There is growing interest among nutritionists in feeding reduced protein diets to broiler chickens. Although nearly a century of research has been conducted providing biochemical insights on the impact of reduced protein diets for broilers, practical limitation still exists. The present review was written to provide insights on further reducing dietary protein in broilers. To construct this review, eighty-nine peer reviewed manuscripts in the area of amino acid nutrition in poultry were critiqued. Hence, nutritional research areas of low protein diets, threonine, glycine, valine, isoleucine, leucine, phenylalanine, histidine, and glutamine have been assessed and combined in this text, thus providing concepts into reduced protein diets for broilers. In addition, linkages between the cited work and least cost formation ingredient and nutrient matrix considerations are provided. In conclusion, practical applications in feeding reduced protein diets to broilers are advancing, but more work is warranted.

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Although broiler (meat-type) chickens are one of the most efficient protein sources that supports the livelihoods and food security of billions of people worldwide, they are facing several challenges. Due to its unknown etiology and heavy economic impact, woody breast (WB) myopathy is one of the most challenging problems facing the poultry industry, and for which there is no effective solution. Here, using a primary chicken myotube culture model, we show that hypoxia and endoplasmic reticulum (ER) stress are an integral component of the etiology of the myopathy. Multiple components of the ER stress response are significantly upregulated in WB as compared to normal muscle, and this response was mimicked by hypoxic conditions in chicken primary myotube culture. Additionally, apoptotic pathways, as indicated by increases in active caspase 3 protein levels and decreases in Birc5, in both WB-affected tissues and hypoxic myotube culture. Finally, as a phenotypic hallmark of WB is enhanced fibrosis and increased collagen aggregation, here, we show that hypoxic conditions increase collagen 1A1 and 1A2 gene expression, as well as collagen 1 protein levels in primary myotubes. These effects were partially reversed by TUDCA, an ER-stress inhibitor, in myotube culture. Taken together, these findings indicate that hypoxia and ER stress are present in WB, hypoxia can upregulate the cell death arm of the unfolded protein response (UPR) and lead to collagen production in a culture model of WB. This opens new vistas for potential mechanistic targets for future effective interventions to mitigate this myopathy.

The objective of the present research was to assess the dietary supplementation of three formulations of essential oils (EO) in chickens under heat stress (HS). Day-of-hatch Cobb 500 chicks (n = 500) were randomly distributed into four groups: 1. HS control + control diets; 2. HS + control diets supplemented with 37 ppm EO of Lippia origanoides (LO); 3. HS + control diets supplemented with 45 ppm LO + 45 ppm EO of Rosmarinus officinalis (RO) + 300 ppm red beetroot; 4. HS + 45 ppm LO + 45 ppm RO + 300 ppm natural betaine. Chickens that received the EO showed significant (p < 0.05) improvement on BW, BWG, FI, and FCR compared to control HS chickens. Average body core temperature in group 3 and group 4 was significantly (p < 0.05) reduced compared with the HS control group and group 2. Experimental groups showed a significant reduction in FITC-d at 42 days, a significant increase in SOD at both days but a significant reduction of IFN-γ and IgA compared with HS control (p < 0.05). Bone mineralization was significantly improved by EO treatments (p < 0.05). Together these data suggest that supplemental dietary EO may reduce the harmful effects of HS.

Background: Valine and isoleucine are similar in chemical structure and their limitation in broiler chicken diets. To evaluate their limitation and interactive effects, multivariate assessment nutrition studies for the branched-chain amino acids (BCAA) are needed. A three level (-1, 0, +1), three-factor Box-Behnken design study was conducted to assess dietary BCAA ratios to lysine of 65, 75, and 85 for valine, 58, 66, and 74 for isoleucine, and 110, 130, and 150 for leucine in male and female Lohman Indian River broilers from 22 to 35 d of age.Results: Live performance of male broilers was not affected by BCAA level. However, male broilers fed increasing isoleucine had improved (P = 0.07) carcass yield as leucine and valine were reduced. Female broilers had improved body weight gain (P = 0.05) and feed conversion (P = 0.003) when leucine and isoleucine were at their lowest levels, independent of valine, but increasing leucine impaired live performance and warranted concomitant increases in isoleucine to restore responses. Increasing dietary isoleucine and valine in female broilers increased breast meat yield (P = 0.05), but increasing leucine tended to diminish the response.Conclusion: The female Lohman Indian River broiler is more sensitive to BCAA diet manipulation than males. Specifically, as dietary leucine is increased in female broilers, dietary isoleucine increases were needed to offset the negative effects. Both increases in dietary valine and isoleucine improved breast meat yield in female broilers, but only when birds were fed the lowest dietary leucine.