Effects of antibiotic treatment during the weaner stage on pig performance and health during finishing

The positive effects of antibiotic treatment on growth and health of pigs during the weaner stage are well known. However the long term ‘carryover’ effects are less well known. There is some evidence that in-feed antibiotics during the weaner stage may have a detrimental impact on the development of the immune system and therefore negative consequences for pig health. We studied the effects of an antibiotic treatment during the weaner stage on the performance, health and welfare of pigs during the finishing stage.

Six weekly batches of 140 piglets each (840 pigs) were split into two treatments during the weaner stage. Control treatment (CT) had no antibiotics in the diet and the treatment group (AB) had in-feed Sulfa-Trimethoprim during the 9 week weaner stage. The farm was positive to influenza, PRRS, APP and had regular episodes of meningitis and ear and tail biting. No in-feed antibiotics were provided in the finisher stage but pigs were grouped after weighing according to treatment (AB; n=15 pens and CT; n=15 pens) for 10 weeks until slaughter at 105kg. Initial and final body weight (BW) and feed intake were recorded. On the day prior to slaughter, all pigs were weighed and their tail lesion (4 point score) and lameness (3 point score) scores were recorded. During the finishing period all instances of general sickness requiring antibiotic treatment, lameness and mortalities were recorded daily.

Results during weaner stage (see poster P158, ESPHM 2015) showed a higher growth rate (+33 g/day; P=0.033) and a higher feed intake (+60 g/day; P=0.051) for AB pigs but no differences in FCR or mortality. Pigs were moved to finisher stage at 45±5.5 kg and there were no effects of the previous AB treatment on growth (P=0.457), feed intake (P=0.876), tail lesion (P=0.573) or lameness (P=0.519) score prior to slaughter, lameness incidence (P=0.252) or mortality (P=0.194) during the finisher stage. However, there was a higher frequency of antibiotic treatments in AB compared to CT pigs (17 vs 11%; P=0.013) during the finisher stage.

In-feed antibiotic treatment of weaners had no effects on growth, feed intake or mortality during the finisher stage or on tail lesion or lameness scores prior to slaughter. However, antibiotic treatment during the weaner stage could have negative effects on general health of pigs during the finisher stage. Further studies are needed to confirm these findings and to further understand the long term effects of in-feed antibiotics in early production stages.

Disclosure of Interest: None Declared.