Onset Of Semen Production Research Articles

Fertility preservation in young patients before allogeneic haematopoietic SCT

As the long-term survival rate of patients receiving HSCT increases, quality of life issues, including the possibility to parent children, deservedly gain ever more attention. We therefore fully endorse the authors’ appeal for fertility preservation in this patient group, and appreciate their efforts to raise awareness of this issue in the medical community. We would like to take the opportunity to emphasise that the options for fertility preservation for this group are restricted. To illustrate this notion we would like to supplement their paper with a brief discussion of the available options. For male patients, fertility preservation is relatively easy, provided that their HSCT starts after puberty, that is the onset of semen production. Semen cryopreservation is a readily available option that can be offered in practically every fertility centre and can be performed with no or hardly any delay in the treatment. For pre-pubertal boys, unfortunately, there are to date no options. The cryopreservation of spermatogonial stem cells with the aim of retransplanting them after cure resulting in the initiation of spermatogenesis, is currently being investigated. 2 For female patients the situation is more complicated. Considering the young age of most patients, emergency in vitro fertilisation followed by cryopreservation of the generated embryos will in the majority of cases not be an option, as this requires a stable relationship with a male partner. The cryopreservation (by means of vitrification) of oocytes is the next logical alternative. This option is suitable for postpubertal girls and requires hormonal ovarian hyperstimulation to increase the number of mature oocytes that can be obtained. 3 Depending on the number of oocytes one wishes to obtain, one or more cycles of hyperstimulation may be required. As a consequence, treatment will have to be postponed for at least 14 days or up to several months. It should be determined for each patient individually what period of postponement of the treatment is acceptable. In prepubertal girls, or in those cases where delay of the treatment is not advisable, immature oocytes may be obtained and vitrified. These oocytes have to be matured in vitro ,b efore they can be used for fertilisation at a later stage of life. To the

Effect of Photoperiod and Quantitative Feed Restriction in a Broiler Strain on Onset of Lay in Females and Onset of Semen Production in Males: a Genetic Hypothesis

The effects of feed restriction and photoperiod on body weight (WTSXM) and age (ASXM) at onset of mature semen production in males and onset of lay in females of a broiler female line were examined. Feeding treatments were as follows: ad libitum (AL) and quantitative feed restriction (QR). Photoperiod treatments were as follows: open shed (OS), in which the chicks were reared under naturally increasing daylight with supplemental light; dark room (DR), in which chicks were reared under short days, gradually increasing from 6 h of light (L) to 11.5L; and dark room to open shed (DR-OS), in which chicks reared under short days in the dark room were transferred to the open shed at 149 d. Treatment effects were similar in direction in males and females, suggesting similar control of entry into reproduction of the two sexes, although within a given treatment, males matured earlier than females. Effects of feeding and photoperiod treatments were additive. Relative to QR, the AL feeding treatment increased WTSXM by 832 g for males and 1,089 g for females; ASXM was decreased by 15.8 d for males and 9.3 d for females. Relative to OS, the DR photoperiod increased WTSXM by 591 g for males and 513 g for females; ASXM was increased by 17.5 d for males and 26.8 d for females. The DR-OS photoperiod increased WTSXM by 86 and 169 g for males and females, respectively; ASXM was increased by 6.1 d and 4.9 d, respectively. Under DR, the delay in onset of sexual maturity caused by QR was not due to failure to reach threshold body weight or age and, hence, appears to have resulted from the feed restriction itself. A similar delay for QR was found under OS but might have been due to failure to reach threshold body weight. It is speculated that the delay in onset of sexual maturity caused by feed restriction may be an ecological adaptation or, alternatively, a result of nutritional imbalance.

Onset of spermatozoal degeneration in low-fertility Delaware roosters and test for autoimmune basis.

The objectives of this study were 1) to determine the onset of a heritable reproductive disorder in the rooster that is characterized by extensive spermatozoal degeneration within the ductus deferens, and 2) to determine if autoimmunity was associated with spermatozoal degeneration. Seventy-five percent of the affected roosters did not ejaculate large percentages of degenerate spermatozoa at 20 wk of age, approximately the age of sexual maturity. Rather, seminal quality gradually declined over the next 6 wk, as both ejaculate volume and number of spermatozoa ejaculated increased. The evaluation of testicular and excurrent duct tissues via immunofluorescence failed to reveal either IgY or IgA associated with spermatozoa. While histological examination revealed greater lymphocyte numbers (P less than .05) in the proximal ductus deferens, these cells were not associated with spermatozoa nor spermatozoal clumping. While spermatozoal degeneration tends to be latent at the onset of semen production, it does not appear to be due to spermatozoal autoimmunity.

Effect of Light Intensity During the Breeder Period on Semen Production of Low Weight and Normal Weight Breeder Turkeys

Semen production of low weight and normal weight breeder turkeys was compared when maintained on low or high light intensities during the breeder period. A flock of Large White male breeder turkeys was raised in two houses and received 12 hr of 54 lx incandescent light from 10 to 30 weeks of age. The average body weights of the 32-week-old males in the two houses were 12.6 (low weight) and 19.4 kg (normal weight), respectively. At 30 weeks of age the males were exposed to 15 hr of 6.5 lx (LL) or 100 lx (HL) incandescent light. The semen volume of the low weight males was less than that of the normal weight males during the first few weeks (Weeks 33, 34, 35, and 37), and during the last weeks of semen collection (Weeks 45 to 49, inclusive). Semen volumes of normal weight males were comparable for LL and HL, but semen volumes of low weight males were greater with HL than LL, particularly during Weeks 33 to 42. Body weight at 32 weeks of age or light treatment during the breeder period had no effect on sperm concentration, and, therefore, sperm per ejaculate paralleled semen volume. This study demonstrated that an increase in light intensity during the breeder period did not completely overcome the delay in the onset of semen production caused by low body weight gain during the adolescent period. However, because the overall total number of sperm in the ejaculate of low weight males on HL was greater than those on LL, increased light intensity may improve the sperm production of low weight males.

Effect of Quantity of Protein in the Concentrate Mixture on the Growth, Reproductive Development, and Semen Production of Dairy Bulls

Summary Holstein bull calves 1–2 wk of age were assigned to three levels of dietary protein, with the low protein, normal protein, and high protein groups receiving concentrate mixtures containing 10, 16, and 22% protein, respectively. A single source of hay was used for all groups. Data were collected on growth (body weight, height at withers, and heart girth), onset of semen production, and semen quantity and quality until the bulls reached 104 wk of age. At 104 wk of age the 18 unrelated bulls were removed from experiment; the three sets of monozygous twins were kept on experiment and data collected to 208 wk of age. No statistically significant differences among experimental treatments were noted in any of the criteria used in evaluation. It is concluded that when good-quality hay is fed liberally, a concentrate mixture containing 10% protein is adequate for normal growth and reproductive development of dairy bulls.

Effect of Total Digestible Nutrient Intake from Birth to Four Years of Age on Growth and Reproductive Development and Performance of Dairy Bulls

Summary Neonatal Holstein bull calves were assigned to four levels of energy intake representing 70, 100, 115, and 130% of the National Research Council recommended TDN allowances for growing dairy calves. The groups were designated L, N, M, and H, respectively. Two additional groups were on a changeover at 104 wk. of age–LH changed from 70 to 130% and HL from 130 to 70%. Data were collected on growth (body weight, height at withers, and heart girth), onset of semen production, and semen quantity and quality until the bulls reached 208 wk. of age. The average age at the onset of semen production was 61, 45, 41, and 44 wk., respectively, for the L, N, M, and H groups. Comparable figures for body weight at the onset of semen production were 523, 643, 675, and 784lb. At 80 wk. of age, the average motile sperm output per ejaculate was 1.15 billion for the L group; this was about 50% of that for the H group. After 112 wk. of age there was no difference in output of motile sperm per ejaculate associated with level of energy intake. Between 156 and 208 wk. of age, the H bulls became much slower in sexual reaction time than bulls in other groups. During this period weaknesses of the feet and legs also became evident in the H bulls. Depletion trials at 4 yr. of age confirmed the relatively low sexual responses of the H bulls and also showed that M as well as H bulls were deficient in their ability to recover response after satiation to a stimulus animal. Sperm output and extra-gonadal sperm reserves were similar among bull groups. Limited fertility data collected on the L, N, and H groups showed no marked difference in fertility attributable to the level of TDN intake.