Summary. The concentration (mean±S.E.M.) of oestrogen in semen (0·89±0·04 ng/ml) of bulls was 8·9-fold higher than in blood plasma (0·10±0·01 ng/ml) while the concentration of androgen in semen (1·15±0·26 ng/ml) was 2·7-fold lower than in blood plasma (3·21±0·47 ng/ml). This concentration of oestrogen in semen was not influenced by 0,1,3 or 5 false mounts or when ejaculations occurred at 2-min intervals. When 100 mg oestradiol-17β were injected i.v. the oestrogen level in semen followed that in the plasma.
G. W. SALISBURY and C. N. GRAVES
A technique is presented for the collection of ejaculated bovine spermatozoa directly into an inhibitory diluent which renders the cells immotile and prevents the absorption of carbohydrate from the seminal plasma. When removed from the inhibitory diluent, such cells have low endogenous respiration which is markedly increased by the addition of fructose to the incubation medium or by pre-incubation in a fructose solution before washing and then subjecting the cells to a period of endogenous respiration. After storage at 5° C for 24 hr in the collection medium, and after their subsequent removal from the inhibitory medium, the endogenous respiration rate of such spermatozoa and their respiration in the presence of fructose is greater than the initial respiration level. All these responses are typical of bovine epididymal spermatozoa.
C. N. GRAVES and P. J. DZIUK
A degree of control of oestrus in cattle by progestagens is possible by either injection (Nellor & Cole, 1956), implantation (Dziuk, Cmarik & Greathouse, 1966) or feeding (Dhindsa, Hoversland & Smith, 1967). Following withdrawal of the progestagen, heat occurs in 2 to 9 days and each cow can be mated or artificially inseminated according to signs of heat (Hansel, Donaldson, Wagner & Brunner, 1966). In some instances, treated cows may ovulate but not show the characteristic manifestations of oestrus and thus are not inseminated (Van Blake, Brunner & Hansel, 1962). The objectives of the current study were two-fold: first, to determine if ovulation in the cow could be controlled precisely, and second, by insemination at some predetermined time to eliminate detection of oestrus, to determine if the eggs could be fertilized.
The forty-seven cows
C. N. GRAVES and G. W. SALISBURY
The ability of bovine spermatozoa to metabolize carbohydrates and other compounds oxidatively has been studied, using spermatozoa free of the components of the seminal fluids. Only glucose, fructose, mannose and galactose of the hexoses were significantly oxidized by the spermatozoa.
P. J. O'REILLY, C. N. GRAVES and P. J. DZIUK
The comparative efficiency of two semen extenders, eggyolk-Illini Variable Temperature extender (E) and reconstituted milk (M), in the maintenance of fertilizing ability was tested by heterospermic insemination using semen from Black (B) and White (W) males whose offspring were distinguishable. Semen from the different males was combined just before insemination to give a mixture of equal numbers of spermatozoa from each. Each of the male/semen combinations BE+WE, BM+WM, BE+WM and BM+WE was inseminated into one of four groups of females.
There were no significant differences between groups in the proportion of does kindling or in litter size. When the BE+WE combination was used, 69% of progeny were W and when the BM+WM combination was used, 86% were W. When the BM+WE combination was inseminated, 96% of progeny were W. However, when BE+WM was used, only 32% of progeny were W. Spermatozoa stored in E were associated with a significantly greater proportion of offspring than spermatozoa from males stored in M when BE was compared with WM (P <0·001) and when WE was compared with WM (P<0·01). It is concluded that the competitive advantage enjoyed by spermatozoa stored in E is due to the superiority of the E extender in maintaining fertilizing ability. This finding suggests that appropriate heterospermic inseminations could be used to distinguish between semen handling techniques and extenders.
G. W. SALISBURY, C. N. GRAVES, N. T. NAKABAYASHI and R. G. CRAGLE
This study was conducted to determine the effect of added sulphur compounds, substrates and various inorganic ions on the metabolic activity of epididymal spermatozoa from twenty-one bulls and five goats. The addition of sulphur at physiological levels in the form of sulphide, sulphite, sulphate and glutathione in several different media caused no stimulation of respiration. An apparent stimulation of oxygen uptake by the addition of cysteine was shown to be due to auto-oxidation of the added cystein. Calcium and magnesium in a Ringerphosphate medium had no obvious effect on metabolism, while phosphate decreased oxygen uptake but increased glycolysis and lactate accumulation in the presence of substrate. Substrate, present even for a short period of time before removal, stimulated metabolism markedly during the subsequent incubation period.
R. D. BAKER, N. L. VANDEMARK, C. N. GRAVES and H. W. NORTON
To determine the effects of parasympathetic-influencing drugs on reproductive phenomena in bulls, four ejaculates were collected at 15-min intervals from each of six bulls beginning 30 min after a subcutaneous injection of 400 mg pilocarpine, 200 mg atropine, or physiological saline solution. Each treatment was administered twice, so that a total of 144 ejaculates was collected. Pilocarpine significantly (P<0·01) decreased the concentration of spermatozoa and increased the time required to mount, the duration of ejaculation, the volume of semen, the number of spermatozoa per ejaculate and the concentration of chloride in the semen. Atropine had the reverse effect on these characteristics and significantly (P<0·01) increased the concentration of fructose in the semen. These results demonstrate that atropine and pilocarpine, which are known to influence the parasympathetic system, alter the reaction time of the bulls, the secretion of one or more accessory sex glands, the passage of spermatozoa through the male reproductive tract, and the emission of semen during ejaculation.
K. K. MITTAL, G. W. SALISBURY, C. N. GRAVES and B. A. RASMUSEN
Bull semen is very strongly antigenic in rabbits. At least twenty antigenic components were detected by micro-immunoelectrophoresis.
There was a drastic reduction in oxygen uptake, fructose utilization and lactic acid production by bull spermatozoa when mixed with specific antisemen serum. This decreased metabolic activity in the presence of the antisemen was due to death of the spermatozoa as indicated by the live-dead staining technique.