Progress 07/01/00 to 06/30/06
Outputs
The primary output of this project was a long-term selection experiment for placental efficiency in swine. Associated with that was training of three graduate students, two MS and on MS and PhD. In addition, an algorithm and software for identifying animals to sample for germplasm preservation. A simulation model for comparing swine artificial insemination programs was also developed. Results were disseminated by publishing in refereed journals and departmental reprots and presenting at regional, national and international scientific meetings.
Impacts
Impacts of this project include identifying animals for sampling for the USDA germplasm preservation project, modification of industry protocols for swine artificial insemination, and abandoning an ineffective method for selection for litter size in swine which had been advocated based on unreliable small-scale preliminary studies.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
The objective of this study was to evaluate correlated responses in conceptus development after four generations of divergent selection for an index (SI) including total born (TB), birth weight (BW) and placental weight (PW). At generation four, the breeding values were higher in L than H for PW, were higher in H than L for PE, and were not different for BW, SI and TB. Estimates of genetic divergence were 20.7 +/- 2.7 g, 0.24 +/- 0.03, and 0.11 +/- 0.02, per generation for PW, PE, and SI, respectively (P < 0.01), but not significant for BW. However, the correlated response in TB was an unexpected genetic divergence trend towards a higher TB in L of 0.07 +/- 0.02 piglets per generation (P < 0.01). Fifty generation-three second parity females were re-mated within line to produce generation-four litters for evaluation at d 30, 50, 70, 90, and 110 of gestation. Uterine length was not different between lines at any gestational age. Fetal weight was not different between
lines from d 30 to d 90, but was lower in H than L at d 110 (1280.6 +/- 77.0 vs. 1551.1 +/- 75.3 g, respectively; P = 0.02). Placental weight increased in both lines from d 30 to 50, at which point it remained relatively unchanged through the rest of pregnancy, except in L that showed a second increase from d 90 to 110. Line differences in placental efficiency were not significant at any gestational. Implantation site length was not different between lines at any point. Implantation site area was significantly higher in H than L at d 30 and 50 (163.9 +/- 18.0 vs. 100.2 +/- 22.5 cm2 and 257.9 +/- 16.4 vs. 186.9 +/- 20.2 cm2, respectively; P < 0.05), but was not different between lines for the remainder of pregnancy. As expected, selection for increased PE resulted in a lower PW in H. However, this change was associated with a phenotypic reduction in BW despite the selection pressure for a higher BW in H. Data from selection were also used to determine factors influencing survival at
farrowing and weaning in litters produced by first parity females. Farrowing survival (FS) and weaning survival (WS) were considered traits of the piglet and were scored 1 if the individual was alive at those time points or 0 if dead. Estimates of direct heritability were 0.16 and 0.18 for FS and WS, respectively. Estimates of maternal heritability were 0.14 and 0.10 for FS and WS, respectively. Variables associated with FS and WS were determined using logistic regression procedures. Birth weight, placental weight, their interaction, and total born can be used as predictors of survival at farrowing. The same model, excluding TB, is the best predictor for WS. In the presence of birth weight information, placental efficiency does not improve the prediction of survival probability. While it was clearly disadvantageous for a piglet to be below the litter mean in birth weight, being above the mean does not provide a substantial advantage. Results from this experiment suggest that it is
possible to select for increased survival at farrowing and at weaning.
Impacts
Selection for increased placental efficiency has resulted in significant genetic change but contrary to expectations has resulted in a negative genetic trend in litter size. It is likely to be most useful to maintain birth weight in conjunction with selection for litter size in highly prolific lines.
Publications
- H. Mesa, T. J. Safranski, j. Green, K. M. Cammack, and W. R. Lamberson. 2005. Selection for Placental Efficiency in Swine: Conceptus Development. 7th International Conference on Pig Reproduction (abstract).
- F.J. Henao, W.R. Lamberson, M.C. Lucy, and A. Hernandez. 2005. OVULATION RATE AND EMBRYO SURVIVAL IN THREE PORCINE GENOTYPES BETWEEN 18 AND 26 DAYS OF GESTATION. 7th International Conference on Pig Reproduction (abstract).
- Mesa H., T.J. Safranski, K.M. Cammack, R.L. Weaber, and W.R. Lamberson. 2006. Genetic and Phenotypic relationships of farrowing and weaning survival to birth and placental weights in pigs. J. Anim. Sci. 84:32-40.
- H. Mesa, T.J. Safranski, K.A. Fischer, K.M. Cammack, and W.R. Lamberson, 2005. Selection for placental efficiency in swine: genetic parameters and trends. J. Anim. Sci. 83:983-991.
- H. Mesa, T. J. Safranski, K. M. Cammack, and W. R. Lamberson. 2005. Selection for an index of placental efficiency and litter size in swine. Midwest ASAS (abstract).
- K. M. Cammack., H. Mesa, P. Sutovsky, and W. R. Lamberson. 2005. Heat-induced subfertility in male mice. Midwest ASAS (abstract).
- H. Mesa, T. J. Safranski, K. M. Cammack, R. L. Weaber and W. R. Lamberson. 2005. Genetic and Phenotypic Relationships of Farrowing and Weaning Survival to Birth and Placental Weights in Pigs. 7th International Conference on Pig Reproduction (abstract).
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Progress 01/01/04 to 12/31/04
Outputs
In a terminal evaluation phase of the divergent selection experiment for placental efficiency, the objective was to evaluate correlated responses in conceptus development and traits physiologically relevant for placental function in the selected lines. Fifty generation-3 second parity females from lines H and L were mated within line to produce generation-four litters for evaluation at d 30, 50, 70, 90, and 110 of gestation. Fetal weight was not significantly different between lines from d 30 to 90, but was lower in H than L at d 110 (P = 0.02). Crown-rump length was not significantly different between lines from d 30 to 70, but tended to be longer in H than L at d 90 (P = 0.09) and was shorter in H than L at d 110 (P = 0.04). Placental weight increased in both lines from d 30 to 50, at which point it remained relatively unchanged through the rest of pregnancy, except in L that showed a second increase from d 90 to 110. As a result, placental weight was not
significantly different between lines from d 30 to 90, but was lower in H than L at d 110 (P < 0.01). Line differences in placental efficiency were not significant at any gestational age. These results suggest that in western breeds, a reduction in placental weight through selection is not accompanied by physiological changes to increase placental function and may result in decreased prenatal survival. Subsequently, data from this experiment were used to determine factors influencing survival at farrowing and at weaning in swine. Farrowing survival (FS) and weaning survival (WS) were considered traits of the piglet and were scored as 1 if the individual was alive at those time points or as 0 if it died. Estimates of direct heritability were 0.16 and 0.18 for FS and WS, respectively. Estimates of maternal heritability were 0.14 and 0.10 for FS and WS, respectively. Variables associated with FS and WS were determined by using logistic regression procedures. Birth weight, placental
weight, their interaction, and total born can be used as predictors of survival at weaning and farrowing. In the presence of birth weight information, placental efficiency does not improve the prediction of survival probability. Results from this experiment suggest that it is possible to select for increased survival at farrowing and at weaning. Information on a piglet's birth weight, placental weight, its litter average birth weight, and the individual's deviation from that average can be used to produce piglets with high survival probability.
Impacts
Selection for increased placental efficiency has resulted in significant genetic change but contrary to expectations has resulted in a negative genetic trend in litter size. It is likely to be most useful to maintain birth weight in conjunction with selection for litter size in highly prolific lines.
Publications
- Whitworth K, GK Springer, LJ Forrester, WG Spollen, J Ries, WR Lamberson, N Bivens, CN Murphy, N Mathialigan, JA Green, and RS Prather. 2004. Developmental expression of 2489 gene clusters during pig embryogenesis: an expressed sequence tag project. Biol Reprod. 71:1230-43.
- Hampton JH, JF Bader, WR Lamberson, MF Smith, RS Youngquist, and HA Garverick. 2004. Gonadotropin requirements for dominant follicle selection in GnRH agonist-treated cows. Reproduction 127:695-703.
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Progress 01/01/03 to 12/31/03
Outputs
Our model for evaluating the effectiveness of artificial insemination in swine was used to compare alternative estrous detection schedules that varied in effectiveness and timing. A fourth generation of index selection for components of reproduction in swine was completed in 2003. Significant divergence in breeding values for birth weight, placental weight and placental efficiency was observed after generation 4. No divergence in litter size was observed. Selection ahs been completed. Evaluation of second parity females at days 30, 50, 70, 90 and 110 of gestation is in progress. Five sows from each line will be slaughtered. Ovulation rate, number, weight and size of viable and nonviable fetuses, weight and size of placenta and size of placental contact area are being measured.
Impacts
Selection for placental efficiency has resulted in genetic change but has not been effective in improving litter size. It is likely to be most useful to maintain birth weight in conjunction with selection for litter size in highly prolific lines. The artificial insemination model has the potential for guiding development of optimal artificial insemination schedules. It has been implemented by a commercial company to guide appropriate use of an estrous synchronization product.
Publications
- Mesa, H., Safranski, T.J., Johnson, R.K. and Lamberson W.R. 2003. Correlated response in placental efficiency in swine selected for an index of components of litter size. J. Anim. Sci. 81:74-79
- Sterle, J.A., Cantley, T.C., Matteri, R.L. Carroll, J.A., Lucy, M.C. and Lamberson W.R., 2003. Effect of recombinant porcine somatotropin on fetal and placental growth in gilts with reduced uterine capacity.
- Rosenfeld, C.S., Grimm, K.M., Livingston, K.A., Brokman, A.M., Lamberson, W.E. and Roberts R.M. 2003. Striking variation in the sex ration of pups born to mice according to wheher maternal diet is high in fat or carbohydrate. PNAS 100(8)4628-4632.
- Bracken, C.J., Safranski, T.J., Cantley, T.C., Lucy, M.C., Lamberson W.R., 2003. Effect of time of ovulation and sperm concentration on fertilization rate in gilts. Theriogenology 60:669-676.
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Progress 01/01/02 to 12/31/02
Outputs
A third generation of index selection for components of reproduction in swine was completed in 2002. One additional generation of selection will be conducted. Significant divergence in breeding values for birth weight, placental weight and placental efficiency was observed after generation 3. No divergence in litter size was observed. A computer program for selecting animals for the USDA SGUP was completed and tested. The program was found to identify animals for collection with lower interrelationship than randomly identified animals. In addition, genotyping of identified animals showed that a greater proportion of alleles present in the population were captured in the animals identified by the program than in animals identified at random. This suggests that use of the program for identifying animals for collection will be effective in maintaining genetic diversity. The program was used to identify Hereford and Yorkshire boars for collection of semen.
Impacts
1) The artificial insemination model has been used by a commercial company to evaluate the production and economic benefits associated with use of a new product for controlling the timing of ovulation in swine which facilitates single fixed time inseminations. 2) The procedure for selection for components of reproduction in swine is under consideration for adoption by a commercial swine breeding company for use in their nucleus herds. 3. A computer program designed to identify animals for germplasm preservation has been used by the USDA to identify Hereford and Yorkshire boars for collection. The program will be used for selections in other breeds and species in the future.
Publications
- Lamberson W R; Firman J D. 2002. A comparison of quadratic versus segmented regression procedures for estimating nutrient requirements. Poultry Science. 81: 481-484.
- Mesa Echeverri, Henry. 2002 Effect of index selection for reproductive components on placental efficiency and litter size in swine. M.S. Thesis, University of Missouri.
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Progress 01/01/01 to 12/31/01
Outputs
For objective 1) identify economically optimal scenarios of estrous detection and insemination of swine, the swine A.I. model has been modified to incorporate flexible time and success of estrous detection and replications are currently in progress. For objective 2) create a model that permits better description of the interacting components of litter size in swine, a third generation of selection on placental efficiency has been conducted. Divergence in placental weight and birth weight observed in the previous generation of selection was reduced in the current generation. Currently, measurements have been taken on 1859 pigs form 165 litters. The heritabilities of placental weight and placental efficiency are estimated to be .25(.06) and .28(.07), respectively. An additional generation of selection will be conducted before terminal evaluation and model development is initiated. For objective 3) refine and validate an existing selection procedure that results in
maximum retention of genetic variation in endangered livestock populations, verification initial validation of the model has been conducted. The model has been used to select the first 16 Yorkshires boars for sampling for the USDA Swine Germplasm Preservation Program. Identification of additional boars in the Yorkshire breed is in progress and as is preparation of pedigrees for Hereford swine. A preliminary version of the programmed algorithm has been supplied to the USDA facility in Ft. Collins, CO. Pedigree and genetic marker data has been obtained from the Brookville, FL station that will allow evaluation of the effectiveness of the algorithm for maintaining allele variation in preserved subpopulations.
Impacts
The swine artificial insemination model will lead to improved artificial insemination scheduling resulting in increased conception rate and litter size with reduced number of services. The selection algorithm will contribute to the preservation of genetic variation in common and rare breeds breeds of swine in the U.S.
Publications
- Calder, M.D., M. Manikkam, B.E. Salfen, R.S. Youngquist, D.B. Lubahn, W.R. Lamberson, and H.A. Garverick. 2001. Dominant bovine ovarian follicular cysts express increased levels of messenger RNAs for luteinizing hormone receptor and 3 beta hydroxysteroid dehydrogenase Delta(4), Delta (5) isomerase compared to normal dominant follicles. Biology of Reproduction 65(2):471-476.
- Strauch, T.A., E.J. Scholljegerdes, D.J. Patterson, M.F. Smith, M.C. Lucy, W.R. Lamberson, and J.E. Williams. 2001. Influence of undergraded intake protein on reproductive performance of primiparous beef heifers maintained on stockpiled fescue pasture. Journal of Animal Science. 79(3)574-581.
- H. Mesa, T.J. Safranski, W.R. Lamberson. 2001. Divergent Selection for an Index of Reproductive Components in Swine. 6th International Conference on Pig Reproduction. June 3-6, 2001.
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Progress 01/02/00 to 12/31/00
Outputs
A base model for a swine artificial insemination simulation model has been developed and peer reviewed. Some basic results have been published. We anticipate subsequently using the model to evaluate alternative artificial insemination and estrous detection protocols for swine. The USDA has initiated a program to store genetic materials (semen, DNA, embryos, or oocytes) from all US breeds of livestock. I have undertaken the task of developing a procedure for identification of specific animals to serve as donors and subsequent application of the procedure for swine. An algorith for identifying semen donors has been developed and preliminary testing is in progress. Programming of the algorithim for application in the project is underway. In a project to evaluate optimally timed, low-dose insemination in gilts, a procedure for transrectal ultrasonography of gilts was developed. This procedure facilitates diagnosis of reproductive problems in swine herds. It was learned
that optimally timing insemination to occur shortly before ovulation would not result in economically viable fertility if dosages of semen were reduced to .5 billion cells.
Impacts
This swine artificial insemination simulation model provides a mechanism to evaluate expected biological and economic results of changes in swine artificial insemination protocols. The results of semen preservation project will be a reserve of materials to serve a a safeguard against future loss of genetic variation. Sampling broadly divergent animals within breed is critical to assuring that as many alleles as possible are represented in the stored materials. In the project to evaluate optimally timed, low-dose insemination in swine, a procedure for transrectal ultrasonography of gilts was developed. This procedure facilitates diagnosis of reproductive problems in swine herds.
Publications
- W. R. Lamberson and T. J. Safranski. A model for economic comparison of swine insemination programs Theriogenology 54:799-807 2000.
- M. Kaps, W. O. Herring and W. R. Lamberson. Genetic and environmental parameters for traits derived from the Brody growth curve and their relationships with weaning weight in Angus cattle J. Anim. Sci. 78:1436-1442 2000.
- Bracken, C. J., W. R. Lamberson and T. J. Safranski. Factors associated with incidence of PG600 intervention in weaned sows. J. Anim. Sci. 78 (Suppl. 2):75 2000.
- Bracken, C. J. Fertilization rate using a low-dose insemination. M. S. Thesis, University of Missouri 2000.
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Progress 01/01/99 to 12/31/99
Outputs
technologies in livestock production. Mathematical and biological models have been used in evaluations. A project to estimate the impact of cloning on reducing phenotypic variation in production traits of swine revealed that the reduction in phenotypic variance is closely related to heritability. Significant reductions would be expected in highly heritable traits, but modest reductions are expected for lowly heritable traits. Mating systems that utilize males from a specific clone mated to females from a complementary, but unrelated clone could be key to taking advantage of improved genetic merit while also gaining some reduction in phenotypic variation. The reduction in phenotypic variation would yield benefits to packers and consumers. Contributions were made to a collaborative effort with the objective of determining the effects of physiological components on litter size of swine. It was determined that fetuses cannot make use of space vacated due to death of
adjacent littermates. Since placental area is limited in sows with high ovulation rate, it is important that the placental unit is efficient in transporting nutrients. Preliminary results suggest that placental efficiency is heritable, can be easily measured, and if increased, may result in higher litter size. A project to evaluate the use of marker assisted selection for identifying potential parents that should be used to minimize loss of genetic variation in endangered populations resulted in development of a powerful procedure for that purpose. In vivo testing is needed to determine the magnitude of the possible side effect of increasing the frequency of detrimental recessive genes. Transgenic mice were used as a model for transgenic livestock to determine the relative merits of selection within transgenic populations versus introgression of transgenes into new background genotypes. The magnitude of effects of transgenes depends on the background genotype suggesting that a
specialized background genotype should be developed to optimize the performance of a specific transgene. Results from a bioeconomic model designed to facilitate the evaluation of alternative swine insemination programs showed that use of breeding schedules that maximized reproductive performance did not result in maximum return to producers. Increased input costs were not offset by extra income. Evaluation of biological characteristics of specific populations may be necessary to optimize breeding schedules. A procedure was developed for easy transrectal ovarian ultrasound of gilts and sows, which would facilitate these evaluations.
Impacts
Formalization of a conceptual model of the physiological components that influence litter size in pigs has led to research to identify the genetic means for controlling the components. Results from a bioeconomic model of insemination of swine has demonstrated that managing breeding for maximum production does not ensure maximum economic returns. Alternative breeding strategies were developed.
Publications
- Moura,. A. S. A. M. T, D. E. Spiers and W. R. Lamberson. 1998. Thermogenic response of MT-bGH mice. Growth, Developmen and Aging. 62:149-159.
- Holder, R. B., A. S. A. M. T. Moura and W. R. Lamberson. 1999. Selecting for lean gain efficiency in mice using different selection criteria. J. Anim. Sci. 77:575-581.
- Kaps, M., A. S. A. M. T. Moura, T. J. Safranski and W. R. Lamberson. 1999. Components of growth in mice hemizygous for a MT/bGH Transgene. J. Anim. Sci. 77:1148-1154.
- Kaps, M, W. O. Herring and W. R. Lamberson. 1999. Genetic and environmental parameters for mature weight and Angus cattle. J. Anim. Sci. 77:569-574.
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Progress 01/01/98 to 12/31/98
Outputs
As part of an effort to develop a neural network model to predict time of ovulation in swine to facilitate increased usage of genetically superior boars in artificial insemination programs, a procedure utilizing an ultrasound probe mounted on a PVC handle has been developed. Utilization of this procedure reduces discomfort to the pig, permits utilization of the procedure in gilts, and increases the speed of evaluations. Length of lactation, parity, body condition score, number of piglets weaned, and ovarian structure on day three after weaning have been identified as important inputs to the neural network model. Matings planned based on an index of rarity of genetic markers has been found to reduce the rate of loss of genetic variation in endangered livestock populations when compared to conventional mating schemes such as minimization of inbreeding. Screening of potential parents for anonymous genetic markers and then ranking the parents based on the rarity of
markers in their genome is suggested. One possible method of weighting would utilize the reciprocal of the frequency of each allele that is evaluated. The optimum weighting depends on the size of the population and the number of loci which are screened.
Impacts
(N/A)
Publications
- Dyer, C.J., Carroll, J.A., Sterle, J.A., Lamberson, W.R. and Matteri, R.L. 1998. Leptin mRNA expression in the porcine placenta. J. Anim. Sci. 76(Suppl. 2):68.
- Garton, B.L., Spain, J.N., Trout, W.E., Spiers, D.E. and Lamberson, W.R. 1998. The relationship between students' learning styles and teaching performance in an introductory animal science course. J. Anim. Sci. 76(Suppl. 1):369.
- Lamberson, W.R. 1998. Marker allele frequency index selection as a method for reducing loss of genetic variation in small populations. World Congr. Genet. Appl. Livestock Prod. 28:107-110.
- NacNeil, M.D., Newman,S., Lamberson, W.R. and Hochman, Z. 1998. Decision support systems to aid beef producers in choosing a crossbreeding strategy. World Congr. Genet. Appl. Livestock Prod. 27:437-440.
- Sterle, J.A., Boyd, C., Peacock, J.T., Koenigsfeld, A.T., Lamberson, W.R., Gerrard, D.E. and Lucy, M.C. 1998. Insulin-like growth factor (IGF)-I, IGF-II, IGF-binding protein-2 and pregnancy-associated glycoprotein mRNA in pigs with somatotropin-enhanced fetal growth. J. Endocrinol. 159(3):441-450.
- Sterle, J.A., Cantley, T.C., Carroll, J.A., Matteri, R.L., Lucy, M.C. and Lamberson, W.R. 1998. Recombinant porcine somatotropin effects on placental characteristics in gilts with reduced uterine capacity. J. Anim. Sci. 76(Suppl. 1):242.
- Kaps, M., Herring, W.O. and Lamberson, W.R. 1998. Genetic parameter estimates for mature weight in Angus cattle. J. Anim. Sci. 76(Suppl. 2):30.
- Matteri, R.L., Carroll, J.A., Monnig, J.E., Sterle, J.A., Veum, T.L. and Lamberson, W.R. 1998. Polymorphisms of porcine leptin cDNA. J. Anim. Sci. 76(Suppl. 2):68.
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Progress 01/01/97 to 12/31/97
Outputs
Effects of alternative methods of replicated selection for improved efficiency of feed utilization was evaluated in mice. No differences were observed for feed:gain ratio although intake declined in lines in which that component of efficiency was emphasized. Of greatest importance was a significant decline in reproductive performance of all lines selected for improved efficiency relative to controls. During a 100 day terminal evaluation period total number of pups born were 19.9 and 13.7 and weaned were 19.2 and 30.4 for control and average of select lines, respectively. Lean and fat gain and metabolism were examined in mice transgenic for a mouse metallothionein/bovine growth hormone construct. Transgenic mice were found to gain lean and fat more rapidly and for a longer period than nontransgenic littermates. Asymptotic weight of lean and fat was greater for transgenics than nontransgenic sibs. Resting metabolic rate was not found to differ between the two groups;
however, transgenics had impaired ability to regulate body temperature when exposed to temperatures below thermoneutral.
Impacts
(N/A)
Publications
- MOURA, A.S.A.M.T., KAPS, M., VOGT, D.W. and LAMBERSON, W.R. 1997. Two-way selection for daily gain and feed conversion in a composite rabbit population. J. Anim. Sci. 75:2344-2349.
- MOURA, A.S., HOLDER, R.B., LAMBERSON, W.R. and SPIERS, D. 1997. Reproductive performance and metabolic rate in mice selected for lean gain efficiency. J. Anim. Sci. 75(Suppl. 1):32.
- LAMBERSON, W.R., STERLE, J.A. and HERRING, W.O. 1997. Decision support software for beef cattle crossbreeding. J. Anim. Sci.
- STERLE, J.A. et al. 1997. Insulin-like growth factor (IGF)-I, IGF-II, and IGF binding protein (BP)-2 in liver and reproductive tissues of pregnant pigs treated with recombinant porcine somatotropin (rpST). J. Anim. Sci. 75(Suppl. 1):88.
- LAMBERSON, W.R., BOYLE, A.M. and LUCY, M.C. 1997. A simulation model for comparing timing of insemination. 5th Intl. Conf. Pig Reprod., June 1-4, The Netherlands.
- STERLE, J.A. et al. 1997. Effect of recombinant porcine somatotropin (rpST) on fetal and placental growth in gilts with reduced uterine capacity. 5th Intl. Conf. Pig Reprod., June 1-4, The Netherlands.
- BOYLE, A.M. and LAMBERSON, W.R. 1997. Predicting optimal insemination time in sows. J. Anim. Sci. 75(Suppl. 1):88.
- KAPS, M., MOURA, A.S. and LAMBERSON, W.R. 1997. Effects of a metallothionein/bovine growth hormone transgene on components of growth in mice. J. Anim. Sci. 75(Suppl. 1):153.
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Progress 01/01/96 to 12/30/96
Outputs
Six generations of selection on alternative criteria to increase efficiency of feed utilization in mice were completed and terminal evaluations conducted. Similar responses were obtained via selection for increased gain adjusted to constant intake and decreased intake adjusted to constant gain. Both criteria, as well as selection for feed:gain ratio, resulted in decreased reproductive rate. A bioeconomic model for comparison of alternative artificial insemination strategies was developed. Results suggest that with low semen costs three inseminations with twice per day estrous detection is optimal, but with semen costs of more than $10, breedings of two inseminations provide greater returns. If precisely timed, single inseminations are provide potentially greatest return. An expert system providing decision support for determining appropriate crossbreeding systems from beef producers was released through University Extension. The program, Cross-Choice, is available on
the World Wide Web.
Impacts
(N/A)
Publications
- Sterle, J. A. and W. R. Lamberson. 1996. Effects of exposure to an estrual female on attainment of puberty in gilts. Theriogenology 45:733-744.
- Lamberson, W. R. and G. R. Eckardt. 1996. Local changes in uterine dimensions inthe pregnant pig. Anim. Reprod. Sci. 43:35-41.
- Holder, R. B. and W. R. Lamberson. 1996. Selection for alternative measures of feed efficiency in mice: Population and procedures. USDA Anim. Welfare. Newsletter 6:14-16.
- Yuan, W., et al. 1996. Responses of porcine corpora lutea to somatotropin administration during pregnancy. J. Anim. Sci. 74:873-878.
- Powell, M. R., et al. 1996. Use of melengestrol acetate-based treatments to induce and synchronize estrus in seasonally anestrous ewes. J. Anim. Sci. 74:2292-2302.
- Lamberson, W. R., et al. 1996. Relationships of serum IGF-II concentrations to growth compositional and reproductive traits of swine. J. Anim. Sci. 74:1753-1756.
- Moura, A. S., et al. 1996. Two way selection for average daily gain and feed efficiency in a composite rabbit population. J. Anim. Sci. 74(Suppl. 1):110.
- Sterle, J. A., et al. 1996. Increased uterine capacity by injections of recombinant porcine somatotropin (rpST)to gilts during gestation. J. Anim. Sci. 74(Suppl. 1):143.
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Progress 01/01/95 to 12/30/95
Outputs
The general objective of this project is to identify effects of advances in reproductive technology on livestock breeding programs. Two studies involved determining interactions of growth factors with pre- and post-natal growth and reproduction. Daily injections of porcine somatotropin were administered to sows from d 30 to 43 of gestation. Fetal weights were higher at d 45 of gestation in litters from treated sows. Fetuses with small placentas and thus expected to be small received the greatest benefit of treatment. A subsequent study examining the effects of porcine somatotropin on uterine capacity is in progress. A second study involved measuring parameters of IGF-I and -II concentration in growing pigs and associations of the concentrations with growth, reproductive and compositional traits. Both hormones and their sum were associated with increased growth, particularly before 12 weeks of age. Concentrations of the hormones were weakly linked with compositional and
reproductive traits.
Impacts
(N/A)
Publications
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Progress 01/01/94 to 12/30/94
Outputs
The general objective of this program is to identify effects of advances in reproductive technology on livestock breeding programs. A specific aim of this project is to examine the effectiveness of genetic selection on improvement of productivity in a population of mice with a segregating transgene that affects growth. Results of the project are expected to be of use in developing strategies for utilization of transgenic livestock. Animals from three mouse founder lines with a metallothionein/bovine growth hormone fusion gene were obtained from Ohio University. Selection for increased litter size resulted in decreased fertility and loss of the selected line in the third generation. Results from a model of the population suggested that selection resulted in increased frequency of the transgene and proportion of sterile homozygous transgenic females. Interaction of gender by transgenotype was examined for growth, efficiency of feed utilization and body composition (fat
free mass estimated using total body electrical conductivity). Presence of the transgene had a greater effect on weight and efficiency of females than intact or castrate males. No effect of the transgene was found on body composition.
Impacts
(N/A)
Publications
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Progress 01/01/93 to 12/30/93
Outputs
SEE MO-ASRB0029and MO-ASHC0030.
Impacts
(N/A)
Publications
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