Influence of dietary vitamin E and zinc on performance, oxidative stability and some blood measures of broiler chickens reared under heat stress (35 °C)This study was conducted to determine the effects of vitamin E (αTA; dL-α-Tocopheryl acetate) and zinc (Zn; ZnCl2) on performance, oxidative stability and some blood measures of broiler chickens under normal and hot temperatures. One hundred sixty 10-day-old male chicks were assigned to four groups in four replicates. The birds received two diets, control and enriched with two levels of vitamin E and Zn (100 and 50 mg/kg of diet, respectively) under two ambient temperatures (22 °C and 35 °C). Although the diets enriched with the antioxidant vitamin and element compared with un-enriched diets resulted in the better performance of the birds, significant differences were related to temperature conditions, as the lowest feed conversion ratio (FCR) and the highest body weight (BW) were observed in the group fed the enriched diet under normal temperature. The serum malondialdehyde (MDA), cholesterol (C), triglycerides (TG), glucose (G), total protein (TP), and hematocrit and heterophil: lymphocyte ratio levels were significantly lower in birds reared under 22 °C compared with the group under 35 °C but the hematocrit was not significantly lower in groups fed enriched diets and exposed to normal conditions (P>0.05). It was concluded that a combination of 100 mg of vitamin E and 50 mg of Zn provides the better performance and the least blood C and TG levels accompanying the better oxidative stability in male broilers under normal temperature (22 °C) and that this combination can be considered as a protective strategy in broiler diets for reducing the negative effects of heat stress.

Administration of fish oil (FO) in broiler diets can elevate a-linolenic acid (ALA), eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) levels, which are protective against cardiovascular disease. However, optimization based solely on n-3 polyunsaturated fatty acid (n-3 PUFA) enrichment in chicken meat could lead to lower meat quality, unless the withdrawal period (plan) is applied for 1 week. The present study investigated whether the incorporation of FO in the diet for 32 days followed by its withdrawal for 1 week affected blood lipid profiles, lipoprotein particles, performance and meat flavor in male broiler chickens. Two hundred and forty birds (1-day-old, Ross 308) were assigned to 1 of 4 dietary groups: 0%, 1%, 2% or 3% FO with four replicates. Broilers were fed for 49 days according to a 4-phase feeding program. The experimental phase comprised day 11 to 42, and FO was removed on day 42. Blood samples were collected during the pre-and post-withdrawal period after the recordings before slaughter. The FO groups demonstrated decreased low-density lipoprotein (LDL) and increased high-density lipoprotein levels on day 42 (P , 0.01); however, these values were not significant after design withdrawal. Diet supplementation with FO elevated the blood levels of palmitic acid (C16:0) and n-3 PUFAs, especially long-chain (LC) PUFAs (EPA, C20:5n-3 and DHA, C22:6n-3), and caused a decline in the level of arachidonic acid (AA, C20:4n-6; P , 0.05). Application of a one-week withdrawal period resulted in a decrease in (P , 0.05) linoleic acid (C18:2n-6) and an increase in the level of AA, unlike their amounts on day 42. Although blood and tissue LC n-3 PUFA levels on day 49 were significantly higher in the FO groups compared with the control, they demonstrated a substantial decrease on day 49 compared with day 42. The best results, mainly the lowest n-6/n-3 fatty acids (FAs) and feed conversion ratio (FCRs), were observed for 3% FO (group T4), even after institution of the withdrawal design. Degradation of total n-3 FAs deposited in tissues occurred after instituting the withdrawal plan diet, but deposited levels of EPA and DHA in tissues could ensure omega-3 enrichment of broiler meat in groups 3 and 4. On the basis of the dissatisfaction of the panelists toward group 4 meats (scored as near to acceptable) and their satisfaction with cooked samples of T3 (scored as good), group 3 meats were selected as good-quality n-3-enriched broiler meat.

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Two experiments were planned to study the influence of dietary fat sources (fish oil (FO) or sunflower oil (SO)) and dietary doses of α-tocopheryl acetate (α-TA) (0, 60 and 120 mg/kg of feed) and vitamin A (0 IU, 10000 IU and 20000 IU) on lipid oxidation of stored eggs in three stages of 0 or fresh, 1 and 2 months of storage time. In the first experiment, 96 hen layers in six treatments including two oil sources (FO and SO) and two dietary [0, 60 and 120 mg/kg doses of α-tocopheryl acetate (α-TA)] were fed for 75 days. In the second experiment, 96 hen layers in six treatments including two sources of ω3 and ω6 (FO and SO) and three doses 0, 10000 and 20000 IU of vitamin A were fed for 75 days. The results showed that using α-TA supplementation, lipid stability of enriched eggs increased and was very effective throughout the stored period of the eggs. Yolk TBA value was higher in fish oil than sunflower oil groups (p < 0.01). The treatments that contained 120 mg/kg of α-TA in diets, showed lower lipid peroxidation than other groups in stages of 2 and 3 storage time (30 and 60 days). The degree of lipid oxidation in fresh, 1 and 2 months of storage eggs was measured by the lipid TBA values. The results showed that TBA value in fresh and stored eggs was higher in groups containing fish oil than other groups (p < 0.01). The MDA value in stage 1 was higher in fish oil group and in 2 and 3 stages was lower in FO + A1. Therefore, addition of Vitamin E and A as natural antioxidants in diets containing oil source for the prevention of lipid oxidation is recommended.

As part of research on utilization of straw as a feedstuff for small ruminants, wheat straw (WS) was pretreated with a warmed solution (4%) of NaOH (sodium hydroxide) and then treated with SO 2 (sulphur dioxide) gases of different sulphur levels (0, 1, 2 and 4 percent, weight/weight of dry matter) for two periods of 1 and 2 smoking days. The chemical composition, and dry matter degradability (DMD) of the neutral detergent fibres (NDF), acid detergent fibres (ADF) and acid detergent lignin (ADL) in sheep rumen was determined, as was also the intake of the treated straw and the performance of Ghizle strain lambs. To estimate rumen DMD, treated WS samples were immersed in the rumen for a 72 h incubation period using the nylon bag (in sacco) technique. The chemical composition of the treated WS was changed with either one of NaOH or NaOH+SO 2 prior to the rumen incubation, and the amounts of lignin, cellulose, hemicelluloses and silica significantly decreased specially in the SO 2 -smoked wheat straw. Dry and organic matter decreased non-significantly (P>0.05). The rumen DMD rate of the WS SO 2 -treated for a period of 48 hours did show higher values (P<0.01) compared to those smoked during 1 day. In sacco degradation also significantly decreased NDF, ADF and ADL. The best results were observed with WS SO 2 samples smoked to 4% level during 2 days, followed by 2% level with the same smoking period. Although, a higher intake of treated WS was calculated for those smoked by 2% SO 2 gas for a period of 1 d, the best performance was observed in lambs fed WS treated by NaOH+SO 2 for a period of 2 days. It is concluded that chemical treatment of wheat straw by NaOH (4%) solution and SO 2 (2%) gas smoking for a period of 2 days, can be used as an applicable method on a farm scale for better utilization of WS as a feedstuff for small ruminants such as sheep.