The analysis of field data, revealed an estimate of .18 for heritability of resistance to pinkeye and an average decrease in weaning weight of 9.5 kg for infected animals. Tear samples were collected for the 2004 pinkeye season for the analysis of two factors (IgA and Lactoferrin) involved in ocular defense. Significant differences were found between infected and non- infected animals, in the levels of tear fluid IgA.