Effects of different antibiotic feeding programs on morbidity and mortality and growth performance of nursery pigs housed in a wean-to-finish facility

Abstract The objective of this study was to evaluate the effects of two antibiotic feeding programs in comparison to nonmedicated controls on the incidence of morbidity and mortality and growth performance of nursery pigs in a commercial setting. The study used 2,250 crossbred pigs in a randomized complete block design (blocking factor = start date). There were two dietary phases with three treatments in each phase: 1) nonmedicated controls vs. 2) 39 mg/kg (35 g/ton) tiamulin + 441 mg/kg (400 g/ton) chlortetracycline fed for 14 d (TIACTC) followed by 39 mg/kg (35 g/ton) tiamulin fed for 21 d (TIA) vs. 3) 28 mg/kg (25 g/ton) carbadox + 441 mg/kg (400 g/ton) oxytetracycline fed for 14 d (CAROTC) followed by 55 mg/kg (50 g/ton) carbadox fed for 21 d (CAR). Necropsy results from mortalities during the study confirmed the presence of pathogens including Pasteurella multocida and Escherichia coli, as well as Mycoplasma hyopneumoniae, Haemophilus parasuis, and Streptococcus suis. The study was carried out for a fixed time of 35 d from 6.7 ± 0.57 to 25.5 ± 2.23 kg BW. Pigs were housed in single-sex pens of 25 in a commercial wean-to-finish facility and there were 30 replicates of each treatment. All pigs were weighed as a group (i.e., pen) on days 0 (start), 14, and 35 (end) of study. Pigs had ad libitum access to feed and water throughout the study period; all feed additions to the feeder were recorded. There was no effect (P > 0.05) of antibiotic feeding program on the incidence of morbidity and mortality at any point during the study. During phase 1, TIACTC- and CAROTC-fed pigs were heavier (P < 0.05) at day 14 and had greater (P < 0.05) ADG (8.3% and 5.6% for TIACTC and CAROTC, respectively) and ADFI (4.3% and 6.5%, respectively) than controls. Pigs fed TIACTC in the first 14 d had greater (P < 0.05) G:F than the other treatments, which were similar for this measurement. In phase 2, feeding CAR resulted in greater (P < 0.05) ADG than controls, with pigs fed TIA being intermediate and different (P < 0.05) than the other treatments. Feeding antibiotics, regardless of treatment, resulted in greater (P < 0.05) ADFI than controls, but there were no differences in G:F. For the overall 35-d study period, feeding antibiotics resulted in greater (P < 0.05) ADG than controls (3.8% and 5.8%, respectively), but no difference (P > 0.05) between treatments for overall G:F. The results of this study confirm the advantage of feeding antibiotics on nursery pig growth.

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PSIV-19 Flavors and Sweeteners in Nursery Pig Diets Increased Intake and Reduced Soft Feces in the First Weeks After Weaning

Journal of Animal Science ◽

10.1093/jas/skab054.303 ◽

2021 ◽

Vol 99 (Supplement_1) ◽

pp. 179-180

Author(s):

Jorge Y Perez-Palencia ◽

Xixi Chen ◽

Jirong Lv ◽

Maíra Resende ◽

Rhuan F Chaves ◽

...

Keyword(s):

Growth Performance ◽

Feed Intake ◽

Block Design ◽

Phase 1 ◽

Poor Performance ◽

Stressful Events ◽

Gut Health ◽

Nursery Pigs ◽

Feeding Program ◽

Dietary Treatments

Abstract The stressful events associated with weaning predispose piglets to reduced feed intake, which in concert with immature digestive and immune systems, results in increased incidences of diarrhea and poor performance. Flavors and sweeteners can be used in diets for young pigs as a means of attracting them to dry feed and increase their feed intake and performance after weaning. The objective of this study was to evaluate the effects of dietary inclusion of flavors and sweeteners and their combination on growth performance and post-weaning gut health of nursery pigs. A total of 1,144 weaned pigs (initial BW 6.61 ± 0.2 kg) were used in a randomized complete block design and assigned to one of four dietary treatments, with 11 replicates (pens) of 26 piglets per pen. Dietary treatments were 1) Control: standard 4-phase nursery feeding program; 2) Sweetener: control plus sweetener (0.015%); 3) Flavor: control plus flavoring (0.05%); 4) Combination: control plus sweetener and flavoring. Experimental diets were provided at a budget of 0.9, 3.4, 4.5, and 24 kg/pig in Phase 1, 2, 3, and 4, respectively. A common phase 5 diet was provided ad libitum until d56 after weaning. Feed disappearance and body weight were measured every other week. A pen fecal score assessment was performed at d4, 7, 10, and 14 after weaning. Overall, there were no differences among dietary treatments for growth performance. However, during the first two weeks post-weaning pigs fed diets containing flavors and sweeteners had a greater (P = 0.097) ADFI than control pigs. On d14, pigs fed diets containing flavors and sweeteners had less incidence of soft and watery feces (χ2 < 0.05) compared to control pigs. This study provides evidence that dietary inclusion of flavors and sweeteners has important benefits to the overall health of nursery pigs likely related to feed intake in the period immediately after weaning.

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PSVI-1 Dietary protease supplementation on growth performance and post-weaning diarrhea of nursery pigs

Journal of Animal Science ◽

10.1093/jas/skaa054.337 ◽

2020 ◽

Vol 98 (Supplement_3) ◽

pp. 191-192

Author(s):

Jorge Y Perez-Palencia ◽

David A Clizer ◽

Christian Ramirez-Camba ◽

Ryan S Samuel ◽

Crystal L Levesque

Keyword(s):

Growth Performance ◽

Phase 1 ◽

Dietary Treatment ◽

Experimental Period ◽

Phase 2 ◽

Deficient Diet ◽

Nursery Pigs ◽

Feeding Program ◽

Dietary Treatments ◽

Fecal Score

Abstract This experiment evaluated the effect of dietary protease supplementation on pig’s growth performance and post-weaning diarrhea in a 43-d trial. A total of 936 weaned pigs [21 d of age, initial BW 5.87 ± 0.31 kg] were used in a 2 × 2 factorial design (2 nutritional levels × 2 protease levels). The nutritional levels corresponded to a standard feeding program and a reduced feeding program (15% lower SID Lys) and without or with protease supplementation (0.0125% inclusion). Piglets were distributed in 36 pens with 26 pigs per pen and 9 replicates per dietary treatment. Pigs received a common Phase 1 diet and experimental diets in Phase 2, 3, and 4, (0.91, 3.4, 4.5, and 24.0 kg/pig, respectively). Phytase was included at 2,500 U in Phase 2 – 4, all diets met energy and AA:Lys requirements for nursery pigs. Feed intake and body weight were determined every 2 weeks. A pen fecal score assessment was performed at d7, 10, and 14. Performance data were analyzed using the PROC MIXED procedure and fecal score data using the PROC FREQ procedure (SAS Inst., Inc., Cary, NC). No significant interactions (P > 0.05) were observed between dietary treatments. From d15 to 43 and during overall experimental period, pigs fed standard diets had greater BW, ADG, and G:F (P < 0.05) than pigs fed deficient diets (Table 1). On d7, pigs fed deficient diet had more (X2 < 0.05) soft and watery feces, and consequently less normal feces compared to pigs fed standard diets (Figure 1). On d7, 10, and 14, pigs fed diets with protease supplementation had more (X2 < 0.05) normal feces compared to control pigs. Overall, effects of dietary protease supplementation on growth performance were not expressive under the conditions of this study but protease addition benefited intestinal health of nursery pigs.

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129 The effect of Activo Liquid supplemented via the water against Mecadox 50 on nursery pig’s growth performance and survival

Journal of Animal Science ◽

10.1093/jas/skz122.134 ◽

2019 ◽

Vol 97 (Supplement_2) ◽

pp. 73-73

Author(s):

Rafael A Cabrera

Keyword(s):

Body Weight ◽

Growth Performance ◽

Block Design ◽

Phase 1 ◽

Experimental Unit ◽

Gut Health ◽

Feed Conversion ◽

Final Body Weight ◽

Significant Difference ◽

Feeding Program

Abstract The objective of this study was to compare Activo Liquid supplemented via the water agaisnt Mecadox 50 on nursery pigs’ growth performance and survival. Activo Liquid is a combination of secondary plant compounds plus organic acid (antimicrobial) supplemented in the water to support gut health and improve performance. The study design of this trial was a Split Plot with 36 replicates (9 replicates/treatment) with 10 pigs/pen. Pigs were allotted by a Randomized Complete Block Design by weight at weaning. Pigs were around 5.7 kg and 19 days of age average on body weight and weaning age, respectively. The nursery houses were not washed for two turns to expose the animals to serious pathogens. The data were analyzed by analysis of variance with pen as the experimental unit. Significant differences were established by P < 0.05. Treatments were Control with 50g/ton of Mecadox for all nursery phases and three Activo Liquid treatments (6 oz per 128 gallon of drinking water administered either for 3, 5 or 7 days post-weaning). A typical nursery feeding program was followed: Phase 1 from d 0 to d 7, Phase2 from d 8 to d 21 and Phase 3 from d 22 to d4 2. They contain 23%, 21% and 19% crude protein respectively. The results showed no significant difference on final body weight among the treatments. All Activo treatments had improved (P < 0.05) feed conversion (Feed:Gain) when compared with the medicated treatment. Activo Liquid 5d treatment post-weaning had numerically lower mortality when compared with all the other treatments. In conclusion, the results of this trial showed that the supplementation of Activo Liquid for 5 d post-weaning at 6 oz/128 gallon of water can safely replace Mecadox 50 g/ton. More research is needed to validate the repeatability of these results and understand Activo Liquid’s mode of action as a powerful antimicrobial.

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PSVI-17 Evaluation of a nutritional water supplement on growth performance of nursery pigs

Journal of Animal Science ◽

10.1093/jas/skz122.366 ◽

2019 ◽

Vol 97 (Supplement_2) ◽

pp. 208-208

Author(s):

Afton Sawyer ◽

Scott Carter ◽

Carson Cooper ◽

Pornpim Aparachita ◽

Megan R Bible ◽

...

Keyword(s):

Growth Performance ◽

Soybean Meal ◽

Block Design ◽

Phase 1 ◽

Experimental Unit ◽

Phase 3 ◽

Nursery Pigs ◽

Randomized Complete Block Design ◽

Water Meters ◽

Water Treatments

Abstract One-hundred forty weanling pigs (5.26 kg; 20 d of age) were used to determine the effects of a nutritional water supplement (WB; Water Boost, Furst-McNess, Freeport, IL) on growth performance of nursery pigs. Pigs were randomly allotted to two water treatments (7 pens/treatment; 10 pigs/pen). The water treatments were 0 and 62.5 mL WB/L of water (stock solution) supplied by water medicators (1:100 dilution). Pigs were fed simple, corn soybean meal diets (no plasma or crystalline lactose utilized) in four dietary phases (Phase 1: d 0-7, Phase 2: d 7-14, Phase 3: d 14-21, and Phase 4: d 21-42). The water treatments were provided on d 0 through d 3. Pigs and feeders were weighed weekly to determine ADG, ADFI, and G:F. Water meters were used to record and calculate water disappearance. Data were analyzed as a randomized complete block design with pen serving as the experimental unit. Water disappearance (L/pig/d) was not affected from d 0-21, but it increased (P < 0.01) for pigs provided WB for d 21-42 (1.71 vs 2.12) and d 0-42 (1.11 vs 1.35). Growth performance was not affected by WB during d 0-21. However, from d 21-42, WB tended to increase (P < 0.10) ADG (483 vs 528 g/d) and ADFI (706 vs 767 g/d), but it had no effect on G:F. For the overall period, pigs provided WB from d 0-3 tended to have improved G:F (0.671 vs 0.684) and numerical increases in ADG (P = 0.14) and ADFI (P = 0.17) were observed. Final ending body weight tended to be increased (P < 0.10) for pigs provided WB (18.6 vs 19.9 kg). These results suggest providing WB for the first three days in the nursery to pigs fed corn soybean meal-based diets increased water disappearance and tended to improve growth performance of nursery pigs.

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Toxicity of canola-derived glucosinolates in pigs fed resistant starch-based diets

Journal of Animal Science ◽

10.1093/jas/skaa111 ◽

2020 ◽

Vol 98 (5) ◽

Cited By ~ 2

Author(s):

Jung W Lee ◽

Shenggang Wang ◽

Yue Huang ◽

Teresa Seefeldt ◽

Abigail Donkor ◽

...

Keyword(s):

Thyroid Gland ◽

Growth Performance ◽

Degradation Products ◽

Block Design ◽

Phase 1 ◽

Average Daily Gain ◽

Relative Weight ◽

Complete Replacement ◽

Nursery Pigs ◽

Organ Weights

Abstract A study was conducted to determine effects of reducing hindgut pH through dietary inclusion of high-amylose cornstarch (HA-starch) on growth performance, organ weights relative to live body weight (BW), blood thyroid hormone levels, and glucosinolate degradation products of nursery pigs fed cold-pressed canola cake (CPCC). A total of 240 pigs (initial BW: 7.1 kg), which had been weaned at 21 d of age, were housed in 40 pens (6 pigs per pen) and fed 4 diets (10 pens per diet) in a randomized complete block design for 28 d. Four diets were a basal diet with CPCC at 0 or 40%, and with HA-starch at 0 or 40% in a 2 × 2 factorial arrangement. The diets were fed in two phases: Phase 1 from day 0 to 14 and Phase 2 from day 14 to 28 and were formulated to have the same net energy, standardized ileal digestible AA, Ca, and standardized total tract digestible P contents. Dietary inclusion of CPCC and HA-starch was achieved by a partial or complete replacement of corn, soybean meal, and soy protein. At the end of the study, one pig from each pen was euthanized to determine organ weights, blood parameters, hindgut pH, and glucosinolate degradation products. Dietary CPCC reduced (P < 0.05) overall average daily gain (ADG) by 15%; increased (P < 0.05) relative weights of liver and thyroid gland by 27% and 64%, respectively; and reduced (P < 0.05) serum tetraiodothyronine (T4) level from 30.3 to 17.8 ng/mL. Heart, kidney, and gastrointestinal tract weights; serum triiodothyronine level; and hindgut pH of pigs were unaffected by dietary CPCC. Dietary HA-starch reduced (P < 0.05) overall ADG, relative weight of thyroid gland, cecal, and colonic pH; but increased (P < 0.05) relative weight of colon; tended to increase (P = 0.062) serum T4 level. Dietary CPCC and HA-starch interacted (P = 0.024) on relative weight of thyroid gland such that dietary CPCC increased (P < 0.05) weight of thyroid gland for HA-starch-free diet (120 vs. 197 mg/kg of BW) but not for HA-starch-containing diet (104 vs. 130 mg/kg of BW). Dietary CPCC and HA-starch interacted (P = 0.001) on cecal isothiocyanate content such that dietary CPCC increased (P < 0.05) level of isothiocyanates for HA-starch-containing diet but not for HA-starch-free diet. In conclusion, dietary CPCC reduced growth performance, increased liver, size and interfered with thyroid gland functions of pigs. However, the negative effects of dietary CPCC on thyroid gland functions of nursery pigs were alleviated by dietary HA-starch.

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262 Effects of phase-feeding programs on growth performance of nursery pigs

Journal of Animal Science ◽

10.1093/jas/skaa054.157 ◽

2020 ◽

Vol 98 (Supplement_3) ◽

pp. 89-90

Author(s):

Henrique S Cemin ◽

Luke A Swalla ◽

Jamie L Pietig ◽

Sharlie A Hansen ◽

Stewart T Galloway ◽

...

Keyword(s):

Statistical Analysis ◽

Single Phase ◽

Production Systems ◽

Phase 1 ◽

Experimental Period ◽

Phase 2 ◽

Treatment Trial ◽

Nursery Pigs ◽

Feeding Programs ◽

Feeding Program

Abstract Production systems commonly have multiple fill events in the nursery, which can lead to inaccurate feeding of dietary budgets. A simpler feeding program may provide practical benefits to producers. Five trials were conducted to compare nursery phase-feeding programs. Two treatments consisting of a 2-phase or a single-phase program were applied for 22 d postweaning. The 2-phase program consisted of a feed budget of 1.4 kg of a phase 1 diet formulated with 1.45% SID Lys and 5.4 kg of a phase 2 diet with 1.36% SID Lys. The single-phase program provided 6.8 kg of a unique diet with 1.38% SID Lys. Diets were corn, soybean meal, and whey permeate-based and contained 3,000 mg/kg Zn. All other nutrients met or exceeded the NRC (2012) recommendations. After the experimental period, pigs were fed a common diet for 23 d. In the five trials, 5,090 pigs were used with a total of 63 and 69 replicates per treatment for 2-phase and single-phase programs, respectively. There was no treatment × trial interactions (P > 0.10), thus data was combined for statistical analysis using SAS PROC MIXED. From d 0 to 22, pigs fed the single-phase program had higher (P = 0.041) ADFI and a tendency (P = 0.075) for higher BW. From d 22 to 45, pigs previously fed the single-phase program had a tendency (P = 0.057) for higher ADG. Overall (d 0 to 45), pigs fed the single-phase program had higher (P = 0.037) ADG and a tendency (P = 0.077) for higher final BW, with comparable (P > 0.10) ADFI and G:F to the 2-phase program. In conclusion, feeding a single-phase nursery program in the first 22 d postweaning resulted in higher overall ADG and similar ADFI and G:F compared to a 2-phase nursery program.

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185 The Impacts of Commercial Dietary Acidifiers on Growth Performance of Nursery Pigs

Journal of Animal Science ◽

10.1093/jas/skab054.141 ◽

2021 ◽

Vol 99 (Supplement_1) ◽

pp. 87-87

Author(s):

Payton L Dahmer ◽

Cassandra K Jones

Keyword(s):

Growth Performance ◽

Block Design ◽

Phase 1 ◽

Dietary Treatment ◽

Negative Control ◽

Experimental Unit ◽

Nursery Pigs ◽

Commercial Diet ◽

Randomized Block Design ◽

Pig Performance

Abstract A total of 360 weanling pigs (DNA 200 x 400; initially 9.7 ± 0.23 kg BW) were used in a 21-d growth trial to evaluate the effects of commercial diet acidifiers in nursery diets. Upon weaning, pigs were weighed and allotted to pens (6 pigs/pen, 10 replicate pens/treatment, blocked by 2 separate nursery rooms) and pens were then randomly assigned to one of 6 treatment diets: 1) negative control (no antibiotics or acidifiers) and the control with 2) 0.25% Acidifier A (KEM-GEST™, Kemin Industries, Des Moines, IA); 3) 0.3% Acidifier B (ACITVATE® DA, Novus International, Saint Charles, MO); 4) 0.5% Acidifier C (OutPace®, PMI Additives, Arden Hills, MN); 5) 50 g/ton carbadox; 6) 400 g/ton chlortetracycline. Pigs were fed common phase 1 and phase 2 starter diets without antimicrobials for 21 days, then fed experimental diets for 21 days. Data were analyzed as a completely randomized block design with pen as the experimental unit. Dietary treatment significantly impacted (P < 0.05) all growth response criteria for each week of the experiment. Overall (d 0 to 21), ADG was the greatest (P < 0.0001) for pigs fed a diet containing CTC. Likewise, ADFI was increased (P < 0.0001) for pigs consuming CTC compared to those fed the negative control, acidifier A, acidifier B and carbadox diets, while those fed acidifier C were intermediate. Feed efficiency was poorest (P < 0.0001) in pigs fed a diet with carbadox. By the end of the experiment, pigs fed CTC were significantly heavier (P < 0.0001) than pigs fed all remaining treatments. In summary, feeding CTC improved nursery pig performance while carbadox unexpectedly reduced it. The addition of dietary acidifiers did not improve growth performance compared to a negative control.

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Supplementation of protease to low amino acid diets containing superdose level of phytase for wean-to-finish pigs: effects on performance, post-weaning intestinal health and carcass characteristics

Translational Animal Science ◽

10.1093/tas/txab088 ◽

2021 ◽

Author(s):

J Y Perez-Palencia ◽

R S Samuel ◽

C L Levesque

Keyword(s):

Amino Acid ◽

Growth Performance ◽

Block Design ◽

Phase 1 ◽

Carcass Characteristics ◽

Dietary Treatment ◽

Relative Reduction ◽

Intestinal Health ◽

Serum Iga ◽

Feeding Program

Abstract This experiment investigated the effects of protease supplementation to low amino acid (AA) diets containing phytase on pig growth performance, post-weaning intestinal health and carcass characteristics. A total of 936 weaned pigs [21 d of age, initial BW 5.87 ± 0.31 kg] were used in a 2 × 2 factorial design comparing the main effects of AA supply [Standard feeding program: balanced for all nutrients with adjustment of Ca and P due to inclusion of phytase (2,500 FTU/kg in Phase 1 to 4; 500 FTU/kg in Phase 5 to 9) vs. Low AA feeding program: 15% lower standardized ileal digestible lysine with relative reduction of all other essential AA] and protease level (0 vs. 0.0125%). Pens were assigned to dietary treatment according to a randomized complete block design with 26 pigs per pen and 9 replicates per dietary treatment. Feed and water were provided on an ad libitum basis for all phases throughout the wean-to-finish period. Feed intake and body weight were determined every 2 weeks during nursery period and monthly in the grow-finish period. Intestinal health in the first 17 days was assessed based on lactulose:mannitol ratio (L:M), serum IgA, and pen diarrhea assessment. Overall, pigs fed standard wean-to-finish diets had greater (P < 0.05) ADG and G:F than pigs fed low AA diets. Pig growth performance was not different throughout the wean-to-finish period with or without protease supplementation and with no interaction between AA supply and protease supplementation. There were no differences among dietary treatments for carcass characteristics. No difference was observed for urinary L:M and serum IgA; however, the L:M ratio was approximately 32% lower in pigs fed low AA diets + protease compared with pigs fed standard and low AA diets at d 5 and d 17 post-weaning. Pigs fed protease supplemented diets had lower incidence of diarrhea (χ2 < 0.05) compared with pigs fed diets without protease. Results of the experiment indicate that dietary protease supplementation benefits intestinal health of nursery pigs.

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PSVI-14 Blend of Additives in Nursery Pig Diets as an Antibiotics Substitute Increases the Growth Performance and Intestinal Health

Journal of Animal Science ◽

10.1093/jas/skab054.328 ◽

2021 ◽

Vol 99 (Supplement_1) ◽

pp. 201-201

Author(s):

Sudario Roberto Silva Junior ◽

Rhuan F Chaves ◽

Maíra Resende ◽

Ygor Henrique De Paula ◽

Kenio De Gouvêa Cabral ◽

...

Keyword(s):

Growth Performance ◽

Animal Feed ◽

Block Design ◽

Average Daily Gain ◽

Basal Diet ◽

Intestinal Health ◽

Total Period ◽

Nursery Pigs ◽

Randomized Block Design ◽

Diarrhea Incidence

Abstract Antibiotics growth promoting (AGP) in animal feed has been restricted. With this, several additives have been tested in order to replace AGP and ensure intestinal health. The objective of this study was to evaluate the effects of a blend of additives on growth performance, diarrhea incidence and cecal content microbiota of nursery pigs. A total of 576 weaned pigs (6.21 ± 1.16 kg) were assigned into 4 treatments (12 replicates) in randomized block design: basal diet without additives (NC); basal diet with 120 ppm of halquinol (PC); NC + 0,05% blend of lactic acid (3,5%), benzoic acid (2,5%), flavonoids (3,5%) (B5); NC+ 0,1% of same blend (B10). The pigs were weighed 0 and 42 days into the experiment. On day 10, one animal per pen (10 replicates) was euthanized for microbiota analyses. The diarrhea incidence was calculated by the percentage of visual pens with diarrhea, by day, in the period. The growth performance was analyzed by GLIMMIX procedure and the means were compared with Tukey test (P < 0.050) (SAS, 2009). Diarrhea incidence was analyzed by GENMOD procedure (SAS, 2009). The Kruskal Wallis test was used to compare microbial biodiversity (P < 0.050) by statistical program STAMP. The final weight (P = 0.010) and average daily gain (P = 0.001) of B10 and PC were higher than NC. Regarding diarrhea, it was observed that the B5 and B10 had lower incidence when compared to other groups in the total period. In the microbiome analyses, it was observed that the B5, B10, and PC groups had lower (P = 0.021) biodiversity when compared to the NC piglets. However, the B5 and B10 group had higher biodiversity when compared to the PC group. In conclusion, the supplementation with 0,1% blend of additives can be a substitute for AGP.

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268 In-feed Antibiotics Elicit Intestinal Integrity Modifications Early in Post-weaning Life

Journal of Animal Science ◽

10.1093/jas/skab054.158 ◽

2021 ◽

Vol 99 (Supplement_1) ◽

pp. 99-99

Author(s):

Jessica M Johnson ◽

Emma T Helm ◽

Nicholas K Gabler ◽

Eric R Burrough ◽

Carson M De Mille

Keyword(s):

Growth Performance ◽

Fixed Effects ◽

Ex Vivo ◽

Phase 1 ◽

Physiological Mechanisms ◽

Nursery Pigs ◽

Ussing Chambers ◽

Intestinal Integrity ◽

And Function ◽

Dietary Treatments

Abstract The physiological mechanisms by which in-feed antibiotics improve pig growth performance are largely unknown. One proposed mode of action is improvements in intestinal integrity and function. Therefore, the objective of this study was to test the hypothesis that in-feed therapeutic and sub-therapeutic antibiotics would improve intestinal integrity and function in nursery pigs. Twenty-four weaned pigs (6.1±1.1 kg BW) were randomly allotted to individual pens and assigned one of three dietary treatments as follows (n = 8 pigs/trt): 1) control, no antibiotics (CON), 2) CON + sub-therapeutic chlortetracycline [40 ppm in feed (sCTC)], and 3) CON + chlortetracycline-tiamulin [400 ppm + 35 ppm, respectively (CTCDen)]. The study consisted of two consecutive 14 d phases. Chlortetracycline-tiamulin was only fed in phase 1, sCTC was fed in both phases. Phase 1 and 2 ADG, ADFI, and G:F were determined. After 28 d, ileal and colonic ex vivo intestinal integrity was assessed via transepithelial resistance (TER) and macromolecule flux (FD4) in modified Ussing chambers. All data were analyzed for the fixed effects of treatment and start BW as a covariate. In phase 1, compared with CON and sCTC, CTCDen tended to have greater ADG (0.28, 0.31, and 0.33 kg/d, respectively, P = 0.10) and ADFI (0.28, 0.30, and 0.35 kg/d, respectively, P = 0.09). No differences in phase 1 G:F were observed (P = 0.11). Phase 2 ADG, ADFI, and G:F did not differ (P > 0.10). Further, ileal TER and FD4 did not differ (P > 0.10). Colonic TER tended to be increased in sCTC compared with CON and CTCDen (78, 56, and 59 Ω/cm2, respectively, P = 0.07). Compared with CON, colonic FD4 flux was decreased in sCTC and CTCDen by 35–40% (P = 0.03). Altogether, these data indicate that in-feed antibiotics improve colon integrity early in production which may contribute to improved growth performance.

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