J. P. Brillard

Possible causes of subfertility in hens following insemination near the time of oviposition

Spermatozoa incubated in uterine fluid collected 7 or 18 h after ovulation showed no significant differences either in motility or in fecundity, despite wide variations of composition of the uterine fluid itself. The absence of uterine fluid in the oviduct 1 h before oviposition may be partially responsible for spermatozoa being unable to migrate easily to the storage sites after insemination of this time. Females inseminated intravaginally at the presumed time of oviposition showed consistently low fertility, irrespective of whether an egg was present in the uterus or not. Normal fertility rates could be achieved with inseminations intravaginally at or near the time of oviposition if the uterine contractions associated with oviposition were inhibited by treatment with indomethacin. Hens inseminated intravaginally 1 h after oviposition retained lower proportions (0.4 to 0.7%) of the initial dose of spermatozoa (measured 2 h after insemination) in their oviduct that hens inseminated 5 to 6 h after oviposition (4.5 to 23.3%).

Comparison of various characteristics of duration of fertility in hens.

1. Maximum duration (Dm, number of days post-insemination until last fertile egg) and efficient duration (De, number of days post-insemination until first infertile egg) of fertility, number of fertile eggs (F), dead embryos and hatched chicks (H) during the 21 d following the latter of two intravaginal inseminations (with 125 x 10(6) spermatozoa) on two consecutive days were measured in a total of 2549 layer-type hens at three ages (starting at 30, 44 and 55 weeks of age). 2. De and Dm were highly correlated (0.46 less than or equal to r less than or equal to 0.67). Both De and Dm were also well correlated with F (0.45 less than or equal to r less than or equal to 0.80) and H (0.45 less than or equal to r less than or equal to 0.76) whereas correlations between numbers of dead embryos and other variables were very low and often not significant (0.04 less than or equal to r less than or equal to 0.29). 3. The highest repeatabilities between hen ages were observed for F (0.34 less than or equal to r less than or equal to 0.49) and H (0.36 less than or equal to r less than or equal to 0.48) and the lowest for numbers of dead embryos (0.02 less than or equal to r less than or equal to 0.28). 4. Because of low fertility 18 d after insemination, the period over which measurements were made could have been reduced by 3 d without significant differences in the ranking of the females. 5. The number of perivitelline spermatozoa found in eggs laid on day 2 is not a good predictor of duration of fertility but could allow the culling of hens associated with lowest De or Dm.

Effect of photoperiod on plasma concentrations of luteinizing hormone and testosterone and on semen output in turkey breeder males

dietary zinc: tissue zinc accumulation and reproductive organ weight changes. Poultry Science, 63: 1207–1212. CORMICK, C.C. & CUNNINGHAM, D.L (1987) Performance and physiological profiles of high dietary zinc and fasting as methods of inducing a forced rest: a direct comparison. Poultry Science, 66: 1007–1013. JOHNSON, A.L. & BRAKE, J. (1992) Zinc-induced molt: evidence for a direct inhibitory effect on granulosa cell steroidogenesis. Poultry Science, 71: 161–167. ZIMMER MANN, N.G. & ANDREWS, D.K. (1990) Performance of leghorn hens induced to molt by limited feeding of diets varying in nutrient density. Poultry Science, 60:1883– 1891.

Effect of photoperiod on testicular development and on quantitative characteristics of spermatogenesis in breeder male turkeys

concentration were obtained in Mantovani et al.’s (1993) study of pheasants caged in a controlled environment (18°C–20°C and 14L:10D). With regard to spermatozoa vitality and morphology, the means did not differ significantly throughout the reproductive season. A decreasing trend was found for immature spermatozoa during the study and a negative simple linear regression was calculated between percentage immature spermatozoa and experimental days (Y =10·07–0·029x; P<0·05). Immature spermatozoa are considered spermatozoa when the residual cytoplasm is still attached to the posterior end of the nucleus (Wakely and Kosin, 1951). In accordance with Wakely and Kosin’s (1951) study on turkeys, the presence of immature spermatozoa in ejaculates could indicate more intense sexual activity. In the pheasant, the immature spermatozoa were noted most frequently in April, when males of this species increase the frequency of the mating behaviour. The semen production of the pheasant is strongly age-related at least in temperate environmental conditions. Semen parameters and trends appear similar in pheasants reared in the open air or in the above-mentioned controlled environment. In April–June, i.e. for 8–10 weeks of the natural reproductive season, the quantitative and qualitative semen production of males subjected to manual collection of sperm seem beneficial for fertility. This period is perfectly synchronized with female reproductive activity characterized by the highest rate of egg production.

Females of birds and hymenoptera: Two complementary strategies for in vivo spermatozoa storage and fertilisation

The reproductive strategies developed by insects are extremely diverse. For example, their spermatozoa can be heteromorphic, such as in Lepidoptera diptera, in which several types of spermatozoa are simultaneously produced and transferred by a single male. In other species, such as Homoptera diptera, spermatozoa are much longer than the male or female’s body. Moreover, depending on species, the number of sperm available to fertilise one ovum may vary from millions (as in most vertebrates) to a few individuals. At extremes, the populations of sperm and eggs available may be very close to each other (numerical isogamy) (Bressac et al., 1994). The adaptive functionality of the insect spermatozoon should therefore be perceived as an uncommon feature of the animal world which strongly contrasts with the relative homogeneity of vertebrates for this specific trait. One of the fundamental similarities developed by both birds and insects is the prolonged storage of spermatozoa in the female tract. In both cases, spermatozoa transferred by the male are stored in specifically adapted sites called spermatheca (insects) or sperm storage tubules (SST) (birds). After mating once or several times, insects store spermatozoa for a lifetime (e.g., depending on species, from some days to several years). Similarly in a number of avian species, spermatozoa, once deposited intravaginally in the female tract, may maintain their fertilising potential for an entire reproductive season. In both cases, sperm competition (which may result from multiple matings) occurs just before (avian species) or directly within (insects) the storage sites. Hymenoptera (bees, wasps, ants, parasitoids, etc.) have an original reproductive system called arrhenotoquous parthenogenesis, in which females arise from the fertilisation of one ovum by a single spermatozoon whereas males are directly produced by the development of a haploid ovum. This means that the conditions of sperm release from the spermatheca play a key function in ultimately determining the sex ratio of the offspring. As a consequence, the number of daughters is a precise indicator of the functionality of sperm release. Thus in two parasitoid wasps (Eupelmus orientalis and Dinarmus basalis ) fertilised in experimentally controlled conditions, a quantitative analysis of spermatozoa used after a single mating was conducted to assess the population of spermatozoa involved at each of the reproductive stages (produced by sexually mature males, transferred to females, stored by females or used at different times after oviposition). In both species, the number of spermatozoa stored in the female tract was limited (100–800/female) and their release was gradual over reproductive life. A comparison of these two species indicates that Eupelmus orientalis does not use the entire population of stored spermatozoa (Bressac & Chevrier, 1998)while Dinarmus basalis had already exhausted their sperm stocks at half of their reproductive life and therefore produced uniquely males during the second half. From this standpoint, birds appear closer to Eupelmus orientalis than to Dinarmus basalis. Indeed, in avian species already studied (fowl and turkey), after intravaginal deposition in large numbers (several hundred million) in the oviduct, spermatozoa undertake a severe process of selection before prolonged storage in the SST (Brillard & Antoine, 1990; Brillard & Bakst, 1990; Brillard, 1993). Ultimately, a minimum number of 600 (turkey) to 2000 (fowl) spermatozoa must be present at the fertilisation sites (infundibulum) to ensure 100% fertilisation (Table). This example provides some

Estimation of fertilizing ability of fowl spermatozoa by in vivo and in vitro tests

56: 1216–1220. CEROLINI, S., KELSO, K.A., NOBLE, R.C., SPEAKE, B.K., PIZZI, F. & CAVALCHINI, L.G. (1997) Relationship between spermatozoan lipid composition and fertility during ageing in the chickens. Biology of Reproduction, 57: 976–980. KELSO, A.K., CEROLINI, S., SPEAKE, B.K., CAVALCHINI, L.G. & NOBLE, R.C. (1997) The effects of dietary supplementation with a -linolenic acid on the phospholipid fatty acid composition and the quality of spermatozoa in the cockerel from 24 to 72 weeks of age. Journal of Reproduction and Fertility, 110: 53–59. MCMURRAY, C.H., BLANCHFLOWER, W.J. & RICE, D.A. (1980) Influence of extraction techniques on the determination of a -tocopherol in animal feedstuffs. Journal of the Association of Official Anayitical Chemistry, 63: 1258–1261. SURAI, P. (1992) Vitamin E feeding of poultry males. Proceedings of the XIXth World Poultry Congress, Amsterdam, Vol. 1, pp. 575–577.