The Effect of Adding Oxalic Acid and Phytic Acid to The Diet of Poultry on Calcium Contents of Eggshells
Data of thirty White Leghorn laying hens average 154 days of age were used in a study to evaluate the effect of adding either 0.2, 0.5 and 0.8% oxalic acid (Oa) or 1, 2, and 3% phytic acid (Pa)to the diet upon the quantity of calcium (Ca) deposited in the eggshell. Five hens were randomly assigned to each of six group groups. Data were collected for 48 hours periods at the beginning and end of a seven day feeding period for two week. Numerical data collected included milli gram (mg) of calcium per gram (g) of eggshell (Es) and per egg, weight of oven dried eggshell, average daily feed intake, body weight change, and weight of egg yolk and albumen. No significant changes were noted for quantity of Ca per g of Es for either type of acid fed for the final 48 hr period.
It was observed that initial to final period hens receiving Oa 0.2, 0.5 and 0.8% in their feed had significant reduction of Ca per egg of 256, 195 and 116 mg, respectively. As the percent Oa was increased in the diet, a reduction of Ca per egg occurred (P<0.05). This change was not found when adding Pa to the diet. Hens receiving 1, 2, and 3% Pa had found mean increased of 328, 214 and 347 mg of Ca per Es. When combing the data of all levels of acid within a chemical treatment groups, those hens receiving Pa had significantly more Ca change per Es than those receiving Oa. The group receiving Oa had mean Ca increases per egg 176 mg and those receiving Pa had 297 mg (P<0.05). The highest percent of each chemical additive induced a significant depression of feed intake (P<0.05). In conclusion, adding Oa or Pa to the feed of hens had no significant effect on Ca content of eggshells during the final 48 hr period, however hen receiving Oa did have a reduction in Ca contents/Es from the initial to final period. As the quantity of Oa was increased in diet the Ca/Es decreased however, this level of effect was not found in groups receiving Pa. High percentages of each acid did decrease feed consumption. No significant effects were observed on body weight change, egg yolk, or albumen.
Key words: Eggshell, oxalic acid, phytic acid, calcium.