Effects of dry whey powder and calcium butyrate supplementation of corn/soybean-based diets on productive performance, duodenal histological integrity, and Campylobacter colonization in broilers

Abstract

Background: Campylobacter is the main cause of gastroenteritis in humans in industrialized countries, and poultry is its principal reservoir and source of human infections. Dietary supplementation of broiler feed with additives could improve productive performance and elicit health benefits that might reduce Campylobacter contamination during primary production. The aim of this study was to assess the effect of dietary supplementation with whey (a prebiotic) and calcium butyrate (a salt of a short-chain fatty acid) on productive traits, duodenal histological integrity, and Campylobacter colonization and dissemination in broiler chickens during the 42-day rearing period.

Results: Six hundred one-day-old Ross-308 chickens were placed into 20 ground pens and assigned to one of 4 corn/soybean-based dietary treatments (5 replicates of 30 chicks per treatment) following a randomized complete block design: 1) basal diet with no supplementation as the control, 2) diet supplemented with 6% dry whey powder, 3) diet containing 0.1% coated calcium butyrate, and 4) diet containing 6% whey and 0.1% calcium butyrate. At age 15 days, 6 chickens per pen were experimentally inoculated with Campylobacter jejuni. The results showed that supplementation of the corn/soybean-based diet with 6% whey alone or, preferably, in combination with 0.1% coated calcium butyrate improved growth and feed efficiency, had a beneficial effect on duodenal villus integrity, and decreased mortality. These favourable effects were particularly significant during the starter period. Six days after oral challenge, Campylobacter was widespread in the flock, and the birds remained positive until the end of the rearing period. Although Campylobacter was not isolated from environmental samples, it was detected by real-time polymerase chain reaction (PCR) in dust, air filters, and drinkers while birds shed culturable C. jejuni cells. No differences (p > 0.050) in colonization or shedding levels that could be attributed to the diet were observed during the assay.

Conclusions: Beneficial effects on performance and intestinal health were observed, particularly during the starter period, when chickens were fed a diet supplemented with both whey and coated calcium butyrate. However, none of the tested diets provided the chicks any differential degree of protection against Campylobacter infection.

Keywords: Broiler; Campylobacter jejuni; Coated calcium butyrate; Dry whey powder; Experimental infection.

Fig. 1

Schematic representation of the experimental trial. Time values are in days. Downward solid arrows indicate the days when birds were slaughtered for collection of caecal content and duodenal tissue samples. Upward arrows show time points for sample collection as indicated in the boxes. Sampling of faeces on day 15 was carried out immediately before oral inoculation

Fig. 2

Dynamics of Campylobacter infection throughout the rearing period of 42 days, as determined by real-time PCR (Ct values) analysis of environmental (air, dust, and drinkers) and animal (faeces, cloacal swabs and cloacal content) samples. Samples above the dotted horizontal line were positive by microbiological culture, whereas those below were negative

Fig. 3

Campylobacter load in experimentally inoculated (grey) vs. non-inoculated (white) broilers as determined by real-time PCR analysis of cloacal swabs at days 21, 28, 35 and 42 (a) and broilers’ caeca at days 28 and 42 (b), representing shedding and colonization levels, respectively. Real-time PCR Ct values were transformed into Log₁₀ Campylobacter cell equivalents per cloacal swab (a) or per g of caecal content (b). The boundary of the box closest to zero indicates the 25th percentile, the continuous line within the box marks the median, a dashed line marks the mean and the boundary of the box farthest from zero indicates the 75th percentile. Error bars above and below the box indicate the 90th and 10th percentiles. Outlying points (5th and 95th percentiles) are represented as closed dots. Significant differences between orally inoculated and horizontally infected are marked with an asterisk