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Biomedical subjects

T N Edey

Publications and source records attributed to T N Edey.

At least 19 recordsLinked to original sources
PubMed1986

Postpubertal sexual development in merino rams after differential feeding through puberty.

Spring-born Merino ram lambs were reared on 130%, 165% or 200% of recommended maintenance energy requirements from 7 to 12 mo of age and were then placed on a common plane of nutrition from 12 to 25 mo of age. During the latter 13 mo, the 24 rams were studied for changes in live-weight and testicle characteristics. Semen characteristics and sexual activity were observed from 12 to 19 mo of age. At the beginning of the study, groups coming from low (L), medium (M), and high (H) nutrition had liveweights of 38.9, 46.8, and 53.6 kg (P < 0.05) and scrotal circumferences of 24.6, 28.9, and 32.1 cm (P < 0.05), respectively. When the rams were given common feed conditions, the differences between groups in both liveweight and scrotal circumference quickly decreased and were not significant by the sixth month. No significant differences existed between groups in ejaculate characteristics during semen collection, except in sperm density which, at the end of semen collection, was significantly (P < 0.05) higher in Group M (3.98 x 10(9)/ml) than in Group L (2.55 x 10(9)/ml). However, in analyses of pooled data, there were significant differences between months of collection in sperm density, total number of sperm per ejaculate, and percentages of live and abnormal sperm. The data indicate that differential nutrition during the first year of life will affect some reproductive characters contemporaneously, but with restored feeding, reproductive differences are resolved more quickly than those in liveweight and the changes proceed despite countervailing photoperiodic influences.

Journal Article↗
PubMed1984

Effect of litter size on blood haematocrit and liveweight in Booroola Merino and Merino ewes during pregnancy and the post-partum period.

Blood haematocrit and liveweight were determined throughout pregnancy and the post-partum period in 217 Booroola Merino and Merino ewes in order to relate these parameters to litter size at birth. In pregnant ewes, haematocrit declined from three until five months gestation, rose immediately after parturition then declined until two months post-partum. During the third to fifth month of gestation, haematocrit decreased in proportion to litter size. Nonpregnant ewes, measured at similar intervals, did not show the same pattern. Haematocrit of nonpregnant animals was higher than that of triplet-bearing ewes at three, four and five months gestation, but was only significantly different to single- and twin-bearing ewes at five months. The liveweight of pregnant ewes increased up to parturition and then declined until two months post-partum. The liveweight of nonpregnant ewes increased over the experimental period. It was concluded that the number of foetuses a ewe carried had significant effects on the decline in haematocrit during pregnancy. Haematocrit was not a precise indicator of litter size in sheep. Haematocrit, ewe liveweight and ovulation rate together in a multiple regression only accounted for 37% of the variation in litter size.

Journal Article↗
PubMed1982

Early induction of parturition and initiation of lactation in sheep.

Dexamethasone and estradiol benzoate were used to induce parturition in ewes at about day 120 of gestation as part of a program to reduce the time taken to progeny-test carpet-wool rams by evaluating the birthcoats of their offspring. Ten ewes received 5 injections of 12 mg dexamethasone over 2.5 days commencing on day 117. Eight lambed 3.1 +/- 0.53 days after the final injection. Of 14 ewes which received 20 mg estradiol benzoate on day 118, three delivered lambs, 2.0 +/- 0.41 days after injection. All lambs were born dead or died within 2 hours of birth. Following parturition all ewes came into lactation. The dexamethasone group produced more colostrum, with higher total solids content than the estradiol group. However, the volume was less than in a control group which lambed at full term. It was concluded that dexamethasone could be used successfully to induce parturition at 120 days and that onset of lactation was similar to that which occurs at full term.

Journal Article↗
PubMed1979

Pituitary response of prepuberal lambs to oestradiol-17 beta.

In two experiments 48 prepuberal Merino ewe lambs were injected with oestradiol-17 beta (E2) or saline to study the effect of E2 on their plasma LH levels and on oestrus and ovulation. In the three groups which received 30 (experiment I), 50 and 30 (experiment II) microgram E2 respectively, 27 out of 28 lambs showed an LH response, the corresponding mean LH peaks being 64.3 +/0 22.5, 153.6 +/-33.4 and 91.7 +/- 16.9 ng/ml at mean intervals of 11.1, 11.2 and 10.5 h, respectively, after injection. None of the 20 lambs in the control groups had an LH level higher than 18 ng/ml 12 h after injection. In the three E2 groups, 41.7, 62.5 and 37.5% of animals showed oestrus within 26 h of injection while in the control groups only one animal showed oestrus. Of 13 animals showing oestrus in the E2 groups, 11 failed to ovulate. The mean pre-injection plasma FSH level in experiment I was 102.7 ng/ml, and in four 5--7-month-old lambs over several weeks uas 155.3 ng/ml. Despite these high pre-injection levels of FSH, it appears that the follicles were unable to respond to the LH peak which followed the E2 injection.

Animals↗
PubMed1975

Fertility and sperm transport in Merino ewes at the first oestrus following embryonic death.

The embryos of ewes were killed with colchicine on Day 17 of gestation and the ewes were mated at the subsequent oestrus. Fertility was reduced at this mating, and fewer spermatozoa were found in the uterus and oviducts than in control animals. The total number of spermatozoa in the cervix and their distribution between the lumen and walls of the cervix were not altered, but the linear distribution along the cervical walls was changed. The density of the reamining spermatozoa in the control animals after flushing the cervix showed a progressive decrease from the posterior to the anterior segments. This did not occur in the untreated ewes. It seems likely that impaired sperm transport contributed to the lowered fertility.

Analysis of Variance↗