The redox system is essential for maintaining cellular homeostasis. When redox homeostasis is disrupted through an increase of reactive oxygen species or a decrease of antioxidants, oxidative distress occurs resulting in multiple tissue and systemic responses and damage. Poultry, swine and fish, raised in commercial conditions, are exposed to different stressors that can affect their productivity. Some dietary stressors can generate oxidative distress and alter the health status and subsequent productive performance of commercial farm animals. For several years, researchers used different dietary stressors to describe the multiple and detrimental effects of oxidative distress in animals. Some of these dietary challenge models, including oxidized fats and oils, exposure to excess heavy metals, soybean meal, protein or amino acids, and feeding diets contaminated with mycotoxins are discussed in this review. A better understanding of the oxidative distress mechanisms associated with dietary stressors allows for improved understanding and evaluation of feed additives as mitigators of oxidative distress.

Cobb 400, male broilers (n = 4,752) were housed in 12 pens/diet and 33 birds/pen. There were 3 levels of phytate P (0.24, 0.345, or 0.45%) and 4 phyt

Cobb 400, male broilers (n=4,752) were fed one of 12 diets, with 12 pens/diet and 33 birds/pen. Treatments consisted of 3 levels of phytate P (0.24, 0.345, or 0.45%) and 4 doses of phytase (0, 500, 1,000, or 2,000 phytase units (FTU)/kg). Diets were formulated with reduced Ca (0.22%), available P (0.20%), energy (80 to 120 kcal/kg), and amino acids (1 to 5%) when compared with breed requirements. Prediction equations suggested feeding dietary phytate P > 0.275, 0.295, or 0.319% reduced feed intake (FI) and body weight gain (BWG) and increased feed conversion ratio, respectively, from day 0 to 21. Supplementing phytase at 561, 1,285, or >2,000 FTU/kg resulted in the maximum FI, BWG, or feed efficiency, respectively. From day 0 to 42, maximum BWG or feed efficiency were achieved at phytate P concentrations <0.281 or 0.25%, respectively. Supplementing phytase at 449 or 2,000 FTU/kg maximized BWG or feed efficiency, respectively. Tibia ash weight, percent or Ca concentration were maximized at phytate P concentrations 2,000 FTU/kg maximized tibia ash weight or percent respectively. In the absence of phytase, phytate (IP6) concentration in the gizzard was greatest in birds fed 0.45% phytate P and phytase supplementation between 1,132 to 1,285 FTU/kg resulted in the lowest IP6 concentration in the gizzard. There was no effect of dietary phytate P on the concentration of phytate esters (IP5 or IP4) in the gizzard, which were minimized at 1,208 FTU/kg of phytase. In the absence of phytase, the concentration of phytate ester (IP3) or inositol in the gizzard was greatest in birds fed 0.345% phytate P and phytase supplementation at ∼500 FTU/kg minimized IP3, whereas 2,000 FTU/kg maximized inositol, except in birds fed 0.45% phytate P, which was maximized at 202 FTU/kg of phytase. Prediction equations can be useful to determine the influence of phytase and phytate P on broiler performance, phytate degradation and bone ash.

Arbor Acres Plus male broilers (n = 1,152) were obtained at hatch and allocated to 1 of 6 diets from hatch to d 10 post-hatch. There were 16 replicate cages per diet and 12 birds per cage. Five of the diets were formulated to contain graded concentrations of standardized ileal digestible (SID) Ca at 0.60, 0.50, 0.40, 0.30, or 0.20%. A sixth reference diet was formulated using total Ca coefficients for each ingredient and contained 0.96% total Ca. Available P (avP) was maintained at 0.48% in all 6 diets. Data were subjected to an analysis of variance and the model included diet and block. Means were separated using contrasts to determine linear or quadratic effects of SID Ca and using the Dunnett's test to compare the reference diet to all SID Ca diets. There was no effect of graded levels of SID Ca on intake or gain. Birds fed diets containing 0.60, 0.50, 0.30, or 0.20% SID Ca ate (P < 0.05) or gained (P < 0.05) more compared with birds fed the reference diet. Mortality corrected FCR improved (linear, P < 0.05) as the SID Ca concentration in the diet increased from 0.20 to 0.60%. Tibia ash percent was greatest in birds fed 0.50% SID Ca and lowest in birds fed 0.20% SID Ca (quadratic, P < 0.05). Tibia ash percent was lower (P < 0.05) in birds fed diets formulated to contain 0.20% SID Ca compared with birds fed the reference diet. No other differences in tibia ash were reported. Apparent ileal digestibility (AID) or retention of P was greater (P < 0.05) in birds fed diets formulated using SID Ca compared with birds fed the reference diet. The AID of P increased (linear, P < 0.05) as the SID Ca content in the diet decreased from 0.60 to 0.20%. The AID or retention of Ca was similar in birds fed 0.60 or 0.50% SID Ca and increased as SID Ca decreased to 0.20% (quadratic, P < 0.05). Regression equations developed using bone ash and apparent P retention estimate the SID Ca requirement of Arbor Acres Plus broilers from hatch to d 10 post-hatch was 0.53 and 0.49%, respectively. This corresponds to a SID Ca to available P ratio of 1.1 to 1.02.

Male broilers (n = 576) were obtained and allocated to 96 cages with 6 birds per cage. From hatch to d 24, 16 randomly allocated cages were fed a nutrient adequate reference diet. The reference diet was formulated to contain 0.96 and 0.87% total Ca from hatch to d 10 and d 11 to 24, respectively. The remaining 80 cages were fed a nutrient adequate diet, formulated to contain 0.50% standardized ileal digestible (SID) Ca from hatch to d 10. On d 11, five diets containing 0.56, 0.46, 0.36, 0.26, or 0.16% SID Ca were randomly assigned to 16 cages per diet. Means were separated using polynomial contrasts and Dunnett's Multiple Comparison tests. From hatch to d 10, birds fed diets formulated to contain 0.50% SID Ca gained more (P < 0.05) compared with birds fed the reference diet. From d 11 to 24, there was no effect of diet on feed intake or BW gain. Birds fed 0.46 or 0.16% SID Ca were less (P < 0.05) efficient compared with birds fed the reference diet. Birds fed 0.26 or 0.36% SID Ca were more efficient compared with birds fed all other levels of SID Ca (quadratic, P < 0.05). Tibia ash percent was greatest in birds fed 0.56 or 0.46% SID Ca, decreased (quadratic, P < 0.05) as dietary SID Ca decreased and was lower (P < 0.001) in birds fed the 0.26 or 0.16% SID Ca diets compared with birds fed the reference diet. Apparent ileal digestibility (AID) of Ca or retention of P was greater (P < 0.05) in birds fed the diets formulated using SID Ca compared with birds fed the reference diet. Apparent P retention was greatest in birds fed 0.36% SID Ca (quadratic, P < 0.05). Regression equations developed using P retention, AID of Ca, and percent tibia ash estimated the SID Ca requirement of 11 to 24-d-old broilers was 0.380, 0.488, and 0.515%, respectively. This corresponds to a SID Ca to available P ratio of 0.86 to 1.17.

Myo-inositol (inositol) affects memory, and the incidence of depression and anxiety in mammals. An experiment was designed to determine if pure inositol (0.16%), or high levels of phytase (3000 FTU/kg) affect the behaviour of fully beaked Lohmann LSL lite hens fed amino acid sufficient (19% crude protein (CP)) and deficient diets (16% CP), from 19 to 59 weeks of age. The data collected included live-scan behaviour observations and novel object (NO) tests (both at 1, 10 and 40 weeks of the trial); heterophil-to-lymphocyte (H/L) ratios (week 1 and week 40 of the trial); end of trial feather cover, and comb and skin lesions; and daily mortality. Reducing CP increased sitting by 2.5%. Inositol, but not phytase, reduced the latency to peck at the NO by 300 sec. Inositol reduced vent feather cover by 12% and tended to increase mortality by 13%. No effects on H/L ratio, and comb or skin lesions were found. In conclusion, regardless of the source, inositol reduced vent feather cover, while it tended to increase mortality. Only pure inositol reduced fearfulness in laying hens.