The effect of safflower meal substitution in a lysine fortified corn-soybean meal diet on performance, egg quality, and yolk fat profile of laying hens

Two experiments were conducted to study the performance, egg quality, and yolk fat profile of laying hens fed rations containing de-hulled-extruded safflower meal (SFM) in partial or total substitution of de-hulled soybean meal (SBM). In Experiment 1, a balanced diet containing SFM with crystalline L- lysine (SFD) was formulated to meet or slightly exceed the Hy-line W-98 commercial management guide. A corn-SBM (control) also was formulated without supplemental lysine. These 2 diets contained 0.80 and 0.93% lysine, respectively. A third SFM containing diet (SFDL) was mixed in which L- lysine was further added to match the lysine level of the control diet (0.93%). All diets were isocaloric and isonitrogenous. In Experiment 2, a corn-SBM diet (control) and diets with SFM substituted for 20, 40, 60, 80, and 100% of the soybean protein in the control diet were prepared. The 3 treatment diets in trial 1 were replicated in a completely randomized design among 20 individually caged hens and fed for 168 d. In trial 2, the 6 treatment diets were similarly replicated among 12 individually caged hens and fed for 140 d. Production parameters such as egg production, egg mass, feed conversion, and hen weight were not affected by any of the dietary treatments in either experiment. Similarly, all SFM containing diets had no effect on egg weight, specific gravity, Haugh unit score, or shell thickness throughout the experimental periods of both trials. Dietary SFM at a substitution rate higher than 40% SBM resulted in an increase (P < 0.01) in yolk color score. Yolk fat, cholesterol, and fatty acid concentrations did not change in response to an increase in dietary SFM level. Therefore, SFM can be incorporated in practical corn-SBM laying hen diets up to a protein substitution rate of 40% without reduction in performance and egg quality parameters.