Effect of different ratios of calcium and available phosphorous on growth performance, laying performance, and egg quality in layer chickens

Calcium and phosphorus are considered to be the major macro-minerals in layer diets, due to their expressive contribution to the metabolism in birds and the quality of the eggs. Those two minerals are closely related in a such that a deficiency in one can interfere with the proper utilization of the other. However, few studies have been conducted to evaluate the requirement of Ca and P along with the correct synergy between them in layer diets. Therefore, the current study compared the different percentage ratios of Ca and available P on the growth, productive performance, and egg quality of Hy-Line Brown^® hens.

One hundred and eighty, 40-week-old Hy-Line Brown® hens (1798±10.012 g) were randomly allotted into one of five dietary treatments with six replicates per treatment (six hens per cage). The dietary treatments were formulated to obtain five different percentage ratios of Calcium and available Phosphorous (Ca:P %) as; 1) 80 CaP (3.12:0.25 %); 2) 90 CaP (3.51:0.28 %); 3) 100 CaP (3.90:0.31 %); 4) 110 CaP (4.29:0.34 %); and 5) 120 CaP (4.68:0.37 %). Birds were fed on a restricted basis (110 g/hen/day; according to the Hy-Line Brown^® management guide). The body weight of birds was recorded biweekly, and feed intake along with egg production parameters were measured weekly basis. The feed conversion ratio (per dozen of eggs) was calculated weekly. The egg quality parameters were determined in the third week of the experiment.

Dietary effects were not found (P> 0.05) in response to the body weights and FCR of layers. However, “120 CaP” markedly improved (P< 0.05) body weight and feed efficiency compared to other treatments. A numerical improvement (P< 0.05) in the hen-day egg production was reported from the hens fed “120 CaP” in week 41, 43, and 44. Nonetheless “90 CaP” substantially improved (P< 0.05) the egg mass at week 43.

Moreover, egg quality parameters were not affected (P< 0.05) by the dietary treatments while “80 CaP” numerically improved the egg weight (64.49 g; p< 0.05). Layers fed “100 CaP” were reported to have markedly higher (P< 0.05) albumen height and Haugh unit compared to its counterpart diets (12.33 mm and 108.08 HU, respectively). In addition, “110 CaP” fed birds produced thick and stronger-shelled eggs (P< 0.05) while “120 CaP” numerically improved (P< 0.05) shell colour (29.08) and yolk colour (7.17) compared to other dietary treatments

Supplementing different percentage ratios of Ca and available P to diets did not cause significant changes in growth performance, egg production performance and egg quality of layers up to 44 weeks, which indicates “80 CaP” could be used in reduced-cost diets without impairing the performance of Hy-Line Brown^® layers.

     

Key words: calcium, egg quality, growth performance, laying performance, phosphorus.