Growth, Nutrient Utilization and Threonine Requirement of Growing Chicken Fed Threonine Limiting Diets with Commercial Blends of Phytogenic Feed Additives

Phytogenic additives and organic acids in broiler chicken diets

“…The inclusion of PA in the diets with and without OA improved the NMC of the broilers; however, the combination of additives resulted in lower metabolization, which, in this case, shows no additive effect for NMC, since OA did not improve metabolizability when compared with the control diet. The present study contradicts the results obtained by Muhl & Liebert (2007), who found no differences in protein metabolizability and nitrogen balance of broiler chickens fed commercial PA.…”

“…Similar results were found by Hernandéz et al (2004) and García et al (2007), who observed improved ileal digestibility of dry matter and crude protein of the birds fed phytogenic additives. However, studies have shown that the use of plant extracts and essential oils may not improve AME values and protein and dry matter metabolizability (Cross et al, 2007;Muhl & Liebert, 2007;Barreto et al, 2008;Rizzo et al, 2010). According to Lee et al (2003) and Rizzo et al (2010), diets with highly digestible ingredients can mask the improvement these additives can provide to the metabolizability of nutrients, which is not observed in this study, even when using vegetal-derived feeds with high biological value.…”

“…No differences are seen in the literature for alternative additives, antibiotics and diets without additive supplementations in broilers, as they are generally raised in low health challenge environments (Hernández et al, 2004;Fukayama et al, 2005;Muhl & Liebert, 2007;Toledo et al, 2007;Rizzo et al, 2010), demonstrating that in the present study it was possible to provide real health challenges, which poultry industries constantly encounter in largescale poultry production.…”

“…The use of PA showed higher carcass yield in broilers that were fed this additive (P<0.01) (Table 5), contradicting Muhl & Liebert (2007), who found no differences in the carcass yield of broilers fed plant extracts. This result demonstrates that the broilers that received PA had better nutrient absorption, favoring deposition in the muscle tissue, a fact observed in the metabolism trial, considering that the broilers in this treatment had higher metabolism coefficients of nitrogen, fat and gross energy.…”

Phytogenic additive as an alternative to growth promoters in broiler chickens

“…HERNÁNDEZ et al (2004) observed that two blends of plant extracts (oregano, cinnamom, and peeper at 200mg.kg -1 and sage, thyme, and rosemary at 5,000mg.kg -1 ) affected digestibility and improved the performance slightly, but not significantly. MUHL & LIEBERT (2007) evaluated the effects of two commercial phytogenic feed additives on male chickens and no significantly response on growth performance, nutrient utilization and threonine efficiency was observed. Anyway, it can be considered that the effect of plant products on broiler chicken performance under practical production conditions is still not sufficiently established and the results indicate the difficulty in translate in vitro observations to in vivo conditions.…”