Adding a Macroalgae Blend to Commercial Laying Hen Diets Improves Egg Quality and Body Weight Gain

Ingredients other than in-feed antimicrobial compounds can offer a sustainable approach to improving gastrointestinal (GI) health and animal performance. Efficient egg production and egg quality are of major importance to the poultry industry, but their optimisation is dependent on numerous factors. Nutrition and disease factors are among the most common factors affecting egg production and quality (Roberts, 2004). It follows that a healthy GI tract is required for efficient digestion and absorption of nutrients and, consequently, for egg production and egg quality. Marine macroalgae represent a promising feed ingredient, due to the presence of several bioactive components that have been reported to benefit GI health (Salehi et al. 2019). These bioactive compounds including polysaccharides, peptides, essential fatty acids, antioxidants such as polyphenols and other phytogenic compounds vary significantly between macroalgal species (Salehi et al., 2019). This variation in content of bioactive compounds between algae species provides opportunities for selection of different species to vary the amounts of specific categories of bioactive compounds that benefit GI health in laying hens. The authors hypothesised that a blend of marine macroalgae containing varying proportions of selected brown, green and red algal species may convey benefits that improve egg production and egg quality in commercial hens.

Wheat and soyabean meal-based diets were formulated to be iso-nutritive and to meet the recommended nutrient requirements of the NRC (1994) for layers (Table 1). Three dietary treatments were produced by increasing the concentration of a proprietary, marine macroalgae blend (MAB, OceanFeedTM, supplied by Ocean Harvest Technology Ltd.) to provide a Control (0 g/ kg), Control plus MAB at 5 g/ kg feed and Control plus MAB at 10 g/ kg feed. Diets were fed in two phases, weeks 1-12 and weeks 13-24. The diets were presented to the birds in mash form and were prepared without the inclusion of growth promoting antimicrobials. Diets were analysed for nutritional homogeneity prior to the start of the trial. The hens were allowed continuous access to feed and water throughout the study.

This study was conducted in accordance with Regulations (EC) No 1831/2003 (EC, 2003) and No 429/2008 (EC, 2008) as outlined in the European Food Safety Authority’s (EFSA) technical guidance document on the assessment of efficacy of feed additives (EFSA, 2018). A total of 288 Hyline pullets (Gallus gallus domesticus) at the point-of-lay were randomly allocated to 72 cages, 4 birds per cage in 3 blocks of 24 cages. Three dietary treatments were randomly allocated to cages within blocks providing 24 replicate cages per block. The house was cleaned prior to placement and was equipped with programmable artificial lighting, automated gas heating and forced ventilation. The temperature inside the building was maintained as per breeder recommendations. A 24-hour lighting programme of 16 hours light and 8 hours dark was maintained throughout the trial. The 3 dietary treatments were allocated at random to cages with blocks. Each 4-bird cage served as an experimental unit, providing 24 replicates per treatment. Zootechnical performance parameters measured included: feed intake, egg number, egg weight, average egg weights, egg mass, hen body weight, feed conversion efficiency and incidence of cracked, soft-shelled, and dirty eggs. Egg production (%/hen/day) was calculated as [total egg number per (number hens * number of days hens were alive) x 100]. Feed conversion efficiency (FCE) was calculated as [Egg mass (g/cage/day) per average daily feed intake (g/cage/day)].

Prior to statistical analyses, the data were assessed for outliers using the Box Plot method of JMP® PRO 14.2 (SAS Institute Inc., Cary, NC) and assumptions of Analysis of Variance (ANOVA) using Shapiro–Wilk test for testing normal distribution and Welch test for testing equal variances, respectively. Where data met the assumptions of the ANOVA test, data were analysed as a randomised completely block design by JMP® PRO 14.2 using the Fit Model. Treatment was included as a main effect and block as random effect in the model. The results were presented as the least squares means. Statistical significance was declared at P ≤ 0.05. The Tukey-Kremer test was used to separate differences between means. Data that did not meet the assumptions for ANOVA were transformed to facilitate meeting of the assumptions or non-parametric analysis was employed if assumptions for ANOVA were not met. For all response criteria, cage served as the experimental unit.

Body weight of hens were not different among dietary treatment groups; however, the change in body weight during the trial period tended to be higher in hens offered diets containing MAB (p=0.065, Table 2). Egg production, egg mass, egg weight and feed conversion efficiency were not significantly affected by diet over the 168-day study period. However, for egg quality parameters, the average albumen height (mm) and Haugh units were increased by in eggs from hens fed diets containing the MAB (Table 3, Figure 1).

While egg production was similar, hens offered diets with MAB tended to have higher body weight gain after consuming the diets for 168 days. An increase in weight suggests a more efficient extraction of nutrients; however, this was not confirmed by improved feed conversion efficiency. Haugh Units (HU), which combines the egg mass with the albumen height, is generally accepted as an indicator of egg quality (Eisen et al. 1962). An improvement in albumin height and in HU noted with dietary MAB in this trial suggests an improvement in overall egg quality. Given HU is widely accepted as a key indicator of egg quality and freshness (Eisen et al. 1962, Williams, 1992), it is an important value metric for egg producers. Further studies involving supplementation with the MAB used in this study, to greater numbers of laying hens over longer periods of time are proposed to confirm the possible benefits for laying hen welfare and productivity. Further, a more detailed assessment of the quality factors and the composition of eggs from hens fed diets containing MAB should be included in future studies.