Evaluation of antibiotic effects on phosphorus digestibility and utilization by growing-finishing pigs fed a phosphorus-deficient, corn-soybean meal diet

Maximum levels of cross-contamination for 24 antimicrobial active substances in non-target feed. Part 6: Macrolides: tilmicosin, tylosin and tylvalosin

The specific concentrations of tilmicosin, tylosin and tylvalosin in non-target feed for food-producing animals, below which there would not be an effect on the emergence of, and/or selection for, resistance in bacteria relevant for human and animal health, as well as the specific antimicrobial concentrations in feed which have an effect in terms of growth promotion/increased yield, were assessed by EFSA in collaboration with EMA. Details of the methodology used for this assessment, associated data gaps and uncertainties, are presented in a separate document. To address antimicrobial resistance, the Feed Antimicrobial Resistance Selection Concentration (FARSC) model developed specifically for the assessment was applied. However, due to the lack of data on the parameters required to calculate the FARSC, it was not possible to conclude the assessment until further experimental data become available. To address growth promotion, data from scientific publications obtained from an extensive literature review were used. Levels in feed that showed to have an effect on growth promotion/increased yield were reported for tilmicosin and tylosin, whilst for tylvalosin no suitable data for the assessment were available. It was recommended to carry out studies to generate the data that are required to fill the gaps which prevented the calculation of the FARSC for these three antimicrobials.

Phosphorus utilization response of pigs and broiler chickens to diets supplemented with antimicrobials and phytase

Three experiments were conducted to evaluate the phosphorus (P) utilization responses of pigs and broiler chickens to dietary supplementation with antimicrobials and phytase and to determine if P digestibility response to phytase is affected by supplementation with antimicrobials. Experiment 1 used 4 diets (a basal negative control formulated to contain 0.41% total P and 0.71% calcium [Ca] without added antimicrobials, basal negative control with added carbadox, basal negative control with added tylosin, or basal negative control with added virginiamycin) and six 18-kg barrows in individual metabolism crates per diet. There was no effect of antimicrobials on P and Ca digestibility or retention. Carbadox supplementation increased (P < 0.05) digestibility and retention of gross energy (GE) and supplementation with tylosin increased (P < 0.05) N retention relative to the basal negative control diet. Experiment 2 used eight 19-kg barrows in individual metabolism crates per treatment and 9 dietary treatments arranged in a 3 × 3 factorial of antimicrobials (none, tylosin, or virginiamycin) and phytase (0, 500, or 1,500 FTU/kg). Phytase addition to the diets linearly increased (P < 0.05) apparent total tract digestibility or retention of P, Ca, nitrogen (N) and GE. Supplementation with antimicrobials did not affect apparent total tract digestibility or retention of P, Ca, N or GE. There were linear effects (P < 0.01) of phytase on Ca utilization in diets that were not supplemented with antimicrobials but only tendencies (P < 0.10) in diets supplemented with tylosin or virginiamycin. Phytase linearly improved (P < 0.05) N utilization in diets supplemented with tylosin or virginiamycin but not in diets without added antimicrobials. Experiment 3 was a broiler chicken experiment with the same experimental design as Exp. 2 but feeding 8 birds per cage and 10 replicate cages per diet. Antimicrobial supplementation improved (P < 0.05) feed efficiency and adding tylosin improved (P < 0.05) tibia ash but did not affect nutrient utilization. Dietary phytase improved (P < 0.01) growth performance, tibia ash and apparent ileal digestibility and retention of P regardless of antimicrobial supplementation. Overall, phytase supplementation improved growth performance and nutrient digestibility and retention, regardless of supplementation of diets with antimicrobials. Supplementation of diets with antimicrobials did not affect P digestibility or retention because of a lack of interaction between antimicrobials and phytase, there was no evidence that P digestibility response to phytase is affected by supplementation with antimicrobials.

Digestibility of phosphorus in powder and microgranular phosphate in diets for pigs

AbstractThis study was realized with the objective to determine the apparent and standardized digestibilities of phosphates to pigs in growing phase, employing two methodologies. Forty-two crossbred barrows with an initial weight of 37 ± 1.1kg were used in a randomized-block design in a 2 × 7 factorial arrangement, with two collection methods: total fecal collection and the use of a indicator (acid insoluble ash [AIA]) × seven treatments, which consisted of a control diet (CTR); three diets containing phosphate in powder form (PP): PPA= CTR + powder phosphate A, PPB= CTR + powder phosphate B, and PPC= CTR + powder phosphate C; and another three diets containing the microgranular phosphate (MP): MP15= CTR + microgranular phosphate 15%, MP45 = CTR + microgranular phosphate 45% and MP75= CTR + microgranular phosphate 75%). The values of 15, 45, and 75% correspond to the water-solubility of the phosphates. There were six replicates, and the pig was considered as experimental unit. The standardized digestibility coefficients of the phosphates assessed by the total collection method, in percent values, were: PPA = 86.9, PPB = 84.9, PPC = 81.9, MP15 = 89.4, MP45 = 88.8, and MP75 = 92.6. The standardized-digestibility coefficients of the phosphates evaluated by the indicator method (AIA) in percent values were: PPA = 75.9, PPB = 75.4, PPC = 75.6, MP15 = 84.9, MP45 = 78.0, and MP75 = 79.4. Considering the two methodologies evaluated in the present work, the microgranular phosphates constitute the best alternative for feeding pigs in the growth phase.

Effects of drying methods on nitrogen and energy concentrations in pig feces and urine, and poultry excreta

Accurate estimations of nutrient digestion and retention are critical in nutrient balance and feed evaluation studies because errors that occur are often additive. However, there is no standard universal method for drying feces, urine, or excreta before laboratory analysis. The objective of this study was to evaluate the impact of 4 different drying methods on nutrient concentrations in feces, urine, and excreta. Twelve individually penned growing pigs were fed 1 of 3 diets and 16 pens of 10 growing broilers were fed 1 of 4 diets that differed in NDF and CP. Feces, urine, and excreta that varied in nutrient composition were collected after 7 d of diet adaptation. Samples were dried using 1 of 4 methods: undried (UD), freeze-dried (FD), oven-dried at 55 °C for 48 h (OD55), or oven-dried at 100 °C for 48 h (OD100), after which DM, GE, N, C, and S were determined. In swine feces, drying resulted in a loss of GE (P < 0.10) and S (P < 0.01) by 5 and 58%, respectively, compared with UD feces. There was no difference (P ≥ 0.36) among drying method on DM, GE, N, C, or S concentrations. There were no differences (P ≥ 0.12) in urinary GE due to drying or between drying methods; however, urinary DM was greatest by FD compared with OD (P < 0.05) and greater for OD55 compared with OD100 (P < 0.01). In poultry excreta, GE (P < 0.05), N (P < 0.10), and S (P < 0.01) were reduced by drying by an average of 6, 10, and 66%, respectively. There were no differences (P ≥ 0.50) among drying methods except FD excreta had a greater S concentration than OD (P < 0.10). Regardless of drying method, some GE and N loss appears to be inevitable, but there is no apparent advantage between FD and OD. The apparent greater S losses warrant further investigation.