Effect of sexual and seasonal differences in faecal steroid analysis in birds: optimalization of sample collection ZS. SZİKE*, É. VÁRADI, B. VÉGI, P. PÉCZELY 2 , J. BARNA Research Institute for Animal Breeding and Nutrition, 2100 Gödöllı, Isaszegi u. 200., Hungary 2 :Szent István University, Lab of Reproductive Biology, 2100 Gödöllı, Páter K. u.1., Hungary *Corresponding author: szoke@katki.hu In the last decade many attempts were made on faecal steroid analysis, as a non-invasive method. Birds’ faeces contain metabolites of steroid breakdown eliminated both from the intestines and the kidneys, resulting in a special situation. For the precise analysis determination of the passage time of fodder in studied species is the first step. In mallards, intestinal passage time of marked (coloured) fodder and testosterone (T) turnover were examined by faecal steroid analysis in the reproductive and postrefractory period. In the latter, the discharge of coloured fodder began 36 and 56 minutes after ingestion in males and females, respectively. During reproduction period the discharge began later, 93 and 112 minutes after ingestion in males and females, respectively. The differences between sexes and seasons were significant. Total passage time was similar in both periods and sexes. Knowledge of the frequency of defecation is also advisable. In postrefractory period the frequency of defecation of males (16,0±2,72/ 8 hours) was higher than that of females (13,5±1,20/ 8 hours, p=0,01), however, in reproductive cycle in this respect there were no differences between sexes (9,48±1,48/ 8 hours in males and 11,2±3,11/ 8 hours in females). Following intraperitoneal T injection, faecal samples had been collected for 8 hours and T levels were measured using RIA. In the postrefractory period, there were no significant differences in T levels between sexes. The first T peaks appeared at 1-2 hours, the second one at 2,6-3,3 hours after loading.. During reproduction period in females the T excretion was similar to the data of postrefractory period, while in males the peak values were shifted to the autumnal values. In females, a slighter T peaks appeared in both periods. The duration of response to T loading was about 5 hours in both periods and sexes. For an optimal sample collection it is important to have control values, to collect samples always at the same time, to know the frequency of defecation, the passage time and seasonal and sexual differences as well. Keywords: faecal steroid analysis, passage time, sexual-, seasonal differences, mallard Introduction Non-invasive hormone measures must be carefully validated for the effective research and analyses. Validity is especially important for the endangered species (indigenous domestic animals as well). In mammals, faecal hormones measures have been extensively validated (Wasser and Hunt, 2005). The biological equivalence of faecal steroids is different in mammals and birds. In case of mammals there are two possible forms of excretion: bile-chimus-faeces axis and urine (Shires et al, 1987). In birds - being vertebrates with cloaca, faeces contains metabolites of steroid breakdown eliminated both from the intestines and the kidneys, resulting in a special situation. In mammals one of the basic problems is the different excretion ratios of certain steroid metabolites into urine and faeces (Sturkie, 1976), and in addition, relatively to urinal excretion, chimus-faeces excretion routes can show a considerable delay in mammals.