Influência dos níveis de cálcio e vitamina K na dieta de poedeiras na fase de recria e os efeitos sobre a fase postura

Abstract

Dietary supplementation of calcium (Ca) and vitamin K was studied in laying hens in the laying period. The effect of supplementation was evaluated in serum profile and bone quality of the birds at 18 weeks and later, the residual effect was evaluated in serum profile, bone quality and productive performance in birds at 32 weeks of age, during laying period. Thus, two experiments were conducted using two levels of Ca (0.8 and 1.4 %) and five levels of vitamin K (0, 2, 8, 16, 32 mg / kg) in the diet of Hy - Line laying hens. In Experiment I, 120 birds at 13 weeks of age were used and distributed in a completely randomized design, in a factorial arrangement (2x5), two levels of Ca and five levels of vitamin K, totaling ten treatments, four replicates and 3 birds per experimental unit. The birds were housed in galvanized cages with food and water at will and the experimental diets were provided from thirteen to eighteen weeks (laying period). In Experiment I, interaction between the levels of Ca and vitamin K to the total Ca in the blood, Seedor index, Ca in the bone and in the bone marrow was observed. At the level of 1.4 % of Ca, the total Ca variables in the blood, Seedor index, Ca in the bone and in the bone marrow showed a quadratic response (P < 0.05), compared to the levels of vitamin K. At the level of 0.8% of Ca, no differences (P > 0.05) were found for vitamin K supplementation. As for the level of 1.4 % of Ca, the highest values of total Ca in the blood, Seedor index, Ca in the bone and in the bone marrow were obtained with the supplementation of 17.86; 14.58; 14.48 and 16.80 mg / kg of vitamin K, respectively. In Experiment II, 80 birds at 20 weeks of age were used and fed during the laying period (13-18 weeks) with two levels of Ca (0.8 and 1.4 %) and five levels of vitamin K (0 were used, 2, 8, 16, 32 mg / kg), totaling ten treatments, four replicates and two birds per experimental unit. The birds received commercial feed for the period. For 3 cycles of 28 days, data on egg production and feed intake were collected. At 32 weeks, the serum profile was analyzed at 08h00 and at 16h00, the birds were slaughtered and the bones collected for analysis. In the blood and production variables effects of the treatment were not observed in the laying period (P > 0.05). Effect of treatments on the % of medullar bone (P < 0.05) was observed when birds were fed diets containing 1.4 % of Ca, for other bone quality variables, no significant effects were observed. The supplementation of a diet with vitamin K with 1.4 % of Ca in the laying period allowed an increase in the area of medullary bone that keeps during the production phase that was analyzed.