Abstract: SummaryThe aim of the study was to investigate the effects of different doses of acetylsalicylic acid (ASA) andsodium salicylate (SS) administration on weight gains and serum biochemical parameters in broiler chickens.This study was performed to investigate the safety of ASA and SS in chickens in conditions of moderateoverdose. Seventy five broiler chickens (Sanhuangji breed) were divided into control and experimental groups.The chickens were administered orally with ASA or SS in the following daily doses: 50, 100 and 200 mg/kg for20 days. In the course of the experiment weight gains were recorded. On day 14 and day 20 the chickens weresampled for blood biochemical analysis. Investigated parameters included serum total protein, albumin, uricacid, creatinine, potassium, sodium and calcium contents as well as alanine transaminase activity. After thelast samplings the chickens were dissected and liver and kidney to body weight ratios were recorded. It wasdemonstrated that SS at a dose of 200 mg/kg increased serum total protein level. ASA increased serumproteins at a dose of 100 mg/kg but not at a higher dose. At the dose of 200 mg/kg ASA increased the kidneyto body weight ratio. In all salicylate treated groups the liver weights were lower as compared to the control.No clinical manifestations of intolerance were observed. It is assumed that chickens tolerate ASA and SS well,even in doses producing distinct side effects in several mammalian species.Keywords: acetylsalicylic acid, sodium salicylate, weight gain, serum biochemistry, chickens

Abstract: Incidence and prevalence of lameness and their relationship to milk yield in high-yielding cows Summary The aim of this study was to present, on the basis of results of the conducted research, associations of clinical lameness with milk yield in cows Lameness in dairy cows is an important disease with a multifactorial etiology and represents one of the three most common health problems, after infertility and mastits Currently it is the reason for an increasing risk of culling in dairy cows, especially in high yielding herds The incidence of lameness was from 21% to 50% per 100 cows Some studies indicated that the incidence of lameness increases with lactation rank, while others do not state a significant effect of parity on lameness incidence The prevalence of lameness ranged from 5% to 246% The main factors influencing the prevalence of lameness in dairy cows include calendar season of the year, comfort of stalls, hoof trimming frequency and the presence of concrete floors The main causes of diagnosed lameness include sole ulcers (SU), white line diseases (WLD), interdigital necrobacillosis (IN) and digital dermatitis (DD) Results reported in literature indicate consider- able differences in the incidence of clinical lameness (CL) in dairy cows, from 21 to 50% This is associated with difficulties in its definition and identification in cows Many authors reported that CL is associated with decreased milk production by lame cows, especially in the initial period of lactation Some data indicate a reduced milk yield through lactation in clinically lame high-yielding cows, amounting to 574 for SU and 369 kg for WLD Cows culled due to foot disorders had daily milk, fat and protein yields significantly lower by 113, 141, and 164%, respectively Other authors found no association between lameness and milk yield, while some are of the opinion that this relationship occurs only during mid- and late lactation Several authors reported that the effect of claw and limb disorders on milk yield is not direct, since many factors influence milk production, eg feeding routine and nutrition The use of different statistical analyses in the elaboration of data may lead to different results