The uptake of glycerol, α-aminoisobutyric acid and 2-deoxy-D-glucose by spermatozoa of a line of chickens selected for fertility of frozen-thawed semen and a control line

Identification of gamma-aminobutyric acid transporter (GAT1) on the rat sperm

Some recent studies indicated that GABAergic system is involved in mammalian sperm acrosome reaction (AR), but direct evidence pertaining to the expression of gat1 in mammalian sperm is not yet demonstrated. In this study, we evaluated the presence of 67kDa GAT1 protein and mRNA in rat testis by Western blotting and reverse transcription-polymerase chain reaction. Meanwhile, immunohistochemical and immunofluorescent analyses also identified GAT1 protein on the elongated spermatid and sperm. These results indicated that rat testis is a novel site of gat1 expression. Further studies should be taken to explore the role of GAT1 protein on sperm acrosome reaction.

Effects of genotype and cryopreservation of avian semen on fertility and number of perivitelline spermatozoa

1. The fertility of freshly diluted and cryopreserved samples of semen obtained from a population of chickens selected for duration of fertility of cryopreserved spermatozoa (FS line) and its unselected control (FC line) were compared over a range of spermatozoa concentrations (10, 40, 80, and 160 x 10(6) sperm/50 microliters insemination). 2. The spermatozoa of the FS line had greater fertility than spermatozoa of the FC line, whether freshly diluted or cryopreserved. Cryopreservation resulted in a reduction in fertility, regardless of line. There were no significant line by genotype interactions. 3. There were fewer spermatozoa from the FC line than the FS line found in the perivitelline membrane (perivitelline spermatozoa). The increase in number of perivitelline spermatozoa with increasing sperm concentration was greater in the FS than FC line. However, the slope of the increase in sperm number in the perivitelline membrane with increasing concentrations of cryopreserved spermatozoa was zero. 4. A minimum of 10(3) perivitelline spermatozoa must be found on day 2 post-insemination for duration of fertility to exceed three days. The ability to produce spermatozoa capable of reaching the forming perivitelline membrane appears to be a quantitative, rather than a qualitative, trait and may be subject to genetic manipulation.

Cryopreservation of poultry sperm: the enigma of glycerol

This review summarizes recent data for cryopreservation of poultry sperm and data establishing the contraceptive effect of glycerol. Successful cryopreservation protocols for bovine sperm are compared to the requirements for rooster sperm, with emphasis on glycerol-induced alterations in avian reproductive systems. It has been shown that molar concentrations of glycerol can affect (a) physical features of the cytoplasm (cytoplasmic organization and viscosity), (b) permeability and stability of the membrane bilayer(s), and (c) noncovalent attachment of proteins to the sperm surface. Perturbing effects of glycerol on sperm metabolism and the essentiality of maintaining bioenergetic balance during the temperature changes associated with any cryopreservation protocol are discussed. Emphasis is placed on the processes in avian reproduction that may be altered by interactions with glycerol. Finally, we discuss the potential value of using available genetic models (lines of roosters differing in the capacity of their sperm to survive a freeze-thaw cycle) to clarify and overcome damage to poultry sperm induced by cryopreservation.

Effect of selection for fertility of frozen-thawed semen in chickens on the fertility of fresh and stored semen

Studies were conducted using 68 males from the seventh generation of a line of meat-type breeder chickens selected for increased duration of fertility of frozen-thawed semen and 69 males of the randomly selected control line. These chickens were used to determine the presence or absence of differences between the selected and control lines with respect to fertility and spermatozoal motility when the semen was subjected to the following preinsemination treatments: 1) frozen in a diluent containing 13.6% glycerol; 2) frozen in a diluent containing 1.7% glycerol; 3) fresh undiluted; 4) fresh diluted; 5) diluted and stored for 24 hr; and 6) diluted and stored for 48 hr. Semen from each male was inseminated into 4 to 6 White Leghorn tester hens per experiment. The effects of genotype (line) by preinsemination semen treatment interaction on fertility and spermatozoal motility were also examined. When semen was frozen (Treatments 1 and 2), the selected line had significantly (P less than .01) higher duration of fertility, percent fertility for 7 days postinsemination, and percent fertility for the duration of fertility and spermatozoal motility than the control line. For fresh semen (Treatments 3 and 4), the selected line had significantly (P less than .01) higher fertility estimates and spermatozoal motility than the control line except for percent fertility for the duration of fertility (P greater than .05) of undiluted semen. For stored semen (Treatments 5 and 6), the selected line only had significantly (P less than .05) higher duration of fertility after 24 hr storage and percent fertility for the duration of fertility after 48 hr storage than the control line.(ABSTRACT TRUNCATED AT 250 WORDS)

Eight generations of selection for duration of fertility of frozen-thawed semen in the chicken

The response to eight generations of selection for duration of fertility of frozen-thawed chicken semen, the correlated responses of other fertility parameters of frozen-thawed semen and the fertility of fresh semen, and the heritabilities of frozen-thawed and fresh semen were studied. The selected and control lines were derived from a base meat-type control male population developed at Peel's Poultry Farm Ltd., Port Perry, Ontario. Selection has improved duration of fertility of frozen-thawed semen significantly (P less than .01) with the mean increasing from 1 day in Generation 1 to 5 days in Generation 8 and an average improvement per generation of .29 day since Generation 3. There were significant (P less than .01) correlated increases in percent fertility for 2 to 8 days postinsemination and percent fertility for the duration of fertility of frozen-thawed semen as well as the fertility of fresh semen. Percent hatchability of fertile eggs of frozen-thawed semen did not change. In Generation 8, means and standard errors of fertility parameters of frozen-thawed semen in the selected and control lines, respectively, were: 38.54 +/- 1.39 and 25.58 +/- 1.77 for percent fertility for 2 to 8 days postinsemination, 47.73 +/- 3.54 and 32.02 +/- 2.17 for percent fertility for the duration of fertility, and 78.21 +/- 1.56 and 79.27 +/- 2.53 for percent hatchability of fertile eggs. For fertility of fresh semen, means and standard errors were: 12.69 +/- .20 and 11.54 +/- .42 for duration of fertility, 82.91 +/- 1.45 and 75.71 +/- 2.83 for percent fertility for 2 to 8 days postinsemination, and 71.89 +/- 1.25 and 69.22 +/- 2.06 for percent fertility for the duration of fertility. The means of the heritability estimates of the fertility of frozen-thawed and fresh semen, respectively, ranged from .01 to .31 and -.01 to .21. The realized heritability of duration of fertility of frozen-thawed semen, based on five generations, was .17 +/- .05. The phenotypic correlations of duration of fertility of frozen-thawed semen with percent fertility for 2 to 8 days postinsemination and percent fertility for the duration of fertility of frozen-thawed semen were high and positive and correlations between fertility of frozen-thawed and fresh semen were low but positive.