Effects of Various Calcium Levels and Anionic Salts on Blood Acid-Base Balance, Growth Performance and Development of Tibial Dyscondroplasia in Broilers


Abstract: The aim of this trial was to investigate the effects of chlorine and phosphate salts in the diet, and 2 different levels of diet Ca,on the acid-based balance,growth performance and development of tibial dyscondroplasia (TD)in broiler chicks. Three hundred Ross X PM_3, 1-day-old broiler chicks were used during the 5-week trial.Chicks were divided into 6 groups. Three groups (2 experimental and 1 control)were given diets with Ca levels near the bottom limit of the normal requirement (starter 0.90%and grower 0.80%)and 3 groups (2 experimental and one control)were given diets with higher Ca levels (starter 1.25%and grower 1.15%). No anionic salt was added to 1 of the diets,while the other 2 were supplemented with 100 meq/kg DM CaCl_2 .2H_2O or CaHPO_4 .2H_2O. All the chicks were weighed individually at the beginning of the trial and once per week from then on.Weekly feed consumption of the chicks was recorded. At the end of the 3rd and 5th weeks,from each group 10 chicks were randomly selected and blood samples collected in order to determine the blood pH,pCO_2 ,HCO_{3}^- and N^+ , K^+ and Cl^- levels. A blood gas measurement device was used for this purpose. Subsequently, the right and left tibias were removed in order to check for TD and determine bone ash levels,respectively. The results of the trial indicated that the live weight gain of chicks on a lower Ca diet,except group 2 which was supplemented with Cl,was higher than that of chicks on a higher Ca diet.Cl reduced and PO_ 4 increased the live weight gain of chicks (P<0.05). When compared to that of broilers in the control group, the addition of PO 4 to the diet increased the feed consumption of the chicks.It was also recorded that the FCR was better in chicks on a lower Ca diet, except group 2 (low Ca +Cl), than in chicks on a higher Ca diet.Results of blood analysis showed that the addition of Cl reduced the HCO_{3}^{-} level in the blood. Groups which received additional Cl in their diets had higher levels of Cl in their blood than the other groups. Bone ash analysis revealed that addition of Cl to the diet decreased the amount of bone ash (p<0.05). The addition of Ca to broiler diets reduced the incidence and the severity of TD; however,Cl and PO_4 supplementation increased both the incidence and severity. It was concluded in this trial that the levels of anionic salts and Ca in the broiler diets have a direct influence on the growth performance and development of TD in broiler chicks,and therefore diet Ca levels should be calculated to prevent the formation of TD and not cause any growth performance losses.

Keywords: Broiler,Calcium,Anionic Salts,Blood Acid-Base Balance,Growth Performance,Tibial Dyscondroplasia

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