The objective of the study was to characterize pale breast meat, compare it with normal colored breast meat, and determine whether it should be considered pale, soft, and exudative (PSE). Characteristics of 20 normal and 20 pale broiler breasts, obtained at a commercial slaughter plant, were evaluated. Compared with normal meat, the pale breast meat had a significantly (P < 0.05) lower pH (5.7 vs. 5.9), higher color L* value (60.0 vs. 55.1), higher drip loss (1.34 vs. 0.87%), lower marinade uptake (31.2 vs. 44.3%), and lower cooking yields (95.2 vs. 105.8%). Protein solubility in pale samples was slightly (P < 0.05) lower than in normal samples, which suggests increased protein denaturation in the pale breasts. Correlations between pH and L* value (r = -0.76), pH and marinade uptake (r = 0.64), sarcoplasmic protein solubility and L* value (r = -0.71), and sarcoplasmic protein solubility and moisture uptake (r = 0.66) and cooking yield (r = 0.66) were significant (P < 0.05). Correlations between total protein solubility and moisture uptake or cooking yields were not significant. The low ultimate pH of pale breast muscle appears to be the main determinant of its low water-holding capacity (WHC). This lower pH was unrelated to a higher lactate concentration or glycolytic potential of the pale muscle. Further research is needed to determine the causes of the low pH and possible measures to increase the pH (and functionality) of pale broiler breast muscle. Because the pale breast muscle has a low WHC, it can be considered PSE.

Male broilers were used to evaluate the effect of zinc on performance and immune competence during heat stress (HS). Broilers raised in either a thermoneutral (TN, 23.9 degrees C constant) or HS (23.9 to 35 degrees C cycling) environment were fed a low zinc diet (LZ; 34 mg/kg), an adequate zinc diet (AZ; 68 mg/kg), or a supplemental zinc diet (HZ; 181 mg/kg). Humoral immunity was assessed by intravenous injection of 7% SRBC followed by evaluation of serum for antibody titers in primary and secondary responses. Cell-mediated immunity was assessed using a Sephadex stimulation method to recruit abdominal exudate cells (AEC) to evaluate macrophage phagocytic ability. The HS birds consumed 12.5% less feed, gained 24.6% less weight, and had lower feed efficiency when compared to TN birds. Dietary zinc levels did not impact growth performance or plasma zinc concentration. Numbers of AEC, macrophages in AEC, phagocytic macrophages, and internalized opsonized and unopsonized SRBC were increased by HZ. Total, IgM, and IgG antibody titers for primary and secondary responses were significantly increased in birds receiving HZ under TN conditions. Tibia zinc concentration increased with increasing zinc levels but did not change with temperature. Lymphoid organ weights, primary and secondary antibody responses, incidences of macrophages in AEC, phagocytic ability of macrophages, and plasma zinc concentration were all significantly reduced by HS. These results indicate that the immune response of broilers can be influenced by the level of zinc in the diet and by environmental conditions.

Three experiments were conducted to study the effects of crude enzyme preparations on the performance and gastrointestinal tract size of chicks fed wheat and barley diets. In the first experiment, enzyme addition (100 and 200 mg/kg of Roxazyme G and 1,000 mg/kg of Avizyme SX) to diets containing Bedford barley improved weight gain (6%) and the feed to gain ratio (5%) over a 6-wk period for both male and female broilers. In Experiment 2, enzyme addition to diets containing Scout (hulless) and Bedford (hulled) barley improved (P < or = .05) weight gains of Leghorn chicks by 25 and 11% and the feed to gain ratios by 10 and 6%, respectively. Feed consumption increased significantly (16%) only in the case of birds fed enzyme with Scout barley. Corresponding reductions in the relative weights of the crop and gizzards were 15 and 17% for birds fed Scout barley and 7 and 8% for those fed Bedford barley. Enzyme treatment of the diet containing Scout barley also reduced the relative length of the duodenum, jejunum, and ileum and the relative weight of the proventriculus, whereas a similar treatment of Bedford barley resulted in changes in the relative length of the duodenum and jejunum (P < .05). In the final broiler experiment (42 days), crude enzyme addition (100 mg/kg) to wheat and barley diets improved weight gains by 13 and 9% and feed to gain ratios by 7 and 10%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Two sources of zinc [ZnSO4.H2O or ZnPicolinate (ZnPic)] supplementation were evaluated for their effects on performance, carcass weight, levels of malondialdehyde, and vitamins C, E, A in Japanese quail (Coturnix coturnix Japonica) exposed to high ambient temperature of 34 degrees C. The birds (n = 360; 10-d-old) were randomly assigned to 12 treatment groups consisting of 3 replicates of 10 birds each in a 2 x 2 x 3 factorial arrangement of treatments (temperatures, zinc sources, zinc levels). Birds were kept in wire cages in a temperature-controlled room at either 22 degrees C (thermoneutral) or 34 degrees C (heat stress) for 8 h/d (0900 to 1700 h) until the end of study, and fed a basal (control) diet or the basal diet supplemented with either 30 or 60 mg of Zn as ZnSO4 H2O or ZnPic/kg of diet. Heat exposure decreased (P = 0.001) live weight gain, feed intake, feed efficiency, and carcass weight when the basal diet was fed. A linear increase in feed intake (P = 0.01) and BW (P = 0.01), and improvement in feed efficiency (P = 0.01) and carcass weight (P < or = 0.05) were found in zinc-supplemented quail reared under heat-stress conditions. Serum vitamin C (P = 0.04), E (P = 0.05), and cholesterol (P = 0.01) concentrations increased linearly, whereas malondialdehyde concentrations decreased linearly (P = 0.02) as dietary zinc sulfate and ZnPic supplementation increased. An interaction between dietary zinc sources, temperature, and levels of supplementation (P < or = 0.05) for these parameters was detected. Serum vitamins C, E, and A concentrations were not different in supplemented birds reared at thermoneutral temperature. Supplementation with zinc improved carcass weight and antioxidant status of birds, and the effects of ZnPic were relatively greater than those of ZnSO4.H2O in heat-stressed quail. Results of the present study suggest that supplementation with ZnPic could be considered to be more protective than ZnSO4.H2O by reducing the negative effects of oxidative stress induced by heat stress in quail.

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