Predicting the fertilising ability of avian semen: comparison of a simple colourimetric test with other methods for predicting the fertilising ability of fowl semen.

1. The rate of tetrazolium dye-reduction by fowl spermatozoa measured by an objective colourimetric assay was shown to correlate strongly with sperm motility, morphology, ATP content and fertilising ability. 2. Although dye-reduction appeared less well correlated with fertilising ability than the other variables, the method for its determination has many practical advantages for the assessment of semen quality in poultry.

Effect on fertility of low numbers of fowl spermatozoa inseminated in aqueous diluent or semen components of the fowl and turkey.

A study was undertaken to compare the effect on fertility in the fowl of aqueous medium, natural homologous seminal plasma, heterologous turkey seminal plasma and whole turkey semen when whole fowl semen was excessively diluted with these media and inseminated fresh. High dilution with fowl seminal plasma resulted in the best fertility. Dilution with the turkey semen components produced fertility no different from that with aqueous diluent when the dose of spermatozoa was 5 X 5 or 10 X 10(6). The results of this study confirm that 5 X 5 to 10 X 10(6) good quality spermatozoa are sufficient to produce acceptable fertility in weekly inseminations of fresh semen. This enables good quality semen to be highly diluted. However, at high dilution rates there is a need to reconsider the composition of semen diluents, with respect to simulating as yet unknown properties provided by factor(s) in homologous ductus deferens seminal plasma.

Advanced gonadal development in male turkeys following knife cuts directed to the hypothalamus.

Turkey poults when 4 weeks of age received parasagittal knife cuts of the total hypothalamic area. Each of the two knife cuts was 1.2 mm lateral from midline and extended from the preoptic area to the mamillary hypothalamic region. Five experimentals survived only 3 to 5 days following surgery as none was able to eat or drink. Three experimentals showed prematurely developed wattles and caruncles about the neck, larger testes, and more advanced stages of spermatozoan development and tubule growth compared to sham-operated controls. When male poults were placed in a floor pen two of the three experimentals displayed mating behavior by strutting. No strutting was observed in controls. Similar to the chicken, male poults receiving parasagittal knife cuts throughout the anterior-posterior extent of the hypothalamus and thalamus showed advanced gonadal development.

An exploration of cryoprotective compounds for fowl spermatozoa.

Glycerol is an effective cryoprotective for fowl spermatozoa, but after thawing the frozen semen it must be reduced in concentration from the level adequate to protect spermatozoa during freezing, otherwise it has a contraceptive action. A series of alternative cryoprotective compounds were tested for their effect on fertility when fowl spermatozoa were inseminated fresh in their presence. Under these circumstances dimethylsulphoxide, dimethylacetamide, ethane-diol, propane-diol and methylpyrrolidone did not depress fertility when used in concentrations equivalent to that of glycerol or in amounts reported previously to be non-toxic and adequate to protect cells during freezing. Dimethylacetamide was compared with propane-diol for use in freezing fowl semen and the former enabled encouraging levels of fertility to be obtained.

Concentrations of plasma luteinising hormone, prolactin, progesterone and androgens during the ovulatory cycle of the turkey.

1. Changes in the concentrations of plasma luteinising hormone (LH), prolactin, androgen and progesterone were measured during the ovulatory cycle of the turkey. 2. Single pre-ovulatory peaks of plasma LH, androgen an progesterone were observed which took 8, 8 and 12 h respectively, to increase and return to base-line values. The concentration of plasma prolactin tended to be elevated between 6 h before and 6 h after the LH peak with the maximum values occurring after the peak. 3. The changes in the concentrations of plasma LH and progesterone were 3- and 7-fold respectively while 2-fold changes were observed in the concentrations of plasma androgen and prolactin. 4. The pre-ovulatory concentration of plasma progesterone and prolactin began to decrease 4 and 6 h respectively, after the pre-ovulatory peak of LH. 5. Ovulation and oviposition occurred 6 to 8 h and 36.10 +/- 0.57 h (SEM) (n = 11) respectively after the pre-ovulatory peak of LH. 6. In birds kept on 14 h light/d, pre-ovulatory peaks of LH were initiated only during a 10 to 11-h period starting within 2 h after the onset of darkness. 7. A comparison between these data and those from the fowl suggest that the egg is retained in the turkey's oviduct for about 3 to 4 h longer than in the fowl.

An attempt to improve the fertility of stored fowl semen with certain additives in a basic diluent.

The following substances were added to a basic diluent for fowl semen either separately or in combination: caproic acid, formaldehyde, acetyl carnitine, adenine, inosine, sodium pyruvate, succinic acid, dithiothreitol, sodium citrate and zinc, chloride, bicarbonate and phosphate. No significant improvement in the fertility of semen stored at 5 degrees C for either 24 or 48 hrs was obtained over that produced with the basic diluent. Dithiothreitol and sodium citrate caused a marked lowering of fertility when present in the diluent.

Preservation of fowl semen in liquid nitrogen: application to breeding programmes.

1. A method of freezing semen of individual males was adapted for use under farm conditions using an automated freezing apparatus. 2. An insemination programme to produce high fertility and hatchability with semen which had been deep frozen for 2 months was devised. 3. Over 90 % fertile eggs with a 90 % hatch of all eggs set was obtained with frozen and thawed semen over a period from the 2 nd to the 12th day after the first of four insemination. The persistency of fertility was also tested and 93, 86.6 and 30.7 % of the eggs were fertile during days 2 to 6, 2 to 8 and 9 to 15 after the last insemination. 4. Corresponding with the high fertility rate, chicks were produced by every hen that was inseminated and from every male whose semen was frozen and stored. The implications for future breeding practices of this successful result are discussed.

Effect on fertility of storing fowl semen for 24 h at 5 degrees C in fluids of different pH.

Improved storage of fowl semen above 0 degree C was achieved by adjusting the pH of the diluent. The fertility obtained with semen stored for 24 h at 5 degrees C in diluents buffered at different pH values was compared with that of semen stored in a basic, unbuffered solution. The most satisfactory result was achieved with diluent buffered at pH 6.8 OR 7.1. Worst fertility was obtained at pH 5.8 and pH 7.4 did not prove very satisfactory. There were indications that the effect of pH under the conditions of the experiment was to regulate metabolism and thereby influence the maintenance of the fertilizing ability of the spermatozoa.

Preservation of fowl semen in liquid nitrogen--an improved method.

1. An improved method of storing fowl semen in liquid nitrogen is described. It uses glycerol as a cryopotectant and the degree of fertility obtained with semen stored for up to 2 1/4 years was very promising. 2. The essential features of the method are a slow freezing rate, a reduction of temperature to - 35 degrees C before the semen is plunged into liquid nitrogen and insemination within 15 min of thawing and removing the glycerol from the diluent. 3. It seems likely that further improvements in the technique may be expected through better control of the injection of liquid nitrogen into the freezing chamber, thereby minimising localised, rapid temperature changes around the ampoules during freezing. 4. Preliminary results suggest that it may prove possible to select males for the ability of their spermatozoa to withstand freezing. 5. The importance of recognising differences between males in the initial quality of semen and between females in the physiology of the reproductive organs in determining the fertilising ability of stored semen is discussed.