Cryopreservation of chicken semen of inbred or specialized strains.

Pooled semen from several inbred special chicken strains was diluted with solutions containing glycerol or dimethylacetamide as a cryoprotectant. One-half milliliter samples in capped glass vials were frozen at 3 C/min to -35 C in a programmable freezer and stored in a nitrogen vapor tank. One vial of thawed semen was used to inseminate 4 hens by intravaginal, intrauterine, or intramagnal procedures. The intramagnal technique required minor surgery but always produced chicks in seven lines in contrast to the nonsurgical methods. Frozen semen of one strain stored for 29 weeks produced 12 to 14 chicks per vial when inseminated into 4 hens. This method, therefore, will reliably rescue gene pools from semen after long-term storage.

The survivability of Mycoplasma meleagridis in frozen-thawed turkey semen.

Semen from 15 turkeys was pooled and divided into two groups and diluted with glycerated freezing medium. One group contained naturally occurring levels of Mycoplasma meleagridis while the other was inoculated with a 24-hr culture of the organism. Both groups were frozen under identical conditions. Semen was evaluated for motility and life-dead analysis during various stages of cryopreservation. The number of viable mycoplasmas in both groups was determined prior to and at 1-, 2-, and 6-months frozen storage. The experiment was repeated twice. Semen motility and live-dead evaluation showed no apparent trends outside of the normal decline seen during various stages of cryopreservation. There was no significant decline in M. meleagridis levels in either treatment group in either trial when samples were tested at intervals up to 6 months. The naturally infected semen contained approximately 10(3) cfu/ml, while the inoculated semen had 10(5) cfu/ml. It was concluded that viable numbers of M. meleagridis do not substantially decline in turkey semen during cryopreservation and subsequent thawing. Consideration must be given to potential pathogens in turkey semen cryopreserved for long-term storage.

Effects of glycerol on turkey sperm cell viability and fertilizing capacity.

To test the cryoprotective action of glycerol, intravaginal (I.V.A.I.) and intramagnal (I.M.A.I.) artificial inseminations were performed on 100 turkey hens using semen treated with glycerol; treated with glycerol then diluted and centrifuged; treated with glycerol and frozen-thawed; treated with glycerol, frozen-thawed then diluted and centrifuged; and untreated control. With I.V.A.I. no progeny were obtained from any turkeys within the treated group. I.V.A.I. subsequent to semen dilution and centrifugation to lower the glycerol level yielded only two poults from one of the 36 hens inseminated. When I.M.A.I. was used, many poults were hatched from eggs produced by hens in the four treated groups. To study the cause of glycerol's antifertility action, histological sections of uterovaginal junction (UVJ) and infundibular (INF) tissues were observed. Following I.V.A.I., no sperm cells were found in either the UVJ or INF regions except in the controls where they were readily seen in the UVJ region. Conversely with I.M.A.I., sperm cells were seen in the INF region in all treatment groups while in the controls, sperm cells were also found in the UVJ region.

Effect of semen dose, frequency of insemination, age and productivity of the male on duration and levels of fertility and hatachability in the turkey.

In 3 separate trials, duration and levels of fertility and hatchability were studied in 3 groups of Broad Breasted White turkey hens inseminated on 1, 2 or 3 successive days with 0.030 ml. semen. In the first test, hens in a fourth group were given a single insemination of 0.090 ml. semen. and those in the fifth group received 2 inseminations of 0.045 ml. The semen used in Trial 1, was obtained from males producing different levels of semen, and in Trials 2 and 3 the semen was from males of different age groups. Neither age of the male nor level of semen production appreciably affected duration or levels of fertility in turkey hens. However, duration and level of fertility were slightly better in hens given 2 or 3 inseminations of 0.03 ml. or 2 inseminations of 0.045 ml. of semen on successive days than in comparable hens given a single insemination of 0.030 ml. or 0.090 ml. semen. Hatchability was significantly higher (p = less than .05) in hens inseminated twice with doses of 0.030 ml. as compared with hens inseminated 1 or 3 times with doses of 0.030 ml. In 1 of 2 test years, hatchability in hens inseminated with semen from young males was from 7 to 12 percent greater than for comparable hens inseminated with semen from old males. Semen concentration and percent of normal sperm was generally higher in young males (39 wk.) as compared to older males (89 wk.).

Effect of forced molting on quantity and quality of semen in turkey breeder males as influenced by diet.

Broad Breasted White turkey males were induced to molt by imposing periods of nonstimulatory light and short periods of water and feed deprival starting at 54 weeks of age. Birds kept under 8 or 10 hours of light per day began to molt within 3 weeks, and most had terminated semen production within 4 weeks. When returned to stimulatory light, the birds began to produce semen within 4 weeks and reached peak production within 10 weeks. However, this level of production was lower than the original level attained as young birds. The recycled males produced approximately 20 percent more semen than the males kept under constant stimulatory light, and the semen from the recycled males contained 1 to 2 billion additional sperm per ml. The percentage of normal sperm decreased with increase in age of birds irrespective of light treatment. A skip-a-day-per-week feeding schedule imposed on all males from 54 to 78 weeks of age had no appreciable effect on body weight or efficiency of feed utilization. Also, imposition of feed and water restrictions had no apparent effect on early termination or recovery of semen production.

Scanning electron microscope studies of turkey semen.

Turkey spermatozoa were examined morphologically with the aid of a Cambridge Stereoscan electron microscope. Mean dimensions, in micra, of normal spermatozoa were: acrosome, 1.8; nucleus, 9.1; midpiece, 4.8; tail, 61.0; total length 76.7. The maximum diameter of the head at its widest was 0.8 microns. There was an increase in abnormal spermatozoa in yellowish semen, with coiling being the most prevalent abnormality. The spherical-shaped cells with granular appearance, also present in yellowish semen, were ascertained to be large macrophages. Occasionally, macrophages filled with phagocytized sperm cells were evident. Hens inseminated with yellowish semen had 57.6 percent fertility compared to 92.1 percent for hens inseminated with control semen.