Purdue University Graduate School


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posted on 2024-04-23, 03:07 authored by Taw Jaksun ScaffTaw Jaksun Scaff

Boars in the swine industry are one of the select animals subject to limit feeding. Limit feeding boars occurs once boars are selected to enter the boar stud. Before selection boars are ad libitum fed like a nursery or grow finishing pig. Research involving boar nutrition and the impact it has on growth, development, and semen characteristics are limited compared to the rest of the swine industry. The objective of these studies conducted at Purdue University were to determine how varying nutritional feeding strategies impact semen quality and quantity as well as growth and development of artificial insemination boars.

Feeding fiber is a commonly used strategy in gestating sow nutrition to mitigate some of the negative side effects of limit feeding animals. A variety of fiber sources are available to the swine industry, however most of the common sources used are wheat bran, alfalfa meal, sugar beet pulp, and soybean hulls. Soyhulls are one of the more easily accessible sources of fiber in Indiana and the Midwest U.S. due to large amounts of soybean production and processing which will continue to grow with bi-energy demands. Boars fed the fiber diet (14.3% soyhulls) had increased bodyweight and body condition changes over the twelve-week period. Additionally, fiber inclusion in the diet had no impact on semen characteristics but semen was impacted by the age and breed of the boar. Salivary cortisol levels were reduced in boars fed fiber as well as some changes in behavior were observed.

The addition of fiber had impacts on growth and development but no impacts on semen. Since boars are limit-fed for so long from selection after the grow-finish period until they are culled this drew up the question if feeding boars different levels after selection (1.8 kg/d or 2.7 kg/d) impacted trainability, first time semen collection characteristics, growth and development of young boars. No differences were observed for feeding level impacting trainability with 92% of all boars regardless of treatment being successfully trained. Semen volume was increased in boars fed 2.72 kg/d by approximately 50% but no other semen characteristics were impacted. Boars fed 2.72 kg/d also had increased bodyweight and body condition score measures.

The boars subject to the training study unknowingly arrived at the farm naturally infected with porcine circovirus three (PCV3). Research has been conducted on the ability of viruses (PRRSv, PEDv) to be detected and transmitted through semen. Porcine circovirus three is a relatively new variant of circovirus so the opportunity to evaluate the question of if this virus was able to be detected in seminal plasma and the impacts it has on semen characteristics was presented. Serum and semen samples were collected for polymerase chain reaction analysis of detection of PCV3 conducted at Purdue Animal Disease Diagnostic Laboratory. Porcine circovirus three was able to be detected in the serum of positive boars however no positive detection occurred for seminal plasma samples. Morphological abnormalities such as distal midpiece reflex, distal droplets, and head and tail differed between infected and non-infected boars. Young boars sero-positive for PCV3 had decreased total sperm, total normal sperm motility, and head and tail abnormalities but had decreased distal midpiece reflex abnormalities when compared to PCV3 negative young boars. Young boars were also able to maintain the virus for 98+ days, while some old boars were able to clear the virus withing 14 weeks of becoming positive.

The next chapter evaluated maintenance energy equation listed in the swine NRC 2012 and if it was still accurate for sexually active boars and if weight management through the use of this equation impacted boar performance. Boars were subject to three treatments (150%, 100%, 80%) of maintenance energy for the first nine-week period and 150% and 80% diets were switched for second nine-week period while 100% stayed the same the entire time in a cross-over design. Semen, bodyweight, and body condition parameters were analyzed throughout the two nine-week periods. Boars fed 80% of maintenance had the largest reduction in semen parameters compared to 150% and 100% maintenance fed boars. Additionally, switching 80% feed intake boars to 150% maintenance feed intake, boars were able to recover some of the negative impacts, however they were not able to fully recover in the second nine-week period. Boars fed 100% and 80% maintenance energy lost weight regardless of age. The loss of body weight of the 100% maintenance fed boars indicates the swine NRC 2012 equation is underestimating the modern AI boar maintenance needs. Old boars were able to handle changes in weight and body condition better than young boars as there was reduced variation in serum metabolites analyzed with old boars compared to young boars.

The last chapter of this thesis focused on a big data project from commercial sow farms. The objective of this study was to determine if breeding gilts at first signs of estrus or after has an impact on sow performance and economic value to parity three. A regression model was developed from on farm data to determine the difference in total born piglets to parity 3 between gilts bred on their first estrus or after. Gilts bred on their first estrus had six fewer total piglets to parity three compared to gilts who were bred after the first estrus. Also, gilts bred after their first estrus had a larger percentage of sows being profitable compared to gilts bred on first estrus. This model data was compared to actual data for comparison between the two. The model with the limited variables inputted and compared to the actual data was fairly accurate with economic profitability and with more refinement the accuracy can be increased.

Overall, nutrition of the boar needs to be an area of interest in the swine industry to continue improving efficiency of production. Feeding fiber to boars has minimal impact on semen characteristics but can be used to reduce stress in boars that are limit-fed for weight and body condition management. Limit feeding boars beginning at selection reduces growth and development and had negative impacts on first time semen collection volume. Porcine circovirus 3 was not found in the seminal plasma of naturally infected boars when serum analysis was positive. Boars fed below maintenance levels listed in the swine NRC 2012 have negative impacts on semen, bodyweight, and body condition parameters. Once diets were changed boars were able to recover from the feed restriction but not meet baseline measures prior to feed restriction. Young boars are more sensitive to feeding changes than old boars, this could be due to the young animal still growing while the older animal is closer to mature size. Big data projects can aid producers in making production changes decisions to estimate the economic impact it can have to an individual farm or the entire production system.


Degree Type

  • Doctor of Philosophy


  • Animal Sciences

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Brian Richert

Additional Committee Member 2

Kara Stewart

Additional Committee Member 3

Allan Schinckel

Additional Committee Member 4

Scott Radcliffe

Additional Committee Member 5

Francisco Cabezon

Additional Committee Member 6

Darryl Ragland

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