# Antioxidant and Antimicrobial Properties of Selected Phytogenics for Sustainable Poultry Production
## 6 Anti-Nutritional Factors as Constraints to the Use of Phytogenics in Poultry Nutrition  
The incorporation of phytogenic products in poultry diets is known to improve the performance and health of birds, but their widespread adoption could be limited by the presence of anti-nutritional factors (ANFs) (Table 1). Anti-nutritional factors have been reported to reduce nutrient utilization or feed intake when included in animal feeds [145]. Several studies have reported the toxicological effects of ANFs in poultry [146; 147]. For example, phytates, tannins, and phytosterols in _M. oleifera_ reduced weight gain in Arbor Acres broiler chickens by reducing the digestibility of amino acids [148]. In addition, reductions in crude protein digestibility, metabolizable energy utilization, feed intake, weight gain, and feed conversion efficiency were observed in broilers fed a diet with cassava pellets containing cyanogenic glycosides in place of maize [149; 150]. Feed intake, weight gain, and carcass traits were reduced in chickens fed a diet containing 40 g/kg of polyphenol-rich _C. sinensis_[151]. [PERSON] [152] observed poor growth in broiler chicks fed 3 g saponins/kg diet due to a depressed feed intake. [PERSON] et al. [153] reported that tannins from eucalyptus leaf powder reduced body weight and the overall feed conversion ratio in broilers because tannins bind proteins and form indigestible complexes. With phytogenics used as whole plant parts, it was shown that the high fiber content reduced the performance of the birds by increasing the passage rate [154]. Similarly, [PERSON] et al. [155] found that feeding one-week-old broiler chicks a diet containing _M. oleifera_ high in fiber reduced the daily weight gain and impaired the feed conversion ratio. This is because simple non- ruminants such as chickens have a limited capacity to utilize high-fiber diets due to a lack of microbial digestive enzymes.  
\begin{table}
\begin{tabular}{l l l} \hline \hline
**Phytogenics** & **Anti-Nutritional Factors** & **References** \\ \hline \hline \begin{tabular}{l} Moringa \\ Lippia \\ _Camellia sinensis_ \\ \end{tabular} & \begin{tabular}{l} Tannins, oxalates, phytate, saponins, cyanogenic glycosides, alkaloids, flavonoids \\ \end{tabular} & [156] \\ \begin{tabular}{l} Lippia \\ _Camellia sinensis_ \\ \end{tabular} & \begin{tabular}{l} Tannins, oxalates, saponins, phytate, alkaloids \\ \end{tabular} & [157] \\ \begin{tabular}{l} Garcia \\ _Camellia sinensis_ \\ \end{tabular} & \begin{tabular}{l} Flavonoids, phenolics \\ \end{tabular} & [158] \\ \begin{tabular}{l} Garlic \\ _C_Onion \\ \end{tabular} & \begin{tabular}{l} Alkaloids, tannins, saponins \\ \end{tabular} & [159] \\ \begin{tabular}{l} Peppermint \\ \end{tabular} & \begin{tabular}{l} Alkaloids, saponins, glycosides, tannins, flavonoids \\ \end{tabular} & [108] \\ \begin{tabular}{l} Aloe \\ _Carpobrotus edulis_ \\ \end{tabular} & \begin{tabular}{l} Flavonoids, tannins, alkaloids \\ \end{tabular} & [160] \\ \begin{tabular}{l} _Artemisia afra_ \\ _Carpobrotus edulis_ \\ \end{tabular} & \
\begin{tabular}{l} Flavonoids, alkaloids, phenolic acids, lignans, proanthocyantidins \\ \end{tabular} & [161] \\
\begin{tabular}{l} Saponins, flavonoids, alkaloids, cyanogenic glycosides, tannins \\ \end{tabular} & [162] \\ \hline \hline \end{tabular}
\end{table}
Table 1: Anti-nutritional factors present in selected plants used in poultry diets.