Head to Chest Circumference Ratio Predicts IUGR Related Performance, By George Charbonneau from South West Ontario Veterinary Services

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Intrauterine Growth Restriction (IUGR) piglets are associated with large litter size and is suggested to be a factor in 5% to 10% of pregnancies. A crowded pregnant uterus affects placental functions regarding size, vascularity, and surface area. Smaller placentas are associated with reduced blood flow and nutrient supply to the fetus. By 90 days of gestation, piglets with IUGR exhibit a reduction in secondary muscle fibers and in the mass of fetal organs relative to brain size. The brain develops early during gestation, while the lung matures at a later gestation age. This is referred to as the brain-sparing effect, and it is distinctive in piglets suffering from IUGR, showing dolphin-like head shapes. Dolphin-like heads are characterized by a steep forehead, bulging eyes, and wrinkles perpendicular to the mouth.

IUGR results in less myofiber hyperplasia, fatter carcasses, and lower meat quality compared with heavier piglets within the litter. In addition, piglets affected by IUGR show lower immune organ weights in the thymus, spleen, and mesenteric lymph nodes, as well as a reduced numbers of immune cells.  IUGR piglets are more likely to experience poor postweaning growth rates, gut adaptation delay, altered microbiota, and intestinal disease. These French researchers wanted to evaluate the association between the head-to-chest circumference ratio (HCR) and birth weight (BW), colostrum intake, and average daily weight gain (ADG) at preweaning and postweaning periods. Additionally, associations between HCR and PCV-2 serum antibody titers and the PCV-2 seroconversion ratio (SCR) were assessed. Head and chest circumferences were measured at birth, and HCR was calculated from 110 piglets born from 8 pregnant sows randomly selected from maternity pens.

The researchers found the following

  • Increments in HCR were associated with lower BW, colostrum intake, and ADG. An HCR threshold of 0.82 maximized sensibility and specificity for the classification of lower and greater performance piglets regarding BW, colostrum intake, and ADG during the periods of 0 to 7 and 0 to 69 days of life.
  • Piglets with HCR ≤ 0.82 had lower (log10) PCV-2 serum antibody titers at 26 days of life compared with piglets with HCR greater than 0.82 (3.30 ± 0.05 vs. 3.47 ± 0.05 g/dL).

Take Home Messages

  • The HCR allowed for the identification of piglets with lower growth performance and impaired immune response against PCV-2.
  • The HCR indicator could be used as a selection criterion for preventive management for piglets showing delayed performance potentially associated with IUGR.

Ref: Diego Manriquez , Guilhem Poudevigne , Etienne Roche , Agnes Waret-Szkuta  Association between Head-to-Chest Circumference Ratio and Intrauterine Growth-Retardation Related Outcomes during Preweaning and Postweaning   Animals (Basel) . 2022 Jun 17;12(12):1562. doi: 10.3390/ani12121562.