Selenium is an essential micronutrient in sheep, and deficiency can limit lamb growth and survival. To evaluate how different chemical forms of Se administered to mature ewes at comparative dosages affect ewe and progeny performance, 240 ewes were divided into 8 treatment groups (n = 30 each) and drenched weekly with no Se; at the maximum FDA-allowed concentration with inorganic Na-selenite or ...

Counts were made of the numbers of spermatozoa in the Fallopian tubes of ewes 24 hr after mating or after insemination with either sheep or goat semen. Spermatozoa were recovered from all five mated ewes (10/10 tubes), from all eight ewes inseminated with sheep semen (13/15 tubes) and from four of eight ewes inseminated with goat semen (7/16 tubes). The calculated mean numbers of spermatozoa pe...

The effect of ram percentage on the fertility of maiden ewes joined in autumn was examined on ten properties in New South Wales. On four of these properties a group of maiden ewes was joined to one per cent of rams and another group to three per cent. On another two properties the design was similar, but a third group containing maiden and mature ewes was also joined to one per cent of rams. On...

The efficacy of two doses of progesterone (P4), i.e. 350 and 300mg was evaluated in acycling crossbred ewes (50) during the autumn breeding season. Ewes were treated with intravaginal progesterone sponges with either 350mg or 300mg for 12 days. At standing estrus, ewes were hand mated (three cycles). Progesterone (350mg) gave a better (P<0.05) estrus response (75%), compared to 300mg dose (42%)...

Most North Dakota sheep production scenarios require substantially more resources, such as feed, labor, and facilities during late gestation and lactation. Early identification of pregnancy and pregnancy rate in sheep provides managers several options to increase flock productivity. First, removal of non-pregnant ewes can increase available resources for pregnant ewes. Second, identification of...

A mutagenized clone of Rift Valley fever virus (RVFV; MV P12) used in inoculation of 3 pregnant ewes was immunogenic, nonpathogenic, and nonabortogenic. In contrast, inoculation of a matched group of 3 pregnant ewes with parent RVFV induced clinical disease and abortions. Ewes given MV P12 delivered healthy lambs that had RVFV antibody titers of less than 1:10 at birth, increasing to greater th...

If ewes consumed a high-salt diet or saltbush during the last 3 months of pregnancy and for 3 weeks after birth, we expected the renin activity of their lamb to be suppressed at birth and at 3 weeks of age. We also expected an increase in the concentration of cations other than sodium in the ewe's milk and an increase in the plasma Na concentration of the lamb at birth. To test these hypotheses...

The aim of this study was to determine whether endogenous progesterone regulates synthesis and secretion of luteal oxytocin. In Expt 1, mature ewes (n = 5 per group) were assigned randomly to control or mifepristone (RU486) treatment groups. Ewes were injected s.c. twice a day with vehicle or 10 mg RU486 on days 5-7 of the oestrous cycle (oestrus = day 0). On day 8, after an i.v. injection with...

The objective of this experiment was to determine whether passive immunization against a synthetic inhibin-like peptide (alpha-IF) increases FSH secretion and reproductive performance of ewes bred in the spring. Crossbred ewes were assigned to three treatment groups of 10 ewes each. Progesterone-releasing pessaries (CIDR-G) were inserted and left in place for 12 d. The CIDR-G were removed on Ap...