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Changes in the mineral composition of uterine fluid during shell formation and the rates of color appearance and porphyrin deposition on the shell were measured in two subpopulations of brown egg-laying hens with familial histories of low or high incidences of shell whitening. Increases in shell weight and shell breaking strength were correlated with, and proportional to, time spent by the egg in the uterus and were similar in both subpopulations. Shell reflectance decreased and the amount of porphyrin deposited increased linearly 20 to 24 h after oviposition of the preceding egg. Porphyrin deposition was slightly higher at the 23-h stage in the high whitening population but similar amounts of porphyrin were deposited on the shell during the final stage of shell formation in both groups. The coating on the shell responsible for whitening was deposited during the hour prior to oviposition. Uterine fluid pH, pCO2, bicarbonate, and ionized Ca concentrations changed during shell formation but these changes were not related to the incidence of whitening. A milieu supersaturated with calcite solubility product was observed whatever the stage of shell formation. Inorganic phosphorus was not detectable in the uterine fluid whatever the stage of shell formation. The soluble phosphorus fraction of uterine decreased 22 h after oviposition and phosphorus deposition on the shell increased. At the end of egg formation uterine fluid could not be collected. It was concluded that shell whitening was associated with changes in the kinetics of porphyrin deposition rather than with changes in the amount of porphyrin deposited or modifications of uterine fluid composition.

Basketball players usually score points during the game using the jump shot. For this reason, the jump shot is considered to be the most important element of technique in basketball and requires a high level of performance. The aim of this study was to compare the biomechanical characteristics of the lower limbs during a jump shot without the ball and a countermovement jump without an arm swing. The differences between variables provide information about the potential that an athlete can utilise during a game when performing a jump shot. The study was conducted among 20 second-league basketball players by means of a Kistler force plate and the BTS SMART system for motion analysis. The variables measured included the take-off time, mean power, peak power, relative mean power, jump height, maximum landing force and calculated impact ratio. Surprisingly, more advantageous variables were found for the jump shot. This finding suggests a very high performance level in the jump shot in the studied group and a maximum utilisation of their motor abilities. Both types of jumps were characterised by high mean and peak power values and average heights. The high forces at landing, which result in considerable impact ratios, may have prompted the studied group to land softly. Use of the countermovement jump without an arm swing is recommended to assess and predict the progression of player’s jumping ability.

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