The By-Products of Prickly Pear Processing in Broiler Feed: Case of Dehydrated Husks and Cake

Background: The utilization of agro-industrial by-products is a potential substitution of imported raw materials in broiler feed formulas for developing countries. This study aims to determine the effects of substituting prickly pear husks for maize and prickly pear seed cake for soybean meal on the production performance, slaughter characteristics, and chemical composition of broiler meat. Materials and methods: Two hundred day-old chicks of equal sex ratio (1:1) of Big Fast strain, weighing on average 37±2g, were randomly divided into 4 homogeneous groups of 50 subjects each. Each group was subdivided into 10 packs of 05 animals, banded and numbered. The rations distributed with a substitution rate of 0, 10%, 20%, and 30% of maize and soybean meal by dehydrated husks and prickly pear cake were randomly distributed through the different groups. Results: Average daily gains and body weights at 48 days were improved (p<0.05) for the 10% and 20% groups and the 30% group performed identically to the control. Cold carcass yield was optimal for 10% and 20% groups. The liver weight of the experimental groups decreased signicantly (p<0.05) while that of the gizzards increased signicantly (+24 points). The meat protein rate evolved proportionally to the substitution rate, in contrast to the fat rate, which was depreciated by up to -1.08 points for the 30% group compared to the control. Conclusion: The incorporation of prickly pear processing by-products into broiler feed at rates of 10% and 20% improves zootechnical performance, carcass yields, and the chemical composition of the meat.


Background
In Algeria, the costs of animal production are dependent on imports of the raw materials used in food formulae, thus generating meat products in uenced by the parity of the Algerian dinar with foreign currencies. As pointed out by Guermah et al [1], the feeding of the domestic animal represents 70 % of the cost price of the products produced and remains under the in uence of the prices posted by the world stock exchanges. The latter leads to in ation, making the prices of meat products beyond the reach of the poorest populations. The use of agricultural and agro-industrial by-products in domestic animal rations [2][3][4][5][6][7] is one way of regulating or even lowering the cost price of these products. The use of by-products from the processing of prickly pear (Opuntia cus-indica L. mill) remains an alternative to be considered, given that this species is well represented in arid and semi-arid regions of the country (55,671 ha, [8]), is well adapted to a warm environment [9] and its fruits are used in local culinary customs and the cladodes consumed by the animals living there [10].
The prickly pear can be considered as a versatile crop [11] and as a substitute food due to its e ciency in converting water into the dry matter [12][13][14][15], thus ensuring a balance of digestible energy in pet food.
Prickly pear (FB) is eaten fresh [16], the pericarp accounts for 33% to 55%, the pulp for 45% to 67% and the seeds for 2% to 10% [17]. The fruit is also used for the production of juice, jellies, jams, vinegar, and oil from the seeds. This agro-industry generates by-products made up of husks, seeds, and oilcake, which are a source of environmental pollution because they are not valorized. According to Kenny [18], the yield per hectare is between 12 and 30 tones. If we consider that half of the planted area, i.e. 27836 ha for an average yield of 21T/ha of fruit, is taken care of by the agro-industry, the by-products generated in envelopes (pericarps) (44%) would be 257205T, in seeds (6%) of 35073T translatable into oilcake (97%) of 34021T. This total quantity of 291226T, is without context not negligible if it is valorized in animal feed.
The use of these by-products in poultry farming remains very little studied. Moula et al [19], in their study, used the whole fruit in Algeria in the same way as Badr et al [20] in Egypt, while Regab [21] experimented with the fruit envelope with the addition of enzymes.
For our part, our study aims to experiment with the by-products of the processing of Opuntia fruits (seed casings and cakes) in the diet of broilers.

Materials And Methods
The present study was conducted after approval of Institutional Animal Ethics Committee laboratory of Agriculture departement of Ghardaia University, Algeria.

Animals, diets, and experimental protocol
The trial was carried out at a poultry production unit in the municipality of El Kouif Wilaya of Tébessa (Algeria) in a building with a surface area of 80 m², tted with thermal insulation made of polystyrene panels.
The study was carried out over a rearing period of 48 days, in a closed henhouse equipped with pad-cooling fans and humidi ers ensuring good ambient conditions. The litter consisted of sieved wood shavings.
Two hundred day-old chicks of equal sex ratio (1:1), of Big Fast strain, weighing on average 37±2g, were randomly divided into 4 homogeneous batches of 50 subjects each. Each batch was subdivided into 10 packs of 05 animals, banded and numbered, forming a control batch and three experimental batches.
The seed cakes and dehydrated prickly pear husks were supplied by an agro-industrial processing unit producing vinegar and prickly pear oil, located in the commune of Sidi fredj Wilaya of Souk-Ahras in south-eastern Algeria. The chemical composition of these two by-products is shown in Table 1. Using the WUFFDA software for broiler feed formulation, four rations were constituted, with 0% (control feed), 20%; 30%, and 40% substitution of soya meal by prickly pear seed cake and maize by their husks for the different rearing phases (Table 2). Rations were distributed randomly for the four broiler groups.
For the rst ten days and thanks to gas-powered cattle raisers, a temperature varying between 36 and 38°C was maintained, as well as a 24-hour illumination, which was then reduced to 12 hours during the day and 6 hours at night. At the end of the rearing, 30 chickens taken at random from each batch were sacri ced. The live weight, the weight of the warm and cold carcass, legs, head, feathers, gizzard, viscera, and liver were weighed. The average daily gain (ADG), average daily intake (ADI), and feed and liver were weighed. The average daily gain (ADG), average daily intake (ADI), and feed conversion ratio (FCR) were calculated. At 24 hours post-mortem, the pH was measured by direct insertion (~ 2 cm deep) of the electrode of a pH meter into the pectoral muscle of quails according to the method of EL Rammouz, [23]. Ash, protein, and fat content were determined and calculated according to the Aoac methods [24].

Statistical analysis
Descriptive statistics and single-factor analysis of variance (ANOVA) were performed with the SPSS software (version 18,2008) for the analysis of performance, slaughter parameters, and meat chemical composition. The post hoc test by the application of the S.N.K (Student-Newman-Keules) and Duncan test, to estimate the signi cance or homogeneity between the different subsets (test of comparison between the means). The differences were considered signi cant with a 5% risk of error.

Results
No mortality was recorded during the whole breeding in all groups. During the start-up phase, the 10% group recorded signi cantly (p<0.05) higher weights at 10 days and 20 days than the other groups with +24g and +51g respectively (Table   3). The indices indicate the period in days over which this parameter was calculated. The presence of different letters on the same line indicates a signi cant difference between diets (P < 0.05).
The same trend was recorded for the ADG 1-10d (+2.7 g/d/subject) and the ADG 11-20d (+3 g/d/subject) respectively, as well as for the ADG 1-20d which, during the whole start-up phase, showed a signi cant difference (p<0.05) of +2.7 g/d/subject with the control and +4.2 g/d/subject with the other experimental groups.
During the growth phase, the 10% substitution rate of soybean meal and maize impregnated a signi cant optimization (p<0.05) of the weight at 33 days as well as of the ADG 21-33d with a difference of +126g and +8.7g/d/subject respectively compared to the average of the other batches. The latter being signi cantly similar.
In the nishing phase, the 30% batch took a minimum value (p<0.05) in live weight at 48 days and ADG 34-48d compared to the other batches, the 20% batch recorded higher results than the control batch while the 10% batch with 2225g remained signi cantly dominant (p<0.05), displaying an optimal ADG 34-48d of 77.5g/d/subject. The ADG 1-48d of the 10% and 20% batches showed a higher value than the control batch, while the result of the 30% batch was identical to the control batch.
The average daily intakes of the experimental batches showed less signi cant results compared to the control lot during the rst ten days with a difference of -5 points (Table 4). The presence of different letters on the same line indicates a signi cant difference between the diets (P < 0.05).
Between day 11 and day 20, the substitution of soybean meal and maize produced a depreciation of the group's average daily intake of 20% of -10g compared to the other groups that showed similar results. It can also be noted that during the 34 -48 days interval, the 10% and 20% groups showed identical and superior results to the control groups and 30%, which took a mean value of 2845g impregnating a mean difference of -24g with respect to the witness. The entire farm was characterized by the in uence of the substitution of soy and maize meal by prickly pear seed cake and their envelopes on the 10% group, giving it optimization of the average daily intake, a devaluation of this parameter for the 30% group and an intermediate and identical result for the 20% and control groups.
Between the 34th and 48th day and from the 1 st to the 48th day, the consumption indices of the10% and 20% groups of substitution of soybean meal by seed cake and maize meal by prickly pear husks were signi cantly similar and the least expressive (p<0.05) compared to the control groups and 30%.
The incorporation of prickly pear seed cake and husks in the broiler diet does not affect the weight of the viscera, head, legs, and feathers (Table 5).
Page 9/13 The presence of different letters on the same line indicates a signi cant difference between the diets (P < 0.05).
The hot carcass weights and yields of the 10% and 20% groups had optimal values (p<0.05) compared to the control and the 30% group, which showed similar results (p<0.05). The weights of cold carcasses were signi cantly different (p<0.05) between all the groups with the supremacy of the 10% group inducing signi cantly similar yields (p<0.05) and optimal for the 10% and 20% groups with a difference of about +4 points with the control. The 30% group recorded a minimum value.
The incorporation of FB seed cake and dehydrated husks resulted in a signi cant (p<0.05) decrease in liver weight of the experimental groups with a similar mean value of 46.5g, resulting in a difference of -6.5g with respect to the control. The same observation was noted for the Pf/Pv ratios. On the other hand, the gizzard weights had an optimal and similar value for the experimental batches (average 82.3g), resulting in a signi cant difference (p<0.05) of +24.3g with respect to the control for Pg/Pv ratios expressing the same trend.
The pH of the meat at 24 hours post mortem, for the 10% and 20% groups were not in uenced by the substitutions, which took on the same value with respect to the control, while the 30% group recorded a minimal result with respect to all the other groups. The experimental groups took signi cantly similar (p<0.05) and maximum protein values, imparting a signi cant difference of +2.19g compared to the control. The mineral matter content was not in uenced by the incorporation of FB seed cake and seed envelopes.

Discussion
The incorporation of the by-product of prickly pear processing (husks) and the by-product of oil extraction from BF seeds (oilcake) did not cause mortality in the experimental groups as reported by Badr et al [20] in Cobb chickens fed BF husks and Bakr et al [25] in rabbits fed BF zest. However, Moula et al [19], on broilers fed with 10% prickly pear cladodes in the diet, found a mortality rate of 10%, while Ragab [21] found a mortality rate of 3.3% in quails fed on diets containing 15% prickly pear shells.
The incorporation of FB g seed husks and seed cakes at a rate of 10% and 20% in the feed of broiler chickens has led to an increase in live weight and ADG. This is in line with the results found by Badr et al [20], who found an improvement in weight performance due to the substitution of maize by FB envelopes of 5-15% in Cobb broilers. However, Moula et al [19] for a 5% and 10% incorporation of FB cladodes in the broiler feed, observed no signi cant effect on body weight and ADG, in contrast to Ragab [26] who found in Hy-Line W-36 cocks fed with FB envelopes, a non-signi cant effect on body weight at 70 days but a positive effect on ADG. As in quails, Ragab [21] found that the incorporation of 15% and 30% FB envelopes had no in uence on body weight and ADG, while in rabbits, Hassan et al [27] reported nal weights and ADG with a ration containing 25% and 50% FB envelopes, These results contradict those reported by El-Neney et al [28] who found that a 20% and 30% incorporation of FB envelopes resulted in a signi cant increase in live weight. In fattening sheep, Islam et al [29] and Aware et al [30] reported a positive effect on body weight with incorporation rates of 60% and 80%. Throughout the rearing period, the substitution of maize and soybean meal by prickly pear husks and meals respectively had a signi cant effect on average daily intake and feed conversion of broilers for the 10% and 20% groups. For their part, Badr et al [20] observed in Cobb chickens fed rations containing 5%, 10% and 15% FB envelopes, average daily intakes, and lower consumption indices than for the control, as did El-Neney et al [28] for the incorporation of FB envelopes and Zeedan et al [31] for the incorporation of FB cladodes, and in rabbits at levels of 10%, 20%, and 30%.
The incorporation of prickly pear husks and cakes at a rate of 10% and 20% in the feed for broilers has led to an increase in the weight of hot and cold carcasses, and livers and gizzards but had no signi cant effect on other slaughter parameters, in contrast to the ndings of Regab [26] in male chicks of line W-36 and Regab [21] in quails, which recorded no in uence of the incorporation of FB envelopes on the slaughter parameters. However, Badr et al [20] found that at an incorporation rate of 5%, 10%, and 15%), a signi cant in uence on carcass and offal weights was observed. In rabbits, Abu Shammalah [32] found that the use of FB envelopes in rabbit rations in uences carcass characteristics. The crude protein content of the meat increased while the fat content decreased, in proportion to the rates of incorporation of BF envelopes in the rabbit ration, in line with the results reported by El-Neney et al [28] and Zeedan et al [31]. These results remain in contradiction with those of Regab [21,26] and Moula et al [19].

Conclusion
The incorporation of prickly pear husks and cakes in the feed of broiler chickens at rates of 10% and 20% improves zootechnical performance, carcass yields, and the chemical composition of the meat.