Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2013
Publication Date: 7/1/2013
Citation: Oliver, W.T., Wells, J. 2013. Lysozyme as an alternative to antibiotics improves growth performance and small intestinal morphology in nursery pigs. Journal of Animal Science. 91(7):3129-3136.
Interpretive Summary: Antibiotics are used in swine feed as a growth promotant, to improve feed efficiency, and to reduce the susceptibility to bacterial infections. As a result, the use of antibiotics improves the profitability of production for swine producers. However, swine producers are currently under tremendous pressure to eliminate subtherapeutic antibiotic use throughout the production cycle. Finding safe and effective alternatives to traditional antibiotics will give swine producers viable options in the event that the removal of traditional antibiotics is needed. Research conducted at the U.S. Meat Animal Research Center determined that feeding an antimicrobial, lysozyme, to nursery pigs was as effective as traditional antibiotics in increasing growth performance, improving gastrointestinal health, and decreasing pathogen shedding. Thus, lysozyme is a suitable alternative to antibiotics for nursery pigs.
Technical Abstract: Lysozyme is a 1,4-ß-N-acetylmuramidase that has antimicrobial properties. The objective of this experiment was to determine if lysozyme in nursery diets improved growth performance and gastrointestinal health of pigs weaned from the sow at 24 d of age. Two replicates of 96 pigs (192 total 96 males, 96 females) were weaned from the sow at 24 days of age, blocked by weight and gender, and then assigned to 1 of 24 pens (4 pigs/pen). Each block was randomly assigned one of three dietary treatments for 28 d: control (two 14 d phases), control + antibiotics (carbadox/copper sulfate), or control + lysozyme (100 mg/kg diet). Pigs were weighed and bled on d 0, 14, and 28 of treatment. Blood was analyzed for plasma urea nitrogen (PUN) and IgA. At 28 d, pigs were killed and samples of jejunum and ileum were collected and fixed for intestinal morphology measurements. An additional jejunum sample was taken from the median BW 12 pigs per treatment to determine trans-epithelial electrical resistance (TER). Pigs consuming antibiotics or lysozyme grew at a faster rate than control pigs (0.433 ± 0.009 and 0.421 ± 0.008 vs. 0.398 ±0.008 kg/d, respectively; P < 0.03), which resulted in heavier ending BW (20.00 ± 0.31, 19.8 ± 0.29, and 18.83 ±0.32 kg, respectively (P < 0.03). Feed intake was not different (P > 0.48), but Gain:Feed was improved in pigs consuming antibiotics or lysozyme (0.756 ± 0.014, 0.750 ± 0.021, and 0.695 ± 0.019 kg/kg; P < 0.05). Immunoglobulin A (P < 0.03) and PUN (P < 0.01) increased during the experiment, regardless of dietary treatment (P > 0.48). Dietary treatment did not affect TER (P > 0.37), but gilts had lower TER compared to barrows (P < 0.04). No differences in villi height or crypt depth were observed in the ileum (P > 0.53). However, jejunum villi height was increased and crypt depth was decreased in pigs consuming antibiotics or lysozyme (P < 0.001), resulting in an increased villi height:crypt depth of 72% (P < 0.001). Thus, we concluded that lysozyme is a suitable alternative to carbodox/copper sulfate diets fed to pigs weaned from the sow at 24 d of age.