pigs (total dietary potassium content 1.26%) and 6% CSW for finishing pigs (total dietary potassium content 1.33%) reduced growth performance only by 5%, while feed efficiency and carcass quality were not influenced. However, at these high rates of co-products usage, abnormalities were seen in the kidneys of some of the pigs. These kidney abnormalities were also seen in pigs that were fed corn and soybean meal containing diets with added potassium carbonate. These findings indicate that (1) even higher levels of co-product usage should be evaluated and (2) that some simple dietary interventions to reduce abnormalities in kidneys should be explored. These two aspects will be explored further in future studies in which pigs will be fed high potassium containing co-products from mycotoxins-free corn from the 2007 harvest. 1

2 Reducing the negative impact of high dietary potassium levels on growth performance and carcass characteristics of growing-finishing pigs fed large amounts of co-products Detailed description of research activities, results and implications J. Guimaraes, C.L. Zhu and C. de Lange Department of Animal and Poultry Science, University of Guelph INTRODUCTION AND OBJECTIVES With the increased demand for corn for the production of bio-fuel, corn prices are increasing and alternative energy sources for use in pig feeds need to be explored. In the Ontario industry there is a concern about the negative impact of extensive co-product usage in growing-finishing pig diets on growth performance and carcass lean yield. It is hypothesized that these negative effects are attributed to the high potassium content in co-products from the food and bio-fuel industry. Experiments were conducted to determine the impact of high co-product usage on growth, carcass lean yield and measures of meat quality in pigs and to determine whether these can be attributed to high potassium levels. MATERIALS AND METHODS In preliminary studies the usage of large amounts of corn steep water (CSW) in diets for growing pigs was explored. However, largely due to the high mycotoxin content in CSW from the 2006 Ontario corn harvest (20 ppm vomitoxin) feed intake was reduced, and this prevented us from assessing the impact of high dietary potassium levels. Therefore, subsequent studies were conducted using diets that contained whey permeate as the main high potassium containing co-product. In a full-scale swine liquid feeding experiment, 160 sixty pigs (purebred Yorkshire pigs from the University of Guelph herd), half male and half female, with an average initial body weight of 26.1 ± 0.5 kg were exposed to one of four dietary treatments to establish whether feeding large amount of co-products affects animal performance and carcass characteristics. The animals were assigned to 20 pens with 4 male and 4 female pigs per pen, according to a randomized design, but balancing for initial body weight and litters across treatments. All the animals were liquid fed using the Big Dutchman Hydrojet Liquid Feeding System, at Arkell Swine Research Station, Guelph, Canada. Additional water was available at all times from a low-pressure drinking bowl. Since water consumption seems to be associated with increased tolerance to high potassium levels in swine diets (Patience and Zijlstra, 2001), water usage was assessed per every two pens on the same treatment. Diets were formulated (Table 1) to assess the various responses to different dietary inclusion levels of co-products in a two-phase feeding program (25 to 65 kg body weight for phase 1; 65 kg boy weight to market weight for phase 2). Pigs on treatment 1, the control treatment, received typical corn and soybean meal based diets. For 2

3 treatment 2, the moderate co-product treatment, diets contained 10% whey permeate and either 2% CSW for growing pigs and 3 % CSW for finishing pigs. For treatment 3, the aggressive co-product usage treatment, diets contained 20% whey permeate and either 4% CSW for growing pigs and 6% CSW for finishing pigs. Table 1. Ingredient composition of analyzed nutrient content of experimental diets z PHASE 1 PHASE 2 Ingredient (%) Control Moderate High K 2 CO 3 Control Moderate High K 2 CO 3 Corn, 7.8%CP SBM, 47.8%CP Limestone Monocalcium Corn Steep Water (100% DM) Whey permeate (88% DM) K 2 CO Calculated levels (%) Dry Matter Crude Protein Calcium Phosphorus Potassium Sodium Chloride Analyzed levels y Dry Matter Crude Protein Calcium Phosphorus Potassium Sodium z Diets represented typical corn and soybean meal based diets (Control), moderate (Moderate) and high (High) usage of co-products, and Control with added potassium levels (K 2 CO 3 ), to achieve potassium levels similar to that for treatment High. y Complete diets ingredient composition, calculated from analyzed content in the feed supplements, CSW and whey permeate; the feed supplement contained all ingredients except for whey and CSW. In dietary treatment 4, potassium carbonate was added to the control diets to achieve dietary potassium levels similar to those in treatment 3 diets, in order to assess whether potentially negative responses of pigs on treatment 3 were caused by elevated dietary potassium levels. Diet contents of fat, vitamins, fiber and essentials amino acids, such as methionine, threonine and lysine, were similar across the four treatments. Body weights of all pigs on trial were recorded weekly. At approximately 75, 95 kg body weight, and just prior to slaughter, ultra-sound back-fat thickness was measured on all pigs. A total of 40 pigs (2 from each pen) were slaughtered at the University of 3

4 Guelph and urine and blood samples were taken to evaluate electrolyte profiles. On this subsample of pigs meat quality was evaluated in detail (data are forthcoming). The remaining 112 pigs were shipped to a commercial packing plant for routine carcass evaluation (carcass weight, muscle depth, fat depth, and estimated carcass lean yield). During the study, seven pigs were removed from the study, due to extremely poor performance and injuries, resulting in a 5% cull rate. Routine nutrient analysis in the feed, including DM, N, K, Na, Ca and P, were performed according to AOAC (1980). Based on analyzed nutrient contents diets were prepared properly (Table 1). Data was analyzed by analysis of covariance (initial body weight as the covariate) using the GLM procedure of SAS 9.1 (SAS Institute, Inc, Cary NY) and based on a completely randomized block design, and with pen as the experimental unit. Orthogonal polynomial contrasts were used to determine the nature of the response exhibited by the different levels of inclusion of co-products in the diets. Statements of statistical significance were based on P < RESULTS In terms of growth performance (Table 2), increasing dietary levels of co-products reduced average daily gain (ADG) linearly (P = 0.04), contributing to dietary treatment effects on final BW and carcass weight (Tables 2 and 3). However, the numerical reduction in ADG was only 5% and could be attributed largely to differences in average daily feed intake (ADFI; P = 0.01). Feed efficiency was not influenced by dietary treatment (P > 0.10). Growth performance of pigs on the high potassium treatment (K 2 CO 3 ) did not differ from the control, or from the high co-product usage treatment (P > 0.10). No dietary treatment effects were found for the key carcass characteristics (muscle depth, fat depth, or carcass lean yield; Table 3; P > 0.29). Table 2. Growth performance of growing-finishing pigs exposed diets with varying inclusion levels of co-products or with additional potassium from potassium carbonate z (160 pigs in total) Control Moderate High K 2 CO 3 SE P(linear 1:3) y P(diet effect) x Initial BW Final BW ADG (kg/day) ADFI (kg/day) 2.33 a 2.20 ab 2.11 b 2.20 ab F:G z Diets represented typical corn and soybean meal based diets (Control), moderate (Moderate) and high (High) usage of co-products, and Control with added potassium levels (K 2 CO 3 ), to achieve potassium levels similar to that for treatment High (Table 1). y Probability of linear effect of diet inclusion levels of co-products (treatments 1, 2, 3). x Probability of diet effect. a,b Values within rows with different subscript differ (p < 0.05) 4

5 Table 3. Carcass Characteristics of growing-finishing pigs exposed diets with varying inclusion levels of co-products or with additional potassium from potassium carbonate z (n=114) y Control Moderate High K 2 CO 3 SE P(linear 1:3) x P(diet effect) w Carcass weight, kg Lean yield, % Muscle depth, mm Fat depth, mm z Diets represented typical corn and soybean meal based diets (Control), moderate (Moderate) and high (High) usage of co-products, and Control with added potassium levels (K 2 CO 3 ), to achieve potassium levels similar to that for treatment High (Table 1). y Observations obtained at a commercial packing plant. Remaining animals were sent to the University of Guelph and were submitted for detailed meat quality evaluation (data are forthcoming) x Probability of linear effect of diet inclusion levels of co-products (treatments 1, 2, 3) w Probability of diet effect In the current experiment, the slow growing pigs on the high potassium and the high co-products usage treatments presented signs of kidney damage (Figure 1), such as discolorations and formation of lumps. Nutrient analysis of the dried powder found in the lumps on the kidney surface and in the urine revealed a high concentration of calcium (35%) and surprisingly low potassium level (0.74%). Lump Figure 1. Lumps and discoloration of a swine kidney exposed to the high co-product and K 2 CO 3 diets DISCUSSION In this study, the use of high levels of co-products in the diets had no major impact on carcass quality and pig growth performance. This suggests that even higher dietary inclusion levels of co-products might be feasible. However, attention should be paid to the high potassium levels that may accumulate in meat after processing. Potassium is the third must abundant mineral in the body of the pig, and the most abundant in muscle (NRC, 1998). Potassium homeostasis is of extreme importance to animal growth due to interactions with different electrolytes (Golz and Crenshaw, 1990, 1991). Sodium homeostasis, for example, is directly associated with potassium excretion (Malnic et al., 1989). 5

6 In pigs, excretion of potassium takes place largely via the kidneys and urine. Potassium levels are tightly regulated, both intracellularly and extracellularly, and via energy dependent processes a trans-membrane gradient is maintained. This difference in concentration between these two compartments contributes to the proper functioning of a range of physiological cellular processes, such as the transport of glucose and amino acids into the blood stream and tissues (NRC, 1998; Golz and Crenshaw, 1990; Patience and Zijlstra, 2001). An oral potassium load is usually followed by rapid redistribution into tissue stores, such as muscle and liver, to provide protection against nonphysiological fluctuations (Giebisch, 1998). However, if potassium levels are too high, animals might not be able to cope. As a result, disturbances in homeostasis are likely to impair the normal function of a whole range of tissues and, consequently, nutrient utilization (Brobst, 1986). Toxicity levels of potassium are not well defined for pigs. Provide that pigs have access to good quality water, they can tolerate dietary potassium levels that are up to 10 times its requirements (NRC, 1998; Patience and Zijlstra, 2001). When pigs are fed large amounts of co-products kidney function might be compromised. In meat production systems, animals are probably not kept long enough for severe kidney damage to become evident, but animal well-being can be reduced even during the development of early nephropathies. In the current experiment, the slow growing pigs on the high potassium and the high co-products usage treatments presented signs of kidney damage (Figure 1), such as discolorations and formation of lumps that contained large amounts of calcium. An explanation of this finding was proposed by Castenmiller (1985). Blood pressure appears to be lowered by increasing dietary intake of potassium, and, as a consequence, calcium mobilization and excretion increases to maintain blood pressure. The literature is not consistent about what salts might lead to increased calcium excretion. Lemann et al. (1989) claimed that potassium bicarbonate, but not sodium bicarbonate, reduced urinary calcium excretion in humans by enhancing calcium balance. In the same study, potassium citrate appeared to have the same effect as potassium bicarbonate. This finding agrees with those reported by Sellmeyer et al. (2002). However, in the current experiment, some pigs fed diet 4 (added potassium carbonate) presented kidney discoloration and apparently increased calcium excretion, which contradicts findings from previous studies. The reason for these different responses is not well understood, but may be related to the maintenance of acid-base balance and the ratio between sodium and potassium in the diet, and possibly difference in the pigs response to bicarbonate and carbonate intake. It is of interest to evaluate the kidney abnormalities caused by feeding even higher levels of potassium in future experiments, and to evaluate simple dietary interventions to limit the negative impact of feeding high dietary potassium levels to pigs. CONCLUSIONS AND IMPLICATIONS With the increased demand for corn for the production of bio-fuel, corn prices are increasing and alternative energy sources for use in pig feeds need to be explored. A concern with the use of co-products from the bio-fuel and food industry in pig diets is the 6

7 large amount of potassium that is contained in these products. In the current experiment, diets that contained 20% whey permeate (88% dry matter basis) and either 4% of corn steep water (CSW; 100% dry matter bases) for growing pigs and 6% CSW for finishing pigs reduced growth performance by only 5% while feed efficiency and carcass quality was not influenced. However, at these high inclusion levels, abnormalities were seen in the kidneys of some of the pigs, which could be attributed to high dietary potassium levels. These findings indicate that even higher levels of co-product usage should be evaluated and that some simple dietary interventions to reduce abnormalities in kidneys should be explored. These two aspects will be explored further in future studies in which pigs will be fed high potassium containing co-products from mycotoxins-free corn from the 2007 harvest. SELECTED REFERENCES Braun, K. and C.F.M. de Lange Co-products use in swine liquid feeding: aspects of food safety and nutritional value. Easter Nutritional Conference, Ottawa, May 12, pp Brobst, D Review of the pathophysiology of alterations in potassium homeostasis. Journal of American Veterinary Medical Association 188(9): Giebisch, G Renal potassium transport: mechanisms and regulation. American Journal of Physiology, 274 (Renal Fluid Electrolyte Physiology 43): F817-F833. Golz, D.I., Crenshaw, T.D Interrelationships of dietary sodium, potassium and chloride on growth in young swine. Journal of Animal Science 68: Golz, D.I., Crenshaw, T.D Effect of dietary potassium and chloride on cation-anion balance in swine. Journal of Animal Science 69: Lemann, J., Gray, R.W., Pleuss, J.A Potassium bicarbonate, but not sodium bicarbonate, reduces urinary calcium excretion and improves calcium balance in healthy men. Kidney International 35(2): Abstract Malnic, G., Berliner, R.W., Giebisch, G Flow dependence of K+ secretion in cortical distal tubules of the rat. American Journal of Physiology, 256 (Renal Fluid Electrolyte Physiol. 25): F932-F941. NRC (National Research Council) Nutrient Requirements of Swine. Tenth Revised Edition. National Academics Press, Washington, D.C USA. Patience, J.F., Zijlstra, R Sodium, potassium, chloride, magnesium, and sulphur in swine nutrition. In (Lewsim A.J. and L.L.Southern Ed.) Swine Nutrition 2nd Ed. CRC Press. Boca Raton, Fa, USA. Pp Sellmeyer, D.E., Schloetter, M., Sebastian, A Potassium citrate prevents increased urine calcium excretion and bone resorption induced by a high sodium chloride diet. Journal of Clinical Endocrinology and Metabolism 87: ACKNOWLEDGEMENTS This research has been possible through the financial support of Ontario Pork and the Canada-Ontario Research and Development (CORD) Program, an initiative of the federal-provincial-territorial Agricultural Policy Framework designed to position Canada s agri-food sector as a world leader. The Agricultural Adaptation Council administers the CORD Program on behalf of the province. 7