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Research Article | 07 Oct 2026

Determinants of extremely low birth weight piglets per litter in Landrace × Yorkshire sows under commercial conditions in Vietnam

Nam Hoai Nguyen1 ORCID , Dung Van Bui1 ORCID , Lanh Thi Kim Do1 ORCID , Thanh Van Nguyen1 ORCID , Truong Duc Nguyen1 ORCID , and Peerapol Sukon2,3 ORCID Show more
VETERINARY WORLD | Article No. 9 | pg no. 4419-4432 | Vol. 19, Issue 10 | DOI: 10.14202/vetworld.2026.4419-4432
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ABSTRACT

                      
Background and Aim: Extremely low birth weight piglets (LBP) contribute disproportionately to preweaning mortality and reduced production efficiency. However, large-scale commercial evidence regarding piglets weighing <750 g remains limited, particularly in Southeast Asia. This study aimed to quantify extremely LBP per litter and identify their major determinants in Landrace × Yorkshire sows under commercial conditions in Vietnam.
Materials and Methods: This retrospective cohort study used commercial farm records collected from 2018 to October 2025. Descriptive analysis included 17,712 farrowing records from 4,476 sows, representing 211,720 piglets. Two cleaned datasets were analyzed: Model 1 comprised 7,985 records, whereas Model 2 comprised 6,336 records and additionally incorporated the weaning-to-service interval (WSI). Factors associated with LBP were evaluated using zero-inflated Poisson generalized linear mixed models, with sow and boar included as random effects.
Results: The overall incidence of LBP was 4.30%, corresponding to 0.51 LBP per litter, and 31.39% of litters contained at least one LBP. Litter size was the strongest determinant; each additional piglet was associated with an approximately 31%–32% increase in the expected LBP count. LBP exhibited a non-linear relationship with parity, increasing through intermediate parities, peaking at parity 5, and declining thereafter. A parity × litter size interaction indicated a stronger adverse association between increasing litter size and LBP in older sows, with a significant interaction at parity 6 in Model 2. WSI >20 days was associated with increased LBP, whereas gestation length >116 days was associated with lower LBP.
Conclusion: Litter size is the primary determinant of extremely LBP under the studied commercial conditions, highlighting the trade-off between prolificacy and piglet viability. Parity-specific effects, prolonged WSI, and gestation length further influence LBP occurrence. Management strategies emphasizing appropriate litter size management, particularly in older sows, together with reproductive management that avoids prolonged WSI and shortened gestation, may help reduce extremely LBP and improve herd productivity.
                      
Keywords: commercial swine production, extremely low birth weight piglets, gestation length, litter size, parity, piglet viability, Vietnam, weaning-to-service interval.