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ABSTRACT: Heat stress (HS) and water scarcity are significant challenges to sustainable poultry production worldwide. It is, therefore, critical to identify effective strategies to prevent, withstand, or adapt to these challenges. After four generations of divergent selection for water efficiency, the present study was undertaken to determine the effect of HS on meat quality and muscle myopathy incidences in high (HWE)- and low (LWE)-water efficient broilers. Day-old male chicks (240 chicks/line) were allotted randomly by line and body weight-matched groups to 12 controlled-environmental chambers (2 pens/chamber). At d29, birds were exposed to 2 environmental conditions (thermoneutral (TN), 25°C; or cyclic HS, 36°C, 9h/d) in a 2 × 2 factorial design. On d49, birds were processed, carcass parts were weighed, meat quality and muscle myopathy incidence were assessed. Processing data were analyzed by Two-way ANOVA and Tukey's HSD multiple comparison test, and frequency of muscle myopathy score between groups was determined using Chi-square and Fisher's exact test. Significance was set at P < 0.05. As no significant environment by line interaction was discerned, the 2 main factors were analyzed separately. High water efficient birds had significantly higher tender- and leg quarter (LQ)-weight as well as carcass without giblet (WOG), chilled carcass WOG (CWOG), wing, LQ, and rack yields compared to their LWE counterparts. Both abdominal fat content and yields were significantly greater in LWE than HWE chickens. Chronic HS exposure significantly decreased dock, WOG, fat, CWOG, breast, tender, wing, and LQ weights as well as breast yield. HWE chickens had a significantly lower b* value compared to the LWE birds and HS significantly reduced the drip loss and the b* value compared to TN condition. Compared to LWE, HWE birds had higher and lower incidence of severe woody breast (WB) and white striping (WS) under TN and HS, respectively. HS reduced the incidence of both myopathies in both lines. In conclusion, the genetic selection for water efficiency seems to improve carcass yield, reduce fat content, and decrease the breast b* value. HWE birds had higher incidences of WB and WS under TN, which is reversed under HS conditions.

SUMMARY: Spirulina platensis is an emerging poultry diet source due to its essential nutrition and bioactive ingredients. Spirulina microalgae confers beneficial effects on broiler's growth performance, immune response, and antioxidant activity. We investigated the effect of Spirulina platensis on BCO lameness, one of the most driving factors for economic and animal well-being concerns in the poultry industry. Additionally, supplementation of Availa ZMC containing organic trace minerals – zinc, manganese, and copper – was shown to alleviate lameness by 20 to 25%. We hypothesized that pairing microalgae and organic trace minerals might confer a synergistic effect in reducing BCO. A 2 × 2 factorial study, with microalgae (5% Spirulina platensis and 5% Spirulina platensis plus 0.15% Availa ZMC) and without microalgae (0.15% Availa ZMC and a negative control diet), plus one BCO source group were applied to 1,320 one-day-old chicks with 5 replicates of 60 chicks per treatment for lameness assessment. No significant difference in lameness was observed between the negative control and BCO source group (60.0% vs. 54.5%, P = 0.56). Compared to the negative control, Availa ZMC significantly reduced lameness by 51.2% (60.0% vs. 29.3%, P < 0.001), while microalgae slightly increased lameness by 6.3% (60.0% vs. 63.8%, P = 0.1). Availa ZMC plus microalgae alleviated lameness by 16.7% (50.0% vs. 60.0%, P = 0.005) compared to the negative control, which was statistically lower than microalgae alone and higher than Availa ZMC alone. These findings suggested the inclusion of 5% Spirulina platensis did not reduce BCO lameness, while Availa ZMC significantly alleviated lameness. When combined, there was no significant interaction between Availa ZMC and microalgae in mitigating broiler lameness.

ABSTRACT: White striping (WS) is an emerging myopathy that results in significant economic losses as high as $1 billion (combined with losses derived from other breast myopathies including woody breast and spaghetti meat) to the global poultry industry. White striping is detected as the occurrence of white lines on raw poultry meat. The exact etiologies for WS are still unclear. Proteomic analyses of co-expressed WS and woody breast phenotypes previously demonstrated dysfunctions in carbohydrate metabolism, protein synthesis, and calcium buffering capabilities in muscle cells. In this study, we conducted shotgun proteomics on chicken breast fillets exhibiting only WS that were collected at approximately 6 h postmortem. After determining WS severity, protein extractions were conducted from severe WS meat with no woody breast (WB) condition (n = 5) and normal non-affected (no WS) control meat (n = 5). Shotgun proteomics was conducted by Orbitrap Lumos, tandem mass tag (TMT) analysis. As results, 148 differentially abundant proteins (|fold change|>1.4; p-value < 0.05) were identified in the WS meats compared with controls. The significant canonical pathways included BAG2 signaling pathway, glycogen degradation II, isoleucine degradation I, aldosterone signaling in epithelial cells, and valine degradation I. The potential upstream regulators include LIPE, UCP1, ATP5IF1, and DMD. The results of this study provide additional insights into the cellular mechanisms on the WS myopathy and meat quality.