PSI-41 Tibia attributes in aged Lohmann LSL-lite hens fed corn-soybean meal diet with different levels of calcium and 25-hydroxy vitamin D3.

Abstract

Among effective nutritional factors on bone dynamics in reproducing fowl, Ca and vitamin D are very important. We investigated the effect of different levels of Ca and 25-hydroxy vitamin D3 (25OHD3) on tibia characteristics in Lohmann LSL-lite layers from 74 to 81 wk of age. Four levels of Ca (3.0, 3.5, 4.0 and 4.5% of diet) and three levels of 25OHD3 (0, 69 and 138 µg/kg of diet) were tested with a basal level of 330 KIU of vitamin D3/kg. Eighty-four individually housed hens had free access to feed and water and were sacrificed at the end of wk 81 for tibia samples. Tibia ends (spongy bone epiphysis and metaphysis) were separated from diaphysis. The ends and diaphysis were longitudinally cut and medullary bone separated by scrapping. The ends, cortical and medullary sections were dried at 105°C for measuring percentage of dried weight (PDW) of each parts to the whole tibia. Dried sub-part samples ashed at 600°C for measuring total ash content (AC) and ash concentration (ACO) of each part of tibia. The inclusion of Ca had no effect on the PDW of sub-parts of tibia (P>0.05). Conversely, 25OHD3 linearly (P=0.014) increased PDW of medullary and decreased PDW of cortical (P=0.001). There was no (P>0.05) interaction effect between Ca and 25OHD3 or Ca levels on PDW, AC and ACO in medullary and cortical part. The main effect of 25OHD3 was such that medullary AC and ACO increased (P<0.01) by 33 and 15% in response to the highest level, respectively. In concomitant, cortical AC and ACO were decreased (P<0.05) in response to highest level of 25OHD3. In conclusion, Ca level had no effect on tibia attributes in late of egg production cycle. However, supplemental 25OHD3 increased medullary bone attributes (PDW, AC and ACO) at the expense of decreasing cortical bone attributes.