Productive Performance and Egg Quality of Brown Egg-laying Hens in the Late Phase of Production As Influenced by Level and Source of Calcium in the Diet

A total of 1,152 Lohmann Brown laying hens were used to study the influence of level (3.5 and 4.0%) and source (coded FIN, COA, and OYS) of Ca in the diet on productive performance and egg quality from 58 to 73 wk of age. The FIN diet contained all the Ca carbonate as fine limestone (LIM). In the COA and OYS diets, 40% of the fine LIM was substituted with either coarse LIM or oyster shell. Each treatment was replicated 8 times (24 hens). Productive performance and egg quality traits were recorded every 4 wk, and tibia characteristics and shell quality traits were determined at 73 wk of age. An increase in Ca intake from 4.08 to 4.64 g/hen per day improved egg production (71.2 vs. 74.9%; P < 0.001), egg mass (49.0 vs. 51.4 g; P < 0.05), and feed conversion ratio (2.43 vs. 2.30 kg of feed/kg of egg; P < 0.001). In addition, an increase in Ca intake improved shell weight (9.98 vs. 10.20%; P < 0.05), shell thickness (0.342 vs. 0.351 mm; P < 0.01), and shell density (82.0 vs. 83.8 mg/cm2; P < 0.001). Calcium source had no effect on productive performance, tibia characteristics, or egg quality except for shell density, which was greater for hens fed COA than for hens fed FIN, with hens fed OYS being intermediate (81.9 vs. 84.0 vs. 82.7 mg/cm2, respectively; P < 0.05). It was concluded that Brown egg-laying hens in the late phase of production require more than 3.5% Ca in the diet (4.08 g of Ca/hen per day) and that the substitution of 40% of fine LIM with COA or OYS does not affect productive performance and has little impact on shell quality and tibia characteristics.