Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Several studies were conducted to examine the influence of the collection environment on semen quantity and quality of A.I. boars. The first study examined interactions between boar age and collection dummy height. Boars were assigned to begin training at 160 or 190 days of age and, within each age, were exposed to a collection dummy height of 18 or 22 inches. At the end of two weeks, 100% of the 190-day old boars were successfully trained. Boars exposed to the 18 inch dummy mounted 4 days earlier (p < 0.05) than their counterparts trained on the 22 inch dummy. At 160 days of age, 42.9% of the boars were successfully trained for semen collection on a dummy set at 22 inches compared to 87.5% of the collected from the dummy at 18 inches (p < 0.05). The average shoulder height was 24 and 26 inches for the 160 and 190 day old boars, respectively, and did not influence training success (p > 0.47). Motility, morphology and acrosin activity were not affected by boar age or dummy height (p > 0.43). In contrast, at the same chronological age, boars trained at 160 days of age, regardless of dummy height, produced 25% more spermatozoa per ejaculate (p < 0.01) than boars trained at 190 days of age. The second study examined acute and latent effects of the collection glove on viability of spermatozoa. Ejaculates from 12 boars were collected with a bare hand over a 5 week period and used in the study. After collection a sample of the neat semen was exposed to the following types of gloves: none (control); 2 types of vinyl; 6 types of nitrile; 1 type of latex; and 1 type of polyethylene. After 2 minutes, motility did not differ from the control (p > 0.17). After 5 minutes, latex gloves and one type of the nitrile gloves exhibited significant reductions (p < 0.05) in motility. After 15 minutes, 2 additional types of nitrile gloves showed a reduction in motility (p < 0.05). In semen extended immediately after collection and stored for 72 hours, viability decreased to below 50% with the latex gloves, 4 of 6 types of the nitrile gloves and 1 type of vinyl gloves (p < 0.01). The two types of nitrile gloves whose semen motility did not decrease below 70% showed considerable variation among boars (boar x treatment, p < 0.07). At all time points, motility for one type of vinyl and the polyethylene gloves did not differ (p > 0.25) from controls. Collectively, these data indicate that training conditions affect sperm production but not quality, while the collection environment tends to influence semen quality rather than quantity. Specifically, boars can be trained for semen collection very efficiently at 160 days of age. However, success at this age depends upon the height of the collection dummy. Moreover, early training resulted in significant long-term increases in total spermatozoa per ejaculate. Conversely, 8 of the 10 types of gloves commonly used for semen collection adversely affected semen quality. The negative impact of these gloves appeared between 24 and 72 hours of storage in extended semen as opposed to immediately after collection in neat semen. PARTICIPANTS: These projects involved 16 different individuals including the principal investigator, the co-investigator, and collaborators (2) listed on the original project. In addition, there was a Ph.D. student, 3 M.S. students and 6 undergraduate students that assisted with collection of data. The second study was done in conjunction with two new collaborators within the swine industry. The current year's activity provided training for 1 Ph.D., 3 M.S., and 6 undergraduate students. In addition, a portion of the work was presented as an invited talk to 450 Canadian Swine producers and Swine Industry representatives as part of the Banff Pork Seminar. TARGET AUDIENCES: The target audiences for this work were other scientists; pork producers; swine veterinarians; swine consultants; and graduate and undergraduate students studying animal science. Information was presented at a total of 9 swine industry meetings whose attendance accounted for 5.5 million of the roughly 6 million sows in the U.S. Information was also used in teaching undergraduate courses with a total enrollment of 250 students and graduate courses with a total enrollment of 10 during 2010. All of the undergraduate and graduate students were involved in laboratory exercises. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Over 95% of the 6.5 million sows in the U.S. are bred via artificial insemination. Consequently, producing and maintaining high quality insemination doses is of utmost importance for the swine industry in terms of producing an inexpensive and safe supply of pork for consumers. A recent survey of 44 boar studs representing approximately 10,000 boars in the U.S. indicated that most boars are not trained for semen collection until they are 8 to 9 months of age. This delay in training can result in 2 to 3 months of lost semen production. Training boars for A.I. collection at younger ages than this has both economic and genetic implications and would allow studs to implement early screening procedures for boars based on their semen quality. In the same survey, 99.5% of boar studs used the gloved hand technique for semen collection. However, the choice of glove used for collection was based mainly on cost rather than performance. Identification and removal of gloves that adversely affect semen quality should increase fertility of sows and, hence, reduce costs of production for producers.
Publications
- Wrench, N., Flowers, W.L., Farin, C.E., Dix, D.J., Pinto, C.R.F., and Klinefelter, G.R. 2010. Anim. Reprod. Sci. 119:219-227.
- Stewart, K.R., Flowers, W.L., Rampacek, G.B., Greger, D.L., Swanson, M.E., and Hafs, H.D. 2010. Endocrine, ovulatory and reproductive characteristics of sows treated with an intravaginal GnRH agonist. Anim. Reprod. Sci. 120:112-119.
- Flowers, W.L. 2010. Trouble shooting reproductive problems. 2010. Proceedings, Banff Pork Seminar. http://www.banffpork.ca/proceedings.cgi.
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: A series of studies examined the effect of reactive oxygen species on various aspects of sperm physiology in fresh and extended porcine semen. Changes in ejaculate parameters, semen quality and sperm lipid peroxidation were examined over time in boars. Sexually mature boars were randomly assigned to a collection frequency of 3 (n=5) or 1 (n=5) times per week and collected over a 5 week period. On weeks 0, 2 and 5 the ejaculate was split, extended in a commercially available 3-day or 5-day extender and evaluated at 0, 1, 3, and 7 days following collection. Malondialdehyde (MDA) was used to evaluate sperm lipid peroxidation and was standardized by measuring activity from 375 x 106 sperm/mL. Boars maintained under a high collection frequency had increased levels of reactive oxygen species. There was considerable variation among boars maintained on the low collection frequency. Some individuals consistently had levels 2 to 3 times greater than others. The quality of insemination doses made from these ejaculates decreased at a much faster rate compared with those with low levels of free radicals. Increases in the accumulation of free radicals preceded measurable changes in commonly used semen tests such as motility and morphology by 24 to 36 hours. Use of 5-day semen extenders appeared to attenuate the precipitous decrease in semen quality on insemination doses made from ejaculates with high levels of reactive oxygen species. The effectiveness of dietary selenium on preventing the negative effects of reactive oxygen species on sperm quality was also examined. Dietary treatments were a non-supplemented negative control basal diet or the basal diet supplemented at 0.3 ppm with either organic selenium or inorganic selenium. Boars were fed the dietary treatments from the time of weaning (21 days of age) until the end of the study (383 days of age). Boars were maintained on a 1 time per week collection frequency during most of the study and then collected six times over four days. Dietary treatment did not affect volume, concentration, total sperm in the ejaculate, sperm motility, progressive motility, morphology, lipid peroxidation or glutathione peroxidase activity. Results from these studies were presented at two international meetings, one national, and four regional meetings focused on swine health and reproduction. PARTICIPANTS: Dr. K.L. Lovercamp was a Ph.D. student. He is currently an Assistant Professor at Central Missouri State University. Dr. K.R. Stewart was a Ph.D. student. She is currently an Instructor in the Department of Animal Science at North Carolina State University. Mrs. S.S. Crowell was a M.S. student. She is currently a research scientists at Duke University. Ms. F.B. Turner was a M.S. student. She is currently a 2nd year veterinary student at North Carolina State University College of Veterinary Medicine. Each of these students attended an international and a national research meeting to present work from their theses and this project. In addition, work conducted by Dr. Lovercamp, Ms. Turner and Mrs. Crowell were presented at 12 different regional and state meetings specifically designed for pork producers. TARGET AUDIENCES: Target audiences are swine producers, swine consultants, swine veterinarians and other scientists working with male fertility. Information was made available via meetings, newsletters, and presentation at scientific conferences. These presentations have resulted in 50 invitations from producers and other industry groups to help them incorporate new strategies for estimating semen quality and establish more rigid quality control methods for semen processing. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Over 95% of the 6.5 million sows in the U.S. are bred via artificial insemination. Consequently, producing and maintaining high quality insemination doses is of utmost importance for the swine industry in terms of producing an inexpensive and safe supply of pork for consumers. Results from current studies demonstrated that reactive oxygen species (free radicals) increase in extended semen before other commonly used indicators of semen quality. Consequently, their measurement provides a more sensitive method for detecting problems with semen than is currently being used within the industry. They can also be used for diagnostic purposes for identifying system-wide problems with production of fertile insemination doses. Their incorporation into analytical tests should increase fertility of sows and, hence, reduce costs of production for producers. Unfortunately, additions of selenium did not prove to be effective methods for helping boars cope with situations during which free radical production increases.
Publications
- Crowell, S.S. 2009. Evaluating temperature effects and extension cooling rates on boar semen quality. M.S. Thesis (under the direction of W.L. Flowers). North Carolina State University, Raleigh. 147 pages.
- Flowers, W.L. 2009. Swine: Reproduction Management. In: Encyclopedia of Animal Science. W.G. Pond and A.W. Bell (eds.), Marcell Dekker, Inc., New York , 829-831.
- Flowers, W.L. 2009. Biotechnology: Artificial Insemination. In: Encyclopedia of Animal Science. W.G. Pond and A.W. Bell (eds.), Marcel Dekker, Inc., New York , pp. 137-139.
- Lovercamp, K.W. 2009. Factors affecting the presence of reactive oxygen species in the fresh and extended porcine ejaculate. Ph.D. Thesis (under the direction of W.L. Flowers). North Carolina State University, Raleigh. 224 pages.
- Stewart, K.R. 2008. Effects of FSH administration during the neonatal period on adult sperm production in boars. Ph.D. Thesis (under the direction of W.L. Flowers). North Carolina State University, Raleigh. 204 pages.
- Turner, F.B. 2008. Evaluating relationships between various estimates of semen quality based on fertility assessments of boars. M.S. Thesis (under the direction of W.L. Flowers). North Carolina State University, Raleigh. 146 pages.
- Flowers, W.L. 2009. Selection for boar fertility and semen quality: the way ahead. In: Control of Pig Reproduction VIII. H. Rodriguez-Martinez, J.L. Vallet, and A.J. Ziecik (eds), Nottingham University Press, Nottingham, UK, pp. 67-78.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: A series of studies were conducted to examine novel ways of increasing sperm production and estimating the fertility of adult boars. Boars were given either saline or 100 ug/kg body weight of FSH from either 4-22 days or 22-40 days after birth. Subsets of boars from each treatment group were castrated at various times over the next 18 months, while others remained intact and subjected to a comprehensive semen analyses. Boars receiving FSH between 4 and 22 days of age had higher testosterone concentrations beginning at 77 days of age compared with the other treatments. In addition, the period of sertoli cell proliferation was increased by about 40 days in boars receiving neonatal FSH administration (98 days of age) compared with their untreated counterparts (42 days of age). This resulted in an increased number of primary spermatocytes and total number of spermatozoa produced per ejaculates in adult boars. There were no effects of FSH treatment on estimates of semen quality in adults. These results indicate that neonatal FSH treatment increased the length of time over which sertoli cell proliferation occurred during sexual maturation which, in turn, resulted in an increase in the production of spermatozoa in adult animals. Additional studies used heterospermic inseminations and paternity testing to examine relationships among common assessments of semen quality and fertility in twelve adult boars. Results from the heterospermic inseminations were used to rank boars into three fertility groups based on the average number of pigs sired per litter: High (71%); Medium (51%); and Low (25%). Proportions of motile spermatozoa; spermatozoa exhibiting progressive forward motility; spermatozoa with normal acrosome morphology; spermatozoa undergoing an acrosome reaction; and the average straight line velocity of motile spermatozoa all exhibited positive relationships with fertility. In addition, 2 seminal plasma proteins (26 kD / 7.2 pI and 28 kD / 6.6 pI) had positive linear relationships with boar fertility, while 3 seminal plasma proteins (19 kD / 9.2 pI; 35 kD / 6.3 pI; and 186 kD / 8.7 pI) had negative associations with the proportion of piglets sired per litter by each boar. Multiple regression analyses showed that concentrations of the 28 kD / 6.6 pI protein (66.1%); proportion of acrosome-reacted spermatozoa (15.6%) and concentrations of the 17 kD / 3.8 pI protein (5.9%) accounted for 87.6% of the variation in fertility in this population of boars as measured by heterospermic inseminations and paternity testing. PARTICIPANTS: W.L. Flowers was the principal investigator. He performed all the semen collections and surgical procedures. He performed a portion of the all the laboratory analyses and the data analyses. K.W. Lovercamp and K.R. Stewart were Ph.D. students. Dr. Stewart assisted with the surgical procedures and performed laboratory and data analyses. A portion of the work reported was Dr. Stewart's Ph.D. research project. Mr. Lovercamp assisted with the semen collections and laboratory analyses. S.E. Shute and F.B. Turner were M.S. students. Ms. Turner performed laboratory and data analyses, while Ms. Shute assisted with laboratory analyses. A portion of the work reported was Ms. Turner's M.S. research project. L.M. Thompson, K.J. Kenney, and A. Odo were B.S. students that assisted with all aspects of the project. TARGET AUDIENCES: The target audiences for the project were other scientists working in animal and human fertility; swine genetic suppliers; and swine producers. A portion of this work was presented at producer meetings in Iowa, Canada, and Missouri. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
These data demonstrate that manipulation of the neonatal environment of young boars which coincides with active periods of testicular organization offer potential for enhancing adult production of viable spermatozoa. Consequently, environmental conditions early in a boar's life should receive equal if not greater consideration than those adult animals encounter. Furthermore, use of heterospermic inseminations for estimating relative fertility in boars revealed several new relationships between commonly used semen quality estimates and boar fertility which may prove very useful in developing proactive semen fertility tests. Collectively, the results from these studies provide potential for increasing sperm production from boars and then screening its relative fertility prior to its use for breeding.
Publications
- Flowers, W.L. 2008. Genetic and phenotypic variation in reproductive traits of AI boars. Theriogenology 70, 1297-1303.
- Flowers, W.L. 2008. Applying reproductive technologies in practice. Proceedings, 2008 London Swine Conference. http://www.londonswineconference.ca/proceedings/2008/LSC2008_WFlowers 2.pdf.
- Flowers, W.L. 2008. New opportunities for reproductive management. Proceedings, 2008 London Swine Conference. http://www.londonswineconference.ca/proceedings/2008/LSC2008_WFlowers .pdf.
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Progress 10/01/06 to 09/30/07
Outputs
Semen production records were obtained from three terminal sire lines (n=278 boars per line) housed in two studs (n=417 per stud) over a four-year period. A genetic line by age interaction was present for total spermatozoa per ejaculate. Sperm production was similar and increased over time in all genetic lines between 9 and 12 months of age. At this point, sperm numbers continued to increase in line A over the next four months eventually reaching a plateau around 120 billion spermatozoa per ejaculate. In contrast, sperm production did not increase appreciably after 12 months of age in lines B or C and remained fairly constant at levels around 88 billion. Subsequent analyses were conducted to examine possible interactions between genetic lines and season on sperm production. As was the case with the previous analysis, a time by genetic line interaction was present. The general pattern for each genetic line was for the total number of spermatozoa to decrease after May;
reach its lowest level in July or August; and then begin to increase. The interaction was the result of differences among lines in the magnitude of these changes. The decrease in sperm production was significantly less for line A compared with lines B and C. On a percentage basis, boars from line A had a 6.7% decrease, while their counterparts in lines B and C experienced a 15% or greater reduction. In addition, sperm production in line C appeared to recover more rapidly compared with line B. Numbers of spermatozoa per ejaculate were similar in August between these two lines. However, in November and December, boars from line C were producing more sperm cells than those from line B.
Impacts
These data demonstrate that considerable phenotypic variation in semen output exists among commercial boars and that a significant portion of this variation has a genetic basis. Consequently, more attention should be given to incorporating sperm production traits in breeding programs for terminal sire lines. Moreover, there also are genetic lines of boars whose sperm production is not impacted significantly by exposure to elevated ambient temperatures. Exploitation of these genetic lines conceivably could lead to the development of "heat-tolerant" AI boars.
Publications
- Flowers, W.L., Spears, J.W., and Nielsen, F.H. 2007. Effect of boron supplementation on semen quality in mature boars. J. Anim. Sci. 85(Suppl. 1), 538.
- Turner, F.B., Thompson, L.M., Kinney, K.J., Shute, S.E., Flowers, W.L., Schultz, R.A., and Pratte, B. 2007. Effect of bacitracin supplementation on lactation management, neonatal piglet performance and subsequent reproductive performance of sows. J. Anim. Sci. 85(Suppl. 1), 578-579.
- Flowers, W.L. 2007. Genetic parameters of semen characteristics and reproductive traits in A.I. boars. Proceedings, 6th International Conference on Boar Semen Preservation, p. 26.
- Lovercamp, K.W., Seal, M.C., and Flowers, W.L. 2007. Effect of collection frequency and extender on sperm quality parameters and membrane lipid peroxidation in boars. Proceedings, 6th International Conference on Boar Semen Preservation, p. 11.
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Progress 10/01/05 to 09/30/06
Outputs
Experiments were designed to characterize the influence of collection frequency, season, and length of storage prior to insemination on concentrations of reactive oxygen species and semen quality estimates of porcine semen. Boars were collected either 1.5 or 4 times per week over a 7 week period during the summer and winter months. Each ejaculate was split and extended in either BTS or Androhep semen extender and evaluated at 0 1, 2, 5 and 7 days after collection. There was a definite effect of season and collection frequency with concentrations being significantly higher during the summer than winter months and in boars collected 4 times per week compared with those collected 1.5 times per week. Concentrations of reactive oxygen species tended to be highest in boars collected 4 times per week during the summer and could not be explained solely as an additive effect. This indicates that the combination of high collection frequencies and elevated ambient temperatures
is particularly detrimental in terms of production of reactive oxygen species by extended semen. An interesting observation across all treatments was the relationship between the proportion of spermatozoa with normal morphology and reactive oxygen species. When normal morphology was 90% or higher, there was no consistent relationship with concentrations of reactive oxygen species. In contrast, when normal morphology was between 70 and 90%, there was a significant inverse relationship - as normal morphology decreased, concentrations of reactive oxygen species in semen increased.
Impacts
These results demonstrate that semen with acceptable levels of morphology and motility differ considerably in terms of concentrations of reactive oxygen species. Quantification of production of free radicals by spermatozoa appear to be a better estimate of their quality than traditional physical characteristics such as motility and morphology.
Publications
- Griffin, J.K., Flowers, W.L., and Seal, M.C. 2007. Effect of neonatal environment of reproductive function of adult boars. J. Anim. Sci. 84 (suppl. 1), 205.
- Flowers, W.L., and Seal, M.C. 2007. Effect of consistency of collection frequency on semen quality in boars. J. Anim. Sci. 84 (suppl. 1), 90.
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Progress 10/01/04 to 09/30/05
Outputs
Experiments were designed to characterize the effect of the neonatal environment of boars on their adult reproductive function. Boars were allowed to nurse in litters of 6 or 10 for 21 days. After lactation boars were managed under identical conditions. Boars raised in litter of 6 pigs reached puberty sooner and were trained for semen collection off a dummy sow at younger ages than boars that nursed in litters of 10 pigs. Boars raised in small litters produced more spermatozoa than their counterparts reared in large litters over a 2-year period. This difference was more pronounced for boars that were born in the Spring and underwent sexual maturation in the Summer compared with those that were born in the Fall and reached puberty the during the Winter. Semen quality estimates including the percentage of motile spermatozoa, the percentage of morphologically normal spermatozoa, capacitation status, and acrosin activity were not different. Heterospermic inseminations and
subsequent paternity testing were used to assess the relative fertility of boars in each treatment. Boars raised in litters of 6 sired 75% of the piglets born in these heterospermic mating combinations.
Impacts
These results demonstrate that the first three weeks of life is a critical period for the development of the adult reproductive function in boars. Relatively simple management changes during this period of time advanced sexual maturation, increased sperm production, and enhanced fertility.
Publications
- Belstra, B., Flowers, W.L., See, M.T., and Croom, W.J. 2005. Characterization of collagen degradation marker excretion during postpartum uterine involution in sows. Anim. Reprod. Sci. 85, 131-145.
- Flowers, W.L. 2005. Pregnancy detection in swine. P.I.H. Handbook. National Pork Board. 8 pages.
- Flowers, W.L. 2004. Swine: Reproduction Management. In: Encyclopedia of Animal Science. W.G. Pond and A.W. Bell (eds.), Marcell Dekker, Inc., New York , 831-833.
- Flowers, W.L. 2004. Biotechnology: Artificial Insemination. In: Encyclopedia of Animal Science. W.G. Pond and A.W. Bell (eds.), Marcel Dekker, Inc., New York , pp. 130-132.
- Flowers, W.L. 2004. Swine Management Systems: Intensive. In: Encyclopedia of Animal Science. W.G. Pond and A.W. Bell (eds.), Marcell Dekker, Inc., New York, pp. 1-4.
- Roski, K., Flowers, W., Rampacek, G.B., Gregor, D.L., Swanson, M., and Hafs, H.D. 2004. Ovulatory and reproductive characteristics of sows treated with an intravaginal GnRH agonist gel. J. Anim. Sci. 82 (suppl. 1), 369.
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Progress 10/01/03 to 09/30/04
Outputs
Experiments were designed to characterize temporal relationships between estrus and ovulation on commercial sow farms. An effect of lactation length was present on each farm for duration of estrus. In contrast, significant interactions between farm and season; and between parity and season were present for the duration of estrus and the interval between the onset of estrus and the occurrence of ovulation. In general, the duration of estrus decreased as lactation increased. On two farms, the length of estrus and the interval between the onset of estrus and ovulation were longer during the summer compared with the spring, whereas on the third farm, there was no effect of season. On each farm, during the summer, sows with a parity of 3 or higher had longer estrous periods and later ovulations during estrus compared with younger sows. No differences were observed during the spring. Factors that influenced the estrous and ovulatory characteristics of these herds, also,
affected the number of inseminations that were administered during the 24-hour interval before ovulation. As estrus and the interval between ovulation and the onset of estrus increased, the number of inseminations during the 24-hour period before ovulation decreased. This reduction, however, did not affect the reproductive performance of the herds.
Impacts
These results demonstrate that season and parity can significantly affect the duration of estrus and the occurrence of ovulation relative to the onset of estrus and that these effects are not universal across all farms. However, it appears that current mating regimens commonly used in the industry are capable of compensating for these inconsistencies in terms of farrowing rate and numbers of pigs born alive.
Publications
- van Heugten, E., O'Quinn, P.R., Funderburke, D.W., Flowers, W.L., and Spears, J.W. 2004. Growth performance, carcass characteristics, plasma minerals, and fecal mineral excretion in grower-finisher swine fed diets with levels of trace minerals lower than common industry standards. J. Swine Health Prod. 12, 237-241.
- Belstra, B., Flowers, W.L., and See, M.T. 2004. Factors affecting temporal characteristics of estrus and ovulation on commercial sow farms. Anim. Reprod. Sci. 84, 377-394.
- Creech, B.L., Spears, J.W., Flowers, W.L., Hill, G.M., Lloyd, K.E., and Armstrong, T.A. 2004. Effect of trace mineral level and source (inorganic vs. chelated) on performance, mineral status and fecal mineral excretion in pigs from weaning through finishing. J. Anim. Sci. 82, 2140-2147.
- Popwell, J.M. and Flowers, W.L. 2003.Variability in relationships between semen quality and estimates of in vivo and in vitro fertility in boars. Anim. Reprod. Sci. 81, 97-113.
- Knox, R.V. and Flowers, W.L.. 2004. Using real-time ultrasound for pregnancy diagnosis in swine. P.I.H. Handbook. National Pork Board. 12 pages. Flowers, W.L. 2004. Synchronization of estrus in swine. P.I.H. Handbook. National Pork Board. 8 pages.
- Singleton, W.L., and Flowers, W.L. 2004. Management of boars in A.I. Centers. P.I.H. Handbook. National Pork Board. 8 pages.
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Progress 10/01/02 to 09/30/03
Outputs
Experiments were designed to characterize relationships between common semen quality and fertility estimates for three boars known to differ in farrowing rate, number of pigs born alive, and monospermic penetration rate. This strategy relied on the variability in semen quality parameters that normally occurs in an individual boar over time. When comparisons were made among boars, farrowing rates, numbers of pigs born alive, and monospermic penetration rates were significantly different, but progressive motility, normal head and tail morphology, and acrosome morphology were not. However, when comparisons were made among ejaculates within individual boars, there were significant effects of semen quality on both in vivo and in vitro fertility. For boar 3495, the proportion of spermatozoa exhibiting progressive motility and distribution of spermatozoa in a percoll gradient had a positive linear effect on number born alive and monospermic penetration rate, respectively.
For boar 2901, quadratic equations best described changes in litter size as a function of progressive motility and normal acrosomes. In addition, monospermic penetration rate increased linearly as normal acrosomes and the proportion of spermatozoa recovered from a percoll gradient increased. For boar 4291, the relationship between progressive motility and number born alive and between normal acrosomes and number of pigs born alive were also quadratic. However, a significant linear relationship was present only between normal acrosomes and monospermic penetration rate.
Impacts
These results demonstrate that simply relying on the means of common semen quality estimates from some boars has limited value in terms of being used as a prospective indicator of their in vivo or in vitro fertility. In contrast, characterization of relationships between semen quality and fertility estimates is useful for estimating differences in the fertility of ejaculates from individual boars. However, both quantitative and qualitative differences in these relationships among boars are present and a given semen quality estimate that is a good predictor of in vivo or in vitro fertilization for one boar, may not be applicable for others.
Publications
- Flowers, W.L. 2002. Using reproductive biology to improve suboptimal reproductive performance. Proceedings, The 17th Congress of the International Pig Veterinary Society, Volume 1, pp. 43 - 48.
- Belstra, B., Flowers, W.L., See, M.T., and Croom, W.J. 2002. Characterization of collagen degradation marker excretion during postpartum uterine involution in sows. J. Anim. Sci. 81, Suppl. 2, 14.
- Belstra, B., Flowers, W.L., and See, M.T. 2002. Factors affecting temporal characteristics of estrus and ovulation on commercial sow farms. J. Anim. Sci. 81, Suppl. 2, 90.
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Progress 10/01/01 to 09/30/02
Outputs
The influence of the neonatal environment of boars on adult reproductive function was examined in 40 boars. Littermate pairs of boars were raised in litters of either 6 or 10 pigs for a 21-day lactation. At one year of age, boars that were raised in small litters during lactation were heavier (161.2 + 2.3 kg) and had larger testicles (181.3 + 5.1 cm3) compared with their littermates raised in large litters (144.3 + 2.7 kg and 153 + 6.7 cm3). Behavioral aspects associated with sexual maturation such as mounting activity and recognition time higher and lower, respectively, for boars nursing in litters of 6 compared with boars nursing in litters of 10. Finally, spermatozoa per ejaculate in adult boars was greater if they were raised in litters of 6 (75.0 + 0.3 billion) than in litter of 10 (58.3 + 0.3 billion) as neonates. Using heterospermic insemination and paternity testing, boars raised in litters of 6 tended to have a slight advantage in terms of fertility compared
with boars raised in litters of 10. Boars from litters of 6 sired 63% of the 670 piglets born when 2 billion spermatozoa from males in each treatment group were used for insemination. Results from these studies indicate that the first 21 days of a boar's life is of critical importance in terms of his future reproductive potential. In addition, it appears that reducing the competition among littermates during lactation can have beneficial effects on pubertal development, sperm production, and possibly fertility as an adult.
Impacts
Results from this project demonstrate that environmental factors early in a boar's life can have significant effects on his reproductive function as an adult. Identification of these critical periods and enhancement of positive attributes during their occurrence could lead to improvements in fertility and the well-being of adult boars.
Publications
- Armstrong, T.A., Flowers, W.L., Spears, J.W., and Nielsen, F.W. 2002. Long-term effects of boron supplementation on reproductive characteristics and bone mechanical properties in gilts. J. Anim. Sci. 80, 154-161.
- Flowers, W.L. 2002. Increasing fertilization rate of boars: Influence of number and quality of spermatozoa inseminated. Online J. Anim. Sci., Proceedings 2000/2001 National and Sectional Meetings [serial online]. doc. E
- Kegley, E.B., Spears, J.W., Flowers, W.L., and Schoenherr, W.D. 2002. Iron methionine as a source of iron for the neonatal pig. Nutrition Reseach 22, 1209-1217.
- Flowers, W.L. 2002. Neonatal environment and its effects on adult reproductive function in boars. Proceedings, Triangle Consortium on Reproductive Biology Annual Meeting, p. 14.
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Progress 10/01/00 to 09/30/01
Outputs
The influence of season, genetics (genotype A, B, and C), and production environment (boar studs I - VI) on concentrations of two seminal plasma proteins, protein 1 - 26 kDa; pI=6.2; protein 2 - 55 kDa, pI=4.5, were examined using 760 boars. The proportion of boars whose ejaculates contained 10 or greater relative units of these two proteins was greater from March through May (35.7 + 1.3%) than during June, July, and August (25.3 + 2.5%). A significant interaction between genotype and production environment was present. No differences were observed among boars on studs II, IV, and VI. In two studs, I and III, ejaculates from boars in genotype A contained the highest levels of these two proteins (7.5 + 0.8 relative units) compared with the other two genotypes (B=4.3 + 1.3; C=5.5 + 0.5). In contrast, ejaculates from boars of genotype C has the highest concentrations in boar stud V (C=7.0 + 0.7; A=5.1 + 0.5; B=5.3 + 0.7). These differences, in each case, were due to an
increased proportion of boars whose ejaculates contained more than 10 relative units of these proteins rather than an increase in output from each individual boar. Based on these results, there appears to be significant variation in the production of two seminal plasma proteins that previously have been shown to be correlated with fertility. Periods of warm temperatures and high humidity had a negative effect, while certain production environments enhanced their production in some genotypes. In the population studied, these effects manifested themselves in a subset of boars whose seminal plasma protein levels either increased or decreased, rather than affecting all boars equally.
Impacts
Results from this project demonstrate that concentrations of two seminal plasma proteins in boars are influenced by season, genotype, and the production environment. The observation that these effects were the result of a subset of boars whose values either increased or decreased is important, because it provides indirect evidence that production of these proteins can be manipulated in a positive manner. Enhancement of the production of these two proteins via normal management techniques could lead to improvements in boar fertility and increases in the sustainability of pork production systems by eliminating the use of subfertile boars.
Publications
- Flowers, W.L. 2001. Production of Fertile Insemination Doses. In: Manipulating Pig Production VIII. P.D. Cranwell (ed.) Australasian Pig Science Association, Melbourne, Australia, pp.14-21.
- Flowers, W.L. 2001. Effects of the Inseminator and Insemination Type on Efficacy of A.I. In: In: Manipulating Pig Production VIII. P.D. Cranwell (ed.) Australasian Pig Science Association, Melbourne, Australia, pp. 28-36.
- Flowers, W.L. 2001. Increasing fertilization rate: the male perspective. J. Anim. Sci. 79 (suppl. 2), 91.
- Flowers, W.L., Spears, J.W., and Hill, G.M. 2001. Effect of reduced dietary Cu, Zn, Fe, and Mn on reproductive performance of sows. J. Anim. Sci. 79 (suppl. 2), 61.
- Flowers, W.L., and Turner, Z.A. 2001. Relationships between seminal plasma protein profiles of ejaculates and sow fertility. Proceedings, 6th International Conference on Pig Reproduction, Columbia, MO.
- Belstra, B.A., Flowers, W.L., Rozeboom, K.J., and See, M.T. 2001. Factors affecting temporal relationships between estrus, ovulation and insemination in a commercial sow herd. J. Anim. Sci. 79 (suppl. 1), 464.
- Popwell, J.M., and Flowers, W.L. 2001. Effect of capacitation environment of spermatozoa on fertilization of porcine oocytes in vitro. J. Anim. Sci. 79 (suppl. 1), 229.
- van Heugten, E., O'Quinn, P.R., Funderburke, D.W., Flowers, W.L., and Spears, J.W. 2001. Effects of supplemental trace mineral levels on carcass characteristics and carcass value. J. Anim. Sci. 79 (suppl. 1), 67.
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Progress 10/01/99 to 09/30/00
Outputs
The relationship between concentrations of two seminal plasma proteins, protein 1 - 26 kDa; pI=6.2; protein 2 - 55 kDa, pI=4.5, and boar fertility was examined using 400 boars and 84,448 sows over a period of one year. Sows bred with ejaculates from boars with greater than or equal to 10 relative units of these two proteins had higher farrowing rates (86.7 + 3.4) and larger litters (11.2 + 0.3) compared with sows bred with ejaculates from boars containing 7.5 to 9.9 (78.4 + 3.1 and 10.4 + 0.3) or 5.0 to 7.4 (71.3 + 3.9 and 9.5 + 0.3) relative units. However, considerable variation among farms in farrowing rate and litter size was observed within each seminal plasma group. For ejaculates with greater than or equal to 10 relative units of seminal plasma proteins, farrowing rates were between 80.0 and 94.0% and litter sizes were between 10.2 and 12.2 pigs (n=3,532 sows on 10 different farms). Comparable values for ejaculates containing 7.5 to 9.9 and 5.0 to 7.4 relative
units were 70.2 to 86.0% and 8.8 to 11.2 pigs (n=3,611 sows on 10 farms) and 65.4 to 80.3% and 7.8 to 10.7 pigs (n=2,321 sows on 10 farms), respectively. Based on these results, quantification of two seminal plasma proteins appears to be an accurate proactive test for qualitative, but not quantitative assessments of semen fertility.
Impacts
Results from this project demonstrate that under commercial conditions monitoring two seminal plasma proteins is a more precise technique for estimation of semen fertility compared with microscopic tests. Quantification of these two proteins can be used to determine ejaculates that possess reduced fertility even though they may appear normal based on current microscopic tests. Use of this technique increases the sustainability of pork production systems by eliminating the use of subfertile boars.
Publications
- Flowers, W.L., Armstrong, J.D., White, S.L., Woodard, T.O. and Almond, G.A. 2000. Real time ultrasonography and pregnancy diagnosis in swine. J. Anim. Sci. 78 (suppl. 3): 213-220.
- Hill, G.M., Link, J.E., Spears, J.W., and Flowers, W.L. 2000. Impact of reduced trace minerals on mineral and anti-oxidant status in swine. J. Anim. Sci. 83 (Suppl. 1):175.
- Flowers, W.L., and Knox, R.V. 2000. Pregnancy diagnosis. P.I.H. Handbook. Purdue Cooperative Extension Service. No. 231. 5 pages.
- Hughes, P., Flowers, W.L., Kemp, B., Kirkwood, R., Levis, D., Soede, N., Thacker, P., and Tilton, J. 2000. Reproductive Management of Pigs: Guides and Problem Solving. Sus Multimedia Publications, Fargo, N.D.
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Progress 01/01/99 to 12/31/99
Outputs
Results from the first experiment indicate that two, seminal plasma proteins, protein 1 - 26 kDa; pI=6.2; protein 2 - 55 kDa, pI=4.5 appear to have a strong, positive correlation with the ability of spermatozoa to fertilize eggs in vitro. Sperm cells from boars with high levels of these two proteins consistently exhibited significantly greater egg penetration rates than spermatozoa from boars with reduced concentrations of the same similar plasma proteins. In contrast, two of the proteins examined did not appear to be related to semen fertility. In the second experiment, when semen pooled from two boars differing in their seminal plasma protein profile were used to breed sows, the majority of pigs born alive were sired by the boar with high levels of these two proteins. Collectively, these results indicate that, under a standard collection regimen, concentrations of two seminal plasma proteins provide a useful way to rank boars in terms of their subsequent fertility.
In a third experiment, there was a positive relationship between fertility and concentrations of the 2 seminal plasma proteins. Ejaculates with the highest levels of these proteins (> 10 relative units) exhibited the highest farrowing rates (86.7 + 3.4 %) and greatest number of pigs born alive (11.2 + 0.3) compared with those with lower levels (7.5 - 9.9 relative units, farrowing rate = 78.4 + 3.1%, number of pigs born alive = 10.4 + 0.3; 5.0 - 7.4 relative units, farrowing rate = 71.3 + 3.9%, number of pigs born alive = 9.5 + 0.3). These data demonstrate that quantification of these two proteins in seminal plasma holds promise for use in the development of a proactive semen fertility test.
Impacts
Results from this project demonstrate that monitoring two seminal plasma proteins is a more precise manner for estimation of boar fertility. Use of this technique by producers increases the sustainability of pork production systems by eliminating the matings with subfertile boars.
Publications
- Flowers, W.L. 1999. Boar fertility and artificial insemination. Proceed. 15th IPVS Congr. 1:45-53.
- Britt, J.H., Almond, G.W. and Flowers, W.L. 1999. Diseases of the Reproductive System. In: Diseases of Swine, 8th edition. B.E. Straw, S. D'Allaire, W.L. Mengling and D.J. Taylor, eds. Iowa State University Press, Ames, IA pp. 883-912.
- Popwell, J.M. 1999. Porcine semen quality estimates and capacitation environments and their relationship to fertilization in vitro. (PHD THESIS). North Carolina State University, Raleigh, N.C.
- Poolperm, P., Flowers, W.L. and Almond, G.W. 1999. Evaluation of antibiotics in boar semen extender. Proceed. 15th IPVS Congr. 4:36-37 (ABSTRACT).
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