ABSTRACT This study aimed to investigate the effects of xylanase (Xyl) individually or in combination with B. subtilis and B. licheniformis associated or not with yeast cell wall in pig diets with a reduction of 100 kcal/kg of metabolizable energy (ME) content. Pig performance, bone parameters, intestinal morphometry, and bioeconomic indices were evaluated. A total of 75 pigs (25 females and 50 barrows; 25.02±3.21 kg) obtained from crossing Large White × Landrace were used. The experimental design consisted of randomized blocks, with five treatments and five blocks, totaling 25 experimental units subjected to treatments: basal diet (B); basal diet with reduction of 100 kcal/kg of ME (BEM); BEM with supplementation of xylanase (0.01%; BX); BX with supplementation of direct-fed microbials (composed of B. subtilis and B. licheniformis; 0.02%; BXM); and BX supplemented with 0.10% of symbiotic (which includes B. subtilis, B. licheniformis, and yeast cell wall; BXS). There were no differences in bone parameters. The BEM diet resulted in a lower villus height:crypt depth ratio in the jejunum than that seen upon using the BXS diet as feed. In the first period, pigs fed BEM diet had a 12% higher average daily feed intake than those fed the BXM diet. There were no differences in the pig performance during the second period. Over the total period, pigs fed BEM diet had greater FCR compared with pigs fed BXM diet. The inclusion of feed additives in diets with reduced ME content contributes to the maintenance of performance and characteristics of the metacarpus and jejunum of growing pigs and provides better bioeconomic indices. Xyl (Xyl B 10 kcalkg kcal kg (ME parameters morphometry evaluated 7 (2 5 barrows 2502321 02 3 21 25.02±3.2 used blocks 2 (B) (BEM) 0.01% 001 0 01 (0.01% BX) directfed direct composed 0.02% 002 BXM) 010 0.10 which BXS. . BXS) heightcrypt height crypt period 12 1 ( 250232 25.02±3. (B (BEM 0.01 00 (0.01 0.02 0.1 25023 25.02±3 0.0 (0.0 0. 2502 25.02± (0. 250 25.02 (0 25.0 25.

ABSTRACT Growth performance, organ biometrics, bone characteristics, and intestinal morphometry were evaluated in broilers fed a diet containing orange (Citrus sinensis L.) essential oil. A completely randomized design was used, with five treatments with orange essential oil (0, 100, 200, 300, and 400 mg kg−1 diet) and six replications with 20 birds per experimental unit. In the pre-starter phase, feed intake and weight gain of all birds linearly increased, while feed conversion decreased with the addition of orange essential oil in the feed. At day 21, bone density (Seedor Index) and body weight were higher in the birds that received the maximum level of essential oil (400 mg kg−1) compared with those not treated with essential oil. The observed effects resulted from the better functioning of the physiological mechanisms of digestion and absorption of nutrients, characterized by the increase in villus height. Glycemia and weights of gastrointestinal tract organs of broilers at 21 days of age were not influenced by the evaluated essential oil. The results show that the addition of phytogenic additives to the diet does not cause any physiological impairment in birds.