The Influence of Short‐Term Anion Salt Exposure on Urine pH and on Resistance to Experimentally Induced Hypocalcaemia in Cows

Abstract

The objective of this experiment was to induce acidification by anion salt supplementation for 2 days or 10 days and to study the prophylactic effects of such supplementation in preventing hypocalcaemia in cows. It was further attempted to monitor the extent to which any effect on the calcium-regulating mechanisms would persist following a 10-day period of acidification with anion salts. Study animals were three untreated control cows and three cows supplemented with ammonium chloride and ammonium sulphate in their ration for 2 days or 10 days through the rumen cannula. The basic ration of hay was dominated by Urochloa spp. The pH of the urine of the control cows was around 8.00 throughout the experiment and was considered normal. Anion-supplemented cows produced urine with a daily mean pH between 5.5 and 7.0, possibly due to anion salt exposure. The ability to withstand hypocalcaemic challenges was tested by a standardized intravenous infusion of disodium ethylenediaminetetraacetate (Na2EDTA). The calcium regaining time (CRT), expressed as time spent to reach 1.00 mmol/l of ionized calcium during recovery from the EDTA-induced hypocalcaemia, was used to compare cow responses. In the control cows the unexpectedly short CRT, especially during the weekly EDTA tests, could be a result of the repeated induced episodes of hypocalcaemia caused by the EDTA infusions. The improved CRT in the anion-supplemented cows may thus be interpreted as the combined effect of the repeated hypocalcaemic episodes due to EDTA infusions and probably the effect of anion-induced metabolic acidosis on endocrine-regulated calcium homeostatic mechanisms. The effect of anion salt exposure for 10 days on the improvement of calcium-regulating mechanisms was not clear due to the unexpected improvement of CRT that was exhibited by the untreated control cows as well. An on-farm trial of the effect of a 2-day or 10-day anion exposure of dry cows on calcium-regulating mechanisms is suggested.

Scientific Opinion on the safety and efficacy of ammonium chloride for bovines, sheep, dogs and cats

“…The treatment diet induced a mild metabolic acidosis. Mellau et al (2002) studying the effect of anionic salts in the prevention of hypocalcaemia in cows administered ammonium chloride (approximately 0.6 % in the diet) via ruminal cannula for 2 days or 10 days. The pH of the urine of the control cows was around 8.0 throughout the experiment, and anion supplementation reduced urinary pH to 5.5 to 7.0.…”

Long‐term Effects of Dietary Anion–Cation Balance on Acid–Base Status and Bone Morphology in Reproducing Ewes

“…Since then, numerous publications have validated the utility of adding anions to pre‐partum diets for milk fever prevention (Goff and Horst, 1997; Pehrson et al., 1999; Schonewille et al., 1999; Van Dijk and Lourens, 2001; Mellau et al., 2002; Roche et al., 2003).…”

“…The time period of feeding the salts in previously reported trials has ranged from 2 to 45 days (Block, 1984; Mellau et al., 2002). Oetzel (2000) suggests that cows must consume the salts for at least 5 days to produce the desired physiological response.…”

Safety and efficacy of Amoklor (ammonium chloride) as a zootechnical additive for ruminants, cats and dogs

“…The acidifying capacity of ammonium chloride following the dietary-cation-anion-difference (DCAD) concept (Suttle, 2010), and the activation of the calcium metabolism in pregnant ruminants by a mild metabolic acidosis is also used to prevent milk fever (hypocalcaemia) occurrence in dairy cows after parturition, as demonstrated in some feeding studies (e.g. Block, 1984;Oetzel et al, 1988;Mellau et al, 2002;Goff et al, 2004;Goff, 2008). In such cases, ammonium chloride is given for 10-14 days before parturition until calving.…”

“…17 Technical dossier/Supplementary information October 2015/3.proposed conditions of use.pdf metabolic acidosis is also used to prevent milk fever (hypocalcaemia) occurrence in dairy cows after parturition, as demonstrated in some feeding studies (e.g. Block, 1984;Oetzel et al, 1988;Mellau et al, 2002;Goff et al, 2004;Goff, 2008). In such cases, ammonium chloride is given for 10-14 days before parturition until calving.…”