Abstract

In total, 144 Arbour Acres broiler chickens were distributed among four treatment groups (six replicates per treatment; six chickens per replicate) during days 20–40 of age. The chickens were offered iso-caloric and iso-nitrogenous diets containing four dietary oil levels (DOL): 0 (oil non-supplemented diet, control), 2, 4, and 6% in a relatively low-energy diet (12.4 MJ ME/kg diet). During the experimental period, the chickens were reared under natural hot weather conditions (32.5 ± 4 °C, 54 ± 7% relative humidity). Growth, feed conversion ratio (FCR), protein (PCR), metabolisable energy (MECR) ratio, and European production efficiency index (EPEI) were similar among groups fed up to 4% DOL but raising DOL to 6% impaired these traits. Besides, DOL at 6% decreased digestibility of dry matter, crude protein, and ash. Furthermore, a 6% DOL showed the lowest digestibility of dry matter, crude protein, and ash. Dressing percentage was the highest in 2%, and abdominal fat percentage showed the same trend in 6% DOL, but the gizzard percentage was the lowest in 6% DOL. The liver percentage increased significantly with fat/oil inclusion compared to the control. Meat dry matter and either extract increased considerably due to offering different DOLs, with maximum values at 6%. The inclusion of dietary oils in diets significantly increased serum malondialdehyde (MDA) but decreased serum total antioxidant capacity (TAC)/MDA ratio compared to the 0% DOL. In conclusion, under natural summer conditions, from 20 to 40 days of age, broilers' best productive characteristics were achieved using 0-2% DOL, and the best immune response was obtained for 4–6% DOL.

• Highlights

• Hot weather negatively influences the productivity of broilers.

• Fats/oils are essential for animal and human nutrition for several reasons; however, they are expensive compared to other energy sources.

• Improving the production index is essential to keep broilers farming profits under hot weather.

摘要

在20至40日龄期间，总共将144只Arbor Acres肉鸡分布在四个治疗组中（每个处理重复六只；每重复重复六只鸡）。为鸡提供了等热量和等氮的日粮，其中包含四种饮食油水平（DOL）：0（低能量饮食中的无油饮食），2、4和6％的低能量饮食（12.4 MJ ME） / kg饮食）。在实验期间，将鸡在自然炎热的天气条件下（32.5±4°C，54±7％相对湿度）饲养。在饲喂4％DOL的组中，生长，饲料转化率（FCR），蛋白质（PCR），代谢能（MECR）和欧洲生产效率指数（EPEI）相似，但将DOL提高到6％会损害这些特征。此外，6％的DOL降低了干物质，粗蛋白和灰分的消化率。此外，DOL含量为6％时，干物质，粗蛋白和灰分的消化率最低。敷料百分数最高，为2％，而腹部脂肪百分数在6％的DOL中表现出相同的趋势，但g的百分率在6％的DOL中最低。与对照组相比，含脂肪/油的肝脏百分比显着增加。肉干物质和任一种提取物由于提供了不同的DOL而大大增加，最大值为6％。与0％DOL相比，日粮中包含食用油可显着增加血清丙二醛（MDA），但降低血清总抗氧化能力（TAC）/ MDA比。总之，在20至40日龄的夏季自然条件下，使用0-2％的DOL可获得肉鸡的最佳生产特性，而对于4-6％的DOL则可获得最佳的免疫应答。

• 强调

• 炎热的天气对肉鸡的生产率产生负面影响。

• 出于多种原因，脂肪/油对于动物和人类的营养至关重要。但是，与其他能源相比，它们昂贵。

• 改善生产指数对于在炎热的天气中保持肉鸡养殖利润至关重要。