Olive oil production generates various by-products that can be used in animal nutrition. These by-products contain several polyphenolic compounds that may exhibit antioxidant properties. The present study was designed to evaluate the effects of adding olive pulp to the feed on broiler performance, carcass yield and antioxidant enzymes. Two hundred (200), as hatched, day-old, Cobb 500 broilers were reared in total for 42 days. There were 4 dietary treatments. In T1 treatment, no olive pulp was added to starter, grower and finisher diet. In T2 treatment, olive pulp was added to starter, grower and finisher diet at a level of 0, 2.5 and 5% respectively. In T3 treatment, olive pulp was added to starter, grower and finisher diet at a level of 0, 5 and 5% respectively. In T4 treatment, olive pulp was added to starter, grower and finisher diet at a level of 0, 5 and 8% respectively. Performance, carcass yield and a number of biochemical parameters were examined. Oleuropein and hydroxytyrosol were present in the olive pulp at 952 and 216 mg/kg respectively. Broilers performed well and no differences were observed between treatments on final body weight, carcass yield, total antioxidant activity and expression of selected antioxidant enzymes. Discriminant analysis was further applied and revealed that samples clustered according to added level of olive pulp. Samples from broilers fed T2 and T3 diet were located in the middle of the plot away from other treatments exhibiting high values of carcass, breast yield and most of the antioxidant enzyme activities. In conclusion, olive pulp can be used up to 5% in diets of broilers and future studies conducted on-farm conditions may pronounce its impact on growth performance and antioxidant potential.

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SummaryTwenty-four dairy sheep and goats, respectively, were assigned each to three homogenous subgroups per animal species and fed the same diet in quantities which met 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude

The interest for safe and natural foods of animal origin is currently increasing the use of plant feed additives (PFA) as antioxidants in animal nutrition. However, studies with livestock animals dealing with PFA as antioxidants are scarce. The aim of the present review was to evaluate the antioxidant impact of PFA compared with synthetic vitamins on animal food product yield and quality. For this purpose, peer-reviewed studies published between 2000 and 2020 were collected. Most papers were carried out on ruminants (n = 13), but PFA were also tested in swine (n = 6) and rabbits (n = 2). The inclusion of PFA in the diets of pigs, rabbits, and ruminants improved the products’ quality (including organoleptic characteristics and fatty acids profile), oxidative stability, and shelf life, with some impacts also on their yields. The effects of PFA are diverse but often comparable to those of the synthetic antioxidant vitamin E, suggesting their potential as an alternative to this vitamin within the diet.

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