HORMONAL CONTROL OF REPRODUCTION IN EWES DURING THEIR NORMAL BREEDING SEASON

1967 ◽  
Vol 47 (1) ◽  
pp. 71-76
Author(s):  
Sheikh Saif-Ur Rahman ◽  
W. D. Kitts
Keyword(s):  
Oral Administration ◽  
Breeding Season ◽  
Dosage Level ◽  
Hormonal Control ◽  
Post Treatment ◽  
Breeding Activity ◽  
Intramuscular Injections

Injected or orally-administered progestagens have been shown to synchronize estrus in mature ewes during their normal breeding season. Oral administration of 6–methyl-17-αα-acetoxyprogesterone (MAP) or 6-chloro-Δ6-dehydro-17-acetoxyprogesterone (CAP) for 10 days was more effective in synchronizing estrus than intramuscular injections of repositol progesterone. CAP appeared to be more active in controlling breeding activity than MAP (2.5 mg CAP per head vs. 60 mg MAP per head). The administration of 2.5 mg CAP per head per day for 18 days was as effective as the feeding of 3.5 mg per head per day for 10 days. CAP, at a dosage level of 2.5 mg, administered over a 10-day period to motivate first post-treatment estrus, was more effective when injected intramuscularly than when administered orally. The administration of Pregnant Mare Serum did not result in an increase of lambing percentage.

The effect of the oral administration of melatonin at two times of the year on ovarian activity in ewes

1986 ◽  
Vol 1986 ◽  
pp. 53-53 ◽  
Author(s):  
S. Wigzell ◽  
J. J. Robinson ◽  
R. P. Aitken ◽  
W. A. C. McKelvey
Keyword(s):  
Oral Administration ◽  
Breeding Season ◽  
Daily Administration ◽  
Ovarian Activity ◽  
Melatonin Treatment ◽  
Breeding Activity ◽  
Normal Period

It has previously been shown (Robinson et al., 1985) that the normal breeding season of Greyface and Scottish Blackface ewes can be advanced by the daily administration of the indoleamine melatonin; the administration of the melatonin beginning midway during the anoestrous period. If melatonin is administered towards the end of the normal breeding season, oestrous activity can be extended, but only for a period of about six weeks until the ewe becomes refractory to the melatonin treatment (Nett and Niswender, 1981). There is no information on the administration of melatonin at the beginning of the anoestrous period.In the following experiments we report results for the influence on the subsequent breeding activity of Greyface ewes of the oral administration of melatonin at the beginning of their normal period of anoestrus. We also report the results of an investigation on the effects of melatonin in advancing the breeding season of Scottish Blackface ewes maintained on either a high or low plane of nutrition. The experiments were carried out under natural daylength conditions at 57°N.

The effects of single injections of progesterone on oestrous cycle length in ewes

1973 ◽  
Vol 80 (3) ◽  
pp. 525-526 ◽  
Author(s):  
I. W. Dixon ◽  
C. J. Thwaites
Keyword(s):  
Cycle Length ◽  
Effective Means ◽  
Post Treatment ◽  
Route Of Administration ◽  
Oestrous Cycle ◽  
Conception Rate ◽  
Factorial Experiment ◽  
Massive Dose ◽  
Intramuscular Injections

SummaryTwo hundred and forty mature Merino ewes were used in a factorial experiment to investigate the effects of single injections of either 0, 40, 80 or 160 mg progesterone on the length of the subsequent oestrous cycle. Equal numbers of ewes (15 per group) received subcutaneous and intramuscular injections, and equal numbers were treated either on the day of oestrus or the following day.Oestrous cycle length was significantly reduced in all treated groups, with a minimum cycle length of 7–10 days following treatment with 80 or 160 mg progesterone. Neither route of administration nor day of treatment significantly affected the response. The conception rate achieved by treated ewes at the first post-treatment oestrus did not differ significantly from that in comparable controls.The results suggest that a single massive dose of progesterone on the day of oestrus is an effective means of shortening the oestrous cycle of the ewe without loss of fertility.

Studies on the breeding season of Icelandic ewes and ewe lambs

1978 ◽  
Vol 90 (2) ◽  
pp. 275-281 ◽  
Author(s):  
Ø. R. Dýrmundsson
Keyword(s):  
Breeding Season ◽  
Individual Variation ◽  
First Year ◽  
Cyclic Activity ◽  
Breeding Activity ◽  
Ewe Lambs ◽  
The Mean ◽  
Considerable Individual Variation ◽  
A Minor ◽  
First Year Of Life

SummaryThe paper reports on a study, conducted in four successive seasons, of sexual development and breeding activity in females of the Iceland breed, the only breed of sheep kept in the country. The ewe lambs normally attained puberty in their first year of life, on average at 7 months of age, with marked individual variation in both age and body weight at first oestrus. Ewe lambs always showed oestrus on average slightly later than mature ewes (2–9 years), the mean date of onset of the breeding season of the latter being 8 December, however, with considerable individual variation. Furthermore, ewe lambs had a shorter breeding season (1–4 months) than ewes (4–6 months) and they appeared to experience more silent heats resulting in less regular cyclic activity. There seemed to be a minor increase in the duration of the oestrous cycle with age and ewe lambs clearly exhibited shorter oestrus (heat) than ewes. With seasonal breeding activity ranging from November to May the mid-breeding season occurs some 4–7 weeks after the shortest day.

scholarly journals HORMONAL CONTROL OF REPRODUCTION IN LACTATING AND NON-LACTATING ANESTROUS EWES

1967 ◽  
Vol 47 (1) ◽  
pp. 65-69 ◽  
Author(s):  
Sheikh Saif-Ur Rahman ◽  
W. D. Kitts
Keyword(s):  
Oral Administration ◽  
Hormonal Control

Oral administration of 6-chloro-Δ6-dehydro-17-acetoxyprogesterone (CAP) and 6-α-methyl-17-α-acetoxyprogesterone (MAP) over a period of either 14 or 17 days, successfully induced estrus of lactating and non-lactating anestrous ewes. CAP was found to be more effective than MAP, at the concentrations employed (2.5 mg CAP to 40 mg MAP daily). The effectiveness of CAP and PMS in promoting predictable and early-cycling estrus in anestrous ewes was not enhanced by treatment with estradiol-17-β. Conception and lambing percentages were higher from the hormone-treated non-lactating ewes than from the hormone-treated lactating ewes.

scholarly journals The breeding ecology of the pipefish Nerophis lumbriciformis and its relation to latitude and water temperature

2001 ◽  
Vol 81 (6) ◽  
pp. 1031-1033 ◽  
Author(s):  
N. Monteiro ◽  
V.C. Almada ◽  
A.M. Santos ◽  
M.N. Vieira
Keyword(s):  
Water Temperature ◽  
Breeding Season ◽  
Marked Reduction ◽  
High Water ◽  
Inhibitory Effect ◽  
Breeding Ecology ◽  
High Water Temperature ◽  
Temporal Differences ◽  
Breeding Activity ◽  
Different Temperatures

The breeding season of Nerophis lumbriciformis (Pisces: Syngnathidae), has not yet been determined for the southernmost part of its range. A total of 863 individuals was examined between March 1997 and November 1999. In Portugal, the breeding season of this species occurs throughout the year, with a marked reduction during summer and autumn, whilst in Britain it occurs from May to September. Despite these temporal differences, the water temperature at which breeding takes place is similar in the two areas (13–16°C). Together with preliminary laboratory observations with animals kept at different temperatures, these data support the hypothesis that the decrease in breeding activity during summer and autumn in Portugal is due to an inhibitory effect of high water temperature.

6.10 Cupric Oxide Needles in Hypocuprosis in Sheep

1983 ◽  
Vol 7 ◽  
pp. 139-139
Author(s):  
A. Whitelaw
Keyword(s):  
Oral Administration ◽  
Cupric Oxide ◽  
Dosage Level ◽  
Steady Increase ◽  
Gelatin Capsule ◽  
Deficient Diet ◽  
Dosage Rate ◽  
Liver Copper ◽  
Mean Diameter

The work of Dewey (1977), in Australia, showed that the oral administration of cupric oxide wire (CuON), in lengths of between 5-10 mm and a mean diameter of 0.5 mm, at a dosage rate of 10 g in a gelatin capsule to mature sheep, produced a steady increase in liver copper (Cu) concentrations over 16 days to levels over 1000 mg/kg DM above the initial levels. The 'needles' lodged primarily between the abomasal folds and, by 64 days, were no longer detectable. In grazing conditions, a dose of 20 g was administered to sheep. At neither dosage level were deleterious effects noted. Suttle (1981) administered 0.5 g CuON to hypocupraemic ewes maintained on a Cu-deficient diet and alleviated hypocupraemia for 111 days when the diet was supplemented with molybdenum (Mo) and sulphur (S), and 301 days when the diet was not so supplemented.

Photoperiodism in the ewe: 1. The effect of long supplemented daylengths on the breeding activity of pregnant and non-pregnant Teeswater-Clun ewes

1970 ◽  
Vol 12 (1) ◽  
pp. 107-113 ◽  
Author(s):  
M. J. Ducker ◽  
C. J. Thwaites ◽  
J. C. Bowman
Keyword(s):  
Breeding Season ◽  
Experimental Period ◽  
Breeding Activity ◽  
The Mean ◽  
Natural Breeding

SUMMARYDaylengths of 13 or 20 hr were applied to six groups of nine ewes during the 2nd to 8th, 8th to 14th and 14th to 20th week of pregnancy. Two groups of nine non-pregnant ewes received a constant 13- or 20-hr daylength during the above experimental period. A group of 10 non-pregnant ewes which initially received a 20-hr daylength were subjected to a 13-hr daylength in the last 14 to 20 weeks of the experimental period. After parturition (26 March) all the ewes received increasing natural daylength.The mean number of days from the onset of the experimental light treatments (17 November) to the cessation of oestrous activity did not vary significantly between the three non-pregnant groups of ewes and was on average 89 days.Only two of the 82 ewes, both non-pregnant, exhibited oestrus prior to the longest day (22 June). The various light treatments did not significantly affect the mean dates of occurrence of the natural breeding season of the groups of ewes.

Effect of light on spring breeding of mutton merino ewes

1969 ◽  
Vol 73 (2) ◽  
pp. 177-180 ◽  
Author(s):  
H. Goot
Keyword(s):  
Birth Weight ◽  
Sexual Activity ◽  
Breeding Season ◽  
Control Group ◽  
Artificial Light ◽  
Breeding Activity ◽  
Short Day ◽  
Light Group ◽  
Effect Of Light ◽  
Length Of Gestation

SUMMARYMutton Merino ewes, all of which had lambed in the preceding in-season, were divided into two groups some 30 days after lambing.The ‘light’ group was subjected, over 84 days, to a simulated decrease in daylength, achieved by first adding artificial light to the daylight and then stepping down the light at weekly intervals, from approximately 17 h, on 22 January, to natural daylength (13 ¾ h), on 20 April 1967. The control group was exposed to the normally increasing daylength.Starting on 1 March, the ewes in both groups were ‘teased’ and hand-service commenced on 20 April.The breeding activity (oestrus, ewes lambing, lambs born and twin births) as well as the length of gestation and birth weight appeared to be unaffected by the light.It would appear that the ‘short-day’ photoperiodic theory is not applicable to all breeds of sheep, and it is suggested that in sheep with a long sexual season genetic heterozygosity may be responsible for regulating the breeding season by allowing other environmental stimuli, besides light, to trigger-off sexual activity.

A comparison of the effects of ram introduction and treatment with melatonin upon the breeding activity of seasonally anovular ewes

1988 ◽  
Vol 1988 ◽  
pp. 93-93
Author(s):  
M. Rekik ◽  
M.J. Bryant ◽  
F.J. Cunningham
Keyword(s):  
Breeding Season ◽  
Breeding Activity ◽  
Ram Effect

Both the introduction of rams and treatment with melatonin will hasten the onset of the breeding season of sheep. The response of British breeds of sheep to the introduction of rams is generally considered to be confined to a period of only a few weeks before the usual date of onset of the breeding season (Fraser, Stamp and Cunningham, 1987). However, treatment with melatonin and the “ram effect” may work synergistically as melatonin would be expected to advance the period when the ewes are sensitive to the introduction of rams. This experiment investigated the hypothesis that exposure to high, sustained levels of melatonin from an intravaginal implant would lead to a response to the introduction of rams in mid-seasonal anoestrus similar to that obtained around the onset of the breeding season.

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