Einleitung: Die Kationen-Anionen Bilanz (DCAB) des Futters modifiziert den Säure-Basen Status von Tieren und findet Anwendung in der Prävention von Milchfieber bei Kühen, MMA bei Sauen und Urolithiasis bei Haustieren. Durch die Veränderung des Kationen-Anionen-Verhältnisses in Futterrationen können biologische Prozesse beeinflusst werden, der Stickstoffmetabolismus. Ziel der Untersuchung: Die vorliegende Studie befasst sich mit der Frage, ob eine kaliumbedingte Variation der DCAB des Futters für wachsende Schweine einen Einfluss auf bestimmte Parameter des Säure-Basen-Haushaltes und möglicherweise auch auf die Stickstoffbilanz hat. Materialien und Methoden: Dem Versuch standen insgesamt 38 männlich kastrierte Mastschweine (Dreirassen-Kreuzung von Pietrain x Deutsches Edelschwein x Deutsche Landrasse) mit einem Einstallungsalter von ca. 12 Wochen und einer Lebendmasse von 17,3 kg bis 30,3 kg zur Verfügung. In randomisierter Reihenfolge erfolgte die Zuteilung der Schweine zu den acht Versuchsfuttern; Rohproteingehalt von 140 g kg-1 Futter und 200 g kg-1 Futter, sowie je 4 g, 10 g, 14 g oder 20 g Kalium kg-1 Futter. Die Versuchsfutter wiesen eine konstante Konzentration an Natrium und Chlorid auf. Die Hauptfutterkomponenten waren Mais und Weizen. Die beiden Rohproteingehalte wurden durch unterschiedliche Sojaextraktionsschrot- und Maisklebermengen gewonnen. Über Kaliumhydrogencarbonat (KHCO3) und Kaliumchlorid (KCl) resultierte die Einstellung der genannten Kaliumkonzentrationen sowie der vier DCAB-Stufen von -125 mEq kg-1, 66 mEq kg-1, 168 mEq kg-1, und 342 mEq kg-1 Futter. In einer Adaptionsphase von 15 Tagen gewöhnten sich die Scheine an das Versuchsfutter und die Umgebung. Die Einstallung erfolgte in Einzelboxen und die Versuchstiere erhielten Wasser ad libitum. Während der anschießenden zwei Bilanzphasen von je fünf Tagen wurden die Schweine in Bilanzkäfigen gehalten. Zwischen den beiden Bilanzphasen kam es zu einer fünftägigen Pause ohne Änderung der Fütterung. In der Bilanzzeit wurden der gesamte Harn und Kot der Tiere gesammelt sowie der dazugehörige pH-Wert kontinuierlich bestimmt. Harn- und Kotaliquots wurden für Stickstoff- und Elektrolytanalysen einbehalten. Jede fünftägige Bilanz endete mit der Gewinnung einer Blutprobe von jedem Schwein aus der Vena jugulares zur Bestimmung von Kalium, Natrium, Chlorid, pH-Wert, Hydrogencarbonat, Basenüberschuss und Aminosäuren. Ergebnisse: Kalium hat einen Einfluss auf den Harn pH-Wert. Analog zur steigenden Kaliumaufnahme (DCAB↑) wurden die Harn pH-Werte basischer (-125 mEq kg-1 Futter = Ø 5,93; 342 mEq kg-1 Futter = Ø 8,37). Die Blut pH-Werte, die im Durchschnitt bei 7,21 lagen, wie auch die Hydrogencarbonat- und Basenüberschusskonzentration, reagierten aufgrund der renalen Kompensation nicht wesentlich auf die unterschiedlichen DCAB im Futter. Die dazugehörigen Kot pH-Werte waren bei -125 mEq kg-1 Futter und 66 mEq kg-1 Futter um 0,16 höher als bei den anderen beiden DCAB-Stufen. Die Stickstoffaufnahme variierte zwischen 0,90 g kg-1KM d-1 und 1,22 g kg-1KM d-1 aufgrund der beiden Rohproteingehalte (14 und 20 %) in den Versuchsrationen. Eine Senkung der DCAB im Futter bewirkte eine Verbesserung der Stickstoffverdaulichkeit von 86,1 % auf 89,9 % (p<0,05). Hingegen zeigten die Diäten mit der kaliumärmsten Konzentration die höchsten renalen Stickstoffexkretionen von 442 mg kg-1KM d-1 gegenüber den anderen drei Kaliumkonzentrationen (345 mg kg-1KM d-1). In Folge dessen ergibt sich eine Stickstoffretentionssteigerung mit zunehmender DCAB im Futter. Jedoch wurde bei 66 mEq kg-1 Futter (Kalium 10 g kg-1 Futter) die höchste Stickstoffretention von 643 mg kg-1KM d-1 festgestellt. Die Untersuchung der Blutproben ergab keine Beeinflussung der Summe aller Aminosäuren, die bei ø 44,66 mg dl-1 lag. Die Summe der essentiellen Aminosäuren war bei einer DCAB von 66 mEq kg-1 Futter im Blut geringer als bei den übrigen Variationen. Einige Parameter der Elektrolytbilanzen waren zwischen den Futtervariationen verschieden: Bei dem Versuchsfutter mit einer DCAB von -125 mEq kg-1 Futter (Kalium 4 g kg-1 Futter) schieden die Schweine Na: 2,83 mg kg-1KM d-1 und Cl: 1,54 mg kg-1KM d 1 weniger mit dem Kot und Na: 7,05 mg kg-1KM d-1 weniger mit dem Harn aus gegenüber den weiteren Versuchsgruppen. Die renale Chloridexkretion zeigte keine Variabilität. Die renale, als auch die fäkale Kaliumausscheidung nahm analog zur DCAB des Futters zu (DCAB im Futter: -125 mEq kg-1; 66 mEq kg-1; 168 mEq kg-1; 342 mEq kg-1; K-Abgabe in mg kg-1KM d-1, renal: 74,0; 273,3; 431,1; 609,1; fäkal: 24,5; 31,2; 32,6; 44,0). In der Gesamtheit betrachtet ergibt sich für die Natrium- und Chloridretention keine richtungsweisende Beeinflussung im Zusammenhang mit der DCAB der Versuchsrationen. Die Kaliumretention hingegen stieg von 66,5 mg kg-1KM d-1 (-125 mEq kg-1 Futter) auf 167,0 mg kg-1KM d-1 (342 mEq kg-1 Futter) an, was nicht von den Kaliumkonzentrationen im Blut wiedergegeben wurde. Entsprechendes gilt für die Natrium- und Chloridkonzentrationen im Blut. Schlussfolgerungen: In der Alkalisierung des Harns zeigt sich, dass der DCAB des Futters Einfluss auf den Säure-Basen Status nimmt. Der systemische pH-Wert blieb aufgrund der Puffersysteme des Organismuses weitestgehend unberührt. Durch die KHCO3-Zulagen wurde das intragastrale bzw. das intestinale pH-Milieu verändert, was sich in der schlechteren Verdaulichkeit von Stickstoff bei höherer DCAB wiederspiegelt. Die Stickstoffretention steht in keinem Zusammenhang mit der Stickstoffverdaulichkeit. Mit dem DCAB von 66 mEq kg-1 Futter bzw. K: 10 g kg-1 Futter wurde die beste Retention für Stickstoff beobachtet. Die täglichen Gewichtszunahmen und die Futterverwertungen der Versuchsschweine konnten dies allerdings nicht reflektieren. Anzumerken sei, dass für einen eindeutigen Effekt auf die tägliche Zunahme eine längere Beobachtungsphase notwendig wäre (Sprung der täglichen Zunahmen von 520 g für -125 mEq kg-1 Futter auf das Niveau von 692 g für 66 mEq kg-1 Futter und mehr). Eine Empfehlung in Anlehnung an diese Studie wäre ein DCAB-Wert um die 66 mEq kg-1 Futter. Wird dieser Wert erhöht sinkt die Stickstoffverdaulichkeit auf der anderen Seite verschlechtert sich die Stickstoffretention bei Verringerung der DCAB. / Initiation: The dietary cation-anion balance (DCAB) of the feed modifies the acid-base balance and is used in the prevention of milk fever in cows, MMA in sows and urolithiasis in pets. The modification of the cation-anion ratio in diets can take an impact on biological processes inducting nitrogen metabolism. Objectives of investigations: This study objectively clarifies, whether potassium-based variation of the DCAB of the food has an influence on certain parameters of the nitrogen balance and the acid-base balance. Materials and Methods: The trial covered a total of 38 male castrated pigs (three racial crossing Pietrain x Large White x German Landrace) with a housing-age of approximately 12 weeks and a live weight of 17.3 kg to 30.3 kg. In randomized order, the pigs were allocated to the eight experimental feed: crude protein content of 140 g per kg feed and 200 g per kg feed, as well as 4, 10, 14 or 20 g of potassium per kg feed. The sodium and chloride concentrations in the feed were kept constant. The main food components were corn and wheat. The two crude protein levels were determined by various soybean meal and corn gluten quantities. Potassium hydrogen carbonate (KHCO3) and potassium chloride (KCl) were used to establish the four DCAB levels of -125 mEq kg-1, 66 mEq kg-1, 168 mEq kg-1, and 342 mEq kg-1 feed. In an adaptation period of 15 days pigs were accustomed to food and environment. They were kept in individual pens and were given water ad libitum. During the following two trial phases of five days each, the pigs were kept in balance cages. Between the two trial periods, there was a break of five days (no diet change). During the trial period all urine and excrement of the animals was collected, and the respective pH-value was continuously measured. Aliquots of urine and faeces were used in nitrogen and electrolyte analyses. At the end of each five-day record a blood sample from the jugular vein was taken from each pig for determination of potassium, sodium, chloride, pH-value, hydrogen carbonate, base excess, and amino acids. Results: Potassium has a significant influence on renal pH values. Analogous to increasing potassium intake (DCAB ↑), the urine pH value turned more basic (-125 mEq kg-1 feed = 5.93; 342 mEq kg-1 feed = 8.37). The blood pH levels, which averaged at 7.21, as well as the hydrogen carbonate concentration and base excess concentration, did not respond to the different DCAB in the feed because of the renal compensation. The associated feces pH values at -125 mEq kg-1 feed and 66 mEq kg-1 feed were higher by 0.16 than at the other two DCAB levels. The nitrogen intake varied between 0.90 g kg-1BM d-1 and 1.22 g kg-1BM d-1, based on both crude proteins (14 % and 20 %) in the experimental feeds. A reduction of DCAB in the feed resulted in an improvement of the nitrogen digestibility from 86.1 % to 89.9 % (< 0.05). However, diets with the lowest concentration of potassium showed the highest renal nitrogen excretions of 442 mg kg-1BM d-1 compared to the other three concentrations of potassium (345 mg kg-1BM d-1). As a consequence, nitrogen retention increases with increasing DCAB in the feed. However, the highest nitrogen retention of 643 mg kg-1KM d-1 was found with a 66 mEq kg-1 diet (potassium 10 g kg-1 feed). The examination of blood samples revealed no influence on the sum of the amino acids, which was 44.66 mg dl-1. The sum of the essential amino acids was reduced at a DCAB of 66 mEq kg-1 in blood, similar to the other variations. Some parameters of the electrolyte balances were different between the feed variations: In the experimental diet with a DCAB of -125 mEq kg-1 diet (potassium 4 g kg-1 feed), the pigs eliminated Na: 2.83 mg kg- 1BM d-1 and Cl: 1.54 mg kg– 1BM d-1 less in the feces and Na: 7.05 mg kg- 1KM d-1 less in the urine with respect to the other experimental groups. Renal chloride excretion showed no variability. The renal and fecal excretion of potassium increased proportionally to the DCAB of the feed (DCAB in the feed: -125 mEq kg-1, 66 mEq kg-1, 168 mEq kg-1; 342 mEq kg-1; K output in mg kg- 1BM d-1, renal: 74.0; 273.3; 431.1; 609.1; fecal: 24.5; 31.2; 32.6; 44.0). When viewed against the totality of results for the sodium and chloride retention, there were no trend-setting influences in connection with the DCAB of the experimental diets. The potassium retention, however, increased from 66.5 mg kg- 1BM d-1 (-125 mEq kg-1 feed) to 167.0 mg kg- 1BM d-1 (342 mEq kg -1 feed), which was not reproduced from the potassium concentrations in the blood. The same applied to the sodium and chloride concentrations in the blood. Conclusions: The alkalization of the urine shows that the DCAB of the feed influences the acid-base status. The systemic pH remained largely unaffected due to the buffer systems of the organism. The intragastric, respectively the intestinal, pH medium was changed by the addition of potassium hydrogen carbonate, which is reflected in the poorer digestibility of nitrogen at higher DCAB. The nitrogen retention is not related to the nitrogen digestibility. The best retention of nitrogen was observed with the DCAB of 66 mEq kg-1 feed (K: 10 g kg-1 feed). The daily weight gain and feed utilizations of the pigs certainly could not reflect this. It should be noted, however, that a longer observation period would be necessary for a clear effect on daily gain (jump of the daily weight gain from 520 g of -125 mEq kg-1 feed to the level of 692 g for 66 mEq kg-1 feed and more). A recommendation based on this study would be a DCAB value of 66 mEq kg-1 feed. If this value increases, the nitrogen digestibility decreases; on the other hand, the nitrogen retention deteriorated with reducing DCAB.

Einleitung: Die Kationen-Anionen Bilanz (DCAB) des Futters modifiziert den Säure-Basen Status von Tieren und findet Anwendung in der Prävention von Milchfieber bei Kühen, MMA bei Sauen und Urolithiasis bei Haustieren. Durch die Veränderung des Kationen-Anionen-Verhältnisses in Futterrationen können biologische Prozesse beeinflusst werden, der Stickstoffmetabolismus. Ziel der Untersuchung: Die vorliegende Studie befasst sich mit der Frage, ob eine kaliumbedingte Variation der DCAB des Futters für wachsende Schweine einen Einfluss auf bestimmte Parameter des Säure-Basen-Haushaltes und möglicherweise auch auf die Stickstoffbilanz hat. Materialien und Methoden: Dem Versuch standen insgesamt 38 männlich kastrierte Mastschweine (Dreirassen-Kreuzung von Pietrain x Deutsches Edelschwein x Deutsche Landrasse) mit einem Einstallungsalter von ca. 12 Wochen und einer Lebendmasse von 17,3 kg bis 30,3 kg zur Verfügung. In randomisierter Reihenfolge erfolgte die Zuteilung der Schweine zu den acht Versuchsfuttern; Rohproteingehalt von 140 g kg-1 Futter und 200 g kg-1 Futter, sowie je 4 g, 10 g, 14 g oder 20 g Kalium kg-1 Futter. Die Versuchsfutter wiesen eine konstante Konzentration an Natrium und Chlorid auf. Die Hauptfutterkomponenten waren Mais und Weizen. Die beiden Rohproteingehalte wurden durch unterschiedliche Sojaextraktionsschrot- und Maisklebermengen gewonnen. Über Kaliumhydrogencarbonat (KHCO3) und Kaliumchlorid (KCl) resultierte die Einstellung der genannten Kaliumkonzentrationen sowie der vier DCAB-Stufen von -125 mEq kg-1, 66 mEq kg-1, 168 mEq kg-1, und 342 mEq kg-1 Futter. In einer Adaptionsphase von 15 Tagen gewöhnten sich die Scheine an das Versuchsfutter und die Umgebung. Die Einstallung erfolgte in Einzelboxen und die Versuchstiere erhielten Wasser ad libitum. Während der anschießenden zwei Bilanzphasen von je fünf Tagen wurden die Schweine in Bilanzkäfigen gehalten. Zwischen den beiden Bilanzphasen kam es zu einer fünftägigen Pause ohne Änderung der Fütterung. In der Bilanzzeit wurden der gesamte Harn und Kot der Tiere gesammelt sowie der dazugehörige pH-Wert kontinuierlich bestimmt. Harn- und Kotaliquots wurden für Stickstoff- und Elektrolytanalysen einbehalten. Jede fünftägige Bilanz endete mit der Gewinnung einer Blutprobe von jedem Schwein aus der Vena jugulares zur Bestimmung von Kalium, Natrium, Chlorid, pH-Wert, Hydrogencarbonat, Basenüberschuss und Aminosäuren. Ergebnisse: Kalium hat einen Einfluss auf den Harn pH-Wert. Analog zur steigenden Kaliumaufnahme (DCAB↑) wurden die Harn pH-Werte basischer (-125 mEq kg-1 Futter = Ø 5,93; 342 mEq kg-1 Futter = Ø 8,37). Die Blut pH-Werte, die im Durchschnitt bei 7,21 lagen, wie auch die Hydrogencarbonat- und Basenüberschusskonzentration, reagierten aufgrund der renalen Kompensation nicht wesentlich auf die unterschiedlichen DCAB im Futter. Die dazugehörigen Kot pH-Werte waren bei -125 mEq kg-1 Futter und 66 mEq kg-1 Futter um 0,16 höher als bei den anderen beiden DCAB-Stufen. Die Stickstoffaufnahme variierte zwischen 0,90 g kg-1KM d-1 und 1,22 g kg-1KM d-1 aufgrund der beiden Rohproteingehalte (14 und 20 %) in den Versuchsrationen. Eine Senkung der DCAB im Futter bewirkte eine Verbesserung der Stickstoffverdaulichkeit von 86,1 % auf 89,9 % (p<0,05). Hingegen zeigten die Diäten mit der kaliumärmsten Konzentration die höchsten renalen Stickstoffexkretionen von 442 mg kg-1KM d-1 gegenüber den anderen drei Kaliumkonzentrationen (345 mg kg-1KM d-1). In Folge dessen ergibt sich eine Stickstoffretentionssteigerung mit zunehmender DCAB im Futter. Jedoch wurde bei 66 mEq kg-1 Futter (Kalium 10 g kg-1 Futter) die höchste Stickstoffretention von 643 mg kg-1KM d-1 festgestellt. Die Untersuchung der Blutproben ergab keine Beeinflussung der Summe aller Aminosäuren, die bei ø 44,66 mg dl-1 lag. Die Summe der essentiellen Aminosäuren war bei einer DCAB von 66 mEq kg-1 Futter im Blut geringer als bei den übrigen Variationen. Einige Parameter der Elektrolytbilanzen waren zwischen den Futtervariationen verschieden: Bei dem Versuchsfutter mit einer DCAB von -125 mEq kg-1 Futter (Kalium 4 g kg-1 Futter) schieden die Schweine Na: 2,83 mg kg-1KM d-1 und Cl: 1,54 mg kg-1KM d 1 weniger mit dem Kot und Na: 7,05 mg kg-1KM d-1 weniger mit dem Harn aus gegenüber den weiteren Versuchsgruppen. Die renale Chloridexkretion zeigte keine Variabilität. Die renale, als auch die fäkale Kaliumausscheidung nahm analog zur DCAB des Futters zu (DCAB im Futter: -125 mEq kg-1; 66 mEq kg-1; 168 mEq kg-1; 342 mEq kg-1; K-Abgabe in mg kg-1KM d-1, renal: 74,0; 273,3; 431,1; 609,1; fäkal: 24,5; 31,2; 32,6; 44,0). In der Gesamtheit betrachtet ergibt sich für die Natrium- und Chloridretention keine richtungsweisende Beeinflussung im Zusammenhang mit der DCAB der Versuchsrationen. Die Kaliumretention hingegen stieg von 66,5 mg kg-1KM d-1 (-125 mEq kg-1 Futter) auf 167,0 mg kg-1KM d-1 (342 mEq kg-1 Futter) an, was nicht von den Kaliumkonzentrationen im Blut wiedergegeben wurde. Entsprechendes gilt für die Natrium- und Chloridkonzentrationen im Blut. Schlussfolgerungen: In der Alkalisierung des Harns zeigt sich, dass der DCAB des Futters Einfluss auf den Säure-Basen Status nimmt. Der systemische pH-Wert blieb aufgrund der Puffersysteme des Organismuses weitestgehend unberührt. Durch die KHCO3-Zulagen wurde das intragastrale bzw. das intestinale pH-Milieu verändert, was sich in der schlechteren Verdaulichkeit von Stickstoff bei höherer DCAB wiederspiegelt. Die Stickstoffretention steht in keinem Zusammenhang mit der Stickstoffverdaulichkeit. Mit dem DCAB von 66 mEq kg-1 Futter bzw. K: 10 g kg-1 Futter wurde die beste Retention für Stickstoff beobachtet. Die täglichen Gewichtszunahmen und die Futterverwertungen der Versuchsschweine konnten dies allerdings nicht reflektieren. Anzumerken sei, dass für einen eindeutigen Effekt auf die tägliche Zunahme eine längere Beobachtungsphase notwendig wäre (Sprung der täglichen Zunahmen von 520 g für -125 mEq kg-1 Futter auf das Niveau von 692 g für 66 mEq kg-1 Futter und mehr). Eine Empfehlung in Anlehnung an diese Studie wäre ein DCAB-Wert um die 66 mEq kg-1 Futter. Wird dieser Wert erhöht sinkt die Stickstoffverdaulichkeit auf der anderen Seite verschlechtert sich die Stickstoffretention bei Verringerung der DCAB. / Initiation: The dietary cation-anion balance (DCAB) of the feed modifies the acid-base balance and is used in the prevention of milk fever in cows, MMA in sows and urolithiasis in pets. The modification of the cation-anion ratio in diets can take an impact on biological processes inducting nitrogen metabolism. Objectives of investigations: This study objectively clarifies, whether potassium-based variation of the DCAB of the food has an influence on certain parameters of the nitrogen balance and the acid-base balance. Materials and Methods: The trial covered a total of 38 male castrated pigs (three racial crossing Pietrain x Large White x German Landrace) with a housing-age of approximately 12 weeks and a live weight of 17.3 kg to 30.3 kg. In randomized order, the pigs were allocated to the eight experimental feed: crude protein content of 140 g per kg feed and 200 g per kg feed, as well as 4, 10, 14 or 20 g of potassium per kg feed. The sodium and chloride concentrations in the feed were kept constant. The main food components were corn and wheat. The two crude protein levels were determined by various soybean meal and corn gluten quantities. Potassium hydrogen carbonate (KHCO3) and potassium chloride (KCl) were used to establish the four DCAB levels of -125 mEq kg-1, 66 mEq kg-1, 168 mEq kg-1, and 342 mEq kg-1 feed. In an adaptation period of 15 days pigs were accustomed to food and environment. They were kept in individual pens and were given water ad libitum. During the following two trial phases of five days each, the pigs were kept in balance cages. Between the two trial periods, there was a break of five days (no diet change). During the trial period all urine and excrement of the animals was collected, and the respective pH-value was continuously measured. Aliquots of urine and faeces were used in nitrogen and electrolyte analyses. At the end of each five-day record a blood sample from the jugular vein was taken from each pig for determination of potassium, sodium, chloride, pH-value, hydrogen carbonate, base excess, and amino acids. Results: Potassium has a significant influence on renal pH values. Analogous to increasing potassium intake (DCAB ↑), the urine pH value turned more basic (-125 mEq kg-1 feed = 5.93; 342 mEq kg-1 feed = 8.37). The blood pH levels, which averaged at 7.21, as well as the hydrogen carbonate concentration and base excess concentration, did not respond to the different DCAB in the feed because of the renal compensation. The associated feces pH values at -125 mEq kg-1 feed and 66 mEq kg-1 feed were higher by 0.16 than at the other two DCAB levels. The nitrogen intake varied between 0.90 g kg-1BM d-1 and 1.22 g kg-1BM d-1, based on both crude proteins (14 % and 20 %) in the experimental feeds. A reduction of DCAB in the feed resulted in an improvement of the nitrogen digestibility from 86.1 % to 89.9 % (< 0.05). However, diets with the lowest concentration of potassium showed the highest renal nitrogen excretions of 442 mg kg-1BM d-1 compared to the other three concentrations of potassium (345 mg kg-1BM d-1). As a consequence, nitrogen retention increases with increasing DCAB in the feed. However, the highest nitrogen retention of 643 mg kg-1KM d-1 was found with a 66 mEq kg-1 diet (potassium 10 g kg-1 feed). The examination of blood samples revealed no influence on the sum of the amino acids, which was 44.66 mg dl-1. The sum of the essential amino acids was reduced at a DCAB of 66 mEq kg-1 in blood, similar to the other variations. Some parameters of the electrolyte balances were different between the feed variations: In the experimental diet with a DCAB of -125 mEq kg-1 diet (potassium 4 g kg-1 feed), the pigs eliminated Na: 2.83 mg kg- 1BM d-1 and Cl: 1.54 mg kg– 1BM d-1 less in the feces and Na: 7.05 mg kg- 1KM d-1 less in the urine with respect to the other experimental groups. Renal chloride excretion showed no variability. The renal and fecal excretion of potassium increased proportionally to the DCAB of the feed (DCAB in the feed: -125 mEq kg-1, 66 mEq kg-1, 168 mEq kg-1; 342 mEq kg-1; K output in mg kg- 1BM d-1, renal: 74.0; 273.3; 431.1; 609.1; fecal: 24.5; 31.2; 32.6; 44.0). When viewed against the totality of results for the sodium and chloride retention, there were no trend-setting influences in connection with the DCAB of the experimental diets. The potassium retention, however, increased from 66.5 mg kg- 1BM d-1 (-125 mEq kg-1 feed) to 167.0 mg kg- 1BM d-1 (342 mEq kg -1 feed), which was not reproduced from the potassium concentrations in the blood. The same applied to the sodium and chloride concentrations in the blood. Conclusions: The alkalization of the urine shows that the DCAB of the feed influences the acid-base status. The systemic pH remained largely unaffected due to the buffer systems of the organism. The intragastric, respectively the intestinal, pH medium was changed by the addition of potassium hydrogen carbonate, which is reflected in the poorer digestibility of nitrogen at higher DCAB. The nitrogen retention is not related to the nitrogen digestibility. The best retention of nitrogen was observed with the DCAB of 66 mEq kg-1 feed (K: 10 g kg-1 feed). The daily weight gain and feed utilizations of the pigs certainly could not reflect this. It should be noted, however, that a longer observation period would be necessary for a clear effect on daily gain (jump of the daily weight gain from 520 g of -125 mEq kg-1 feed to the level of 692 g for 66 mEq kg-1 feed and more). A recommendation based on this study would be a DCAB value of 66 mEq kg-1 feed. If this value increases, the nitrogen digestibility decreases; on the other hand, the nitrogen retention deteriorated with reducing DCAB.

O efeito do balanço cátion-aniônico da dieta (BCAD) no desempenho, balanço macromineral (cálcio, fósforo, sódio e potássio), na fermentação ruminal , pH urinário e na concentração sérica de cálcio, foi estudado utilizando-se 25 ovinos machos, da raça Santa Inês, por um período de 75 dias. O delineamento experimental foi em blocos ao acaso, com cinco tratamentos. Para a manipulação do BCAD foram adicionados sulfato de amônio e bicarbonato de sódio, obtendo-se os seguintes tratamentos: -160, -40, 140, 250 e 500 mEq/kg MS. O aumento do BCAD resultou em aumento da IMS, aumento em ganhos diários e eficiência alimentar (P<0,05). O pH ruminal, pH urinário e o volume urinário aumentaram com aumento do BCAD (P<0,05). O perfil de ácidos graxos ruminais não foi afetado pelo BCAD. O BCAD influenciou o metabolismo macromineral principalmente o de cálcio, com a diminução do BCAD o cálcio sérico aumentou. Dietas aniônicas aumentaram a excreção urinária de cálcio, entretanto a retenção não foi afetada. / The dietary cation-anion balance (DCAB) effect in performance, macromineral (calcium, phosphorus and sodium) balance, urinary pH and calcium serum concentration, was studied in 25 males sheeps, from Santa Ines breed, during 75 days. The design used was randomized complete blocks, with five treatments. For DCAB manipulation were added ammonium sulfate and sodium bicarbonate in order to achieve the values: -160, -40, 140, 250 e 500 meq/kg DM. Increasing the DCAB resulted in higher DMI, daily gains and feed efficiency (P<0,05). Rumen pH, urine pH and urine volume increased as DCAB increased (p<0,05). Ruminal VFA profile was not affected by DCAB. The DCAB affected the calcium metabolism, decresing the DCAB the serum calcium increased. Dietary anionic increased urinary excretion of calcium, however calcium retention was not effect.

Os efeitos do balanço cátion-aniônico da dieta (BCAD) na degradabilidade ruminal da MS e PB do farelo de soja, degradabilidade ruminal da MS e amido do fubá de milho, foram estudados em dois experimentos com diferentes proporções de volumoso:concentrado (experimento 1 - 60:40; experimento 2 - 40:60), em 12 bezerros Holandeses (peso médio de 91,55kg e de 117,62kg respectivamente), portadores de cânulas ruminais, realizados no Campus Administrativo de Pirassununga/SP, na FZEA/USP. Os períodos experimentais foram de 35 dias, sendo 14 dias de adaptação dos animais às gaiolas e às dietas e 21 dias de colheita de dados, com 15 dias de descanso. O delineamento foi o inteiramente casualizado, com três tratamentos e quatro repetições em ambos os experimentos. Para a manipulação do BCAD, foram adicionados sulfato de amônio e bicarbonato de sódio, obtendo-se os seguintes tratamentos no experimento 1: -123, +218 e +341 mEq/kg MS; e no experimento 2: -127, +207 e +397 mEq/kg MS. Utilizou-se silagem de milho como fonte de volumoso. Os níveis de BCAD influenciaram as degradabilidades ruminais da MS e PB do farelo de soja com a proporção de volumoso:concentrado de 60:40 (P<0,10). As degradabilidades ruminais da MS e amido do fubá de milho com a proporção volumoso:concentrado de 60:40, não foram afetadas pelos níveis de BCAD (P>0,10), assim como as degradabilidades ruminais da MS e PB do farelo de soja, MS e amido do fubá de milho com a proporção volumoso:concentrado de 40:60 (P>0,10). / The DCAB effects on dry matter (DM) and crude protein (CP) degradability of soybean meal and DCAB effects on DM and corn meal degradability were investigated in two trials with different rate of roughage:concentrate (experiment 1: 60:40, experiment 2: 40:60). Twelve Holstein calves with ruminal cannula were used in each experiment (91,55 kg and 117,62 kg of mean weight, respectively). Both experiments were conducted at FZEA/USP, Pirassununga/SP. The experimental periods were constituted by 35 days (14 days adaptation and 21 days data collection) with 15 days of interval. It was used completely design, with three treatments and four repetitions. For DCAB manipulation were added ammonium sulfate and sodium bicarbonate in order to achieve the following values: experiment 1: -123, +218, +341 mEq/kg DM, experiment 2: -127, +207, +397 mEq/kg DM. The diet was based on corn silage as forage. The DCAB ratios affected DM and soybean meal CP degradabilities when 60:40 roughage:concentrate ratio were used (P<0,10). DM and corn meal degradabilities were not affected by DCAB ratios (P>0,10), as well as DM and soybean meal CP degradabilities when 40:60 roughage:concentrate ratio were used P<0,10).

Foram utilizadas 8 vacas Holandesas em lactação, distribuídas em um quadrado latino (4x4), replicado, conduzidos durante o verão, por um período de 72 dias. O objetivo desse trabalho foi estudar quatro níveis de dietas catiônicas, sobre a IMS, produção, composição e propriedades físico-químicas do leite, pH urinário, temperatura corporal e parâmetros ácido-base do sangue, em vacas após o pico de lactação. Para a manipulação do BCAD, foram adicionadas diferentes concentrações de bicarbonato de sódio nas dietas, obtendo-se os seguintes tratamentos: +150, +250, +400 e +500mEq/kg MS. A temperatura corporal das vacas não foi afetada pelo balanço cátion-aniônico da dieta. O bicarbonato, o pH, o CO2 total e a pCO2 do sangue aumentaram linearmente com o aumento do BCAD. A concentração de cálcio no sangue apresentou resposta quadrática, com maior valor para o menor BCAD. As concentrações de sódio e potássio do sangue não foram modificadas significativamente pelo BCAD e a concentração de cloro diminuiu linearmente com o aumento do BCAD. O aumento do BCAD resultou em aumento da ingestão de matéria seca e produção de leite. Não houve diferença significativa para as variáveis: porcentagem de gordura, densidade e índice crioscópico, do leite. O pH do leite aumentou linearmente e a acidez apresentou resposta cúbica, com o aumento do BCAD. Conclui-se que a manipulação do BCAD afeta o equilíbrio ácido-base das vacas, mesmo dentro de variação positiva. Devido ao aumento da IMS e da produção de leite, verificou-se efeito benéfico do uso de dietas catiônicas, para vacas após o pico de lactação. / Eight lactating Holsteins cows were distributed in 4 x 4 replicated Latin square, during the summer, for a period of 72 days. The objective of this research was to study the effect of four cationic diets levels, on the dry matter intake, milk production, composition, and physico-chemical parameters, urinary pH, body temperature and blood acid-base parameters, in cows, after the lactation peak. For DCAB manipulation were added different concentrations of sodium bicarbonate in the diets and the following treatments were obtainned: +150, +250, +400 e +500mEq/kg DM. The cows body temperature was not affected by dietary cation-anion balance. Blood bicarbonate, pH, total CO2 and pCO2 increased linearly with the increase of dietary CAB. Calcium concentration in the blood decreased quadratically with dietary CAB increased. Sodium and potassium concentration in the blood were not modified significantly with the DCAB and concentration of chloride decreased linearly with increase of DCAB. Increasing BCAD resulted in higher DM intake and milk yield. The diets did not affect milk fat percentage, density and crioscopic index. Milk pH increased linearly and acidity decreased cubically with the increase of dietary CAB. It was concluded that DCAB manipulation affected the acid-base status of cows, even inside of positive variation. Due to the increase of DM intake and milk yield, it was verified a beneficial effect of the cationic diets for cows after the lactation peak.

Os efeitos do balanço cátion-aniônico da dieta (BCAD) na degradabilidade ruminal da MS e PB do farelo de soja, degradabilidade ruminal da MS e amido do fubá de milho, foram estudados em dois experimentos com diferentes proporções de volumoso:concentrado (experimento 1 - 60:40; experimento 2 - 40:60), em 12 bezerros Holandeses (peso médio de 91,55kg e de 117,62kg respectivamente), portadores de cânulas ruminais, realizados no Campus Administrativo de Pirassununga/SP, na FZEA/USP. Os períodos experimentais foram de 35 dias, sendo 14 dias de adaptação dos animais às gaiolas e às dietas e 21 dias de colheita de dados, com 15 dias de descanso. O delineamento foi o inteiramente casualizado, com três tratamentos e quatro repetições em ambos os experimentos. Para a manipulação do BCAD, foram adicionados sulfato de amônio e bicarbonato de sódio, obtendo-se os seguintes tratamentos no experimento 1: -123, +218 e +341 mEq/kg MS; e no experimento 2: -127, +207 e +397 mEq/kg MS. Utilizou-se silagem de milho como fonte de volumoso. Os níveis de BCAD influenciaram as degradabilidades ruminais da MS e PB do farelo de soja com a proporção de volumoso:concentrado de 60:40 (P<0,10). As degradabilidades ruminais da MS e amido do fubá de milho com a proporção volumoso:concentrado de 60:40, não foram afetadas pelos níveis de BCAD (P>0,10), assim como as degradabilidades ruminais da MS e PB do farelo de soja, MS e amido do fubá de milho com a proporção volumoso:concentrado de 40:60 (P>0,10). / The DCAB effects on dry matter (DM) and crude protein (CP) degradability of soybean meal and DCAB effects on DM and corn meal degradability were investigated in two trials with different rate of roughage:concentrate (experiment 1: 60:40, experiment 2: 40:60). Twelve Holstein calves with ruminal cannula were used in each experiment (91,55 kg and 117,62 kg of mean weight, respectively). Both experiments were conducted at FZEA/USP, Pirassununga/SP. The experimental periods were constituted by 35 days (14 days adaptation and 21 days data collection) with 15 days of interval. It was used completely design, with three treatments and four repetitions. For DCAB manipulation were added ammonium sulfate and sodium bicarbonate in order to achieve the following values: experiment 1: -123, +218, +341 mEq/kg DM, experiment 2: -127, +207, +397 mEq/kg DM. The diet was based on corn silage as forage. The DCAB ratios affected DM and soybean meal CP degradabilities when 60:40 roughage:concentrate ratio were used (P<0,10). DM and corn meal degradabilities were not affected by DCAB ratios (P>0,10), as well as DM and soybean meal CP degradabilities when 40:60 roughage:concentrate ratio were used P<0,10).

O efeito do balanço cátion-aniônico da dieta (BCAD) no desempenho, balanço macromineral (cálcio, fósforo, sódio e potássio), na fermentação ruminal , pH urinário e na concentração sérica de cálcio, foi estudado utilizando-se 25 ovinos machos, da raça Santa Inês, por um período de 75 dias. O delineamento experimental foi em blocos ao acaso, com cinco tratamentos. Para a manipulação do BCAD foram adicionados sulfato de amônio e bicarbonato de sódio, obtendo-se os seguintes tratamentos: -160, -40, 140, 250 e 500 mEq/kg MS. O aumento do BCAD resultou em aumento da IMS, aumento em ganhos diários e eficiência alimentar (P<0,05). O pH ruminal, pH urinário e o volume urinário aumentaram com aumento do BCAD (P<0,05). O perfil de ácidos graxos ruminais não foi afetado pelo BCAD. O BCAD influenciou o metabolismo macromineral principalmente o de cálcio, com a diminução do BCAD o cálcio sérico aumentou. Dietas aniônicas aumentaram a excreção urinária de cálcio, entretanto a retenção não foi afetada. / The dietary cation-anion balance (DCAB) effect in performance, macromineral (calcium, phosphorus and sodium) balance, urinary pH and calcium serum concentration, was studied in 25 males sheeps, from Santa Ines breed, during 75 days. The design used was randomized complete blocks, with five treatments. For DCAB manipulation were added ammonium sulfate and sodium bicarbonate in order to achieve the values: -160, -40, 140, 250 e 500 meq/kg DM. Increasing the DCAB resulted in higher DMI, daily gains and feed efficiency (P<0,05). Rumen pH, urine pH and urine volume increased as DCAB increased (p<0,05). Ruminal VFA profile was not affected by DCAB. The DCAB affected the calcium metabolism, decresing the DCAB the serum calcium increased. Dietary anionic increased urinary excretion of calcium, however calcium retention was not effect.

Foram utilizadas 8 vacas Holandesas em lactação, distribuídas em um quadrado latino (4x4), replicado, conduzidos durante o verão, por um período de 72 dias. O objetivo desse trabalho foi estudar quatro níveis de dietas catiônicas, sobre a IMS, produção, composição e propriedades físico-químicas do leite, pH urinário, temperatura corporal e parâmetros ácido-base do sangue, em vacas após o pico de lactação. Para a manipulação do BCAD, foram adicionadas diferentes concentrações de bicarbonato de sódio nas dietas, obtendo-se os seguintes tratamentos: +150, +250, +400 e +500mEq/kg MS. A temperatura corporal das vacas não foi afetada pelo balanço cátion-aniônico da dieta. O bicarbonato, o pH, o CO2 total e a pCO2 do sangue aumentaram linearmente com o aumento do BCAD. A concentração de cálcio no sangue apresentou resposta quadrática, com maior valor para o menor BCAD. As concentrações de sódio e potássio do sangue não foram modificadas significativamente pelo BCAD e a concentração de cloro diminuiu linearmente com o aumento do BCAD. O aumento do BCAD resultou em aumento da ingestão de matéria seca e produção de leite. Não houve diferença significativa para as variáveis: porcentagem de gordura, densidade e índice crioscópico, do leite. O pH do leite aumentou linearmente e a acidez apresentou resposta cúbica, com o aumento do BCAD. Conclui-se que a manipulação do BCAD afeta o equilíbrio ácido-base das vacas, mesmo dentro de variação positiva. Devido ao aumento da IMS e da produção de leite, verificou-se efeito benéfico do uso de dietas catiônicas, para vacas após o pico de lactação. / Eight lactating Holsteins cows were distributed in 4 x 4 replicated Latin square, during the summer, for a period of 72 days. The objective of this research was to study the effect of four cationic diets levels, on the dry matter intake, milk production, composition, and physico-chemical parameters, urinary pH, body temperature and blood acid-base parameters, in cows, after the lactation peak. For DCAB manipulation were added different concentrations of sodium bicarbonate in the diets and the following treatments were obtainned: +150, +250, +400 e +500mEq/kg DM. The cows body temperature was not affected by dietary cation-anion balance. Blood bicarbonate, pH, total CO2 and pCO2 increased linearly with the increase of dietary CAB. Calcium concentration in the blood decreased quadratically with dietary CAB increased. Sodium and potassium concentration in the blood were not modified significantly with the DCAB and concentration of chloride decreased linearly with increase of DCAB. Increasing BCAD resulted in higher DM intake and milk yield. The diets did not affect milk fat percentage, density and crioscopic index. Milk pH increased linearly and acidity decreased cubically with the increase of dietary CAB. It was concluded that DCAB manipulation affected the acid-base status of cows, even inside of positive variation. Due to the increase of DM intake and milk yield, it was verified a beneficial effect of the cationic diets for cows after the lactation peak.