Parity and Body Condition Score Drive Summer Fertility in Sows

What is the ideal body condition to breed sows?
What is the ideal body condition to breed sows?
(Dr. Mark Knauer)

Depending on the dynamics of your production system, consistent weaned pig output can be a large economic driver. Seasonality in reproduction can impair our ability to maintain constant reproductive output. Sows that lactate during warm summer months may have poorer subsequent litter sizes and farrowing rates when compared with sows that lactate during non-summer months. 

Past research suggests heat stress impacts subsequent farrowing rate more than subsequent litter size. Our team recently evaluated the impact of parity and prefarrow sow body condition in a hot environment on subsequent farrowing rates.

We collected data on 1,866 sows at a 3,600-sow commercial farm in eastern North Carolina from May to August 2021. The farm had a history of experiencing more seasonality in reproduction than the other farms within the production system. Traits recorded included the percentage of sows conceiving by seven days after weaning (includes sows culled for no heat), the percentage of sows farrowing a subsequent litter, sow caliper score prefarrow, sow caliper score at weaning and sow caliper lactation loss. 

As you can see in Figure 1, as perhaps expected, first litter sows lost more body condition than multiparous sows as they are, on average, not able to consume as much lactation feed. 

Impact of parity and prefarrow sow body condition score on lactation body condition loss during periods of heat stress

Figure 1. Impact of parity and prefarrow sow body condition score on lactation body condition loss during periods of heat stress. P1 = gilt litters; P2+ = multiparous sows; Sow caliper <12 = “thin”, 12 to 15 = “ideal”, >15 = fat; Sow caliper loss – a one-unit change is equivalent to 1/3 of a body condition score change (1 to 5 scale).

Again, as may be expected, Figure 2 shows first litter sows were less likely to conceive by seven days after weaning relative to multiparous sows. However, there was an interaction between parity and prefarrow sow body condition. First-litter females were more likely to conceive by seven days after weaning if they had more body condition prior to farrowing. 

Similarly, Schenkel and fellow researchers reported in 2010 that heavier body condition in first-litter sows resulted in greater subsequent reproduction in a tropical region in Brazil. Yet, this was not the case for multiparous sows. Prefarrow sow body condition did not appear to greatly impact the percentage of sows conceiving by seven days after weaning in multiparous sows. Our findings in multiparous sows does not support the belief that greater lactation condition loss impairs subsequent reproduction. Further validation is needed.

Impact of parity and prefarrow body condition score on the % of sow conceiving

Figure 2. Impact of parity and prefarrow body condition score on the % of sow conceiving within 7 days of weaning during periods of heat stress. P1 = gilt litters; P2+ = multiparous sows.

As you can see in Figure 3, a similar percentage of first-litter females ultimately farrowed a subsequent litter when compared to multiparous sows. But the first-litter females accumulated more costly nonproductive days in doing so. Within first parity females, there did appear to be a trend for lower herd retention for “thin” gilts. 

In summary, this study suggests this commercial farm should farrow gilts that are just into the “fat” range on the Knauer sow caliper scale. In the U.S., gilts are commonly bred at this condition score if bred between 300 and 330 pounds. The participating farm likely needs to identify “thin” gilts in late gestation and adjust feeding levels accordingly. Going forward, our team will continue to evaluate ideal sow body condition in relation to productivity and profitability in modern genetic lines.

Impact of parity and prefarrow body condition score during periods of heat stress

Figure 3. Impact of parity and prefarrow body condition score, during periods of heat stress, on the % of sows farrowing a subsequent litter. P1 = gilt litters; P2+ = multiparous sows.


References:

Bryan, M. R., C. E. Hostetler, and M. T. Knauer. 2013. Industry productivity analysis – Seasonality in sow farm traits. J. Anim. Sci. 91(Suppl. 2):94.

Knauer, M. T. and M. T. See. 2007 (Abstr.). Genetic relationships between swine maternal traits in different seasons. J. Anim. Sci. 85(Suppl. 2):19.

Knauer, M. T., and D. J. Baitinger. 2015. The sow body condition caliper. Appl. Eng. Agric. 31:175-178.

Schenkel, A. C., M. L. Bernardi, F. P. Bortolozzo, & I. Wentz. 2010. Body reserve mobilization during lactation in first parity sows and its effect on second litter size. Livestock Sci. 132: 165-172.

Read More:

Simple Solutions Are Often Best: Sow Caliper 3.0 Provides New Options

 

Latest News

Get the Facts Straight on Highly Pathogenic Avian Influenza
Get the Facts Straight on Highly Pathogenic Avian Influenza

Now that the mystery illness impacting some dairy herds has been revealed as the same strain of Highly Pathogenic Avian Influenza that has been impacting the U.S. poultry flock, pork producers are asking questions.

Merck Introduces Sequivity with Microsol Diluvac Forte Adjuvant Prescription Vaccine
Merck Introduces Sequivity with Microsol Diluvac Forte Adjuvant Prescription Vaccine

Merck Animal Health announced it has received license approval from the USDA for Sequivity with Microsol Diluvac Forte adjuvant prescription vaccine for use in gilts and sows. 

What Does the Next Generation of the Pork Industry Want?
What Does the Next Generation of the Pork Industry Want?

It’s easy to make assumptions about what others think, but recent research funded by the Indiana Pork Producers Association and the Indiana Soybean Alliance proves it’s always better to go to the source itself.

Skills Survey Reveals U.S. Agriculture & Food Industry Workforce Needs and Gaps
Skills Survey Reveals U.S. Agriculture & Food Industry Workforce Needs and Gaps

U.S. employers report challenges in finding suitable job candidates with work-ready skills to fill open roles in ag. The AgCareers.com U.S. Skills Survey offers insights, data and trends to address skill development.

China's Hog Herd Size to Remain in Surplus This Year Despite Smaller Sow Target
China's Hog Herd Size to Remain in Surplus This Year Despite Smaller Sow Target

China's pig herd will remain in surplus this year despite new government targets to tame oversupply, officials said, as the world's biggest pig breeder struggles to stage a recovery for multi-year low hog prices.

AASV Foundation Announces Recipients of Hogg Scholarship
AASV Foundation Announces Recipients of Hogg Scholarship

Ashley Johnson and Jana Morgan were named the 2024 recipients of the American Association of Swine Veterinarians Foundation Hogg Scholarship.