PHOTO: REINADEVRIES


MYCOTOXINS ▶▶▶


Table 2 – Mean (± SD) effects of DON and activated charcoal in the complete feeding period (D0-35) on body weight gain (BWG; g), feed intake (FI; g) and feed conversion ratio (FCR; g/g) of broilers.


BWG


Treatment No additive


DON (g) MD


Activated charcoal MD No additive


LD Activated charcoal LD


MD LD


No additive Activated charcoal


Effect DON


Additive DON x Additive


2,319 ± 88 2,339 ± 89 2,421 ± 71 2,396 ± 95


2,329 ± 86 a 2,408 ± 82 b


2,370 ± 93 2,368 ± 94


P-value 0.02 0.94 0.48


LSD 64.5 64.5 91.3


FI (g)


3,555 ± 77 3,583 ± 110 3,649 ± 110 3,600 ± 97


3,569 ± 93 3,624 ± 104


3,612 ± 104 3,591 ± 101


P-value 0.13 0.76 0.29


LSD 73.2 73.2


103.5 FCR (g/g)


1.534 ± 0.041 1.532 ± 0.038 1.508 ± 0.026 1.503 ± 0.028


1.533 ± 0.038 1.505 ± 0.026


1.521 ± 0.035 1.518 ± 0.036


P-value 0.04 0.81 0.91


LSD


0.0249 0.0249 0.0352


MD: moderate DON level (2,300 ppb in the diet); LD: low DON level (900 ppb in the diet), a, b Values followed by a different letter within a column differ significantly (P ≤ 0.05).


The importance of mycotoxins in the poultry in- dustry may in- crease when ionophore anti- coccidials are banned from feed.


mitigated when the chickens are subsequently fed a diet with negligible levels (57.3 ppb) of DON for seven days. In the cur- rent study, instead of challenging the birds with Eimeria spp. oocysts, anticoccidials were excluded from the diet formula- tion. Coccidiosis not only leads to clinical signs but can also result in poor performance.


Mycotoxin levels Although the diets were contaminated with a variety of my- cotoxins, the negative impact observed in the current study


b a


was basically caused by DON. Besides DON, the other myco- toxins current in the diets were deoxynivalenol-3-glucoside (DON-3-G), enniatins B and B1 (ENNB+B1), zearalenone (ZEN), ochratoxin A (OTA), alternariol (AOH), and alternariol methyl ether (AME). The levels of ZEN, OTA, AOH, and AME were negligible. The DON-3-G is a metabolite from DON, but without high toxicity to poultry. Therefore, the observed di- etary levels between 10.7 ppb and 1670 ppb in the current study should not be a reason for concern.


The intestinal integrity of broilers Intestinal morphometric changes in the first 14 days of ex- posure were negligible and limited to an increase in the VH:CD ratio in the ileum of broilers fed the MD diet, regard- less of the presence of activated charcoal, indicating that cell proliferation decreased in broilers fed the MD diet without resulting in immediate villus shortening. This was expected, since DON decreases cell proliferation and the crypt is responsible for cell renewing and maintenance of villus length. After 28 days, however, broilers fed the MD diet had a significantly lower villus height and VH:CD ratio than those fed the LD diet. This leads us to infer that birds fed the MD diet were probably trying to maintain villus height by a compensatory increase in the proliferation in the crypt, which required extra energy. Besides this, short- ened villi and deeper crypts will result in suboptimal nutri- ent absorption and impaired animal performance. This matches the observed decreased BWG and increased FCR at D28. The ileum had a higher VH:CD ratio due to an increase in crypt depth, showing that in this intestinal section, cell proliferation was increased to keep villus height similar to the expected (LD diet) levels. Such a compensatory mecha- nism, which costs energy, will result in suboptimal perfor- mance. At D35, no differences were observed, because the finisher diet had negligible levels of DON and intestinal cell turnover takes around 48 h to 96 h. At D14, lesion scores were significantly increased when birds were fed a MD diet supplemented with activated charcoal, whereas at D28, the highest lesion scores were observed in broiler chickens re- ceiving a non-supplemented MD died. No dietary effects were observed at D35. Figure 1 illustrates examples of jeju- num and ileum sections from broilers fed MD and LD diets either supplemented or not with activated charcoal. Based on the morphometric analysis and lesion scores in the jeju- num and ileum, it can be concluded that the jejunum was the intestinal section that was more sensitive to DON than the ileum. Moreover, broiler chickens fed a diet containing moderate levels of DON (2300 ppb) will perform inefficiently. The in- fluence of mycotoxins on poultry performance should be assessed not only on its toxicity per se, but also considering animal age, dietary composition, and the presence of other types of additives, such as anticoccidials.


10 ▶ ALL ABOUT FEED | Volume 29, No. 3, 2021


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