No abstract

Phytogenic additives have been studied intensively in broiler chickens’ production to substitute growth-promoting antibiotics. However, the comprehensive literature on this topic makes it difficult to understand overall results because there are a noticeable number of studies with conflicting conclusions. While several research studies have shown that phytogenic additives may increment broiler chicken’s performance, others make the opposite evident. This study aimed to organize and understand information through meta-analysis considering a great number of publications and the factors that may interfere in the results of phytogenic additives, evaluating whether phytogenic additives can be used as a performance-enhancing additive for broilers, comparing with the effectiveness of growth-promoting antibiotics. The main factor that interferes in the evaluation of phytogenic additives is the microbiological challenge. Phytogenic additives improved average daily gain (ADG) (P < 0.001) and feed conversion (P < 0.001) regardless of microbiological challenge; however, they were worse compared to antibiotics under higher challenge (P < 0.020). A meta-regression of ADG in function of average daily feed intake confirmed that phytogenic additives increased the feed efficiency of broilers, but with less effectiveness than antibiotics. The blends of phytogenic additives increased the ADG in relation to the isolated use of only one phytogenic additive.

The objective of this research was to evaluate the nitrogen-corrected apparent metabolizable energy (AMEn) balance of the following lipid sources: soybean oil, sunflower oil, linseed oil, and fish oil. Two hundred eighty 24-wk-old laying hens of the Hysex White were used. The experimental diets consisted of a basal diet (reference group), basal diet + 10% soybean oil addition (group 1), basal diet + 10% sunflower oil addition (group 2), basal diet + 10% linseed oil addition (group 3), and basal diet + 10% fish oil addition (group 4), distributed in a completely randomized design with seven replicates and eight birds per experimental unit. The metabolic assay was performed by the total excreta collection method. The AMEn values found in the natural material were 9 334 kcal kg−1 for soybean oil, 10 533 kcal kg−1 for sunflower oil, 10 928 kcal kg−1 for linseed oil, and 9 005 kcal kg−1 for fish oil. The AMEn were different among the lipid sources. Sunflower oil and linseed oil had higher AMEn compared with soybean oil and fish oil (P < 0.05). The AMEn of the lipid sources of plant origin had higher values than the gross energy. The fatty acid profile of each lipid source was presented in this work. Thus, it is important to have individual nutritional information for each type of oil for laying hens, making it possible to formulate more appropriate and accurate feed.