Granulated lysozyme as an alternative to antibiotics improves growth performance and small intestinal morphology of 10-day-old pigs.

Lysozyme is a 1,4-β-N-acetylmuramidase that has antimicrobial properties. The objective of this experiment was to determine the effect of a purified granulated lysozyme, compared with antibiotics, on growth performance, small intestinal morphology, and Campylobacter shedding in 10-d-old pigs. Forty-eight pigs (n = 16 per treatment), with an initial BW of 4.0 ± 0.1 kg (P > 0.40), were weaned at 10 d of age, blocked by litter and sex, and assigned to pens (8 pigs/pen). Each block was randomly assigned to consume 1 of 3 liquid dietary treatments for 14 d: a control diet, the control diet + lysozyme (100 mg/kg of diet), or the control diet + antibiotics (neomycin and oxytetracycline, 16 mg/kg of diet). Pigs were weighed and blood was sampled on d 0, 7, and 14. Blood was analyzed for plasma urea N and IgA. After 14 d of treatment, pigs were killed and samples of the jejunum and ileum were collected and fixed to measure villus height and crypt depth. Rectal swabs were taken on d 0, 7, and 14 of treatment, and samples of ileal and cecal contents were taken at d 14 of treatment to determine the presence of Campylobacter. Pigs consuming lysozyme and antibiotics gained BW at a faster rate than did control pigs over the course of the study (402 ± 12 and 422 ± 14 g/d, respectively, 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 pigs in the lysozyme, antibiotic, and control groups, respectively; P < 0.03). Immunoglobulin A decreased and plasma urea N increased over the course of the study (P < 0.1), regardless of dietary treatment (P > 0.6). Crypt depth was increased in pigs fed lysozyme- and antibiotic-treated diets, compared with pigs fed the control diet, in both the jejunum (60.0 ± 2.8 and 62.2 ± 3.0 µm, respectively, vs. 50.7 ± 3.1 µm; P < 0.03) and ileum (76.0 ± 7.5 and 72.2 ± 5.0 µm, respectively, vs. 52.4 ± 3.5 µm; P < 0.02). Villus height did not differ in the jejunum (P > 0.2) but was increased in the ileum of pigs consuming the lysozyme- and antibiotic-treated diets, compared with pigs fed the control diet (312 ± 20 and 314 ± 10 µm, respectively, vs. 263 ± 15 µm; P < 0.4). Small intestinal total mucosa and mucosal protein concentrations, 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 samples from pigs fed antibiotics and 8% of samples from pigs fed lysozyme (P < 0.01). Thus, granulated lysozyme is a suitable alternative to antibiotics for 10-d-old pigs consuming manufactured liquid diets.