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This study was to evaluate the sunflower cake and enzymatic complex fed to broilers from 22 to 42 d of age.
In a completely randomized design, a total of 850 birds were allotted in a 2×5 factorial scheme (with and without enzymatic complex) and five inclusion levels (0%, 5%, 10%, 15%, 20%) of sunflower cake. There were 5 replications and 17 birds in each experimental unit. Data from performance, carcass yield and intestinal morphology were evaluated.
Feed intake, weight gain, final weight and feed:gain ratio linearly worsened as sunflower cake increased. For weight gain, final weight and feed:gain ratio, the birds whose diets contained levels of 15% and 20% of sunflower cake showed worse values (p<0.05) than the birds fed the control diet. When fed the enzymatic complex, birds improved (p<0.05) crypt depth and villus:crypt ratio in the jejunum. As inclusion levels of sunflower cake increased, villus depth and villus:crypt ratio in duodenum, jejunum and ileum linearly reduced and the crypt depth linearly increased. Carcass yield linearly reduced as sunflower cake increased.
Based on performance, sunflower cake can be used up to 10% in broilers feeding from 21 to 42 days of age.
The cost of feed accounts for most of the costs associated with animal production. This encourages the search for new ingredients that can reduce costs by effectively replacing corn or soybean meal, which represent the most common ingredients used in feed formulations . In this regard, byproducts derived from the industrial processing of agricultural products have attracted the attention of researchers .
Sunflower cultivation has expanded significantly in Brazil and is considered one of the largest agricultural bases of the national program of renewable fuels  and is among the most common edible vegetable oil crop in the world.
The extraction of sunflower oil can be performed by two methods: The first and most efficient uses a chemical solvent (hexane) at high temperatures to obtain sunflower meal as a byproduct. The second method is characterized by cold-pressing sunflower seeds to obtain the crude oil, resulting in a byproduct known as sunflower cake (SC). This byproduct contains more ether extract (averaging 18%) than sunflower meal, due to lower efficiency of the oil extraction method compared to the first type described .
The SC can be a good source of energy for broiler chickens and, as reported by Geron , its use in feed formulation for animals can reduce production costs and contribute to sustainable animal production by reducing environment contamination and improving the conservation of natural resources.
However, chemical composition of the SC can shows variation due to the genetics of the cultivar and due to processing of the seeds , which makes it essential to determine the nutritional values of SC before proceeding to include it in feed formulations.
Additionally, some factors can limit the feeding of SC to non-ruminants, such as its high concentration of non-starch polysaccharides, especially cellulose and lignin, which cannot be degraded by endogenous enzymes. The cellulolytic complex of the sunflower plant, therefore, acts as a barrier to birds’ digestive systems, impairing enzyme action and increasing the endogenous nutrient loss, thus reducing the availability of energy from birds’ diets . To increase the efficiency of nutrient utilization from alternative foods it’s commonly proposes the addition of exogenous enzymes. This study evaluates the performance traits, carcass yield and prime cuts, and the intestinal morphology of broiler chickens, from 22 to 42 d of age feeding diets with increasing levels of SC, with or without enzymatic complex supplementation.
The experiment was conducted at the Poultry Section of State University of West Paraná (Unioeste), at the Campus of Marechal Cândido Rondon, PR, Brazil, and the experimental protocol (n° 04411/2011) was approved by Animal Care and Use Committee (Comitê de Ética na Experimentação Animal e Aulas Práticas - CEEAAP/UNIOESTE). The SC was acquired from a sunflower oil production facility in Toledo, PR. A prior digestibility assay determined the chemical and energetic composition and the digestible amino acids used to formulate the experimental diets .
Birds were acquired from a commercial Cobb Slow line breeder’s incubatory and vaccinated for Marek’s disease, Gumboro, fowlpox and infectious bronchitis. From 1 to 21 d of age, birds were created in a conventional barn with new wood shavings in which all birds received the same diet (pre-starter and initial) and water ad libitum. Heat and light was provided for the birds using infrared lamps of 250 watts and a 24 h lighting program. The maximum temperature and relative humidity were 29.33°C and 82.84%, respectively, and the minimal temperature and relative humidity were 23.92°C and 73.50%, respectively.
At 21 d of age birds were weighed individually and separated by weight. After weighing, 850 male broilers, averaging 740.27± 3.77 g, were distributed in a completely randomized design using a 2×5 factorial scheme that combined two treatments i) with and ii) without enzyme complex supplementation (pectinase, 4,000 U/g; protease, 700 U/g; phytase, 300 U/g; betaglucanase, 200 U/g; xilanase, 100 U/g; celulase, 40 U/g; and amilase, 30 U/g) and five levels of SC (0%, 5%, 10%, 15%, and 20%) with five replications and 50 experimental units in total.
Diets and water were provided ad libitum for birds during the entire experimental period. Nutritional values of SC were used as proposed by Berwanger et al . The diets were isonutritive, based on corn and soybean meal and formulated according to the requirements proposed by Rostagno et al  for birds from 21 to 35 d of age and from 36 to 42 d of age (Table 1). The enzymatic complex replaced the inert and a total of 0 was added to the birds’ diets.
The birds’ weight and feed intake (FI) were recorded weekly. Mortality was recorded to correct the FI and feed: gain (F:G) ratio , then weight gain (WG), FI, and F:G ratio were calculated. On d 42, two birds (ranging±5% of the average weight of the experimental unit) were sacrificed to obtain the carcass yield, prime cuts and organs. Birds were submitted to 8 h fasting and euthanized by cervical dislocation and subsequent bleeding. After manual plucking, carcasses were gutted, washed, dripped and weighed and quartered. Subsequently, the weight of the prime cuts, viscera and abdominal fat were recorded.
Carcass yield was calculated by comparing the weight of the eviscerated carcass to the live weight of the birds; the yield of thigh, drumstick, breast, wing, abdominal fat, liver and pancreas were determined in relation to the weight of the eviscerated carcass. Abdominal fat was composed of adipose tissue present around the cloaca, gizzard, proventriculus and adjacent abdominal muscles.
To evaluate the intestinal morphology at d 42 of age, two birds (ranging±5% of the average weight of the experimental unit) were sacrificed. Duodenum, jejunum, and ileum were collected to assess the villus height and crypt depth using light microscopy. After the semi-serial microtome (7 μm), the slides were stained using hematoxylin with eosin technique .
The statistical analysis were performed using the System for Statistical Analyses and Genetics (SAEG) . All variables were submitted to analysis of variance and subsequent polynomial regression. Additionally, Dunnett’s test was used to compare the dietary inclusion levels of SC (5%, 10%, 15%, and 20%) with the control diet (0% SC).
No interaction was observed between enzyme complex and inclusion levels of SC in relation to performance traits, prime cuts, organ yields and intestinal morphology. Non-ruminant animals are not able to digest non-starch polysaccharides and, therefore, the use of endogenous enzymes can be an alternative to improve nutrient utilization and increase energy available to such animals. However, in our study, no differences were observed between treatments with or without enzyme complex supplementation for performance traits (Table 2).
It is important to consider that enzyme supplementation occurred after 21 d of age, the stage in which birds already have a well-developed digestive tract with higher digestion capacity and absorption of nutrients. Tavernari et al  observed higher WG for broiler chickens aged 1 to 21 d that did not receive an enzymatic complex in the diet, although they did not consider energy recovery of enzymes in the diet formulations.
Excluding the birds fed the control diet (0% SC), regression analysis showed that FI, WG, final weight, and F:G linearly worsened (p = 0.23, 0.12, 0.12, and 0.05, respectively) as dietary SC increased, which can be confirmed by the adjustment of regression equations. Studying the inclusion of SC in the diets of broiler chickens from 20 to 42 d of age, Oliveira et al  observed a worse F:G ratio and a quadratic effect on FI, which reduced from 9.6% of SC, indicating that its use should be limited in broiler chicken diets.
The decrease in FI with rising inclusion of SC, as observed in our study, may be associated with reduction in the food passage rate; because when non-starch polysaccharides are undigested, the viscosity of the chyme increases due to its high affinity for water and reduces the food passage rate. It impairs enzyme action and then the digestibility and utilization of other nutrients, which may be related to reduced WG and increased F:G ratio observed in our study.
Considering the Dunnett’s test, we observed no difference in FI between birds fed the experimental diets and those fed as controls. This is in line with scerbo et al , whose found no difference in FI for broiler chickens fed diets with SC up to 12% inclusion. Tavernari et al  studied sunflower meal to broilers from 22 to 42 d of age and did not find differences in FI. When birds’ diets contained up to 15% sunflower meal, Furlan et al  demonstrated improved the performance traits of broiler chickens; however, the authors reported that lysine and energy should be supplemented to meet the requirements.
Birds fed SC levels of 15% and 20% showed worse WG, FW, and F:G values compared to birds fed the control diet. From this we can infer that including up to 10% SC in broiler chicken diets results in similar performance compared to control diet. Oliveira et al  reported that using 12.3% of SC did not negatively affect WG of broilers. Scerbo et al  also demonstrated that a 12% SC inclusion beyond 25 d of age did not impair WG of broilers.
Intestinal morphometry data showed that the enzymatic complex improved (p<0.05) the crypt depth and, consequently, the villus: crypt ratio in the jejunum (Table 3). It is desirable that intestinal villi are high and crypt is shallow because the higher the ratio of villus height: crypt depth, the better will be the absorption of nutrients and the less energy will be needed for cell turnover .
According to Maiorka et al , the development of intestinal mucosa results primarily from two associated cytological events: cellular renewal (mitosis) and cell loss (extrusion). The high amount of cell renewal in intestinal mucosa is due to hyperplasia, which results from high mitotic activity.
Enzyme activity probably reduces intestinal viscosity; otherwise, it could impair the mucous layer and compromise the integrity of intestinal epithelial cells. Moreover, according to Viveros et al , enzymes can improve the microflora by increasing the growth of beneficial bacteria that maintain intestinal health by degrading the fiber in the diet.
Considering the regression analysis, all variables of intestinal morphology worsened as SC levels increased; the villus height and villus:crypt ratio in the duodenum, jejunum and ileum linearly reduced (p = 0.14, 0.066, and <0.01; 0.09, <0.01, and <0.01, respectively), according to increasing levels of SC, while crypt depth increased linearly (p = 0.17, 0.13, 0.13, respectively). This suggests that non-starch polysaccharides have a negative effect on nutrient utilization in the intestinal tract, which justifies the poor broiler performance, according to the inclusion levels of SC in the birds’ diets. Evaluating the inclusion of fiber for broiler chickens, Morita  observed reductions in villus height in three segments of small intestine as fiber increased in the diets.
Similarly, Moghaddam et al  observed a decrease in the villus height and increase in crypt depth in the duodenum and jejunum of cocks as the levels of sunflower meal increased and reported that these effects can reduce nutrients absorption, increase secretion in the intestinal tract and reduce performance and resistance to diseases.
Working with sunflower seeds with high fat content in broilers’ diets, Arija et al  observed the presence of many dark granules inside the enterocytes vacuoles. These could be triglyceride-rich lipoproteins (portomicrons) that developed due to the presence of toxic compounds in sunflower seed, such as chlorogenic acid (7 g/kg), or due to higher oil concentration in the diet (9%) or due to the absence of apoproteins necessary for the synthesis and transport of lipoproteins for the intestinal blood vessels, which cause the vacuolar degeneration of enterocytes as well as hyperplasia of goblet cells.
Dunnett’s test shows that for birds fed 15% and 20% dietary levels of SC, the villus height in the duodenum was lower than that of birds fed the control diet (p<0.05). Considering the villus height of jejunum and ileum, the crypt depth of jejunum and villus:crypt ratio of jejunum and ileum, the birds fed 10%, 15%, and 20% of SC showed worse results (p<0.05) than the control diet, especially for the highest level of SC. Crypt depth of ileum and the villus: crypt ratio of duodenum showed the worst values at 20% of SC.
Carcass, thigh and liver yield were higher (p<0.05) for birds receiving the enzymatic complex, while chest yield, drumstick, wings and pancreas were higher for birds receiving no enzymatic complex (Table 4).
The utilization of enzymatic complex (xylanase, amylase, and protease) in diets for broiler chickens reduced the carcass yield . Tavernari et al  using diets supplemented with enzymatic complex, did not find an effect of enzymes on the yield of broiler chicken carcass, abdominal fat, thigh and chest.
The results observed for liver and pancreas yield are consistent, since the utilization of exogenous enzymes can reduce pancreas activity by a lesser need for enzyme production, which reduces its relative weight . On the other hand, the increasing in liver yield can be explained by its greater activity due to higher nutritional support with enzyme utilization. Santos et al  observed that the addition of enzymatic complex in the broilers’ diets did not affect the relative weight of liver and pancreas.
Carcass yield reduced linearly (p<0.067) as SC levels increased; considering the Dunnett’s test, the birds fed 20% of SC showed lower carcass yield than birds on the control diet. This indicates that the utilization of up to 15% of SC did not impair the carcass yield; however, it linearly reduced due to a negative effect of fiber on nutrient utilization. Additionally, these effects may be related to the linear reduction in the birds’ WG, according to the increasing levels of SC. Tavernari et al  and Oliveira et al , using sunflower meal at levels up to 20% and 30%, observed no effect on carcass yield.
Considering the performance data, SC can be included in broiler chicken diets up to 10% when feeding birds from 21 to 42 d of age. Nutrients utilization may be impaired when SC is more than 5% of the diet.
The work was supported by the Araucaria Foundation of Research Support of Paraná State.
CONFLICT OF INTEREST
We certify that there is no conflict of interest with any financial organization regarding the material discussed in the manuscript.