Effects of different levels of calcium and phosphorous on performance, immunity and percentage of hatching in Khorasan native hens

 One of the main problems in feeding native hens for optimal egg production is mineral deficiency, especially calcium sources. Calcium is present in the blood plasma and is part of the cells and tissues of the body and is essential for the activity of some enzyme systems involved in the transmission of nerve currents, muscle contractions and normal heart rate and also along with phosphorus to transfer fat to the yolk. This experiment was conducted to evaluate the effects of different levels of calcium and phosphorus on performance, immunity, characteristics of eggs, percentage of bone calcium and phosphorous and percentage of hatching in Khorasan province native hens.

A total of 200 native hens from Khorasan station were used in a completely randomized design (factorial experiment) with 4 treatments, 5 replicates. Experimental diets based on two levels of Ca (2.5 and 3.5) and total P (0.5 and 0.75) per percent of diet. The hens had free access to water and food during the experiment. Eggs were collected and weighed daily in each pen and its mean was recorded as its weight and number. At the end of the experiment, one hen was selected from each replication, slaughtered and after isolating the femur, the percentage of calcium and phosphorus was measured. Hemagglutination method was used to measure the antibody titer against SRBC. All data were analyzed using SAS software and the means were compared based on Tukey test.

The results showed that different levels and P did not show any effect on egg weight, egg production, egg mass, feed intake and FCR (P>0.05). Levels of Ca have significant effect on the egg production, so that the highest egg production, egg mass and feed intake was observed in the 3.5% Ca (P>0.05). The interaction of phosphorus and calcium significantly changed the performance indices except egg weight, and The best feed conversion ratio was observed in the group receiving 0.5% P and 3.5% Ca (P<0.05). Different levels of P did not show any effect on shell egg and thigh bone characteristics (P>0.05). Increased P had no effect on the hatchability, But calcium caused an increase 3-9 percent of hatchability during the test period (P<0.05). Increased calcium and phosphorus did not have any significant effects on immunity indexes (P<0.05).

Overall, the results of this experiment showed that the levels of 0.5% P and 3.5% Ca can be reported as levels of calcium and phosphorus requirement of laying hens native.