Translational Genomics For Improving Sow Reproductive Longevity

Piglets feeding
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University of Nebraska

University of Missouri

USMARC

Daniel Ciobanu
Assistant Professor,
Molecular Genetics
University of Nebraska-Lincoln
Animal Science Department
A218k, ANSC
Phone: (402) 472-8066
Fax: (402) 472-6362
Email: dciobanu2@unl.edu
Website: Molecular Genomics Lab
Tim Safranski
Associate Professor,
State Swine Breeding Specialist
University of Missouri
Division of Animal Sciences
S133 Animal Science Research Center
Phone: (573.) 884-7994
Email: SafranskiT@missouri.edu

 
 
 

Matt Spangler

Associate Professor,
Quantitative Genetics Extension Specialisst
University of Nebraska-Lincoln
Animal Science Department
A218h, ANSC
Phone: (402) 472-6489
Fax: (402) 472-6362
Email: mspangler2@unl.edu
 

SUMMARY


Reducing economic losses associated with reproductive inefficiency represents a high priority for pig producers and will contribute to increased profitability and sustainability of the swine industry. Reproductive longevity is measured during the lifetime of an animal and is significantly influenced by many environmental factors. While early age at puberty has been correlated with reproductive longevity of sows, reliable predictors for the onset of puberty, the establishment of productive estrous cycle, and reproductive longevity of an animal remain elusive.

Preliminary genome-wide association data indicate a clear relationship between sources of genetic variation that influence age at puberty and reproductive longevity. The goal of this proposal is to identify genetic markers that will predict which gilts will have early age at puberty and superior reproductive longevity, which in turn will reduce culling rates and the cost associated with developing replacement sows. These markers could be used at weaning to screen gilts based on their potential for reproductive success later in life. Our central hypothesis is that genetic sources that affect age at puberty explain substantial variation in sow reproductive longevity and productivity.

To test the central hypothesis, genome-wide association studies will be coupled with transcriptome and genome sequencing in order to establish the relationships between genetic variation and physiological mechanisms of puberty and reproductive longevity. A unique resource population resource that incorporates genetics from different commercial lines that expresses important differences in growth and reproductive traits will be used to carry out these studies. We expect that this research will generate knowledge that could be applied to predict and improve early puberty onset and reproductive potential of commercial populations through marker assisted selection.

Translational Genomics For Improving Sow Reproductive Longevity

-Agriculture and Food Research Initiative Competitive Grant no. 2013-68004-20370 from USDA National Institute of Food and Agriculture

- Multiyear USDA integrated project (research & extension)

- Long Term Goal: develop genetic markers that will predict early life gilts with superior propensity for reproductive longevity.

Significance of reproductive longevity to the swine industry:

- Reproductive failure is the most frequent reason for early culling

- High sow replacement rates (51%) and death (9%)

- Complex: combination of many traits and genes expressed throughout the life of the animals

- Traditional selection was ineffective

- Generation interval is long



For Scientists

Hypothesis: Genetic sources that affect age at puberty explain substantial variation in sow reproductive longevity and productivity. Age at puberty is the earliest phenotypic indicator of breeding/ rebreeding success and reproductive longevity and is characterized by a high variance and moderate heritability (Tart et al., 2012).

Objective 1. Molecular dissection of the genetic factors that explain differences in age at puberty and reproductive longevity. The working hypothesis of this aim is that a significant proportion of the phenotypic differences in age at puberty and reproductive longevity is represented by common genetic sources and/or networks of variation.

Objective 2. Asses the effect of the interaction between energy input and SNP variation on age at puberty and sow reproductive longevity. The working hypothesis of this aim is that the physiological response of age at puberty is dependent on the interaction of genetic background and energy input (i.e. energy restricted versus unrestricted) - different genetic backgrounds are more or less sensitive to fluctuations in energy balance and therefore exhibit different nutrient-dependent responses with regards to age at puberty.

Objective 3. Identify procedures to apply and transfer marker-association results in selection programs to improve sow reproductive longevity. The working hypothesis of this aim is that major genetic variants that explain significant variation in age at puberty and reproductive longevity will be expressed in multiple commercial populations, and can be used to generate a selection response and economic gain.

Figure 1. Effect of increased age at puberty on the probability of parity 1 litter. Regardless of genetic line or the gilt developmental regimen, the likelihood of a Parity 1 litter decreased as age at puberty increased.
Figure 1
Resource Population


For Producers

The Project Plans to Deliver:

1) Genomic markers that will aide in identification of sows with improved fertility,

2) an enhanced set of genomic tools and procedures to apply marker information in genomic selection to enhance sow lifetime productivity,

3) professional development resources for the swine industry, and

4) significant reduction in production cost to the industry.

Industry participation: In working with diverse industry partners including Pillen Family Farms, Smithfield, and The Maschhoffs. we will transfer the technology and knowledge to a wide range of producers. Demonstration projects tailored to corporate and independent producers are organized to estimate the effect of potential candidate genes and polymorphisms on puberty onset and reproductive longevity.