Intestinal crypt morphometric evaluation in french hillbilly stone gray rolled (pedrés) chickens fed increasing levels cupuasu (white cocoa, theobroma grandiflorum) meal

Introduction

The success of the poultry industry depends on the balance between productivity and profitability (Brandalize, 2001). The feed represents 70-80% of the total production cost. This is why researchers are constantly looking for alternative sources aiming to reduce the cost while not affecting product quality (Alvarenga et al., 2004). Agri-industry byproducts are valuable sources of protein, energy and fiber for animal agriculture and, traditionally, these materials have been used in replacement of energy/protein concentrates (US National Research Council, NRC, 1994).

Cupasu or white cocoa (Theobroma grandiflorum, Translator's notice: a tropical plant in the malvaceae family grown near sea level) is a fruit produced in large amounts in the Brazilian Amazon region. This industry processes the pulp and discards the seeds. This is why the resulting meal is one alternative for hillbilly, rustic chickens.

On the other hand, the physicochemical characteristics of nutrients exert direct effects on the development of the intestinal mucosa, in such a way that the fast weight gain (WG) of these birds is directly related with the morpho-functional integrity of the digestive system (Maiorka et al., 2000; Maiorka and Macari, 2002; Smith et al., 1990).

The intestinal mucosa of birds is composed by both villi and crypts (Macari et al., 1994), which development consists of increasing the height and density of the villi, which are constantly renewed with cells from the crypts (Cunningham, 1993). In the event that a nutrient reduces or halts cell proliferation, villi height is reduced hence nutrient absorption/digestion are adversely affected. (Macari, 1998). In agreement with Applegate et al. (1999) the mitotic division of crypt cells is responsible for 55% of intestinal cell proliferation.

The purpose of this study was to investigate the effect of including increasing levels of white cocoa meal (TSC) on duodenal and jejunal crypt depth in naked neck, hillbilly, stone gray-rolled (Pedrés) chickens.

Materials and Methods

Three hundred (300) of the above-mentioned genotype were housed in 300 10-bird pens. During the experimental period both feed and water were given ad libitum. Feeds were based on corn and soybean meal, including growing TSC levels. The experimental design was completely at random, with 5 treatments (T) and six repetitions i.e., T1: control, with no TSC; T2: Inclusion of 5% TSC; T3: Inclusion of 10% TSC; T4: Inclusion of 15% TSC; and T5: Inclusion of 20% TSC.

The birds wwere fasted for 24 hours prior to being wuthanized, at 71 days of age. Thre (3) cm-long sections of both the duodenum and the jejunum were collected. Tissue sections were length open, washed, and extended flat on the serosa, to be then fixed with 10% formaldehyde for 48 hours, and stored in 70% ethyl alcohol. The samples were processed for conventional histology and included in paraffin blocks in order to obtain 05 µ films. Preparations were stained with hematoxylin-eosin, then studied for the identification and evaluation of the intestinal morphology.

Using an optic microscope coupled to a photographic camera and a specific morphometric software (AXIOSCOPIO VISION Release 4.8.2) crypt depths were measured from the base to the crypt-villus transition region.

Results were subjected to the analysis of variance (ANOVA) and, if needed, Tukey´s test (P<0.05) was used to assure significant differences among treatment means.

Results and Discussion

At 71 days of age, crypt depth was hot influenced (P>0.05) by the different treatments (Table 1). TSC is high in fiber and, as such, it tit not induce cell proliferation or adaptation of the intestinal epithelium. This was also observed in rabbits fed increasing fiber concentrations (Amoroso et al., 2009).

Table 1. Means and standard deviations (SD) of crypt depths (µ) in the different treatments

Treatment/ Region	T1 - Control Mean ± SD (µ)	T2 - 5% Mean ± SD (µ)	T3 - 10% Mean ± SD (µ)	T4 - 15% Mean ± SD (µ)	T5 - 20% Mean ± SD (µ)	CV (%)
*Duodenum*	84.0±8.3	77.5±18.4	74.0±13.7	72.0±8.6	70.3±11.3	14.76
*Jejunum*	85.0±19.1	85.7±20.1	89.0±15.1	91.2±14.3	96.2±19.5	19.82

^{CV = Coefficient of variation.}

Results showed decreasing crypt sizes in the duodenum and increasing crypt sizes in the jejunum, as the dietary TSC inclusion levels increased.

Conclusion

Different dietary inclusion levels of cupasu (white cocoa) meal do not affect crypt sizes in the duodenum or the jejunum and, therefore, cell proliferation in these regions is not affected. This meal can be used in the feed of hillbilly chickens.

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