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Biomedical subjects

L R Piper

Publications and source records attributed to L R Piper.

28 records · Page 2Linked to original sources
PubMed1986

Suppression of ovine plasma FSH by bovine follicular fluid: neutralization by plasma from ewes immunized against an inhibin-enriched preparation from bovine follicular fluid.

Adult Merino ewes were immunized against an inhibin-enriched preparation (bFFI) obtained by affinity chromatography of bovine follicular fluid (bFF). Plasma was obtained in early luteal phase from these ewes and from control ewes immunized against bovine serum albumin. Ten months after ovariectomy the plasma concentration of FSH, but not LH, in control ewes was decreased by four s.c. injections of 8 ml bFFI (17,500 units inhibin/injection). There was no decrease in plasma concentrations of FSH or LH in immunized ewes with the same dose of bFFI. In a second study with long-term ovariectomized ewes, four injections of 20 ml plasma from the immunized ewes significantly reduced the decrease in FSH concentration caused by four injections of steroid-free bFF (2500 units inhibin/injection) in comparison with similar ewes injected with plasma from control ewes. These results show that the plasma of ewes immunized against bFFI contains substances, presumably antibodies, which neutralize the FSH-suppressive effects of bFF and bFFI in ovariectomized ewes.

Animals↗
PubMed1985

Plasma FSH and LH in prepubertal Booroola ewe lambs.

Basal plasma concentrations (four 30-min samples) and GnRH-induced release of gonadotrophins were measured every 15 days between 30 and 90 days and at 110 days of age in Merino ewe lambs from the prolific Booroola ('B') flock (n = 18-23), the medium prolificacy ('T') flock (n = 14-20), and the 'O' flock (n = 4-8) of low prolificacy. At ages of 30 and 45 days B ewe lambs had mean basal plasma FSH concentrations of 145 and 122 ng/ml which were significantly higher (P less than 0.01) than those seen in T (45 and 53 ng/ml), and O (39 and 38 ng/ml) flock ewes. Between 60 and 110 days of age there were no significant differences between genotypes. The increment in FSH concentrations above basal levels induced by the subcutaneous injection of 100 micrograms synthetic GnRH was only significantly (P less than 0.05) greater in B than T and O genotype ewe lambs at 110 days of age but not at other ages. The basal plasma FSH differences between the B, T and O genotypes at 30 and 45 days of age were not consistently related to the size of litter in which lambs were born. At 30 days of age the mean plasma LH concentration of B, T, and O flock lambs were 2.6 +/- 0.5, 1.2 +/- 0.6 and 0.7 +/- 0.8 ng/ml respectively. These differences were not significant. At later ages there were also no significant differences between the genotypes with respect to basal LH, and the increase in LH induced by exogenous GnRH was always similar for the three genotypes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
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↗
PubMed1984

Preovulatory LH characteristics and time of ovulation in the prolific Booroola Merino ewe.

In 4 separate experiments involving 133 ewes the timing of the onset of the LH discharge relative to the onset of oestrus was compared in prolific Booroola Merinos and in other Merinos of low ('C' and 'O' genotypes) and medium ('T' genotype) prolificacy. Despite different average ovulation rates of 3.05, 1.85, 1.18 and 1.37 for Booroola, 'T', 'O' and 'C' ewes, respectively, there were no consistent differences in the time of the LH discharge which occurred on average 4.5 h after the onset of oestrus. Time of ovulation was studied, in two experiments involving 430 Booroola, 'T', 'O' and 'C' ewes, by laparoscopic ovarian examination of subsamples of ewes at 20, 24, 28 or 32 h after onset of oestrus. Ovulation occurred significantly (P less than 0.001) earlier (7.5 h) in Booroola ewes than in those of the other genotypes.

Animals↗
PubMed1983

Ovarian follicles of new-born Merino lambs from genetic lines which differ in fecundity.

Ovaries were obtained from 78 new-born lambs (12 singletons, 25 twins, 28 triplets, 10 quadruplets and 3 quintuplets) from flocks selected for (T902, T903 and Booroola) or against (O) multiple births. Sections of the ovaries were examined with a projection microscope and the numbers of all types of follicles were estimated. There were no differences between genetic lines in the number of primordial follicles, after adjustment for litter size and sire; however, there were significantly more of these follicles in single-born lambs than in lambs born in litters of two or more within genetic lines. The number of vesicular follicles was lower in Booroola than in O lambs.

Animals↗