Progress 10/01/04 to 09/30/09
Outputs
OUTPUTS: Research has reported that embryonic mortality has a tremendous impact on reproductive efficiency. Uterine pH has been reported to influence pregnancy success, and a recent report indicated a significant correlation between blood sulfate concentrations and sulfate concentrations in oviductal and uterine fluids. Therefore, an experiment was conducted to evaluate the relationship between uterine pH and blood sulfate concentrations. Immediately following detection in estrus, heifers were divided into 3 groups (n equals 6 per group). The groups were fed a low, medium, or high sulfur diet (9.6, 18.08, and 31.34 g/d sulfur, respectively). Uterine pH and blood samples were collected on d 7 and 11 after estrus. Uterine pH decreased (P less than 0.01) from d 7 to d 11. Uterine pH tended to decrease among LOW heifers (P equals 0.06), and decreased from d 7 to 11 in MED (P equals 0.01) and HIGH (P less than 0.01). In addition, there was an effect of time (P less than 0.01) on blood sulfate concentrations. Sulfate concentrations increased from d 7 to 11 in LOW (P less than 0.01), MED (P less than 0.01), and HIGH (P equals 0.01) heifers. There was a significant positive correlation between time and sulfate concentrations (P less than 0.01; R-squared 0.56) and a significant negative correlation between sulfate concentrations and uterine pH (P less than 0.01; R-squared 0.32). As time on these diets increased blood sulfate concentrations increased and as blood sulfate concentrations increased uterine pH decreased. PARTICIPANTS: Research Technition n = 1 Graduate Student n = 1 TARGET AUDIENCES: The target audience for this project are Beef and Dairy producers and other research scientists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Reproductive efficiency has a tremendous impact on the sustainability of cattle operations and an may be improved by a better understanding the differences in physiology between cows that maintain a pregnancy compared to cows that loose a pregnancy. This project determined the effect of diet on uterine environment; which plays a tremendous role in the maintenance of pregnancy. Increased dietary sulfur resulted in a decrease in uterine pH which has been correlated to a decrease in embryonic survival.
Publications
- S. D. Fields, B. L. Perry, and G. A. Perry. 2009. Effects of GnRH treatment on initiation of pulses of LH, LH release, and subsequent concentrations of progesterone. Domestic Anim. Endo. 37:189-195.
- G. A. Perry, and B. L. Perry. 2009. Effect of an injection of GnRH at time of insemination following detection in standing estrus on subsequent concentrations of progesterone and pregnancy rates. Theriogenology 71:775-779.
- G.A. Perry, B.L. Perry, and R. A. Cushman. 2009. Association between preovulatory concentrations of estradiol and expression of uterine milk protein precursor, inhibin beta A, period 1, proenkephalin, and receptors for oxytocin, progesterone, and estradiol. Biol. Reprod. 79(Suppl. 1) Abstr. 308.
- G.A. Perry, B.L. Perry, S. D. Fields, J.A. Walker, and C.L. Wright. 2009. Influence of blood sulfate concentrations on uterine pH. J. Anim. Sci. 87(E-Suppl. 2): Abstr 688.
- B.L. Perry, J.A. Walker, C.L. Wright, K. C. Olson, and G.A. Perry. 2009. Influence of heifer development method on post-AI blood metabolites. J. Anim. Sci. 87(E-Suppl. 2): Abstr M288.
- G.A. Perry, B.L. Perry, J.A. Walker, and C.L. Wright. 2009. Influence of post-AI diet change on uterine pH and blood urea nitrogen. J. Anim Sci. (Midwest) Abstr 243.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Research has reported cows detected in estrus around the time of fixed-time AI had increased pregnancy rates compared to cows not in estrus. Therefore two studies were conducted to determine factors that may influence pregnancy rates. Research has indicated that LH pulses play a critical role in CL formation/function, and an injection of GnRH influenced LH pulse frequency. Therefore the objectives of the first study were to determine the effect of standing estrus on LH pulse frequency, total LH release, and subsequent concentrations of progesterone following a fixed-time AI protocol. Furthermore, uterine pH decreased at the initiation of estrus and pH has been reported to influence sperm motility and longevity. Therefore the objective of the second study was to determine the relationship between uterine pH at fixed-time AI and pregnancy rates. In the first study cows were synchronized with the CO-Synch protocol. Estrus was detected by visual detection. Prior to the GnRH injection at time of AI jugular catheters were inserted (5 detected in standing estrus and 5 not detected in standing estrus). Blood samples were collected at 15-min intervals from 0 to 6 h (bleed 1), 12 to 20 h (bleed 2), 26 to 34 h (bleed 3), and 40 to 48 h (bleed 4) after the second GnRH injection. Blood samples were also collected daily for 17 d. There was an effect of bleed on area under the curve (P less than 0.001) as well as average concentration (P less than 0.001) with bleed 1 having greater LH release than bleeds 2, 3, or 4. Bleed 1 had decreased (P equals 0.03) pulse frequency compare to 2, but did not differ (P equals 0.09, P equals 0.82) from 3 or 4. Bleed 2 did not differ (P equals 0.55) from 3, but had greater (P equals 0.04) frequency than 4. Bleeds 3 and 4 did not differ (P equals 0.13). There were no effects of treatment or treatment x time for area under the LH curve (P equals 0.50; P equals 0.97), average concentration of LH (P equals 0.63; P equals 0.83), or LH pulse frequency (P equals 0.22; P equals 0.92). Cows that showed estrus had greater (P equals 0.002) subsequent concentrations of progesterone than those that did not show estrus. In the second study, cows in two herds were synchronized with the CO-Synch protocol or the CO-Synch+CIDR protocol. Uterine pH was determined at fixed-time AI (143). Cows were determined to be in standing estrus by activation of an EstroTect estrus detection aid, determined at timed AI. Pregnancy was determined 70 d after AI. At time of AI, cows that had initiated estrus had decreased (P equals 0.01) uterine pH and increased (P equals 0.05) pregnancy success compared to cows not in estrus. Uterine pH at AI had an approximately linear effect on pregnancy success within the observed pH range. As uterine pH increased pregnancy success decreased (P equals 0.076). In summary, GnRH increased the release of LH during bleed 1 but decreased pulse frequency. Estrus did not have an effect on LH pulses, but increased subsequent concentrations of progesterone, and uterine pH at time of AI was decreased in cows that exhibited estrus and uterine pH tended to have a linear effect on pregnancy success. PARTICIPANTS: Graduate Students = 1 TARGET AUDIENCES: The target audience for this project are Beef producers and other research scientists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The efficiency of fixed-time insemination protocols may be improved by a better understanding the differences in physiology between cows that are detected in standing estrus and cows that are not detected in standing estrus around the time of fixed-time AI. These projects determined the effect of standing estrus at time of fixed-time AI on LH parameters, uterine pH at time of AI, and subsequent concentrations of progesterone. The GnRH injection given at time of Fixed-time AI increased the release of LH during bleed 1 but decreased pulse frequency. However, Estrus did not have an effect on LH pulses, but increased subsequent concentrations of progesterone, and uterine pH at time of AI was decreased in cows that exhibited estrus and tended to have a linear effect on pregnancy success.
Publications
- G. A. Perry, and B. L. Perry. 2008. Effects of standing estrus and supplemental estradiol on changes in uterine pH during a fixed-time AI protocol. J. Anim. Sci. 86: 2928-2935.
- C. E. Engel, H. H. Patterson, and G. A. Perry. 2008. Effect of dried corn distillers grains plus solubles compared to soybean hulls, in late gestation heifer diets, on animal and reproductive performance. J. Anim. Sci.86:1697-1708.
- G. A. Perry, and B. L. Perry. 2008. Effect of preovulatory concentrations of estradiol and initiation of standing estrus on uterine pH in beef cows. Domestic Anim. Endo. 34:333-338.
- G.C. Lamb, C.R. Dahlen, K. A. Vonnehamme, G. R. Hansen, J. D. Arseneau, G. A. Perry, R.S. Walker, J. Clement, J. D. Arthington. 2008. Influence of a CIDR prior to bull-breeding on pregnancy rates and subsequent calving distribution. Animal Reproduction Sciences. Anim. Reprod. Sci. 108(3-4):269-278.
- Lares, S. F., S. D. Fields, B. L. Perry, D. G. Chen, and G. A. Perry. 2008. Relationship between uterine pH at fixed-time AI and pregnancy success in beef cattle. J. Anim. Sci. 86(E-Suppl. 2): Abstr 721.
- Perry, G. A., and B. L. Perry. 2008. Effect of the timing of CIDR insertion on the GnRH-induced LH surge and ovulatory response. J. Anim. Sci. 86(E-Suppl. 2): Abstr W160.
- Perry, G. A. 2008. Reproductive consequences of nutritionally-induced changes in the pH of the bovine reproductive tract. J. Anim. Sci. 86(E-Suppl. 2): Abstr 300.
- Schiefelbein, A. K., B. L. Perry, and G. A. Perry. 2008. Association between preovulatory concentrations of estradiol and expression of uterine receptors for oxytocin, progesterone, and estradiol. Biol. Reprod. 78(Suppl. 1) Abstr. 362
- Perry, B. L., A. K. Schiefelbein, and G. A. Perry. 2008. Association between preovulatory concentrations of estradiol and expression of uterine milk protein precursor, inhibin beta A, and proenkephalin. Biol. Reprod. 78(Suppl. 1) Abstr. 361
- Fields, S. D., B. L. Perry, and G. A. Perry. 2008. Effect of Standing Estrus on LH Pulses and Subsequent Progesterone Following a Fixed-Time AI Protocol. J. Anim. Sci. 86(E-Suppl. 3): Abstr. 87.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: A single injection of gonadotropin releasing hormone (GnRH) results in the release of luteinizing hormone (LH) resulting in ovulation and the formation of a corpus luteum (CL). It has been proposed that giving an injection of GnRH at the time of insemination could increase CL function; thereby, increasing embryo survival. Unfortunately researchers have had conflicting results. Thirty-two mature cows were synchronized with the Select Synch + CIDR protocol. An injection of GnRH (100 mcg) was given at the time of the controlled internal drug release (CIDR) insertion. The CIDRs were left in for 7 days. All cows were given an injection of prostaglandin F2alpha. Onset of estrus was determined as the first of three mounts within a four hour period of time lasting two seconds or longer in duration. After ten cows were determined in standing estrus within a six-hour period of time, indwelling jugular catheters were inserted into the jugulars of each of the cows. At an average of 12
hours after the onset of estrus, five of the cows were given an injection of GnRH (treatment group), and five were not given anything (control group). Blood samples were collected via jugular catheters every 15 minutes for six hours from 12-18, 26-32, 40-46, 54-60, and 68-74 hours after the onset of estrus. Cows were then bled daily for 15 days up until the 18th day of the estrous cycle. Serum samples from the intensive bleeds were analyzed for LH concentrations, and daily blood samples were analyzed for concentrations of progesterone using radio immunoassays. Transrectal ultrasonography was used to determine ovulation. Ovulation was defined as the disappearance of a dominant follicle from an ovary. Differences between the treatment groups in total content of LH, average concentration of LH, LH pulse frequency, and subsequent concentrations of progesterone were determined by analysis of repeated measures in SAS.
PARTICIPANTS: PI - George Perry; Research Technician - Brandi Perry; Graduate Student - Sarah Fields; Graduate Student - Josh Nelson
TARGET AUDIENCES: Scientists and cattle producers
Impacts
The GnRH treated group tended to have a greater total content of LH (P = 0.08) and greater average concentration of LH (P = 0.07) compared to the control group. There was no difference (P = 0.65) in LH pulse frequency. During bleed two, there were no differences in LH total content (P = 0.48) or average concentrations of LH (P = 0.53). However, the control group tended (P = 0.10) to have a greater LH pulse frequency compared to the GnRH treated group. All animals ovulated by 32 hours after the onset of estrus. During bleeds three, four, and five there were no differences (P > 0.10) in LH total content, average concentration of LH, or LH pulse frequency. For subsequent concentrations of progesterone, the GnRH group tended to have greater concentrations than the control group, but there was not a treatment x time interaction. Two of the GnRH treated animals did not have any LH pulses during bleed 2, while 3 animals did have LH pulses. All of the control animals had LH
pulses. The GnRH treated animals that did not have LH pulses during bleed 2 had reduced (P < 0.01) concentrations of progesterone compared to animals that did have LH pulses, and the control group was intermediate. This project explains why sometimes research has shown increases in subsequent concentrations of progesterone while other research has shown decreases in subsequent concentrations of progesterone when given GnRH at the time of insemination.
Publications
- 1)Perry, G. A. Role of follicle size on fertility in cattle. 2007. CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources. 2:14.
- 2)Perry, G. A., M. F. Smith, A. J. Roberts, M. D. MacNeil, and T. W. Geary. 2007. Relationship between size of ovulatory follicle and pregnancy success in beef heifers. J. Anim. Sci. 85:684-689.
- 3)S. D. Fields, B. L. Perry, and G. A. Perry. 2007. Effect of GnRH at time of insemination on LH pulses and subsequent progesterone. J. Anim. Sci. 85(Suppl. 1): Abstr. 123.
- 4)Perry, G. A., B. L. Perry, J. R. Nelson, and J. A. Walker. 2007. Influence of post-AI nutrition of blood urea nitrogen, progesterone, and pregnancy. J. Anim. Sci. 85(Suppl. 1): Abstr. W199.
- 5)Nelson, J. R., B. L. Perry, and G. A. Perry. 2007. Influence of standing estrus and estradiol on time of uterine pH decline during a fixed-time AI protocol. J. Anim. Sci. 85(Suppl. 2): Abstr. 238.
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Progress 01/01/06 to 12/31/06
Outputs
Research has shown following the CO-Synch protocol, cows in estrus within 24 h of TAI had elevated concentrations of estradiol, a shorter interval to ovulation, and greater pregnancy rates compared to cows not in estrus. Our objective was to assess the influence of elevating preovulatory concentrations of estradiol on the percentage of animals exhibiting standing estrus, the interval to ovulation, and the uterine environment. Lactating beef cows (57) received the CO-Synch protocol (100 mcg GnRH on d -9; 25 mg PG on d -2; and 100 mcg GnRH on d 0). Half the cows received an injection of estradiol cypionate (ECP; 1mg) 12 h after the PG injection. More cows administered ECP exhibited estrus (P less than 0.01) compared to cows not administered ECP (66 percent vs. 25percent). No difference (P equals 0.20) was detected in the interval from GnRH to ovulation between treatments (27.4 plus or minus 1.1 and 29.4 plus or minus 1.1 h for ECP and control, respectively), but cows
that exhibited estrus had a shorter interval to ovulation (P less than 0.03) compared to cows that did not exhibit standing estrus (25.4 plus or minus 1.1, 26.0 plus or minus 1.7, 32.0 plus or minus 1.7, and 30.9 plus or minus 1.1h for ECP estrus, no ECP estrus, ECP no estrus, and no ECP no estrus, respectively). Among cows not administered ECP, cows that exhibited estrus within 24 h of GnRH tended (P less than 0.09) to have a lower uterine pH at the time of the second GnRH injection compared to cows not exhibiting standing estrus (6.8 plus or minus 0.09 vs. 7.0 plus or minus 0.07, respectively). Cows administered ECP were intermediate (6.9 plus or minus 0.05). Cows that initiated estrus after the time of pH determination had a similar pH as cows that did not receive ECP and did not exhibit estrus (P greater than 0.47; 7.09 plus or minus 0.17). Cows that received ECP and did not exhibit estrus or initiated estrus within 1 h of pH measurement tended (P less than 0.10) to have a lower
pH (6.79 plus or minus 0.09) compared to cows that did not receive ECP and did not exhibit estrus. In summary, elevating preovulatory concentrations of estradiol increased the proportion of cows exhibiting standing estrus and decreased uterine pH to a level similar to cows exhibiting standing estrus.
Impacts
The efficiency of fixed-time insemination protocols may be improved by a better understanding the differences in physiology between cows that are induced to ovulate and cows that spontaneously ovulate. This project determined the effect of elevating preovulatory concentrations of estradiol on initiation of standing estrus, concentrations of estradiol, timing of ovulation, and uterine pH between cows detected in standing estrus and cows not detected in estrus. Cows with elevated preovulatory concentrations of estradiol exhibited standing estrus and had a decreased uterine pH at time insemination would occur compared to cows with low preovulatory concentrations of estradiol.
Publications
- Perry, G. A., and B. L. Perry. 2006. Influence of preovulatory concentrations of estradiol on interval to ovulation and uterine pH. J. Anim. Sci. 84(Suppl. 1):149 Abstr. 201
- Nelson, J. R., B. L. Perry, and G. A. Perry. 2006. Effects of standing estrus and concentrations of estradiol on uterine pH. South Dakota State University Beef Report p.36-39.
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Progress 01/01/05 to 12/31/05
Outputs
Previous research has reported that ovulatory follicle size at time of insemination following a fixed-time insemination protocol influenced pregnancy rates following artificial insemination, but follicle size had no effect on pregnancy rates when cows spontaneously ovulated. Furthermore, cows that exhibited standing estrus within 24 hours of fixed-time insemination had higher pregnancy rates compared to cows not detected in standing estrus. The objective of this experiment was to assess the relationship between ovulatory follicle size and estradiol concentrations, timing of the LH surge, and timing of ovulation. Cows were synchronized with the CO-Synch (n = 64; induced ovulation) or the Select Synch (n = 20; spontaneous ovulation) protocol. Cows that exhibited standing estrus and were induced to ovulate medium (11.5 to 14 mm) or large (>14 mm) follicles had preovulatory estradiol concentrations similar (P > 0.05) to cows that spontaneously ovulated and higher (P <
0.05) than cows not exhibiting standing estrus. Cows not exhibiting standing estrus had lower (P < 0.05) preovulatory estradiol concentrations compared to cows that spontaneously ovulated. There was no effect (P > 0.36) of follicle size or estrus on LH concentrations. Among cows induced to ovulate, cows that exhibited estrus had a shorter (P < 0.01) interval from GnRH to the LH surge compared to cows not exhibiting estrus. Cows that spontaneously ovulated were intermediate (interval from onset of estrus to LH surge). Standing estrus and follicle size affected the interval from GnRH or onset of standing estrus to ovulation, with cows induced to ovulate and not exhibiting standing estrus having a longer interval to ovulation compared to cows that exhibited standing estrus and were induced to ovulate (P < 0.01) or spontaneously ovulated (P = 0.02). Cows that ovulated medium follicles had a longer (P = 0.03) interval to ovulation compared to cows that ovulated large follicles. Cows that
ovulated small follicles (less than or equal to 11 mm) were intermediate. In summary, estradiol concentrations, timing of the LH surge, and timing of ovulation could explain the increased pregnancy rates in cows that exhibit standing estrus and are induced to ovulate compared to cows that do not exhibit estrus.
Impacts
The efficiency of fixed-time insemination protocols may be improved by a better understanding the differences in physiology between cows that are induced to ovulate and cows that spontaneously ovulate. This project determines differences in preovulatory concentrations of estradiol, the timing of the LH surge, and the timing of ovulation between cows induced to ovulate and cows spontaneously ovulating. Cows induced to ovulate without showing standing estrus had decreased preovulatory concentrations of estradiol, a longer interval to the LH surge and a longer interval to ovulation.
Publications
- Perry, G. A., and Busch, D. C. 2005. Effect of ovulatory follicle size and standing estrus on estradiol concentrations, LH surge, and ovulation. J. Anim. Sci. 83(Suppl. 1):216 Abstr. 306
- Perry, G. A. 2005. Effect of ovulatory follicle size and stading estrus on circulating hormone concentrations and interval to ovulation. South Dakota State University Beef Report p. 131-140.
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