Canola varieties have been develope

Canola varieties have been developed to produce oil
and meal with lower levels of erucic acid and glucosinolatos,
respectively (Bell, 1993). The oil in canola
must contain less than 2% of erucic acid, and the meal
should contain less than 30 µmol/g of aliphatic glucosinolates
(Leeson and Summers, 2005; Khajali and
Slominski, 2012).
Canola meal is used as a protein source in poultry
diets (Canola Council of Canada, 2009). Its composition
and nutritional value vary substantially depending
on the type of processing, and these characteristics also
reflect differences among cultivars (Bell, 1993). In addition,
these factors affect the content and composition
of glucosinolates in canola meal (Jensen et al., 1995).
Such variation can reduce the performance of the birds
by reducing food intake (Tripathi and Mishra, 2007).
For this reason, the determination of the coefficients ofnutrient digestibility of canola meal in the diet can aid
in the optimization of the use of this protein source in
diets for broilers.
Canola meal can be included in the diet of broilers up
to a level of 10% for chick starter and 20% for broiler
grower without affecting the growth performance of
broilers when diets are formulated based on the level
of digestible amino acids (Canola Council of Canada,
2009). According to this source, canola meal may also
be used as a protein source for turkeys, with a level of
up to 30% considered suitable in the grower phase.
Min et al. (2011) indicated that a 25% level of canola
meal can be used in broiler diets without any negative
effect on growth performance. Payvastagan et al.
(2012) also found that feed intake of broilers was not
affected by canola meal. However, weight gain and feed
conversion ratio were negatively affected by the addition
of 20% of canola meal.
If alternative to SBM protein supplements are proposed
for use in animal diets, it is important to consider
the effects of these feed ingredients on the intestinal
mucosa. Figueiredo et al. (2003) tested various inclusion
levels of canola meal (0, 10, 20, 30, and 40%) in
the diets of broilers at 21 d of age and found no dif-ferences (P < 0.05) among levels for villus height and
the villus:crypt ratio; these authors concluded that the
integrity of the villi was not impaired. Likewise, Chiang
et al. (2010) found no significant differences in villus
height or crypt depth in the duodenum of broilers at 21
and 42 d of age fed with a control diet (without canola
meal) and 2 experimental diets, one with fermented
canola meal (10%) and the other with unfermented
canola meal (10%). However, Xu et al. (2012) tested
the inclusion levels of 0, 5, 10, and 15% of fermented
canola meal in the diets of broilers at up to 42 d of age
and observed a higher villus height with 10% canola
meal with no significant difference observed for crypt
depth.
Antinutritional factors contained in canola meal may
affect the growth performance of broilers. Information
on the effect of canola meal inclusion level on nutrient
digestibility and the intestinal mucosa is lacking.
Therefore, the aim of this study was to evaluate the
effect of the substitution of soybean meal (SBM) for
canola meal in broiler diets on production, nutrient digestibility,
and morphometry of the intestinal mucosadevelopment according to the recommendations of Rostagno
et al. (2011). Starter diets were used at 8 to 21
d of age, and grower and finisher diets were used at 22
to 35 d of age. Five levels of canola meal (0, 10, 20,
30, and 40%) were used to replace SBM (see Table 1).
The canola meal used in the present experiment was
obtained from the feed industry. The calcium level of
the experimental diets is higher than recommended due
to the vitamin mix used, which contains a high level of
this mineral. To balance all the other micro ingredients
in the diets, the amount of Ca became high. However,
it happened in all dietary treatments, and therefore, it
did not interfere in the results herein obtained.
Growth Performance
The following growth performance variables were
evaluated: average bird weight, daily weight gain,
feed intake, and feed conversion ratio. The birds were
weighed on the first day of the experiment, then weighed
weekly throughout the remaining experimental period
(8 to 35 d of age). The feed was provided daily and the
leftover feed were was weighed weekly to calculate the
feed conversion data.