Pratima Adhikari

The objective of this study was to determine the effects of two levels of a precision biotic (PB) within a reduced CP diet for performance, digestibility, and blood biomarkers in Dekalb White laying hens from 24 to 42 weeks of age. A total of four diets were fed: (1) an industry-standard positive control (PC) diet with a formulated CP level of 17.5%; (2) a negative control (NC) diet with a formulated CP level of 15.5%; (3) NC with 0.5 kg/ton PB (NC+PB1); (4) NC with 0.7 kg/ton PB (NC+PB2). The NC diet decreased hen–day egg production compared to the PC diet, and supplementation with both levels of PB led to intermediate levels of production. There was a similar trend for the feed conversion ratio (FCR), measured in kilograms of feed per dozen eggs. Feed cost was lower in the reduced CP diets compared to the PC. Apparent total tract digestibility was decreased with PB supplementation without differences in apparent ileal digestibility. The increased plasma uric acid levels in the NC+PB2 group suggest a shift in protein metabolism toward higher efficiency in ammonia detoxification. While more research is needed on PB, this research suggests that supplementation with PB in laying hens could potentially improve performance parameters.

This study’s objective was to determine the effects of two levels of a precision biotic (PB) within a reduced CP diet for performance parameters, digestibility, and blood biomarkers in Dekalb White laying hens from 24 to 42 weeks of age. A total of four diets were fed: 1) an industry standard positive control (PC) diet with a formulated CP level of 17.5%; 2) a negative control (NC) diet with a formulated CP level of 15.5%; 3) NC with 0.5 kg/MT PB (PB1) and 4) NC with 0.7 kg/MT PB (PB2). The NC diet had decreased hen day egg production compared to the PC diet and supplementation with both levels of PB led to intermediate levels of production. There was a similar trend for kilograms of feed per dozen eggs. Feed cost was lower in the reduced CP diets compared to PC. Apparent total tract digestibility was decreased with PB supplementation without differences in apparent ileal digestibility. Increased plasma uric acid levels in the PB2 group suggest a shift in protein metabolism toward higher efficiency in ammonia detoxification. While more research is needed on PB, this research suggests that supplementation with PB in laying hens could potentially improve performance parameters.

To determine the effects of swarming motility (SM), and Multi-locus sequence types (MLST) on the main effect of virulence genotype (VG) of E. coli through an embryos lethality assay between the 12^th -18^th days of incubation. We collected 58 E. coli isolates from asymptomatic commercial hens (n = 42) and lesions of colibacillosis cases (n = 16), then classified their VG as avirulent, moderately-virulent, virulent-healthy, and virulent-colibacillosis categories by the presence of 5 virulence-associated genes (iroN, ompT, hlyF, iutA, and iss). These isolates were further classified as non-motile, motile, or hyper-motile by SM assay. From the 58 isolates we selected 29 for embryo lethality assay (ELA) and determined their MLST. Each isolate was inoculated into 15 embryonated eggs through the allantoic cavity. We found the avirulent isolates reduced the relative embryo weight compared to virulent-colibacillosis and moderately-virulent isolates (37.49 vs. 41.51 and 40.34%, P = 0.03). Among the moderately-virulent and virulent-colibacillosis categories, embryo lethality was lower when isolates were non-motile. Yolk retention was unaffected by virulence categories, motility, or MLST. Interaction between VG and SM substantially influenced the ELA of E. coli isolates.