Effect of Clover grass protein concentrate on performance, digestibility and egg quality of laying hens fed 100% organic diet

Summary

From the beginning of 2018, inclusion of non-organic protein sources are not allowed in the diet of 100% organic poultry in Europe. In this situation, a major nutritional challenge is to make sustainable supply of organic protein and amino acid in competitive price. This necessity triggers to search alternative protein sources for sustainable organic egg production. Clover grass protein concentrate (CPC) is dried protein concentrate prepared by pulping clover grass mixture mainly containing Red clover to obtain green juice followed by fermentation, centrifugation and drying. The crude protein, lysine and methionine content in CPC were determined to be 355.6, 20.3 and 6.3 g/kg dry matter respectively. This research was carried out to study the effect of graded level of clover grass protein concentrate in production performance, digestibility and egg quality of laying hens fed 100% organic diet. Four diets (A, B, C, D) including CPC at level of 0 (control), 40, 80, and 120 g/kg (as fed) mainly at the expense of soya and soya cake were formulated to be iso-nitrogenous (CP=18.7%) and iso-caloric (ME=10.5 MJ/kg) and fed to 240 Hisex hens for 12 weeks of experimental period in floor pen system in randomized block design (4 diets, 6 replicates, 10 birds/replicate) under environmental control system. Here, CPC contributed 0 (control diet), 7.4, 14.8 and 22.2% of dietary crude protein. Data related to daily average feed intake, egg production, and egg quality measures, feed to egg ratio were collected. To study nutrient digestibility, a digestibility trial was conducted in battery cages employing a complete randomized design with same environment as in floor pen system. Every time, the excreta was collected in a bin and stored at -20 ºC to avoid possible microbial degradation. On the last day of the experiment, all eggs were collected to analyze egg quality. The egg shell quality was evaluated through shell fracture strength (N), fracture displacement (mm) at maximum force, fracture gradient (N/mm, elasticity), and the yolk quality through color. The present study showed that partial replacement of organic soybean and soya cake with organic clover grass protein concentrate does not influence negatively egg production parameters. The inclusion of 4, 8, and 12% of CPC in the diets resulted similar feed intake (p=0.647), egg production (p=0.606), egg weight (p=0.11), egg mass per hen per day (p=0.815) and feed conversion ratio (0.436) in comparison to hens fed control diet. The egg productivity (%) was 87.37 for diet without Clover protein concentrate and 89.01 for diet including 12% of Clover protein concentrate and they were not statistically different. The digestibility experiment showed that for all four types of diets, total tract apparent digestibility of dry matter, and nitrogen retention were statistically similar. However, the coefficient of total tract apparent digestibility of methionine and lysine decreased significantly (p<0.001) with the increase of CPC from 4 to 12% in diet. For all diets, egg shell strength and elasticity were comparable, however, the yolk color was significantly different. The lightness of yolk decreased while the redness increased significantly (p<0.0001) with the increase in CPC content in the diets. The yellowness was found significantly (p<0.0001) higher for diets with CPC but not among each other. The clover grass protein concentrate has positive effect on performance, digestibility and egg quality of laying hens fed 100% organic diet and it can substantially substitute organic soybean or its product. It is concluded that clover grass protein concentrate is a promising protein source for organic laying hens to achieve optimum productivity and egg quality.