Bone, blood and faecal response to an acidogenic lick for range cattle using different concentrations of ammonium chloride.

Thirty Brahman-Angus cross heifers at breeding age on extensive grazing were used to test the effectiveness of NH4Cl as an acidogenic agent at 15,18, 21 and 26 % of a dicalcium phosphate lick (A+), compared to a lick of 5 parts dicalcium phosphate and 3 parts salt (A-). Blood and faecal phosphorus (P), faecal calcium (Ca) and faecal magnesium (Mg) were significantly (P<0.05) higher in A+ compared to A-animals at different stages of the experiment. Bone P did not increase in response to NH4Cl but bone Ca was significantly (P<0.05) higher in A+ animals offered 18% NH4Cl and significantly (P<0.05) lower at 15 and 26%. Bone Mg in A+ animals was significantly (P<0.05) higher at 15 and 18% NH4Cl and lower at 26% NH4Cl compared to A- animals. Percentage ash in bone increased linearly from 62.5 to 64.9% in A+ animals as NH4Cl was increased in the lick from 15 to 21% and then decreased to 63.3% but was significantly (P<0.05) greater than the percentage ash in A-animals when the NH4Cl was increased to 26%. Bone mineral status was only marginally improved by adding NH4Cl to the lick in this study but blood P was significantly (P<0.05) improved in A+ compared to A- animals when the lick contained 15, 21 and 26% NH4Cl. Based on bone mineral results reported here, it is recommended that, when NH4Cl is used as an acidogenic agent in licks for range cattle, the amount in the lick should not exceed 21%.