Two experiments were performed in the experimental farm of the University State of Maringá (Paraná, Brazil), All experimental procedures were performed in accordance with the approval of the Animal Use Ethics Committee - CEUA of Maringá State University - UEM (Registration number 8614020316).
In the first experiment was determined the bromatological composition, and the energetic values of the citric pulp obtained to Agroindustry Cooperative of the region, the citric pulp was air-dried in an area cemented and covered. The experimental diet was based on cornmeal and soy (45%), furthermore, this diet being formulated to consideration of the ingredients, and the requirements according to Rostagno et al. (2011). The period experimental was ten days (five days of adaptation + five days of excrete recollection), and during these days the birds received food and water ad libitum.
The metabolizable test was realized according to the methodology described for Sakomura and Rostagno (2016), therefore was utilized 108 broilers of 21 days housed in galvanized wire batteries. The broilers were distributed in a completely random design with three treatments (reference and test rations with 10% and 20% of the test feed), these treatments have formulated with six repetitions, and with six broilers each treatment. During the period of recollections of excreta, were registered the ingest to times of food and the appearance of excreta marked with ferric oxide (1%), with the help of an observer for each repetition. Moreover, was assess the speed of food transit in the gastrointestinal tract of birds, this procedure was performed on the first and last day of the collection period.
The chemical analyses of citrus pulp, experimental diets, and excreta were performed at the Animal Nutrition Laboratory of Maringá State University, which were: dry matter (MS), crude protein (PC), ether extract (EE) and raw energy (EB). On the other hand, the apparent metabolizable energy (EMA) and corrected EMA values of the nitrogen balance were calculated using the equations proposed by Matterson et al. (1965), thus as the metabolizable coefficients of EMA (CEMA) and EMAn (CEMAn). For the determination of the content of total phenolic compounds, hydroalcoholic extracts were obtained according to the methodology of Bloor (2001), expressing the results in milligrams of gallic acid equivalents (EAG) / 100 grams of pulp.
In the second experiment, 966 Cobb 500 male broilers were used, distributed in a completely randomized experimental design, with six treatments (0, 2, 4, 6, 8 and 10% inclusion of citrus pulp), seven repetitions and 23 birds per treatment. The birds were housed in a heated house with negative ventilation and evaporation plate, tubular feeders and nipple drinkers, and water and food were provided at will. After obtaining the digestibility data, the diets were formulated in a feeding program divided into two phases: initial from 1 to 21 days (Table 1) and growth from 22 to 42 days (Table 2), according to nutritional requirements for chickens medium performance fattening (Rostagno et al., 2011).
The chemical composition of citrus pulp used to prepare the diets was 87.04% DM, 9.62% CP, 6.01% EE, 4044.041 kcal / kg EB, 19.79% FB, 30.85% NDF, 36.93% ADF, 21.45% pectin, 345.47mg / 100g of phenolic compounds and 1311.7 kcal / kg EMAn.
Table 1. Percentage and calculated composition of the experimental diets of the initial phase from 1 to 21 days of age.
|
Citrus pulp
|
|
0
|
2
|
4
|
6
|
8
|
10
|
Corn
|
58,56
|
56,27
|
53,53
|
50,86
|
48,48
|
46,31
|
Soybean 45%
|
36,40
|
36,34
|
36,30
|
36,20
|
35,95
|
35,84
|
Citric pulp
|
0,00
|
2,00
|
4,00
|
6,00
|
8,00
|
10,00
|
Dicalcium Phosphate
|
1,70
|
1,70
|
1,70
|
1,70
|
1,70
|
1,70
|
Calcite limestone
|
0,83
|
0,83
|
0,83
|
0,83
|
0,83
|
0,83
|
Soybean oil
|
1,08
|
1,41
|
2,16
|
2,90
|
3,50
|
3,75
|
Salt
|
0,40
|
0,40
|
0,40
|
0,40
|
0,40
|
0,40
|
DL – Methionine, 98%
|
0,305
|
0,313
|
0,321
|
0,330
|
0,340
|
0,350
|
L – Threonine, 98%
|
0,080
|
0,087
|
0,095
|
0,104
|
0,115
|
0,122
|
L – Lysine HCL, 78%
|
0,253
|
0,260
|
0,268
|
0,278
|
0,292
|
0,301
|
Mineral and vitamin supplement
|
0,400
|
0,400
|
0,400
|
0,400
|
0,400
|
0,400
|
Total
|
100,0
|
100,0
|
100,0
|
100,0
|
100,0
|
100,0
|
Calculated composition
Crude protein
|
21,50
|
21,50
|
21,50
|
21,50
|
21,50
|
21,50
|
Metabolizable energy
|
2980
|
2980
|
2980
|
2980
|
2980
|
2980
|
Digestible Lysine
|
1,24
|
1,24
|
1,24
|
1,24
|
1,24
|
1,24
|
Digestible Met + Cist
|
0,89
|
0,90
|
0,90
|
0,90
|
0,90
|
0,90
|
Digestible Threonine
|
0,81
|
0,81
|
0,81
|
0,81
|
0,81
|
0,81
|
Phosphorus available
|
0,43
|
0,43
|
0,43
|
0,43
|
0,43
|
0,43
|
Sodium
|
0,18
|
0,18
|
0,18
|
0,18
|
0,18
|
0,18
|
Calcium
|
0,87
|
0,87
|
0,87
|
0,87
|
0,87
|
0,87
|
Chlorine
|
0,29
|
0,29
|
0,29
|
0,29
|
0,29
|
0,28
|
Crude fiber
|
2,94
|
3,30
|
3,63
|
3,99
|
4,33
|
4,68
|
Grease
|
3,83
|
4,19
|
4,88
|
5,72
|
6,34
|
6,63
|
BED mEq/Kg
|
209
|
207
|
204
|
203
|
200
|
198
|
Polyphenols
|
82,00
|
95,61
|
99,91
|
108,0
|
112,35
|
120,49
|
Flavonoids
|
6,91
|
8,24
|
9,69
|
13,47
|
16,58
|
26,24
|
¹ Vitamin supplement (premix content / kg): Vit. At 11,666.68 IU, Vit. D3 2,333.32 IU, Vit. E 35.00 IU, Vit. K3 1.73 mg, Vit. B1 1.63 mg, Vit. B2 5.33 mg, Vit. B12 16.67 mcg, niacin 35.93 mg, calcium pantothenate 12.67 mg, folic acid 0.80 mg, biotin 0.10 mg. Mineral supplement (food content / kg): iron 50.40 g, copper 12.29 mg, iodine 0.99 mg, zinc 50.40 g, manganese 0.06 g, selenium 0.24 mg, cobalt 0.20 mg
Performance
To evaluate the parameters of performance, during each experimental phase, the birds were weighed and the experimental rations on days 0, 21, and 42 of age to calculate the ingest of food (CR), weight gain, and feed conversion.
Table 2. Percent and composition calculated of the experimental diets of the increase phase on days 21 – 42 of age.
|
Citric Pulp (%)
|
|
0
|
2
|
4
|
6
|
8
|
10
|
Corn
|
65,12
|
63,11
|
60,73
|
58,22
|
55,96
|
53,34
|
Soybean meal
|
29,07
|
28,96
|
28,90
|
28,88
|
28,81
|
28,81
|
Citric pulp
|
0,00
|
2,00
|
4,00
|
6,00
|
8,00
|
10,00
|
Dicalcium phosphate
|
1,11
|
1,12
|
1,13
|
1,14
|
1,15
|
1,16
|
Limestone
|
0,78
|
0,77
|
0,77
|
0,76
|
0,76
|
0,75
|
Vegetable oil
|
2,50
|
2,60
|
3,00
|
3,50
|
3,80
|
4,40
|
Salt
|
0,40
|
0,40
|
0,40
|
0,40
|
0,40
|
0,40
|
DL-Methionine, 98%
|
0,250
|
0,257
|
0,264
|
0,272
|
0,280
|
0,288
|
L- Threonine, 98%
|
0,154
|
0,161
|
0,169
|
0,176
|
0,183
|
0,191
|
L-Lysine HCL, 78%
|
0,224
|
0,233
|
0,240
|
0,247
|
0,255
|
0,261
|
Mineral and vitamin Supplements
|
0,400
|
0,400
|
0,400
|
0,400
|
0,40
|
0,400
|
Total
|
100,0
|
100,0
|
100,0
|
100,0
|
100,0
|
100,0
|
|
Calculated composition
|
Crude protein (%)
|
18,75
|
18,75
|
18,75
|
18,75
|
18,75
|
18,75
|
Metabolizable energy (Kcal/kg)
|
3130
|
3130
|
3130
|
3130
|
3130
|
3130
|
Digestible lysine (%)
|
1,04
|
1,04
|
1,04
|
1,04
|
1,04
|
1,04
|
Met + Cist digestible (%)
|
0,76
|
0,76
|
0,76
|
0,76
|
0,76
|
0,76
|
Digestible threonine (%)
|
0,78
|
0,78
|
0,78
|
0,78
|
0,78
|
0,78
|
Disponible phosphorus (%)
|
0,31
|
0,31
|
0,31
|
0,31
|
0,31
|
0,31
|
Sodium (%)
|
0,18
|
0,18
|
0,18
|
0,18
|
0,18
|
0,18
|
Calcium (%)
|
0,69
|
0,69
|
0,69
|
0,69
|
0,69
|
0,69
|
Chlorine (%)
|
0,18
|
0,18
|
0,18
|
0,18
|
0,18
|
0,18
|
Crude fiber (%)
|
2,67
|
3,02
|
3,37
|
3,73
|
4,08
|
4,43
|
Fat (%)
|
5,36
|
5,50
|
5,93
|
6,46
|
6,80
|
7,42
|
BED mEq/kg
|
179
|
177
|
176
|
174
|
172
|
170
|
Polyphenols (mg/g)
|
91,77
|
95,72
|
102,12
|
124,33
|
131,65
|
135,95
|
Flavonoids (mg/g)
|
4,36
|
7,13
|
11,13
|
15,47
|
19,02
|
23,47
|
1 Vitamin supplement (premix content / kg): Vit. At 9,000.00 IU, Vit. D3 1,800.00 IU, Vit. And 28.00 IU, Vit. K3 1.67 mg, Vit. B1 1.20 mg, Vit. B2 4.00 mg, Vit. B12 12.00 mcg, niacin 28.00 mg, calcium pantothenate 10.00 mg, folic acid 0.56 mg, biotin 0.06 mg. Mineral supplement (premix content / kg): iron 50.00 g, copper 12.00 mg, iodine 1.00 mg, zinc 50.00 g, mango 0.60 g, selenium 0.30 mg, cobalt 0.20 mg BED - Electrolyte balance of the diet.
Biochemical serum levels
On days 21 and 42 of age, two broilers were the selection for experimental unit and average weight (average ± 5%), the blood was recollected of the jugular vein (3 ml) to obtain the serum. The serum was stored in a freezer (-18°C) for the subsequent determination of total cholesterol (mg/dl), triglycerides (mg/dl), and glucose (mg/dl) using the enzymatic-colorimetric method (Gold Analyzes Diagnostics Ltda, Belo Horizonte - Minas Gerais), with spectrophotometer reading model BIOPLUS 2000 (Bioplus Ltda).
Carcass yield
For the analysis of the carcass performance and the cuts at 42 days, 14 birds were sacrificed per treatment after six hours of fasting. In addition, to calculate the carcass performance, the weight of the eviscerated hot carcass without legs, head, neck and abdominal fat was considered about the live weight of the birds. On the other hand, for the performance of noble cuts, it was considered the weight of the entire breast with skin, bones, and legs (thigh and thigh with bones and skin), moreover, back and wings were calculated about the weight of the eviscerated carcass. Abdominal fat around the cloacal bag, gizzard, proventriculus and adjacent abdominal muscles was removed as described by Smith (1993) and finally weighed to calculate the proportion of fat relative to the weight of the gutted shell.
Economic viability
The economic analysis of the experiment was calculated using the following adapted expression from Guidoni et al. (1997):
Pulp MP ≤ PRF (Gain𝑖 - Gain0) - Σ Pj (Cji ∗ CRi - Cj0 ∗ CR0 (Cli * CRi)
Where: PM pulp = maximum pulp price so that the diet has the same economic efficiency as the pulp-free diet (zero inclusion level); PRF = price of kg of live chicken; Gain = average weight gain of broilers in the treatment containing the level of pulp i; Gain 0 = average weight gain of broilers without pulp treatment (zero inclusion level); Pj = price of the remaining ingredients in each diet; Cji = percentage of ingredient j in diet i; CRi = total average feed intake per animal inherent in diet i; Cj0 = percentage of ingredient j in the pulp-free diet; CR0 = total average feed intake per animal in reference to the diet without pulp; Cli = percentage of pulp in the diet i. The economic approach only took food costs into account, it did not cover the other components of the cost of production. The prices of kg of live chicken and inputs from the Maringá-PR region were used, based on the average of the last two years and converted to the price in dollars (1 real = 0.323 dollars), being: corn grain, US $ 0.21 / kg; soybean meal US $ 0.44 / kg; dicalcium phosphate $ 0.67 / kg; limestone $ 0.08 / kg; common salt $ 0.11 / kg; soybean oil $ 0.84 / kg; L-lysine HCl US $ 2.83; DL-methionine $ 4.56 / kg; L-threonine $ 4.01kg; Vitamin and mineral supplement $ 2.35 / kg; and live chicken $ 0.88 / kg. The pulp value was obtained by calculating the kilo already dehydrated.
To analyze the economic viability of the pulp in the performance of broilers, the Bioeconomic Index (EBI) was used:
IBE = GP - PRm * CRm
Where: IBE - Bioeconomic Index; GP: live weight gain (g); PRm - Average diet price ($); PFV - Price of live chicken kg ($); and CRm - Average food consumption (g). To assess the effect of the cost of the diet on the IBE, we consider weight gain and food consumption from 1 to 21 days.
Statistical analysis
The data obtained were analyzed using the statistical program SAEG (2007). Data were analyzed to determine pulp levels using an analysis of variance followed by Dunnett's test with a 5% probability. After the analysis of variance, when there was a difference, the degrees of freedom were divided into polynomials and the treatments including citrus pulp were analyzed by regression for the different linear or quadratic relationships (P <0.05). For the response variables that exhibit a quadratic behavior, the inflection point was calculated as the best relationships and 95% of these values as the confidence limit (Sakomura and Rostagno, 2007).