Lupins and energy-yielding nutrients in ewes. II. Responses in ovulation rate in ewes to increased availability of glucose, acetate and amino acids.

An experiment, using a total of 320 Merino ewes, over two successive breeding seasons was conducted to investigate the separate effects of energy-yielding and protein-yielding nutrients on ovulation rate in sheep. The available energy-yielding or protein-yielding nutrients in the blood of sheep fed a maintenance pelleted ration were increased by either intravenous infusions of metabolites (acetate, glucose or acetate + glucose), feeding lupin grain, modification of the pattern of rumen fermentation to increase propionate production using the ionophore, lasalocid, or by feeding of ruminally undegradable protein (formaldehyde-treated casein). All treatments were given for 9 days prior to and including expected time of ovulation. Ovulation rates were measured by laparoscopy. In the first season (the 1984 experiment) when the effects of lupin grain, glucose + acetate and formaldehyde-treated casein were compared, ovulation rates were increased significantly in the group fed lupin (29%, P less than 0.001) and the group infused with glucose + acetate (24%, P less than 0.01). There was an apparent (17%) but statistically non-significant increase in the group fed casein. In comparisons between lupin grain, glucose, acetate, glucose + acetate, formaldehyde-treated casein and lasalocid in the 1985 experiment there were similar significant increases in ovulation rates in the groups fed lupin, and those infused with glucose or glucose + acetate (approximately 25%, P less than 0.001). The increase in the group infused with acetate was lower at 14% (P less than 0.05) and the increases of 7% in the groups fed casein or lasalocid were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Potential for fecundin to influence the reproductive performance of merino ewes in Western Australia.

Four experiments were conducted at different locations in Western Australia to evaluate the effectiveness of immunizing young (maiden, 1 1/2 year old) and adult Merino ewes with Fecundin to improve their reproductive performances. The ovulation rates of immunized maiden ewes was increased (0.06-0.30) above that of untreated ewes in both experiments 1 and 2. However, there were no significant improvements in the marking percentages for the immunized ewes with the differences between the untreated and immunized ewes ranging from -16.4 to 5.8%. In comparison with untreated ewes immunization 6 and 2 weeks before the start of joining depressed ewe fertility by 26.1% whereas immunization 8 and 4 weeks before the start of joining did not significantly affect fertility. The availability of oat grain ad libitum prior to parturition and during early lactation did not improve the survival of lambs born to immunized ewes. In experiments 3 and 4 immunization of adult Merino ewes increased their ovulation rates (0.41-0.63) above untreated controls and tended to increase the proportion of pregnant ewes which had multiple pregnancies (from -2.3 to 34.2%). The responses at the end of lambing were variable (from -19.8 to 37.5% lambs marked) with high lamb mortalities occurring in some experiments. There was no adverse effect on the reproductive performances following consecutive annual immunizations over 3 years and the absence of treatment for 1 year did not prevent a response in the following year.

Induction of ovulation and cyclic activity in anestrous ewes with testosterone treated wethers and ewes.

An experiment was conducted to evaluate the effectiveness of wethers and ewes treated with testosterone preparations to induce ovulation and breeding activity in anestrous ewes. The testosterone was administered three times at weekly intervals. Wethers and ewes treated with 105 mg testosterone propionate and wethers treated with 100 mg testosterone from testosterone cyclopentyl propionate were as successful as vasectomised rams in inducing ovulation and cyclic activity in ewes. Seven days after the last injection the concentrations of testosterone in peripheral bloods were not significantly different from that in the vasectomised rams. By day 28 the concentrations were significantly lower than in the rams. The testosterone preparations tested are suitable for the induction of male sexual behavior and are rapidly excreted by sheep.

An investigation of the removal of coarse plant material from lupin stubble paddocks for the control of ovine lupinosis.

The removal of course lupin material from lupin stubble paddocks did not reduce the incidence or severity of liver damage caused by the toxins of Phomopsis leptostromiformis. Furthermore, sheep grazing paddocks from which the coarse lupin material had been removed showed body weight changes no different to sheep grazing normal lupin stubbles. In addition, it was found that 6-month old wethers suffered more severe liver damage than 18-month-old wethers, and that lupin material in the paddock remained toxic for a least 6 weeks.

The effect of oestrogen administered during the progestational phase of the cycle on transport of spermatozoa in ewes.

Two split-plot factorial experiments are described, the first with 72 entire cyclic ewes and the second with 80. The pattern of transport of spermatozoa through the reproductive tract was studied, following treatments with progestagen and oestrogen or with oestrogen alone during 2 weeks preceding insemination. A daily dose of 25 mug oestradiol-17 beta administered to ewes for 14 days preceeding oestrus had a deleterious effect on the passage of spermatozoa through the cervix into the uterus within the first 2 hr after insemination. The numbers of spermatozoa recoverable from the cranial region of the cervix 2 hr after insemination appeared to be related to the numbers in the oviducts at 24 hr. These numbers were related to fertility data from an earlier experiment using similar treatments. The data for log numbers of spermatozoa recoverable from the cervix formed a near-normal distribution and so were suitable for formal statistical analysis. There was an interaction between progestagen and oestrogen influence before mating on the pattern of sperm transport through the cervix.

The passage of spermatozoa through the cervix of ovariectomized ewes treated with progesterone and oestrogen.

Thirty spayed ewes were used in a 2 x 3 split-plot factorial experiment (n = 5) in which oestrus was induced with 30 or 90 mug oestradiol benzoate (OB) following a period of progesterone priming. They were inseminated 36 hr after oestrogen and the numbers of spermatozoa in the caudal, mid- and cranial regions of the cervix (sub-plots) were estimated 1, 12 and 24 hr later. At each interval of time and for each region of the cervix, fewer spermatozoa were recovered from the ewes treated with 30 mug OB than from those treated with 90 mug (P less than 0-05).

Proceedings: The transport of spermatozoa in ewes treated with steriod hormones.

PIP: The report cites the results of three experiments designed to determine the effect of estrogen treatment on spayed and entire ewes. In the spayed ewes, estrus was induced by progesterone priming followed by an injection of estroidal benzoate. Measurements at the twelth hour showed a far greater accumulation of spermatozoa in the mid and cranial cervix with dosages of 90 mcg than with 30 mcg. At the 24 hour mark, no measurable difference occurred. In the entire ewes, estrus was controlled using progestagen-impregnated sponges with subsequent administration of 1 mcg or 5 mcg/day of estradiol-17beta. At the 2 hour mark, little effect was observed in the number of spermatozoa entering the caudal cervix though a marked effect was found in the number traversing the cervix into the uterus. At 24 hours, there were no differences between estrogen treated and non-treated ewes in the cervix and uterus. The numbers in the fallopian tubes reflected the numbers found in the uterus and cranial cervix at the 2 hour mark. Estrogen treatment markedly reduced these numbers. Entire ewes also received 25 mcg/day estrogen during the normal luteal cycle. At 2 hours, there was no measurable effect in the caudal cervix but numbers were reduced in the mid and cranial cervix. At 24 hours, numbers in the fallopian tubes reflected this result. The report concludes that the sub-fertility in ewes is mostly due to changes in the cervical environment following estrogen treatment during the progestational phase, resulting in impaired transport of spermatozoa to the uterus.^ieng