Nutrient digestibility, organ morphometry and performance in vaccinated or non-vaccinated Lawsonia intracellularis...

Lawsonia intracellularis is one of the world's most important infectious diseases in pork production with regard to economic losses. So far, studies are missing that describe the effects of a natural infection of piglets on the digestibility of nutrients, possible effects on performance and the morphometrics of the intestine depending on whether piglets are vaccinated, clinically healthy or clinically affected with regard to Lawsonia intracellularis induced diarrhoea.

Digestibility studies were performed on a total of 27 eight-week-old piglets with naturally occurring Lawsonia intracellularis infection in a trial with three repetitions. Nine out of 27 animals were vaccinated as suckling pigs with a commercial Lawsonia intracellularis vaccine (vac; Enterisol®Ileitis). Half of the remaining 18 animals were without clinical signs of infection (non-vac/cs-), half showed moderate clinical signs of Lawsonia intracellularis induced diarrhoea (non-vac/cs+). All three groups were fed one identical complete diet ad libitum. Faecal shedding of Lawsonia intracellularis was found in all groups (25 out of 27 animals). Numerically, the mean excretion in the group non-vac/cs + (7.69 ± 1.65 log₁₀ copies/ g faeces) was higher in comparison to the group non-vac/cs- (5.83 ± 2.35 log₁₀ copies/ g faeces) and vaccinated animals (vac: 6.00 ± 2.89log₁₀ copies/ g faeces). The average daily weight gain (ADG; Ø 8.66 day period) differed significantly (vac: 894^a ± 73.3, non-vac/cs-: 857^ab ± 86.3, non-vac/cs+: 785^b ± 137 g/day). The apparent total tract digestibility (ATTD) of nitrogen was significantly lower in clinically affected animals (vac: 83.0^a ± 1.72, non-vac/cs-: 83.9^a ± 2.03, non-vac/cs+: 80.7^b ± 2.57).The total length of the small intestine in clinically affected animals increased significantly (vac: 15.9^ab ± 1.57, non-vac/cs-: 14.6^b ± 1.12, non-vac/cs+: 16.2^a ± 1.37 m). The relative body weight depending on the length of the small intestine was lower for clinically affected animals (vac: 1.72^a ± 0.21, non-vac/cs-: 1.83^a ± 0.17, non-vac/cs+: 1.56^b ± 0.12 kg/m).

These studies show that clinically moderate L. intracellularis infections lead to significantly lower ADGs in comparison to vaccinated animals. The disease is also found in altered intestinal morphometry and reduced total N digestibility if clinical signs occur.