Performance effects of feed-borne Fusarium mycotoxins on broiler chickens: Influences of timing and duration of exposure

Abstract

In commercial practice, broiler chickens may be exposed to Fusarium mycotoxins either during specific growth stages or throughout the entire production cycle. A 34-day feeding trial was conducted to identify sensitive periods for mycotoxin effects during the growth cycle of broiler chickens. A total of 420 newly-hatched Ross 308 male broilers were randomly assigned to 60 cages with 7 birds/cage. Sources of clean wheat (<0.5 mg/kg deoxynivalenol [DON]) and Fusarium-contaminated wheat (11.4 mg/kg DON) were used to formulate the starter diets (0.41 and 6.62 mg/kg DON) provided from 1 to 21 d of age and the grower diets (0.54 and 7.90 mg/kg DON) provided from 22 to 34 d. Control and DON diets were provided to broilers according to treatments (control, DON 1 to 14 d, DON 15 to 21 d, DON 22 to 34 d and DON 1 to 34 d). Birds were monitored daily for morbidity or mortality. Broiler growth performance (body weight, average daily gain, average daily feed intake and feed to gain ratio) was measured weekly. Segments of duodenum, jejunum and ileum were collected at 21 and 34 d and morphometric parameters (villus height, crypt depth, villus width, muscularis thickness and villi:crypt ratio) were measured. Birds fed the DON starter diet during the first 14 d did not exhibit any changes in growth performance; however, growth performance was suppressed in birds fed DON-contaminated diets during the grower period (22 to 34 d). At 34 d, birds that received the DON grower diet (DON 22 to 34 d and DON 1 to 34 d) were lighter (1,433 vs. 1,695 g) than birds fed the control diet. Feed to gain ratio was higher in birds fed the DON grower diet from 22 to 28 d (1.77 vs. 1.56) and 28 to 34 d (2.24 vs. 1.85) compared with corresponding controls. These results suggest that providing older broiler chicks (22 to 34 d) feed contaminated with Fusarium mycotoxins (specifically DON) may result in production losses. Histopathological analysis of the ileum region revealed that birds provided the DON diets throughout the entire trial (1 to 34 d) had shorter villi (506 vs. 680 μm) and shallower crypt (85 vs. 115 μm) than control birds. Taken together, these results indicate that DON-induced growth suppression may be a result of adverse effects on intestinal morphology during later growth phases of broilers.

Keywords: Chicken; Deoxynivalenol; Feed contamination; Intestine; Sensitive period.

Fig. 1

Schematic representation of the timing of different diets (control and deoxynivalenol [DON]-contaminated) fed to broiler chicken during a 34-day feeding trial. The starter diets were fed from 1 to 21 d (0.41 and 6.62 mg/kg DON) and the grower diets were fed from 22 to 34 d (0.54 and 7.90 mg/kg DON). The DON diets were prepared with wheat that was naturally-contaminated with Fusarium mycotoxins.

Fig. 2

Effects of feeding a deoxynivalenol [DON]-contaminated diet from 1 to 21 d on (A) villus height, (B) villus width, (C) crypt depth and (D) muscularis thickness in different intestinal regions of broiler chickens. Bars represent means ± standard error of the mean (SEM) with n = 6 animals. White bars represent birds fed the control diet and black bars represent birds fed the DON-contaminated diet. Asterisk (*) represents a significant difference within intestinal region (ANOVA, P ≤ 0.05). Villi to crypt ratio was not affected by DON treatment (ANOVA, P > 0.05).

Fig. 3

Effect of feeding deoxynivalenol [DON]-contaminated diets during different growth stages on (A) villi height and crypt depth, (B) villi to crypt ratio and (C) villi width in different intestinal regions of broiler chickens at 34 d. Bars represent means ± standard error of the mean (SEM) with n = 6 animals. The starter diets were fed from 1 to 21 d (0.41 and 6.62 mg/kg DON) and the grower diets were fed from 22 to 34 d (0.54 and 7.90 mg/kg DON). Figure legend in Fig. 3A applies to all subfigures. The bars with different letters a and b are significantly different (P ≤ 0.05, one-way ANOVA followed by Tukey–Kramer test; n = 6/treatment). The muscular thickness did not differ among treatments (P > 0.05, one-way ANOVA).

Fig. 4

Effects of feeding deoxynivalenol [DON]-contaminated diets to broilers for 34 d on morphology of ileum mucosal structures ( × 10, hematoxylin and eosin staining). (A) Ileum of a control bird at 34 d with normal villi. (B) Ileum from a bird fed DON-contaminated diet (∼7 mg/kg DON) from 1 to 34 d showing villi flattening and increased goblet cells (arrows).