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P. S. Weathersbee and J. R. Lodge

Summary. Acepromazine administered i.v. to 3 bulls 15 min before semen collection blocked seminal emission and coitus-induced androstenedione release. Dexamethasone or saline treatment had no noticeable effect.

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G. W. SALISBURY and J. R. LODGE

Summary.

The oxygen consumption of sixteen samples of ejaculated bovine spermatozoa in diluted semen was more rapid in the presence of the respired carbon dioxide than it was for similar spermatozoa respiring in the presence of alkali to absorb the evolved carbon dioxide. Thus, respiratory quotients for seminal spermatozoa calculated from oxygen consumptions obtained by the direct method of Warburg, in the absence of respired carbon dioxide, are in error, being larger than is characteristic of the substrate oxidized.

The oxygen consumption of seventeen samples of ejaculated bovine spermatozoa washed free from seminal plasma was not influenced to the same degree by the absence of the respired carbon dioxide. However, the influence was sufficient to question the accuracy of the direct method of Warburg for measuring respiratory quotients for bovine spermatozoa.

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R. L. Ax, R. J. Collier and J. R. Lodge

Summary.

Roosters were fed 0·1 % caffeine mixed by weight into a standard ration. With continued dietary caffeine administration, the average fertility of eggs collected for 2 weeks from untreated pullets inseminated with semen from the treated males at 0,7 and 14 days after the start of treatment was 30·8, 33·5 and 3·3 %, respectively. After 14 days of treatment fertility was significantly lower (P < 0·001) than before (0 days) or 7 days after treatment. Semen output and sperm concentration were markedly reduced 17-21 days after treatment, and no semen could be collected from the roosters after they had received caffeine for 30 days. Removal of dietary caffeine resulted in resumption of semen production and a return of fertility to the control level. Testicular histology showed that spermatocyte divisions ceased and spermiogenesis was abnormal, although Leydig tissue and the response of the males to massage for semen collection was not affected. The effects on spermatogenesis and fertility were reversible after treatment for 30 days.

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J. F. ROCHE, P. J. DZIUK and J. R. LODGE

Chance is ordinarily considered to be responsible for determining which spermatozoon fertilizes an egg. Results from experiments on competitive fertilization in hens tend to disprove this concept. When fresh and aged cock spermatozoa competed directly, the eggs were fertilized by the fresh spermatozoa, although the aged spermatozoa alone were capable of fertilization (Warren & Kilpatrick, 1929). The cocks were mated alternately at intervals of several days, and the last cock always sired the offspring. When spermatozoa from two apparently equally fertile males of different strains of mice or breeds of rabbits were mixed in equal numbers, one male consistently sired a higher proportion of the offspring (Edwards, 1955; Beatty, 1960) adding further doubt to the concept that chance alone determines which spermatozoon fertilizes an egg.

Spermatozoa, whether motile or immotile, and inert particles

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P. S. WEATHERSBEE, R. L. AX and J. R. LODGE

Summary.

Sixty 6- to 10-week-old male Chinese hamsters were assigned to two groups. In one, the animals were untreated and in the other, they were treated with 0·02 g caffeine/100 ml water orally for 60 days. The sex ratio of the resulting litters showed a significant (P< 0·025) skewing towards females (61·4%) when compared to that of the controls (49·2%).

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N. S. FECHHEIMER, J. R. LODGE and R. C. MILLER

Summary.

The sex of 918 chicken embryos after incubation for 16 to 18 hr was ascertained by chromosomal analysis. The proportion of males was 49·45%±1·6%.

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E. B. KREHBIEL, J. R. LODGE and O. P. SHARMA

Sperm transport through the female reproductive tract in mammals has been studied by several investigators. The results from these studies have shown that in the mouse (Lewis & Wright, 1935), the rat (Blandau & Money, 1944), the hamster (Yamanaka & Soderwall, 1960), the cow (VanDemark & Hays, 1951; Hays & VanDemark, 1952), and the ewe (Mattner & Braden, 1963), spermatozoa are present in the oviducts within minutes of mating or insemination. A rapid transport of spermatozoa to the rabbit oviduct has not previously been reported. The interval between mating and the finding of spermatozoa in the oviducts has ranged from 1 hr (Chang, 1952) to 3 to 4 hr (Braden, 1953) and, for sufficient spermatozoa to fertilize all of the eggs, to as much as 5 to 6 hr (Adams, 1956;

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P. A. MARTIN, T. J. REIMERS, J. R. LODGE and P. J. DZIUK

Summary.

When mixtures of semen containing an equal number of spermatozoa from two males are inseminated, the males usually sire disproportionate numbers of the offspring. In this study, when a mixture of equal numbers of spermatozoa from a Columbian (C) and a Leghorn (L1) cock was inseminated, the C male sired 34% of the offspring. The proportion of offspring was constant regardless of age of males, season, total number of spermatozoa, breed of hen or the interval from insemination to the time of egg-lay over a 15-day period after insemination. The proportion of C offspring observed from inseminating nine different ratios of spermatozoa arranged progressively from 1C:9L, 2C:8L and so on, was 10%, 20%, 23%, 34%, 38%, 44%, 58%, 74% and 82%. These results were in close agreement with mathematically derived estimates. It appears that the relationship between sperm ratios and the proportions of offspring sired by two males competing heterospermically is dependent on the ratio of the number of competing spermatozoa but not on total number, season, breed of hen or the interval from insemination to fertilization.