Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2014
Publication Date: 10/28/2014
Publication URL: http://handle.nal.usda.gov/10113/59756
Citation: Oliver, W.T., Wells, J., Maxwell, C.W. 2014. Lysozyme as an alternative to antibiotics improves performance in nursery pigs during an indirect immune challenge. Journal of Animal Science. 92(11):4927-4934.
Interpretive Summary: Subtherapeutic levels of antibiotics are used in swine feed as growth promotants, 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 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 enzyme, lysozyme, to nursery pigs was as effective as traditional antibiotics in increasing growth performance, including growth, nutrient accretion, and feed efficiency. In addition, lysozyme was effective in pigs under a chronic immune stimulation. Thus, lysozyme is a suitable alternative to antibiotics in swine nursery diets, and lysozyme ameliorates the effects of a chronic immune challenge.
Technical Abstract: Lysozyme is a 1,4-ß-N-acetylmuramidase that has antimicrobial properties. The objective of this study was to determine the effect of lysozyme and antibiotics on growth performance and immune response during an indirect immune challenge. Two replicates of 600 pigs each were weaned from the sow at 26 d of age, blocked by litter and sex, and then randomly assigned to one of 24 pens in either a nursery room that had been fully disinfected or a nursery room left unclean since the previous group of pigs. Within a room, pigs were randomly assigned to either control diets (C; 2 phase nursery regime), control diets + antibiotics (C + A; chlorotetracycline/tiamulin hydrogen fumarate), or control diets + lysozyme (C + Lyso; 100 mg/kg diet). Pig weights and feed disappearance were measured and blood was collected on d 0, 14, and 28 of treatment. A group of 20 pigs were killed at 24 d of age for initial body composition analysis and 10 pigs of median weight were killed per diet room combination for body composition analysis after 28 d of treatment. Control + A and C + Lyso fed pigs grew at a faster rate for the 28 d study compared to control pigs (318 ± 14, 320 ± 15, vs. 288 ± 15 g/d, respectively; P < 0.05), regardless of nursery environment (P > 0.05). The indirect immune challenge did not alter growth performance from d 0 to 14 of treatment, but decreased ADG from d 14 to 28 of the study (415 ± 15 vs. 445 ± 13 g/d; P < 0.05). Feed intake was not altered by the nursery environment (P > 0.61) or dietary treatments (P > 0.10), but feed efficiency was worsened by the indirect immune challenge (P < 0.05) and improved by both C + A and C + Lyso diets (P < 0.01). The immune challenge did not alter nutrient accretion (P > 0.25), but both C + A and C + Lyso pigs had decreased accretion of whole-body lipid (P < 0.01) and increased accretion of protein (P < 0.09). Blood levels of tumor necrosis factor-a (TNF-a; P < 0.01), haptoglobin (P < 0 .09), and C-reactive protein (CRP; P < 0.01) were higher due to the indirect immune challenge, compared to pigs reared in the clean nursery (P < 0.05). In addition, pigs consuming antibiotics or lysozyme had lower TNF-a, haptoglobin, and CRP compared to control pigs, regardless of nursery environment (P < 0.04). Thus, lysozyme is a suitable alternative to antibiotics in swine nursery diets, and lysozyme ameliorates the effects of a chronic indirect immune challenge.