Effect of the Dietary Electrolyte Balance on the Productive Performance of Laying Hens and on the Quality of the Eggs

A trial was conducted to study the effect of two dietary electrolyte balances (dEB, dEB=Na+K-Cl, meq/100g) on the productive performance, quality of eggs and physiological status of Hy-Line Brown laying hens. 128 hens were allocated in cages (4 hens/cage) and divided into two experimental groups (16 repetitions/group). The diets were isoproteic and isocaloric with different electrolyte balance fed ad libitum during the first 15 weeks of laying. The first group was fed with the dEB1 diet (17 meq/100 g), the second group received the dEB2 diet (25 meq/100g). Data of health conditions, feed intake, percentage of laying, mean egg weight, number of cracked and rough eggs were recorded daily. Every four weeks live weight and egg quality parameters were checked. At the end of the trial the hens were submitted to blood sampling for metabolic, enzyme and mineral plasma profile. The hens of the two groups had similar final body weight, feed intake and feed:egg mass ratio. Laying percentage and egg mass weight were higher (P<0.01) in the dEB2 group compared to the dEB1 hens. The percentage of cracked and rough eggs were similar between the groups. The dietary electrolyte balance did not influence egg weight, percentage of yolk, albumen, and shell. The dEB1 and dEB2 eggs had similar albumen height and Haugh Units. The dEB2 hens produced eggs with higher (P<0.01) values in eggshell thickness and yolk colour. The metabolic profile of the hens was not affected by the diets, as plasma glucose, cholesterol, triglycerides and total proteins presented similar values. Plasma levels of ALT (alanine-aminotransferase), AST (aspartate-aminotransferase), -GT( glutamyltranspeptidase) and LDH (lactate dehydrogenase) did not change with the different electrolyte balance. Also the mineral profile was similar as calcium, phosphorus, sodium, potassium, magnesium and chloride had similar values between the groups. The data shows that a dietary electrolyte balance of 25 meq/100 g compared to a 17 meq/100 g one is able to improve the productive performance and the eggshell thickness without altering the metabolic, enzyme and mineral plasma profile during the first period of laying.