Estimating energy utilization in laying hens using imaging technology

An experiment was conducted to evaluate the effects of dietary energy on the performance, and energy storage in first cycle laying hens housed in cages. Hy-Line W-36 laying hens were fed experimental diets from 36 to 52 weeks of age, including seven energy concentrations ranging from 2750 to 3050 kcal/kg with 50kcal/kg differences between each of the diets. Each dietary treatment was assigned 12 replicate cages and 3 birds per cage resulting in 36 hens per treatment or a total of 252 hens for the overall experiment. Diets were generated every two weeks. The hens were control fed 97 g of feed daily to mimic typical commercial feed intake. Eggs were collected and weighed on a daily basis. Egg production, energy intake, feed intake, egg weights, egg mass and feed conversion ratio were determined and calculated every two weeks. Hens were weighed every 4 weeks and all hens were euthanized and scanned using dual x-ray absorptiometry (DXA). Measurements taken over time (egg production, egg weight, egg mass, energy intake, feed intake, feed efficiency, and body weight) were analyzed using ANOVA with repeated measures and if significant differences were noted Tukey’s test was used to separate means. Significance was accepted at (P ≤ 0.05). Egg production (87.8 to 91.7% hen-housed egg production: SEM = 1.05), egg mass (52.9 to 55.1 g/d: SEM = 0.63), were not different (P > 0.05). This lack of differences in performance were expected due to the short-term nature of the experiment, as the laying hens continued to produce eggs at the expense of body energy reserves as indicated by the decreasing fatty tissue with reduced dietary energy. Unlike expectations with the controlled feeding protocol, hens on the two highest energy diets reduced feed intake in comparison to hens fed lower energy diets (P ≤ 0.05). Fat storage, as indicated by carcass fatty tissue generally increased with increasing dietary energy with the exception of the 2850kcal/kg diet that resulted in increased carcass fatty tissue in comparison to both the 2900 and 2950 kcal/kg diets (P ≤ 0.05). These results suggest that dietary energy did not have a significant effect on egg production but did generally increase carcass fatty tissue.

Key Words: dietary energy, laying hen, carcass composition, energy intake.

Abstract presented at the International Poultry Scientific Forum during IPPE 2020.