Effects of dietary calcium levels and limestone particicle size on the performance, tibia and blood of laying hens

Abstract

A total of 405 23-week-old ISA ® Brown layers were distributed in a completely randomized experimental design in a factorial arrangement with nine treatments consisting of three dietary calcium levels (3.5, 3.75, and 4.5%) and three limestone particle sizes (100% fine limestone (FL), 70% FL + 30% coarse limestone (CL) and 50% (FL) + 50% (CL)), with nine replicates of five birds per cage. The following parameters were evaluated: percentage of lay, defective eggs, egg weight, egg mass, feed intake, feed conversion ratio (per kg eggs and per dozen eggs), and mortality. Dietary Ca levels significantly affected lay, with birds fed diets containing 4.5% calcium producing less eggs as compared to those fed 3.0 and 3.75% Ca. Egg production linearly decreased as dietary Ca levels increased, but blood Ca levels (mg/L) increased in 28-week-old birds. The interaction of dietary Ca levels and limestone particle sizes resulted in a reduction in tibial ash Ca content as dietary Ca levels increased and as fine limestone was replaced by coarse limestone. It is concluded that a dietary Ca level of 3.75% and 100% fine particle limestone are required to maintain adequate egg production and available Ca blood level. INTRODUCTIONCalcium is the mineral with the highest concentration in the body of poultry, consisting of 1.5% of its body weight. It is more than one third of total mineral body content of an adult bird (Klasing, 1998) and represents one third of eggshell components.During lay, structural bone loss (medullary and cortical) and the subsequent development of osteoporosis are associated to the medullary bone. Medullary bones in females are shaped in response to estrogen. The role of these bones in mineral homestasis is more important than their structural skeletal function, and it is associated to bone mineralization and eggshell formation. Studies on layer skeleton using fluorochrome (Cransberg et al., 2001) showed that there is no formation of medullary or cortical bone during eggshell formation; only the shape of medullary bones are changed. However, the high mobilization of minerals for eggshell deposition may result in osteoporosis and consequently, in bone fragility.Calcium has an essential role in nutrition and calcium turnover determines the optimal calcium level for bone formation, including the tíbia, but the relationship between calcium turnover and the development of osteoporosis is still not clear (Cransberg et al., 2001

Effects of dietary clinoptilolite and calcium levels on the performance and egg quality of commercial layers

“…Feed intake was not influenced (p>0.05) by dietary clinoptilolite or calcium levels. Consistent and contradictory results have been reported in literature (Nakaue e Koelliker, 1981;Roland, 1988;Roland et al, 1991;Frost et al, 1992;Shariatmadari, 2008;Pelícia et al, 2011). The reported differences may be due to the use of different layer genetic strains as well as different Table 2 -Egg production (EP), intact eggs (IE), egg weight (EW), egg mass (EM), feed intake (FI), feed conversion ratio per dozen eggs (FCR/dz) and per kg eggs (FCR/kg) of layers fed diets with different clinoptilolite (CLINO) and calcium (Ca) levels.…”

Effects of dietary clinoptilolite and calcium levels on uric acid and calcium blood concentrations and bone quality of commercial layers

“…Feed intake was not influenced (p>0.05) by dietary clinoptilolite or calcium levels. Reviewing the literature, there are different and consistent results relative to our findings (Nakaue & Koelliker, 1981;Roland, 1988;Roland et al, 1991;Frost et al, 1992;Shariatmadari, 2008;Pelícia et al, 2011). The contradictory literature reports may be due to the use of different layer genetic strains as well as different zeolite and calcium levels and sources applied in the diets.…”

“…Based on feed intake, it was calculated that calcium intake ranged between 2.96g/hen/day for layers fed the lowest calcium level and 4.34g/bird/day for those fed the highest level. Pelícia et al (2011), working with 3.0-4.5% calcium levels in semi-heavy layer diets at the end of the first laying cycle, also did not observed any differences in calcium blood level, although calcium intake linearly Berto dA, Garcia EA, Vercese F, Santos GC dos, Barreiro FR, Molino A de B, Pelícia K, Silveira AF da…”

Effects of Different Dietary Calcium Levels on the Performance, Egg Quality, and Albumen Transparency of Laying Pigeons

“…Low dietary Ca levels for laying poultry affect egg production and are an issue that is recognized by researchers [21,22]. Some research has also stated that a high Ca diet of 5% has no effect on egg production [23], while other studies have shown that high dietary Ca inhibits egg production in laying hens [12,24]. Based on our study, we hypothesize that too high or too low levels of dietary Ca will both affect egg production and that the optimal dietary Ca level is 1.23%.…”