ASAS / ADSA Animal Health : Dairy , Beef Cattle , and Other Species 772

Replacement boars and gilts are potential carriers of infectious agents for pig production farms. Demand for healthy breeding stock is increasing. Consequently, production facilities of these animals should be of high health. However, from a genetic point of view questions should be raised whether 1) genetic trend realized under high health conditions (SPF) will be expressed in the same magnitude under conventional conditions, and 2) selection under SPF will, in the long term, decrease genetic disease resistance. SPF in the current analysis was defined as controlled free of Pseudorabies, PRRS, TGE, Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae, Brachispira hyodysenteriae, Pasteurella multocida (DNT), Streptococcus suis (Type II), endoparasites and ectoparasites. On the conventional farms used, some, but not all, of the pathogens were present. Data analysis of a genetically linked structure of 2 SPF farms and 3 conventional farms for fertility traits, and 3 SPFand 2 conventional farms for finishing traits yielded different performance levels under SPF for: Total Number Born (TNB, +0.7), Gestation Length (GL, -0.5 d), Nurse sow PreWeaning Mortality (PWM, -1.4 %), Test Growth (25-80 kg; TG, +143 g/d), and Ultrasonic Backfat (USB, +0.58 mm). Heritability tended to be higher only for TNB (0.13 vs. 0.10) under SPF. Genetic correlations between traits measured under SPF and under conventional conditions were positive and high (rg >0.8) for Stillborn, TNB, and TG and moderate (0.5< rg <0.8) for GL, PWM, and USB. It is concluded that selection under the defined SPF conditions will not markedly reduce genetic trend on farms with a conventional health status. A genetic decrease in resistance is difficult to detect. Using health and performance data of SPF sired offspring in a conventional environment will help to control this potential risk.