This study evaluated the effect of an essential oil blend and its delivery routes on broiler chicken growth performance, blood biochemistry, intestinal morphology, and immune and antioxidant status. Eggs were incubated and allotted to 3 groups: non-injected group, in ovo saline group, and in ovo essential oil group. On day 18 of incubation, essential oil in saline or saline alone was injected into the amnion. At hatch, chicks were assigned to post-hatch treatment combinations (1) in ovo essential oil + in-water essential oil (in ovo + in-water EO); (2) in ovo essential oil (in ovo EO); (3) in ovo saline; (4) in-water essential oil; (5) in-feed antibiotics (Bacitracin methylene disalicylate) and (6) a negative control (NC; corn-wheat-soybean diet) in 8 replicate cages (6 birds/cage) and raised for 28 day. The in ovo EO group reduced (p < 0.05) chick length and hatchability, all groups recorded no difference in growth performance at 0–28 day. The in ovo + in-water EO treatment reduced (p < 0.05) blood creatine kinase and aspartate aminotransferase levels whilst increasing (p < 0.05) total antioxidant capacity in birds. The in ovo + in-water delivery of EO might represent a potential antibiotic reduction strategy for the poultry industry but more research is needed to address the concern of reduced hatchability.

This study was planned to investigate the effects of seaweed supplementation, genetic strain, heat stress and their interactions on laying hen performances, blood chemistry and hematology. In a short-term trial, laying hens of the two genetic lines Lohman LSL-Lite (White) and Lohman Brown-Lite (Brown) were supplemented with Chondrus crispus (CC) at 3% for 21 days, while a control group was not. In a long-term trial, the same two strains were assigned to control (0%), 3% red seaweed Chondrus crispus (CC) or 0.5% brown seaweed Ascophyllum nodosum (AN)-supplemented diets for 41 weeks, concluding with a four-week control or heat-stress period. The White hens displayed higher egg production and a lower feed/egg ratio. The short-term inclusion of CC significantly reduced the feed intake, weight gain and feed/egg ratio. The long-term seaweed intake affected the plasma albumin and gamma-glutamyl transferase (GGT) (p < 0.05), and there were significant strain-heat stress interactions; heat stress in the Brown birds was associated with reduced protein, globulin and glucose and increased cholesterol and GGT levels and higher heterophil-to-lymphocyte (H/L) ratios (p < 0.05) in response to heat stress (p < 0.05). In conclusion, a long-term seaweed supplementation affected the plasma protein and enzyme profiles, yet had little effect on hen leukocyte counts and the overall performance.

Poultry and its products are an economical source of high-quality protein for human consumption. In animal agriculture, antibiotics are used as therapeutic agents to treat disease in livestock, or as prophylactics to prevent disease and in so doing enhance production. However, the extensive use of antibiotics in livestock husbandry has come at the cost of increasingly drug-resistant bacterial pathogens. This highlights an urgent need to find effective alternatives to be used to treat infections, particularly in poultry and especially caused by drug-resistant Salmonella strains. In this study, we describe the combined effect of extracts of the red seaweeds Chondrus crispus (CC) and Sarcodiotheca gaudichaudii (SG) and compounds isolated from these in combinations with industry standard antibiotics (i.e., tetracycline and streptomycin) against Salmonella Enteritidis. Streptomycin exhibited the higher antimicrobial activity against S. Enteritidis, as compared to tetracycline with a MIC₂₅ and MIC₅₀ of 1.00 and 1.63 μg/mL, respectively. The addition of a water extract of CC at a concentration of 200 µg/mL in addition to tetracycline significantly enhanced the antibacterial activity (log CFU/mL 4.7 and 4.5 at MIC₂₅ and MIC₅₀, respectively). SG water extract, at 400 and 800 µg/mL (p = 0.05, n = 9), also in combination with tetracycline, showed complete inhibition of bacterial growth. Combinations of floridoside (a purified red seaweed component) and tetracycline (MIC₂₅ and MIC₅₀) in vitro revealed that only the lower concentration (i.e., 15 μg/mL) of floridoside potentiated the activity of tetracycline. Sub-lethal concentrations of tetracycline (MIC₅₀ and MIC₂₅), in combination with floridoside, exhibited antimicrobial activities that were comparable to full-strength tetracycline (23 μg/mL). Furthermore, the relative transcript levels of efflux-related genes of S. Enteritidis, namely marA, arcB and ramA, were significantly repressed by the combined treatment of floridoside and tetracycline, as compared to control MIC treatments (MIC₂₅ and MIC₅₀). Taken together, these findings demonstrated that the red seaweeds CC and SG and their selected, purified components can be used to increase the lifetime of existing, patented antibiotics and can also help to reduce costly (economic and environmental) therapeutic and prophylactic use of antibiotics in poultry. To our knowledge, this is the first report of antibiotic potentiation of existing industry standard antibiotics using red seaweeds and their selected extracts against S. Enteritidis.

Providing lighting schedule during incubation has been shown to improve chick quality and reduce stress posthatch. This study was conducted to evaluate the effects of providing light of different colors during incubation on embryo development, air cell temperature, the spread of hatch, and hatching performance. Four batches of eggs (n = 2,176, 1,664, 1,696 and 1,600) from Ross 308 broiler breeders were used in the experiment. In each trial, eggs were randomly distributed into 4 lighting treatments. The incubation lighting treatments included: incubated under dark as control, illuminated with white, red or blue lights for 12 h daily. There were no incubation lighting treatment differences in embryo development, the spread of hatch, hatchability, embryo mortality, hatch weight, chick length, navel closure quality, yolk-free body weight, or relative spleen weight. However, embryos incubated under red light had lower average air cell temperature than those in dark, white or blue light treatments. This finding may suggest higher melatonin secretion during the scotophase when illuminated with red light. Male chicks incubated under dark had a higher bursa of Fabricius weight than males illuminated with blue light. In conclusion, these results suggest that the red, white and blue light stimulation during incubation had no negative effects on hatchability, embryo mortality, spread of hatch or day-old chick quality, but may have potential impacts on immunity and energy metabolism in broiler embryos.

Implementing a photoperiod during incubation has been shown to be a potential next step to removing one more stressor for newly hatched poultry species. The distribution of hatch over time is a parameter that may be influenced by photoperiod that could benefit from a photoperiod but has not been studied at this time and is the objective of this paper. The impact on hatch rate for three strains of chicken, Barred Plymouth Rock (BR), Lohmann Brown (LB) and Lohmann Lite (LL), was measured following the provision of a 12L : 12D (12 h light : 12 h dark) photoperiod starting at 0, 9 or 17 days of incubation and compared with incubation in the dark. The cumulative number of chicks hatched eggs at four points in time (489, 498, 507 and 516 h of incubation) was analysed using repeated measures analysis in a 3 × 4 factorial arrangement of treatments. Repeated measures analysis was done to determine the main and interaction effects of photoperiod and bird strain, and a regression analysis was used to determine how these effects evolved over time. Lohmann Brown embryos provided a 12L : 12D photoperiod throughout incubation were first to reach 50% of total chicks hatched and rate of hatch from 50% to 75% of total chicks hatched as well. As the LB chicks did not begin to hatch earlier or finish later, the LB strain was the most synchronised when provided a 12L : 12D photoperiod from the beginning of incubation. Similar results were found for LL, but no difference on the percentage hatched over time was found when provided the 12L : 12D photoperiod at the beginning of incubation or at day 9. The BR strain only showed a significant difference in hatch window synchronisation when provided a 12L : 12D photoperiod at day 9 of incubation. These results indicate that the strain of chicken impacts the hatch window, and each strain responds to a photoperiod during incubation differently. This information could be useful for hatchery managers to deal with different strains of chicken for incubation.

The use of high fiber agricultural byproducts in poultry nutrition can help not only to reduce feed cost but also to promote gastrointestinal functionality and growth performance and enhance environmental sustainability. This study was conducted to examine the effect of oat hulls (OH) incorporated in the diet or fed as free choice on growth performance, intestinal morphology, cecal short chain fatty acids (SCFA) production and carcass yield of broiler chickens. Day old broiler chickens were assigned to 4 dietary treatment groups which consisted of a corn–soybean meal–wheat based diet (Basal), Basal + bacitracin methylene disalicylate (BMD), Basal + 3% OH (3% OH) and Basal + free choice OH (FCOH). Each group had six replicate pens of 27 chicks and were raised for 39 d. Feed intake (FI), body weight gain (BWG), and feed conversion ratio (FCR) were determined weekly for each pen. One chicken/pen was slaughtered on d 36 to determine organ weights, jejunal morphology, digesta pH and cecal SCFA and two chickens/pen were slaughtered on d 39 to determine carcass weight and yield. Diet had no effect on FI, except on d 28, when the FCOH group had higher FI than the 3% OH groups. During the starter phase, chickens fed 3% OH had the highest BWG and lowest FCR, which were significantly different (p < 0.05) from those fed FCOH. Chickens fed 3% OH had the highest slaughter, hot carcass, and cold carcass weights, which were significantly different (p < 0.05) from those fed FCOH. Diet had no effect on jejunal villus height and crypt depth, ileal and cecal digesta pH, and cecal SCFA. Chickens fed FCOH had a larger (p < 0.0001) gizzard weight and showed a tendency to have a larger (p = 0.09) ceca weight than other treatment groups. In conclusion, the inclusion of 3% OH in an antibiotic-free diet has the potential to enhance growth performance, while free choice OH increases the gizzard weight of broiler chickens.