Differential responses of Duroc, Hampshire, and crossbred pigs to a superimposed experimental infection with the intestinal threadworm, Strongyloides ransomi.
In both spring and fall, 12 Duroc, 12 Hampshire, and 12 Duroc times Hampshire F1 weanling pigs all reared under the same management were fed in pens of 3 to slaughter weights. Three Duroc and 4 Hampshire boars, essentially unrelated within breed, were used in sampling the breeds. Swine herd management allowed pig infection with Strongyloides ransomi and Ascaris suum, but neither clinical nor subclinical parasitism was evident in the herd. Pigs were percutaneously exposed by pens within breed and season, half to none (control) and half to 3,000,000 (exposed) S. ransomi infective larvae, Breed, treatment, and seasons were prominent sources of variation in pig response. Breeds failed to respond alike to parasitism in respect to experimental periods and exposure levels. This interaction response (P smaller than 0.01) showed that S. ransomi egg production increased rapidly for all breed groups but decreased quicker and greater in Durocs, slowest and least in Hampshires, with cross breds intermediate in these respects. The 2.0830 for mean of log A. suum EPG from exposed Durocs was near double that of control Durocs but the mean for exposed Hampshires was less than half that for controls; crossbreds tended to be intermediate in this respect. Daily gains of 0.70 and 0.73 for Durocs and crossbreds were similar (P greater than 0.10) but averaged 11.7% more (P smaller than 0.05) than the 0.64 kg for Hampshires and gains by control pigs were 20.6% above (P greater than 0.01) that of exposed pigs. Exposed pigs required more feed per kg of gain (P greater than 0.05) than control pigs (3.60 vs. 3.33 kg). Comparison of relative gains and feed efficiences of control and exposed pigs among and within breed groups supported the position that a superimposed exposure of 3,000,000 S. ransomi larvae was more severe for Hampshires, intermediate for crossbreds, and least severe for Durocs.
D000818:Animals; D001196:Ascariasis / Q000469:parasitology / Q000662:veterinary; D001200:Ascaris / Q000472:pathogenicity*; D001835:Body Weight; D004197:Disease Reservoirs; D010270:Parasite Egg Count; D013321:Strongyloides / Q000472:pathogenicity* / Q000502:physiology; D013322:Strongyloidiasis / Q000401:mortality / Q000469:parasitology / Q000662:veterinary; D013552:Swine / Q000469:parasitology; D013553:Swine Diseases / Q000401:mortality / Q000469:parasitology*; D014481:United States