Evaluating Dietary Acidifiers as Alternatives to Conventional Feed-Based Antibiotics in Nursery Pig Diets

A total of 360 weanling pigs (200 × 400, DNA; initially 21.4 ± 0.23 lb BW) were used in a 21-d experiment with 6 pigs/pen, 10 replicate pens/treatment, and 2 separate nursery rooms, each with 30 pens. Pigs were weighed and allotted to pens based on BW in a completely randomized block design to one of six treatment diets: 1) negative control (no organic acids or antibiotics) and the control with 2) 0.25% acidifier A; 3) 0.3% acidifier B; 4) 0.5% acidifier C); 5) 50 g/ton carbadox; and 6) 400 g/ton chlortetracycline (CTC). Upon weaning, a common diet with no antibiotics or additives was fed for 21 d (Phases 1 and 2; days −21 to 0), followed by a 21-d experimental period (Phase 3; days 0 to 21) where treatment diets were fed. Pigs and feeders were individually weighed on a weekly basis to calculate ADG, ADFI, and F/G. Data were analyzed using the GLIMMIX procedure of SAS (v. 9.4, SAS Inst., Cary, NC) with pen as the experimental unit, treatment as a fixed effect, and room as a random effect. Dietary treatment had a significant impact (P \u3c 0.05) on ADG, ADFI, and G:F each week and for the overall experimental period (days 0 to 21). Specifically, from days 0 to 7, pigs fed CTC had increased (P = 0.001) ADG compared with those fed acidifier B, acidifier C, and carbadox, whereas pigs fed the negative control and acidifier A diets were intermediate. Additionally, pigs fed the CTC diet had improved (P = 0.0002) ADFI when compared with all other treatments. From days 7 to 14 and days 14 to 21, pigs fed the carbadox diet had decreased (P \u3c 0.0001) ADG compared with all other treatments. During the overall period (days 0 to 21), pigs fed diets containing carbadox had reduced ADG and ADFI (P \u3c 0.0001), whereas pigs fed CTC had improved (P \u3c 0.0001) ADG compared with all other treatments. Additionally, fecal consistency, and fecal microbial populations were analyzed on a subset of pigs (n = 5 pigs/treatment). Treatment also significantly impacted (P = 0.0005) fecal score but did not affect (P = 0.59) fecal microbial growth from days 0 to 21. In summary, CTC continues to be a valuable additive to improve performance in the nursery. Further investigation surrounding the efficacy of dietary acidifiers as antibiotic alternatives is warranted given inconclusive evidence in this study

Investigating Potential Additive Effects of Formic Acid and Glycerol Monolaurate in Nursery Pig Diets

A total of 350 weanling pigs (200 × 400, DNA; initially, 12.5 ± 0.3 lb BW) were used in a 42-d study with 5 pigs per pen and 14 replicate pens per treatment. At weaning, pigs were allotted to pens in a completely randomized design and pens of pigs were randomly assigned to one of five dietary treatments: 1) negative control (standard nursery diet with no additives); 2) control diet with 3,000 ppm ZnO included in phase 1 and 2,000 ppm ZnO included in phase 2; 3) control diet with 0.7% formic acid (Amasil NA, BASF, Florham, NJ); 4) control diet with 0.18% glycerol monolaurate (Natural Biologics GML, Natural Biologics, Newfield, NY); and 5) control diet with a 1.0% blend of formic acid, sodium diformate, and glycerol monolaurate (FORMI 3G, ADDCON GmbH, Bitterfeld-Wolfen, Germany). Pigs were fed treatment diets from d 0 to d 28 and were then fed a common diet from d 28 to d 42. This allowed diets to be fed as part of a standard 3-phase nursery program. From d 0 to d 7, pigs fed a diet containing ZnO or the 1.0% blend of formic acid, sodium diformate, and glycerol monolaurate had significantly increased (P = 0.03) ADG compared to pigs fed the control. Feed intake did not differ (P \u3e 0.05) during this period. Overall, pigs fed GML had reduced ADG compared to their counterparts fed the negative control, ZnO, or FORMI diets. Feed intake was also not impacted (P = 0.233) by dietary treatments. Fecal DM was evaluated from d 7 to d 28 and there was a significant treatment × day interaction (P = 0.035). Pigs fed GML had significantly lower fecal DM % on d 7, but a higher fecal DM % on d 14 and 21. There was no evidence of difference between treatments for fecal DM by d 28. In summary, there is potential for a blend of formic acid and GML to improve growth performance immediately post-weaning without negatively impacting fecal consistency. Further research is warranted to determine the mode of action of these acids and elucidate their efficacy as alternative feed ingredients to combat post-weaning challenges in swine production

Evaluation of a Microencapsulated Form of Zinc Oxide on Weanling Pig Growth Performance, Intestinal Morphology, and Zinc Excretion

A total of 350 pigs (DNA 200 × 400; initially 13.31 ± 0.04 lb BW) were used in a 42-d study with 5 pigs per pen and 12 pens per treatment. At weaning, pigs were randomly allocated to pens and pens were randomly allotted to dietary treatments. Dietary treatments were: 1) negative control (standard nursery diet containing 110 ppm Zn from trace mineral premix); 2) control diet with 3,000 ppm added Zn in the form of ZnO in phase 1 and 2,000 ppm added Zn in the form of ZnO in phase 2 (High-ZnO); 3) control diet with 400 ppm added Zn in the form of ZnO in phases 1 and 2 (Low- ZnO); 4) 3,000 ppm added Zn in the form of microencapsulated ZnO in phase 1 and 2,000 ppm added Zn in the form of microencapsulated ZnO in phase 2 (High-MZnO); and 5) 400 ppm added Zn in the form of microencapsulated ZnO in phases 1 and 2 (Low-MZnO). Pigs were weighed and feed disappearance was determined to evaluate ADG, ADFI, and F/G. On d 10 and d 28, fecal samples from 3 pigs per pen were collected for fecal Zn concentrations. On d 28, 30 pigs (6 pigs per treatment) were euthanized, and small intestinal tissue was collected to evaluate morphology. There was no evidence of differences in ADG, ADFI, or F/G for the entire treatment period (d 0 to d 28; P \u3e 0.05). During the common phase 3 (d 28 to 42) pigs fed the negative control, High-MZnO, or Low-MZnO had improved (P \u3c 0.0001) ADG compared to pigs fed High- or Low-ZnO, which was driven by an increase in ADFI (P \u3c 0.0001). For the entire experiment (d 0 to 42), pigs fed Low-ZnO or High-ZnO had reduced (P \u3c 0.0001) ADG compared those fed the negative control. There was no evidence that small intestinal morphology differed significantly between treatments (P \u3e 0.05). Finally, a significant treatment × day interaction (P = 0.04) was observed for fecal Zn concentrations, where pigs fed High-ZnO had greater fecal Zn levels on d 10 and d 28 compared to pigs fed all other treatments

Summary of Methodology Used in Enterotoxigenic Escherichia coli (ETEC) Challenge Experiments in Weanling Pigs and Quantitative Assessment of Observed Variability

Post-weaning diarrhea in pigs can be caused by the F4 or F18 strains of enterotoxigenic Escherichia coli (ETEC). To evaluate interventions for ETEC, experimental infection via a challenge model is critical. To our knowledge, there is a lack of explanation for the variability in responses observed across ETEC challenge studies. Our objective was to quantitatively summarize the responses and variability among recent ETEC challenge studies and develop a tool for sample size calculation. The most widely evaluated response criteria across ETEC challenge studies are growth performance, fecal consistency and bacterial shedding, intestinal morphology, and immune responses. Factors that contribute to the variability seen across studies include the type of ETEC studied, dose and timing of inoculation, and the number of replications. Generally, a reduction in average daily gain (ADG) and average daily feed intake (ADFI) are seen following an ETEC challenge, as well as a rapid increase in diarrhea. Fecal bacterial shedding is a common indicator of ETEC infection, but the responses seen across the literature are not consistent due to differences in bacterial enumeration procedures. Emphasis should also be placed on the piglet’s immune response to ETEC, which is commonly assessed by quantifying levels of immunoglobulins and pro-inflammatory cytokines. Again, there is variability in these responses across published work. Small intestinal morphology is drastically altered following infection with ETEC and appears to be a less variable response criterion to evaluate. While there is a large degree of variability across ETEC challenge experiments, we have provided a quantitative summary of these studies, and a Microsoft Excel-based tool was created to help calculate sample sizes for future studies

Evaluation of Biosecurity Measures on a Commercial Swine Operation Using Glo Germ Powder as a Visible Learning Aid

Glo germ, a fluorescent powder, was used to determine the efficacy of common biosecurity practices to prevent the powder from spreading to other areas within a commercial swine farm. The areas tested included an entry bench, the shower where all incoming personnel are required to shower upon farm entry and exit, the clean area following the shower, and inside the barn, which acted as the control with no biosecurity procedures in place given it is fully contained within the broader biosecurity measures of the facility. Pictures, from a standard iPhone, were taken before and after student and personnel movement to observe any differences in Glo Germ coverage. The percentage of Glo Germ coverage in the before and after pictures was evaluated once by 47 untrained panelists and averaged for each location and time point. The control area with no biosecurity measures in the barn had significantly more Glo Germ coverage than the other three locations (P \u3c 0.0001). There was no evidence of a difference in Glo Germ coverage between the entry bench, shower floor, or clean side of shower (P \u3e 0.05). In conclusion, the use of Glo Germ was successfully able to emulate disease entry into the farm and can be used as a learning aid to demonstrate the efficacy of entry benches, clean/dirty lines, and showers

Effectiveness of medium chain fatty acid (MCFA) products and their ability to replace ZnO or carbadox in weanling pig diets

The objective of this experiment was to evaluate medium chain fatty acids (MCFA) effects on nursery pig performance in place of ZnO and carbadox. In this trial, 360 weanling pigs (DNA 200 x 400; 5.4 ± 0.07 kg BW) were fed for 35 days, with 6 pigs/pen and 10 replicate pens/treatment. Pigs were allotted in a completely randomized design to one of 6 treatment diets: 1) control; 2) 3,000 ppm ZnO during Phase 1 and 1,500 ppm ZnO in Phase 2; 3) 50g/ton carbadox; 4) 1% blend of C6:C8:C10; 5) 1% Feed Energy R2 (Feed Energy Corp, Des Moines, IA); 6) 1% FORMI GML (ADDCON, Bitterfeld-Wolfen, Germany). Treatment diets were fed in two phases from weaning to d 19 of the experiment, and a common Phase 3 diet was fed from d 19 to 35. From d 0 to 19, pigs being fed the ZnO or Carbadox diets showed increased (P0.05) ADG compared to those fed carbadox. Differences in ADFI throughout the treatment period (P=0.004) served as the driver behind these effects, while G:F differences were marginally significant (P=0.078). Increased d 19 BW (P<0.05) was observed for pigs fed ZnO and carbadox in relation to the negative control, while other treatments were intermediate. No significant impact was demonstrated on G:F (P=0.320). Overall, these results show that ZnO and carbadox are valuable additives to help maximize growth performance in early stages of the nursery. Some MCFA products, like FORMI GML, may result in similar performance, while others restrict performance. Thus, additional research is needed to study the effectiveness of MCFA to replace ZnO or feed-based antibiotics