Long-term application of clinoptilolite via the feed of layers and its impact on the chemical composition of long bones of pelvic limb (femur and tibiotarsus) and egg cortex

Selected 120 layers, hybrid breed Bovans Goldline, were divided into two balanced groups: control (C) and experimental (E) group. The layers were raised in three-floor cage technology with automatic watering, manual feeding, in the environment with regulated lighting and thermal schedule. The actual experimental period started in the 22nd week and ended in the 68th week of age of the layers. In the period following the filling of the cages the layers received complete feed mixture N1, subsequently, until the end of the experiment, they received feed mixture N2. The feed mixtures for Group C and E were of the same composition, with the only difference that the feed mixture designed for the experimental group contained 1% of clinoptilolite (commercial additive ZeoFeed) as a substitute for the same portion of wheat.. The layers consumed the feed mixtures and drinking water ad libitum. In the layers of Group E the intensity of egg laying increased by 1.1%, which corresponds to an increased number of laid eggs 3.08 per layer. The average weight of laid eggs was 66.3 ± 6.25 g in the layers of Group C, 65.6 ± 5.44 g (P ≤ 0.05) in the experimental layers of Group E. In Group E the consumption of feed mixture per one egg was 4.1 g lower when compared to the control. In 100% dry matter the eggshell of layers that received clinoptilolite (Group E), as opposed to Group C, had a statistically significantly higher (P ≤ 0.01) content of crude protein, calcium and magnesium. Almost the same and insignificant difference in values was found in ash and phosphorus. The values of the same indicators were statistically significantly higher in both monitored bones (femur and tibiotarsus) (P ≤ 0.05; P ≤ 0.01) during the application of clinoptilolite (Group E), with the exception of P in femur, where an insignificant rise in the level of P occurred. The rise in the concentration of Mg in Group E was of particular importance: in femur by 50.4%, in tibiotarsus by 32.4%. If we compare the monitored values in femur and tibiotarsus, we can see that the levels of ash, Ca and P are higher in tibiotarsus, and the levels of crude protein and Mg are lower. The long-term application of clinoptilolite favourably influenced the lodgement of Ca, P, Mg and crude protein in the eggshell as well as in the bones (femur, tibiotarsus), increased the egg production and reduced the consumption of feed mixture per one egg, while the good productive health of the layers was maintained.