The effect of in ovo probiotics on hatchability and development of poults with or without dietary restrictions

Turkeys have to overcome several challenges early in life, including exposure to pathogens and difficulty with the transition from yolk as a nutrient source to CHO dietary sources. Probiotics are thought to help alleviate these symptoms in the post-hatch poult, but any beneficial effects, if given prior to hatch are unknown. Additionally, the optimal level of probiotic that can be injected into the egg must be established. Once optimal levels of hatch are established, the effects post hatch must be known. A series of experiments were performed to determine the benefits of in ovo probiotics. The overall objective was to evaluate different probiotic concentrations injected into turkey eggs prior to hatch on hatchability and intestinal bacterial concentrations. Secondary objectives were to determine the impact of in ovo probiotics on poult hatchability and first week mortality. Finally, whether a probiotic injection could mitigate poult growth ramifications due to delayed access to feed or a 20% dietary reduction in Ca and P. To study these objectives a series of experiments were conducted. The general design of the study was for groups of fertile turkey eggs to be incubated. The eggs were candled on d25 and allocated to different treatment groups: (1) Non-injected eggs hatched in a separate hatcher (Negative Control), (2) eggs injected with 1ml of saline and placed in the hatcher with probiotic injected eggs (Sham Control), (3) eggs injected with various amounts of probiotic solution (Probiotic). The most commonly used concentration was 106cfu/ml. An additional experimental factor of delayed placement on feed was added to experiment 2. Placement of eggs in the incubator was offset by 24h, and the hatched poults were all placed on feed at the same time. Hatch counts were taken for each replicate and cecal contents collected from two birds per replicate to determine bacterial counts on d28. Cecal contents were plated on media plates with LB agar, MRS agar, Bifidobacteria agar or Enterococcusel agar. Intestinal contents were collected to measure nutrient transporters and intestinal morphology in trial two. Birds from experiments two and three were placed on feed for one (experiment 2) or three (experiment 3) wks. At DOH of exp3, half of the hatched poults were given access to a diet with a 20% reduction in calcium and phosphorus. Tibia and femur samples were collected for morphology and ash content from birds during exp3. The injection of 106cfu of bacteria or lower into the egg did not alter hatchability of eggs from trials one and two. Overall, hatchability was reduced by almost 20% in exp3. Bacteria load in the intestine was two to three logs higher in probiotic injected birds compared to control for every trial. The first week livability of probiotic injected birds was not significantly different than controls in exp2, but was almost double in exp3. Sham control poults from exp2 had the highest BW for the entire trial. Probiotic injected birds had improved FCR through d3 in exp2 but the effect on FCR was lost by d7. Probiotic injected birds had lower BW and had shorter, narrower tibias and femurs at d7 and d21 compared to controls. The results indicate that in ovo probiotics can negatively influence poult growth and performance in the first 21d of life, if the bacteria reduce hatchability. When in ovo probiotics are injected into eggs and increase bacterial load in the intestine without altering hatchability, the benefits are improved FCR through the first 3d of life. The results from the series of experiments are a promising insight into the effects in ovo bacteria can have on the early post hatch poult.