Table 2.

Histopathology of feet and organ tissues from heat-stressed wethers fed concentrate diets supplemented with ractopamine HCl or zilpaterol HCl for 21 d

Pathology1	Environment		P	Dietary supplement			P
	Control	Heat stress		No Suppl.	Ractopamine	Zilpaterol
Foot
Wall overgrowth	0%	92%	<0.001	27%	36%	36%	NS
Vacuolated keratinocytes in coronary band	56%	42%	NS	41%	56%	50%	NS
Lung
Lesions	4%	13%	NS	12%	6%	6%	NS
Liver
Lesions	12%	8%	NS	6%	19%	6%	NS
Kidney
Mineralization	80%	75%	NS	82%	81%	69%	NS
Nephritis	12%	8%	NS	6%	25%	0%	NS
Cardiac
Sacrocysts	68%	75%	NS	64%	68%	81%	NS
Lymphocytic aggregates	48%	38%	NS	41%	38%	50%	NS

¹Values are % of lambs in each group presenting the pathology. NS = not significant.