The use of a complex lighting schedule consisting of five blocks of light and five alternating periods of darkness every 24 h completely abolished the normal pattern of egg-laying characteristic of the domestic hen. Animals tended to lay continuously and not in clutch sequences. Ovipositions were not restricted to an 8- to 10-h period of the day, instead they occurred at any time of the solar day with slightly more occurring during the hours of darkness. The preovulatory discharge of LH was not restricted to an 8- to 10-h 'open period' and the interval between the peak values of LH in the plasma and the time of lay of the corresponding egg was 32.3 h, i.e. identical to the interval found using a normal lighting schedule of 14 h light: 10 h darkness. There were some indications that minor fluctuations in the concentrations of LH in plasma occurred rhythmically with the changes in illumination, but the concentrations of progesterone showed only a single, preovulatory peak. The concentrations of corticosterone in the plasma were high and showed marked fluctations but this did not appear to affect either the levels of progesterone or the time of ovulation.
Two experiments were conducted to determine the relationship between thawing temperature and the type of straw in which chicken semen was frozen. In Experiment 1, semen was frozen in three different types of plastic straws: US (.5-ml capacity), French (.5-ml capacity), and French mini (.25-ml capacity). Experiment 1 was divided into two trials to compare semen packaged in the different straws and thawed at 15 (Trial 1) or .5 C (Trial 2). Although there were distinguishable features of the freeze and thaw curves between samples frozen in the different straws, the type of freeze straw had no effect on the fertilizing capacity of frozen semen when thaw temperature was held constant: fertility, Days 2 to 4 after artificial insemination, ranged from 16 to 27% for Trial 1 and 45 to 47% for Trial 2. In Experiment 2, semen was frozen in US straws and thawed at either .5 or 15 C to assess the effect of the thaw temperature. Fertility of frozen semen, Days 2 to 4 after artificial insemination, was significantly higher when semen was thawed at .5 than at 15 C (62 vs. 20%).
The object of this study was to evaluate the effects of extender osmotic pressure (251, 332, and 434 mOsm), extender pH (6.5, 7.0, and 7.5), extender fructose concentration (0, 2.5, 5, and 10 g/liter), and diluting prior to freezing to a constant sperm number (.5, .8, 1, or 2 X 10(9) sperm/ml) on the fertilizing capacity of processed-unfrozen and frozen-thawed chicken spermatozoa. Fertilizing capacity of processed-unfrozen spermatozoa was not affected by changes in extender osmotic pressure, pH, or fructose concentration; it was significantly depressed, Days 2 to 4 postinsemination, by diluting to 5 X 10(9) sperm cells/ml, whereas all other dilution rates had little effect. Fertilizing capacity of frozen-thawed spermatozoa was highest (42 to 51%, Days 2 to 4 postinsemination) when diluted in an extender containing 5g/liter of fructose with an osmotic pressure of 332 mOsm and a pH of either 7.0 or 7.5. Fertility (51%, 2 to 4 days after insemination) obtained with frozen-thawed semen diluted to 1 X 10(9) sperm cells/ml was significantly higher than all other dilutions. The fertilizing capacity of frozen-thawed spermatozoa was generally lower than that of processed-unfrozen spermatozoa regardless of the experimental treatment.
Trois expériences mesurent les effets du gossypol, administré par voie alimentaire, sur la reproduction des coqs et de poules adultes de souche ponte ou chair. Le premier essai a porté sur 128 poules et 45 coqs pubères; il ne montre aucun effet de doses alimentaires inférieures ou égales à 400 ppm de gossypol libre sur la consommation alimentaire, la ponte, la production et la motilité du sperme, la fécondité et l'éclosabilité des oeufs incubés. Les deux essais suivants ont servi à tester l'effet d'une concentration alimentaire de 800 ppm de gossypol libre sur respectivement 10 coqs reproducteurs de souche chair âgés de 82 semaines et rationnés et 12 coqs reproducteurs de souche ponte âgés de 29 semaines nourris ad libitum. A cette dose (environ 20 mgkg PV/j) le glossypol libre a diminué la consommation alimentaire, le poids des animaux et des testicules des coqs de souche ponte et fait augmenter la proportion de spermatozoïdes anormaux dans les éjaculats des coqs de souche chair.
Trois expériences mesurent les effets du tourteau de coton sur les performances des coqs et poules reproducteurs : fertilité, intensité de ponte, poids de l'oeuf, croissance des jeunes. Les effets négatifs du tourteau de coton s'expriment plus nettement sur les capacités de reproduction des poules que sur celles des coqs, mais l'action propre du gossypol mérite des analyses complémentaires pour pouvoir être dissociée des effets multiples causés par d'autres facteurs limitant la consommation ou la digestibilité du tourteau de coton entier.
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