Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2011
Publication Date: 3/20/2012
Citation: May, K.D., Wells, J., Maxwell, C.V., Oliver, W.T. 2012. Granulated lysozyme as an alternative to antibiotics improves growth performance and small intestinal morphology of 10-day-old pigs. Journal of Animal Science. 90(4):1118-1125. Interpretive Summary: Antibiotics have been fed at subtherapeutic levels as growth promoters for more than 50 years and the majority of swine produced in U.S. receive antibiotics in their feed at some point during the production process. The addition of antibiotics to swine diets benefits producers by improving feed efficiency and decreasing susceptibility to bacterial infections. Recently, however, swine producers have been pressured to reduce or remove dietary antibiotics. The identification of suitable alternatives to antibiotics will enable the swine industry to effectively transition away from dietary antibiotic use. Research conducted at the U.S. Meat Animal Research Center determined that feeding a natural antimicrobial, lysozyme, to young pigs consuming a liquid diet was as effective as antibiotics in increasing growth performance, improving gastrointestinal health, and decreasing pathogen shedding. Thus, lysozyme is a suitable alternative to antibiotics for young pigs consuming manufactured liquid diets.
Technical Abstract: Lysozyme is a 1,4-ß-N-acetylmuramidase that has antimicrobial properties. The objective of this experiment was to determine the effect of a purified granulated lysozyme, compared to antibiotics, on growth performance, small intestinal morphology, and Campylobacter shedding in 10-d-old pigs. Forty-eight pigs (n = 16), with an initial weight of 4.0 ± 0.1 kg (P > 0.40) were weaned at 10 d of age, blocked by litter and gender, and assigned to pens (8 pigs/pen). Each block was randomly assigned to consume one of three liquid dietary treatments for 14 d; control, control + lysozyme (100 mg/kg diet), or control + antibiotics (neomycin and oxytetracycline, 16 mg/kg diet). Pigs were weighed and bled on d 0, 7, and 14. Blood was analyzed for plasma urea nitrogen (PUN) and immunoglobulin A (IgA). After 14 d of treatment, pigs were killed and jejunum and ileum samples were collected and fixed to measure villi height and crypt depth. Rectal swabs were taken on d 0, 7, and 14 of treatment, and a sample of ileum and cecum contents were taken at d 14 of treatment to determine the presence of Campylobacter. Pigs consuming lysozyme and antibiotics gained at a faster rate than control pigs over the course of the study (402 ± 12 and 422 ± 14 vs. 364 ± 14 g/d; P < 0.02), resulting in heavier ending BW (9.9 ± 0.3, 9.9 ± 0.3, and 9.0 ± 0.2 kg for lysozyme, antibiotic, and control pigs, respectively; P < 0.03). Immunoglobulin A decreased and PUN increased over the course of the study (P < 0.1), regardless of dietary treatment (P > 0.6). Crypt depth was increased in lysozyme and antibiotic fed pigs, compared to control pigs, in both jejunum (60.0 ± 2.8 and 62.2 ± 3.0 vs. 50.7 ± 3.1 µm; P < 0.03) and ileum (76.0 ± 7.5 and 72.2 ± 5.0 vs. 52.4 ± 3.5 µm; P < 0.02). Villi height did not differ in the jejunum (P > 0.2), but was increased in the ileum of pigs consuming lysozyme and antibiotic diets, compared to control pigs (312 ± 20 and 314 ± 10 vs. 263 ± 15 µm; P < 0.4). Small intestinal total mucosa and mucosal protein concentration, as well as disaccharidase specific activities, were not altered by lysozyme or antibiotics (P > 0.05). Campylobacter was detected in 27% of control samples, but in only 5% of antibiotic fed samples and 8% of lysozyme fed samples (P < 0.01). Thus, granulated lysozyme is a suitable alternative to antibiotics for 10-d-old pigs consuming manufactured liquid diets.