Progress 10/01/02 to 09/30/07
Outputs
Obj. 1. Relationship of preovulatory follicle size and estradiol to embryo/fetal survival. Lactating dairy cows were synchronized for ovulation and artificial insemination (OvSynch/TAI). On the day of AI preovulatory follicle size was larger and plasma concentrations of estradiol and IGF-I were greater in pregnant versus non-pregnant cows. Plasma IGF-I tended to remain higher through day 8 after AI and concentrations were higher in the warm season. Obj. 3a. The effects of nutritionally raising insulin during the periparturient period on reproductive performance in cows. The dominant follicles of postpartum cows were categorized as being ovulatory (O), non-ovulatory high estradiol (NH), non-ovulatory low estradiol (NL), or cystic (C). NL cows had significantly lower pre- and postpartum DMI and energy balance (EB) compared with O cows; they also had postpartum hormone and metabolic profiles indicative of more severe negative EB. A critical facet of successful onset of
lactation is the reduced responsiveness of muscle and adipose tissue to insulin, allowing greater nutrient uptake by the mammary gland in support of milk synthesis. We observed little variation between the different follicle-type groups in circulating glucose during the postpartum experimental period. Circulating insulin, however, was greatest in the future O cows, resulting in this group having the lowest glucose:insulin ratio. Hence, O cows had greater circulating insulin per unit of glucose, especially compared with NL cows. Obj. 3b: Effects of heat stress in vitro on follicular steroidogenesis. Ovaries bearing a healthy dominant follicle were collected from heifers. Theca interna and granulosa cells were isolated and cultured at 37 (the normothermic temperature), 39 and 41 C. The potential effects of heat stress on oxytocin production by granulosa cells from bovine preovulatory follicles was examined. The secretion of oxytocin by granulosa cells was not affected by heat stress
and, consistent with that finding, levels of mRNA for oxytocin were also unaffected by temperature in vitro. The inhibitory effects of heat stress on androstenedione secretion by theca cells were not accompanied by comparable decrease in levels of mRNA for 17α-hydroxylase, whereas the increases in progesterone secretion during heat stress in vitro were correlated with increases in mRNAs for StAR and 3B-hydroxysteroid dehydrogenase, but not for P450 side chain cleavage enzyme. In cultures of both theca and granulosa cells from bovine preovulatory follicles there was a transient increase in heat shock protein (HSP) 90beta (the constitutive form of HSP90) and a sustained increase in mRNA for HSP90alpha during heat stress in vitro, which suggests that changes in levels of these HSPs may mediate some or all of the changes in steroid production in response to elevated temperature.
Impacts
The results of the current study indicate that DMI, and accordingly energy balance, during late pregnancy (3 weeks preceding parturition) may play a pivotal role in predetermining the functionality of the hypothalamo-pituitary-ovarian axis, and hence the fate of the first postpartum follicle wave. Along with DMI, metabolic shifts in peripheral insulin responsiveness and insulin secretion regulate rates of lipolysis and glucose availability associated with differences in follicle outcome. Since early postpartum ovulation is associated with higher fertility during the breeding period, understanding the metabolic regulation of follicle development should provide nutritional strategies to enhance the proportion of cows with ovulatory first wave dominant follicles. Heat stress has a major negative effect on conception rate throughout the world. Our research has elucidated effects of elevated temperature on hormone production by the two endocrine cell types (granulosa and
theca) from bovine preovulatory follicles. The results indicate that heat stress decreases two hormones important before ovulation, estradiol and androstenedione, and prematurely increases progesterone, the major product of the corpus luteum (i.e. heat seems to prematurely luteinize follicles). These results suggest that excessive ambient temperatures have specific effects on steroid production by preovulatory follicles in vivo. This knowledge may eventually suggest treatments to improve fertility in hyperthermic cattle.
Publications
- Castaneda-Gutierrez, E., B.C. Benefield, M.J. de Veth, N.R. Santos, R.O. Gilbert, W.R. Butler, and D.E. Bauman. 2007. Evaluation of the mechanism of action of conjugated linoleic acid isomers on reproduction in dairy cows. J.Dairy Sci 90 (9):4253-4264.
- Lopes, A.S., S.T. Butler, R.O. Gilbert, and W.R. Butler. 2007. Relationship of pre-ovulatory follicle size, estradiol concentrations and season to pregnancy outcome in dairy cows. Anim.Reprod.Sci. 99:34-43.
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Progress 01/01/06 to 12/31/06
Outputs
Obj. 1. Relationship of preovulatory follicle size and estradiol to embryo/fetal survival. Lactating dairy cows (144 total; 60-120 days lactation) were synchronized for ovulation and artificial insemination (OvSynch/TAI). Greater preovulatory follicle size and plasma estradiol on the day of AI were related to pregnancy, but not to embryonic/fetal losses and season did not affect these outcomes. After corpus luteum regression, development and ovulation of the next follicle occurs, however, the regressed corpus luteum may produce an embryotoxic factor. PGFM (13,14 dihydro-prostaglandin-F2a) was measured as an index of residual luteal activity. On the day of AI, PGFM was not different between pregnant or non-pregnant cows, but was 2-fold higher in the cold than warm season. Obj. 3a. The effects of nutritionally raising insulin during the periparturient period on reproductive performance in cows. The dominant follicles of postpartum cows were categorized as being
ovulatory (O), non-ovulatory high estradiol (NH), non-ovulatory low estradiol (NL), or cystic (C). Differences among the cows with different follicle categories in dry matter intake (DMI) and energy balance (EB) were apparent by 3 weeks before parturition. NL cows had significantly lower pre- and postpartum DMI and EB compared with O cows; they also had postpartum hormone and metabolic profiles indicative of more severe negative EB. The multiple logistic regression model for predicting likelihood of an ovulatory follicle included: duration of declining EB, plasma insulin concentration, DMI in the final week before parturition, and plasma glucose on day of parturition (correct in 93 percent of cases). O cows had greater circulating insulin per unit of glucose, especially compared with NL cows. Obj. 3b: Effects of heat stress in vitro on follicular steroidogenesis. Ovaries bearing a healthy dominant follicle were collected from heifers. Theca interna and granulosa cells were isolated
and cultured at 37 (the normothermic temperature), 39 and 41 C. Granulosa cells: consistent with the decrease in estradiol secretion at elevated temperature in previous experiments, mRNA for aromatase was lower at 41 C. The intermediate temperature (39 C) resulted in levels intermediate between 37 C and 41 C. The results for mRNAs for StAR and 3B-HSD provided evidence for a potential role for their proteins in the increase in progesterone with elevated temperature in vitro. Theca cells: androstenedione secretion in culture was decreased by elevated temperature in vitro and there was a heat-related decrease in mRNA for 17a-OH in control cultures at 24 h. mRNA for StAR was significantly affected by temperature in vitro, with increased levels of the mRNA at 41 C and intermediate levels at 39 C. The effects of elevated temperature in vitro on steroid production by granulosa cells (decreased secretion of estradiol and increased secretion of progesterone) are mediated through decreases and
increases in mRNA for aromatase and for proteins involved in progesterone production (StAR, P450scc, and 3B-HSD), respectively. The results for theca cells show effects on mRNAs for 17a-OH and StAR.
Impacts
In lactating dairy cows, follicle development and function (dominance) during the first postpartum follicular wave has 4 outcomes: ovulation (O); non-ovulatory follicles with high circulating estradiol (NH) versus low circulating estradiol (NL); cystic follicles (C). Dietary intake and energy balance during late pregnancy (3 weeks preceding parturition) appear to play a pivotal role in predetermining the functionality of the hypothalamo-pituitary-ovarian axis, and hence the fate of the first postpartum follicle wave. Along with DMI, metabolic shifts in peripheral insulin responsiveness and insulin secretion regulate follicle outcome. Since early postpartum ovulation is associated with higher fertility during breeding, understanding the metabolic regulation of follicle development should provide nutritional strategies to enhance the proportion of cows with ovulatory first wave dominant follicles. Heat stress has a major negative effect on conception rate throughout the
world. Reduced fertility in the summer months has increased in dairy cattle in temperate zones as milk production has increased. The effects of heat stress on ovarian cells in culture was determined. Estradiol and androgen production by follicle cells from preovulatory follicles are decreased at higher temperatures in vitro and progesterone is increased compared to normothermic conditions, suggesting that hyperthermic conditions accelerate the luteinization that would normally occur close to ovulation.
Publications
- Butler, S. T., S. H. Pelton, and W. R. Butler. 2006. Energy balance, metabolic status, and the first postpartum ovarian follicle wave in cows administered propylene glycol. J.Dairy Sci. 89:2938-2951.
- Folger, J.K. and J.E. Fortune, 2006. Heat stress in vitro affects expression of mRNA for steroidogenic enzymes and StAR in granulosa cells from bovine preovulatory follicles. Biology of Reproduction, Special Issue, Proc. of the 39th annual meeting of the Soc. for the Study of Reproduction, page 174.
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Progress 01/01/05 to 12/31/05
Outputs
Obj. 1. Relationship of preovulatory follicle size and estradiol to embryo/fetal survival. Lactating dairy cows (144 total; 72/season; 60-120 days lactation) were treated during either July-September or January-April to synchronize ovulation and artificial insemination (OvSynch/TAI). The size of the largest ovarian follicle (presumptive ovulatory follicle) was measured on the day of the second GNRH injection and AI by ultrasonographic (US) exam of the ovaries. Pregnancy in lactating cows was associated with larger (P less than 0.05) follicle diameter on the day of AI, but the incidence of pregnancy was not different between cold or warm season. Estradiol concentrations on day of AI were greater in pregnant than non-pregnant cows, but not between pregnant cows at day 63 and those losing the conceptus between d 28-63. Cows pregnant at d28 had higher progesterone concentrations from d5 post-AI compared to non-pregnant cows suggesting that a more rapid rate of
post-ovulatory rise of progesterone improves embryo survival. Pregnancy rate in lactating cows was 33 percent at d 28 after AI and 23 percent of these were lost by d 63. Of these conceptus losses, late embryo loss by d 42 accounted for 17 percent (73 percent of total). Follicle size at AI was similar in cows pregnant at d 63 compared to those losing the conceptus between d 28-63. Season did not affect follicle size. Among pregnant cows in the cold season, conceptus loss was associated with lower plasma progesterone from d 22 post-AI onward, whereas for the warm season this difference was not significant until d 30. Overall, preovulatory follicle size and plasma E2 on the day of AI were related to pregnancy, but not to embryonic/fetal losses and season did not affect these outcomes. Obj. 3. The effects of nutritionally raising insulin during the periparturient period on reproductive performance. Drenching cows with propylene glycol daily during the transition period had a clear
beneficial effect on the postpartum metabolic profile including increases in plasma insulin and decreases in plasma NEFA and BHBA concentrations. These metabolic alterations failed to elicit any demonstrable effect on the reproductive parameters. There was no difference between treatments in the proportion of cows having ovulatory, atretic or cystic follicles in the first postpartum follicle wave and no difference in LH pulse frequency. The dominant follicle of each cow was retrospectively categorized as being ovulatory (O; n = 17), non-ovulatory high estradiol (NH; n = 6), non-ovulatory low estradiol (NL; n = 24), or cystic (C; n = 8). Differences among the cows with different follicle categories in dry matter intake (DMI) and energy balance (EB) were apparent as early as 3 weeks before parturition. NL cows had significantly lower pre- and postpartum DMI and EB compared with O cows; they also had postpartum metabolic hormone and metabolite profiles indicative of more severe negative
EB.
Impacts
Follicle size at insemination following ovulation synchronization procedures is relatively uniform, but follicles were larger in cows becoming pregnant compared to non-pregnant cows. Follicle size seems unrelated to subsequent late embryo losses. Plasma estradiol concentrations before ovulation were predictive of pregnancy status and higher circulating progesterone from d5 after insemination seems related to improved embryo survival. Strategies to improve energy balance during the periparturient period in cows, particularly before calving should lead to higher pregnancy rates during the breeding period in early lactation.
Publications
- Butler, W.R.. 2005. Relationships of negative energy balance with fertility. Advances in Dairy Technology 17:35-46.
- Butler, W.R. 2005. Relationships of dietary protein and fertility. Advances in Dairy Technology 17:159-168.
- Butler, W.R. 2005. Inhibition of ovulation in the postpartum cow and the lactating sow. Livest. Prod. Sci. 98:5-12.
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Progress 01/01/04 to 12/31/04
Outputs
Obj. 1. Relationship of preovulatory follicle size and estradiol to embryo/fetal survival. Lactating dairy cows (120 total; 60/season; 60-120 days lactation) were treated during either July-September or January-April to synchronize ovulation and artificial insemination (OvSynch/TAI). The size of the largest ovarian follicle (presumptive ovulatory follicle) was measured on the day of the second GNRH injection and AI by ultrasonographic (US) exam of the ovaries. Pregnancy in lactating cows was associated with larger (P less than .05) follicle diameter on the day of AI, but the incidence of pregnancy was not different among cows with follicle diameter above or below the mean (33 vs 35 percent, respectively). Estradiol concentrations on day of AI were not significantly different between pregnant and non-pregnant cows in either season, nor between pregnant cows at day 63 and those losing the conceptus between d 28-63. Cows pregnant at d28 had higher progesterone
concentrations from d5 post-AI compared to non-pregnant cows suggesting that a more rapid rate of post-ovulatory rise of progesterone improves embryo survival. Pregnancy rate in lactating cows was 33 percent at d 28 after AI and 23 percent of these were lost by d 63. Of these conceptus losses, late embryo loss by d 42 accounted for 17 percent (73 percent of total). Follicle size at AI was similar in cows pregnant at d 63 compared to those losing the conceptus between d 28-63. Season did not affect follicle size in pregnant or pregnant cows losing the conceptus. Among pregnant cows in the cold season, conceptus loss was associated with lower plasma progesterone from d 8 post-AI onward, whereas for the warm season this difference was not significant until d 30. Obj. 3. The effects of nutritionally raising insulin during the periparturient period on reproductive performance. Drenching cows with propylene glycol daily during the transition period had a clear beneficial effect on the
postpartum metabolic profile including increases in plasma insulin and decreases in plasma NEFA and BHBA concentrations. These metabolic alterations failed to elicit any demonstrable effect on the reproductive parameters. There was no difference between treatments in the proportion of cows having ovulatory, atretic or cystic follicles in the first postpartum follicle wave and no difference in LH pulse frequency.
Impacts
Follicle size at insemination following ovulation synchronization procedures is relatively uniform, but follicles were larger in cows becoming pregnant compared to non-pregnant cows. Follicle size seems unrelated to subsequent late embryo losses. Plasma estradiol concentrations before ovulation were not predictive of pregnancy status and embryo loss rate, but higher circulating progesterone from d5 after insemination seems related to improved embryo survival. Strategies to improve energy balance in lactating cows may increase progesterone or other hormones related to embryo viability and lead to higher pregnancy rates.
Publications
- Butler,S.T. and Butler,W.R. 2004. Energy balance, dry matter intake, and hormone profiles of cows with ovulatory and non-ovulatory follicles during the first postpartum follicle wave. J. Dairy Sci. 87(Suppl.1):296.
- Butler,S.T. 2004. Interfaces between metabolic status and the reproductive axis in periparturient dairy cattle. Ph.D. Dissertation. 185 pages.
- Lopes,A.S., Butler,S.T., Gilbert,R.O. and Butler,W.R. 2004. The follicle's influence on embryonic/fetal mortality in cattle. Proc. 20th meeting European Embryo Transfer Assoc., Lyon, France, Sept. 10-11.
- Butler, W.R. 2003. Energy balance relationships with follicular development, ovulation and fertility in postpartum dairy cows. Livest. Prod. Sci.. 83:211-218.
- Butler, W.R. 2003. Negative energy balance may delay subsequent ovulation. Feedstuffs 75(#50):10-13.
- Butler, S.T. and W.R. Butler. 2003. Ovarian activity during the early postpartum period: The role of circulating levels of insulin, IGF-I and urea. Proc. 2003 Cornell Nutrition Conference. pp. 219-231
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Progress 10/01/02 to 09/30/03
Outputs
Obj. 1. Relationship of follicle size and preovulatory estradiol to embryo/fetal survival. Lactating dairy cows (120 total; 60/season; 60-120 days lactation) will be treated during either July-September or January-April to synchronize ovulation and artificial insemination (OvSynch/TAI). The size of the largest ovarian follicle (presumptive ovulatory follicle) is measured on the day of the second GNRH injection and AI by ultrasonographic (US) exam of the ovaries. US examination for the detection of an embryo or fetus is conducted on days 30 and 60 post-AI. Within each season, follicle size (less than vs. more than group mean) will be compared to peripheral concentrations of estradiol at AI and pregnancy status on days 30 and 60. Data collected for the cool season shows a trend (p=.15) for follicle size to be greater in cows that become pregnant (15.9 +/- 2.9 mm) than in non-pregnant cows (14.7 +/- 3.9 mm). Of the cows that were pregnant at d 30 (30 percent), embryo
losses by d 60 was 20 percent, but unrelated to follicle size at ovulation. Obj. 3. The early postpartum period in high producing dairy cows is characterized by chronic severe negative energy balance, hypoinsulinemia, hypoglycemia, and inadequate LH pulse frequency resulting in a varying duration of anestrous. Cows were drenched with either 500 ml of propylene glycol or water daily from day -10 prior to parturition until day 25 postpartum to determine if daily transient elevation in insulin and glucose could ameliorate the effects of negative energy balance on LH pulsatility and the fate of the first follicle wave. Both insulin and glucose were elevated following PG administration. On day 10 postpartum the number of LH pulses, mean LH and pulse amplitude were not different between CTL and PG cows and also the proportion of dominant follicles that became ovulatory (10/29 vs. 11/30) were not different.
Impacts
Follicle size at insemination following ovulation synchronization procedures is relatively uniform and seems to be unrelated to subsequent late embryo losses. Plasma estradiol and progesterone concentrations will be compared to pregnancy status and embryo loss rate as more sensitive assessments of embryo viablity and provide a better understanding of when embryo losses are occurring. Strategies to improve energy balance in lactating cows should lead to higher pregnancy rates.
Publications
- Butler, S. and W.R. Butler. 2003. The effect of daily drenching with propylene glycol during the transition period on the fate of the first follicle wave and LH pulsatility. J. Dairy Sci. 86(Suppl. I):239.
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