A comparison of antibiotic-free and conventional management on nutrient excretion in swine

Abstract Text: Seven hundred twenty-four, mixed-sex pigs were used in a wean-finish experiment to determine the effects of antibiotic free rearing on nutrient excretion compared to conventional rearing.  At weaning, pigs were blocked by BW and sex and randomly assigned within block to rooms and pens in the Swine Environmental Research Building.  Each room contained 6 pens of 10-11 mixed sex pigs with 3 pens over each manure pit.  There were 5 control and 6 antibiotic-free rooms (10 and 12 manure pits, respectively). All pigs were fed a 9-phase wean-finish diet program. Control pigs consumed diets containing antibiotics and were treated with injectable antibiotics when deemed necessary.  Antibiotic-free animals consumed diets with alternatives to antibiotics and received no injectable antibiotics.  At the conclusion of the finisher phase, pits were individually emptied into a Slurrystore, mixed and sub-sampled. Data were analyzed using the GLM procedure in SAS. Previously reported, there was no difference (P > 0.10) in overall growth rate between control and antibiotic free pigs, however there was a greater pig removal rate from the antibiotic free treatment (8.6% vs. 5.7%). No differences were observed between control and antibiotic-free management on the excretion of DM, P, N, and ammonium N (P > 0.10) per kg of carcass weight.  Dry matter excretion was 456 and 445 g/kg of carcass weight for antibiotic free and control animals, respectively.  Phosphorus (0.59 versus 0.45 g/kg carcass), N (43.48 versus 42.56 g/kg carcass) and Ammonium N (35.07 versus 33.01 g/kg carcass) excretion were all approximately 6% lower for control animals compared to those reared without antibiotics.  However, these findings were not significant.  Therefore, future research with a higher number of observations is needed to confirm the lack of differences in nutrient excretion observed between pigs reared with and without antibiotics.

Keywords: swine, antibiotics, manure, excretion, environment