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Biomedical subjects

M B Nottle

Publications and source records attributed to M B Nottle.

24 records · Page 2Linked to original sources
PubMed1995

Cysteamine enhances in vitro development of porcine oocytes matured and fertilized in vitro.

Most porcine oocytes matured and fertilized in vitro fail to develop normally due to abnormal fertilization. The aim of this study was to determine the effect of cysteamine on pronuclear formation and developmental competence in pig embryos produced in vitro. Follicular oocytes were matured in vitro with or without cysteamine in Medium 199 supplemented with sodium pyruvate, FSH, LH, 17 beta-estradiol, antibiotics, and 25% porcine follicular fluid. Matured oocytes were then inseminated for 10 h. In the first experiment, pronuclear formation was assessed immediately after the insemination period. The addition of 50 microM or 500 microM cysteamine to the maturation medium increased male pronuclear development, resulting in a higher proportion of oocytes with synchronously formed male and female pronuclei. The frequency of synchronous pronuclear formation was increased in monospermic oocytes from 10% in the control group to 43% (p < 0.001) and 45% (p < 0.001), respectively, and in polyspermic oocytes from 43% in the control group to 68% (p < 0.05) and 75% (p < 0.001), respectively. In the second experiment, development of the in-vitro produced embryos was assessed after 7 days of culture in vitro. The addition 500 microM cysteamine to the maturation medium increased the percentage of cleaving embryos developing to the 8-cell (37% vs. 16%; p < 0.001), morula (19% vs. 6%; p < 0.001), and blastocyst (12% vs. 1%; p < 0.001) stages. These results demonstrate that the addition of cysteamine to maturation medium increases synchronous pronuclear formation and normal embryonic development in porcine oocytes matured and fertilized in vitro.

Animals↗
PubMed1994

Removal of cytoplasmic lipid enhances the tolerance of porcine embryos to chilling.

The lipid content of porcine 1-cell stage embryos was reduced (delipated) through the use of micromanipulation to remove the lipid layer formed after centrifugation. Of 94 delipated embryos chilled to 4 degrees C for 1 h at the 1-cell or 2- to 4-cell stage, 60 (64%) cleaved in culture with development to the morula-blastocyst stage, whereas all of the control embryos lysed within 24 h. Significantly more embryos developed beyond the 8-cell stage when they were chilled at the 2- to 4-cell stage compared with chilling at the 1-cell stage (44%, 20 of 45 vs. 18%, 9 of 49). Fewer embryos developed after chilling if they were only partially rather than fully delipated. Developmental rates of partially delipated embryos to the 8-cell and blastocyst stages were 33% (13 of 40) and 8% (3 of 40), rates significantly (p < 0.001 and 0.05) lower than the rate for fully delipated embryos (73%, 38 of 52 and 27%, 14 of 52, respectively). The in vitro developmental competence of the unchilled fully delipated embryos was comparable to that of intact zygotes (cleavage: 94%, 45 of 48 vs. 87%, 26 of 30; > or = blastocyst: 40%, 19 of 48 vs. 57%, 17 of 30). These data demonstrate that the sensitivity of porcine embryos to chilling is related to their high lipid content and that they can become tolerant to chilling if their lipid content is reduced.

Animals↗
PubMed1990

Feeding lupin grain for six days prior to a cloprostenol-induced luteolysis can increase ovulation rate in sheep irrespective of when in the oestrous cycle supplementation commences.

Three groups of 40 parous Merino ewes were supplemented with 500 g of lupin grain/ewe/day for 7 days starting on either Day 3, 7 or 11 of the oestrous cycle and induced to ovulate by injecting cloprostenol on the sixth day of feeding. Supplementation with lupin grain significantly increased ovulation rate in all groups compared with corresponding controls by increasing the proportion of ewes with twin ovulations. Increases in ovulation rate did not depend on the stage of the cycle at which supplementation began or when during the luteal phase luteolysis was induced. It is concluded that the ovulatory response to lupin grain is initiated near the time of luteolysis.

Animal Feed↗
PubMed1988

Increases in ovulation rate in lupin-fed ewes are initiated by increases in protein digested post-ruminally.

Parous Merino ewes were maintained outdoors in feedlots during the beginning of the spontaneous breeding season and fed a maintenance ration of wheaten hay. For 14 days, ewes in each of 4 groups (N = 40/group) were given supplements of lupin grain or formaldehyde-treated casein and/or wheat starch. These were calculated to supply equivalent amounts of protein post-ruminally and/or digestible energy. Supplementation with lupin grain significantly increased ovulation rate by 37% by increasing the proportion of ewes with two ovulations. Similar increases in ovulation rate were achieved by increasing the supply of digestible protein post-ruminally in the casein and casein + starch-supplement groups. Increasing the intake of digestible energy separately in the starch-supplement group did not increase ovulation rate. It is concluded that increases in ovulation rate in ewes fed a lupin supplement are the result of significant increases in the amount of protein digested post-ruminally.

Animals↗
PubMed1986

Effect of melatonin on postpartum anestrus in beef cows.

The effect of melatonin treatment on intervals from calving to first postpartum estrus and ovulation was determined in Shorthorn cows which calved May 8 to June 14. Melatonin (500 mg in beef tallow) was injected subcutaneously (s.c.) into 20 cows on June 15 (4 to 38 d postpartum). Ovulation was determined from progesterone concentrations in jugular venous blood collected weekly from June to August. Mean intervals to first estrus and first ovulation were significantly longer in primiparous than in multiparous cows (85 +/- 4 vs 55 +/- 3 d and 83 +/- 4 vs 52 +/-3 d). Melatonin treatment caused a significant increase in the intervals to first postpartum estrus (68 +/- 4 vs 58 +/- 5d) and ovulation (68 +/- 4 vs 55 +/- 5 d). Mean plasma melatonin concentrations during the daytime were significantly higher in treated than in control cows one and two weeks after melatonin injection and were within the lower range of nighttime values reported previously for cows. Thus melatonin treatment raised daytime plasma concentrations of melatonin and delayed the onset of estrus and ovulation. These results support the possibility of a role of photoperiod through melatonin secretion in the onset of postpartum ovarian activity in cattle.

Journal Article↗