Effects of ammonia and hydrogen sulfide on physical and biochemical properties of the claw horn of Holstein cows.

The effects of ammonia and hydrogen sulfide on the physical and biochemical properties of the claw horn of Holstein cows were evaluated. Significant (P < 0.05, 0.01) decreases in hardness and elasticity were found in claw horns soaked in ammonia (NH(3)) and hydrogen sulfide (H(2)S) solutions compared with those that were soaked in water for 12, 24, and 48 h. Water absorption rate, as a indicator of permeability barrier function, increased significantly (P < 0.05) over time during the soaking period and was found to be dependent on the concentrations of NH(3) and H(2)S in the solutions. The contents of ceramide, the main lipid component for the permeability barrier system of the stratum corneum, were significantly decreased in claw horns soaked in NH(3) and H(2)S solutions compared with the values before soaking. Quantities of eluted protein released from claw horns treated with NH(3) and H(2)S solutions were approximately 20 times and 30 to 40 times greater than those released from claw horns treated with water alone. Interestingly, the quantities of cytokeratin 10, the main cytoskeletal protein of the stratum corneum, eluted from claw horns treated with NH(3) and H(2)S solutions were markedly greater than the quantity released from horns soaked in water. Our results suggest that abnormal changes in the physical property of claw horn caused by NH(3) and H(2)S treatment are due to disruption of the biochemical property of the claw horn induced by these chemical agents derived from slurry.