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Title: Additivi di origine vegetale come alternativa naturale alla vitamina e sintetica nell’allevamento del broiler da carne
Other Titles: Plant feed additives as natural alternatives to synthetic vitamin e in organic broiler stock farming
Authors: Danese, Tommaso
Issue Date: 14-Oct-2021
Publisher: Università di Parma. Dipartimento di Scienze medico veterinarie.
Document Type: Master thesis
Abstract: The aim of this trial was to evaluate the potential of two plant feed additives commercial products as substitutes to synthetic vitamin E in organic broiler diet. Two hundred fifty-two 1 day-old Ross 308 male broilers were randomly assigned to 3 dietary groups each divided into 3 replicates of 28 birds, including different antioxidant additives: 1) control group (C), fed a commercial organic feedstuff containing synthetic vitamin E (alfa-tocopherol acetate) as main antioxidant additive; 2) T1 group, receiving the same feedstuff where vitamin E was replaced by a combination of grape seed extract (Resinox 80Q®) and green tea extract; and 3) T2 group, receiving the commercial organic feedstuff including a mix of hydrolysed polyphenols (Oxistim®) as main antioxidant additive. A starter feedstuff was administered until 21 days of age while a grower feedstuff was fed until the end of the trial (42 days of age). The amounts of plant antioxidant additives in T1 and T2 group diets were adjusted to obtain the same dietary antioxidant capacity induced by the vitamin E in the control diet. The antioxidant capacities were equalized among the groups based on an in vitro test (ABTS test) performed on the herbal products. Environmental temperature and humidity were recorded daily. During the first growing phase the temperature was on average 40°C and then decreased to an average of 25°C until the end of the trial. During the whole experiment, 16 h of light were provided daily. Feed and water consumption (FC and WC respectively) were measured daily on a pen basis. Feed conversion rate and feed efficiency were calculated using the available data on feed consumption and body weight. Health status and body weight (BW) were evaluated weekly. Faeces and litter samples were taken at the same intervals. At 42 days of age, 108 broilers were sent to the slaughterhouse. During the slaughtering, after jugulation, individual plasma samples were collected for the metabolic profile determination, while an additional blood sample was obtained from a subsample of 3 birds per pen (9 animals per dietary treatment) for the evaluation of the haematological profile. The whole coelomic content, namely the gizzard, heart, liver, pancreas, spleen, bursa of Fabricious, kidneys, small intestine (duodenum, jejunum, and ileum), caecum, colon and rectum were weighted and sampled for histological evaluation. After removal of head, neck and feet, eviscerated carcasses were weighted and then dissected to separate thighs, wings, and breast. Each part was evaluated for pH, meat cooking loss and colour (L*, a*, b*) as meat quality parameters. The data were analysed using IBM SPSS v6. The statistical significance was set at P<0.05. Weekly individual cumulative feed consumption (g), weekly group feed consumption (g), weekly group cumulative feed consumption (g) and individual cumulative weekly water consumption (ml) were not affected by the treatments. No differences were found for the BW, with exception for the BW at 21 days of age in which the T1 showed a lower average BW compared to T2 (844.1 vs 889.4 g respectively; P=0.022) even if they were not different in comparison with the C group. Individual weekly BW, compared with those reported in the genotype standard (Ross 308 management handbook), maintained a continuous lower trend at 7 days of age (177 g of average weight vs 208 g expected), 14 days of age (454 g of average weight vs 519 g expected), 21 days of age (869 g of average weight vs 985 g expected), 28 days of age (1385 g average weight vs 1573 g expected), 35 days of age (1989.93 g average weight vs 2235 g expected) and at 42 days of age (2472.3 g average weight vs 2918 g expected). Weekly feed:gain ratio and feed efficiency were not affected by the treatments. However, cumulative feed:gain ratio resulted lower in T2 at 42 days of age compared to C and T1 (0.78 vs 0.81 and 0.79 respectively; P=0.036). Furthermore, cumulative feed efficiency showed a statistically relevant difference at the same interval with T2 showing the higher value (1.28 vs 1.26 and 1.24 of C and T1 respectively; P=0.036). The treatments did not affect mortality cases (C=6, T1=8, T2=11; P=0.459). Concerning the metabolic profiles, the treatments with both natural antioxidants, did not affect most of the considered parameters. Exceptions were found for plasmatic vitamin E, which was higher in the C group, as expected, compared to both the natural antioxidants (7.29 vs 5.01 and 5.17 mg/l respectively; P≤0.001) and the creatinine, which was reduced by the T1 treatment (63.0 vs 91.98 and 88.62 µmol/l of C and T2 respectively; P≤0.001). Finally, the ALT value was lower in the T2 in comparison to the C group, the latter being equal to T1 (2.92 vs 3.78 and 3.17 IU/l of C and T1; P 0.012). The natural antioxidants did not affect neither the organs development nor the haematological profile and carcass yield/quality. Overall, these data suggest that natural plant feed additives can replace synthetic vitamin E in organic broiler farming, since any major variation in performances and health status was observed in the present trial. However, specific in vivo and post-mortem tests on the antioxidant status of the tissues should be addressed, and the use these natural antioxidants must be preceded by an accurate evaluation of their antioxidant capacity/activity, especially in the case of not standardised natural extracts.
Appears in Collections:Scienze medico-veterinarie

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