Abstract
Abstract. The influences on eggs of high temperatures and age were examined in hens that were from a poultry farm situated in the south of the Republic of Macedonia where the average summer temperatures were always the highest. The experiment lasted for 9 months and comprised a period of three seasons: summer, autumn and winter. Maximum and minimum temperatures and relative humidity were recorded every day. Layers were of two different ages. During the research, all production parameters were recorded for the flocks: egg production, mortality, feed-consumption, body weight and the percentage of broken and cracked eggs. Once a month 50 eggs out of each age group were examined. An analysis of egg mass, eggshell mass and percentage of calcium carbonate in the eggshell was performed. At the end of the research the results underwent statistically analysis according to the Least Squares Means method. High temperatures in the region had a highly significant influence (<0.01) over egg size, which was smaller than the average. The heat stress showed high significance (<0.01) in relation to the percentage of calcium carbonate in the egg shell, which was lowest in the summer months and highest during the winter months. The age of the layers did not exhibit significant differences in any parameter examined. The percentage of broken and cracked eggs per month was highest in the summer period.
Highlights
Eggshell quality is a major concern in the egg industry
With Japanese quails the values of some blood parameters, egg productivity, egg weight and eggshell thickness were found important statistically lower at high environmental temperature (OZCELIK and OZBEY, 2004)
Egg mass depends of hereditary traits, hen age, season and feed consumption (STADELMAN and PRATT, 1989; MACHAL and SIMEONOVOVA, 2002)
Summary
Eggshell quality is a major concern in the egg industry. Low egg quality almost leads to a 5-8 % loss in production (KESHAVARZ, 1994). Shell quality in the egg is one of the major problems of egg production. Maintaining quality eggshells throughout the production cycle is desirable. Many factors have been found to affect eggshell quality, such as disease, nutritional status of the flock, heat stress and age (ROBERTS, 2004). The decline in eggshell quality as the hens’ age may in part be attributed to reduced intestinal calcium uptake as well as to increased egg size (AL-BATSHAN et al, 1994). The aim at the present study was to determine the influence of hens’ age and high temperatures on the eggshell quality
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