Evaluation of the effects of birth order and other influencing factors on pre-weaning piglet mortality under commercial conditions
The objective of this research was to evaluate the effects of birth order on pre-weaning mortality and to identify factors which could influence piglet survival to weaning. A study of 191 litters born over a two-month period was carried out in two commercial facilities; piglets were allotted to one of four treatments (1. first 25% born, 2. second 25% born, 3. third 25% born, 4. last 25% born, respectively) based on their birth order within each litter. The study was carried out as a split-plot design, with the main plot being the sow. All treatments were represented on each sow. Birth measurements, including birth order, birth weight, rectal temperature and body surface temperature at birth and 3 hours post-natal were recorded. The timing and cause of death of piglets dying prior to weaning, as well as piglet weights at processing, weaning, and death were recorded. Piglets born at the first facility were not cross-fostered, whereas piglets at the second location were cross-fostered. Piglets were cross-fostered between litters born on the same day to create litters of similar piglet size. Piglets born stillborn in their birth litter were born later (P < 0.001) in the birth order compared to piglets born alive (birth order of 10.7 vs. 7.2 in litter, respectively; SEM 0.31). Piglets born in the final 25% of the birth order were heavier (P < 0.001) at birth compared to piglets born earlier in the birth order (1.51 vs. 1.43, 1.44, and 1.43 kg for treatments 4 vs. 1, 2, and 3, respectively; SEM 0.030). Piglets born in the final 25% of the birth order had higher rectal temperatures (P < 0.001) at birth compared to piglets born earlier in the birth order (36.83 vs. 36.50, 36.60, and 36.55ºC for treatments 4 vs. 1, 2, and 3, respectively; SEM 0.062), however, temperatures taken at 3 hours post-natal were similar (P = 0.82) for all treatments. Piglets born in the first 25% of the birth order had the highest levels (P < 0.001) of immunoglobulin-G in their blood compared to piglets born later in the birth order (13.87 vs. 13.53, 13.38, 12.65% blood serum for treatments 1 vs. 2, 3, and 4, respectively; SEM 0.340). The main cause of death for piglets dying pre-weaning was crushing by the sow (54.6% of all pre-weaning mortality), and most deaths occurred within the first 3 days of age (44.3% of all pre-weaning mortality). Piglets surviving to weaning had heavier (P < 0.001) birth weights (1.43 vs. 1.16 kg; SEM 0.015) and higher rectal temperatures (P < 0.001) (36.58 vs. 38.23ºC, respectively; SEM 0.062) at birth compared to piglets dying prior to weaning. This study confirms that the major cause of pre-weaning mortality in piglets is crushing by the sow and suggests that piglets dying prior to weaning have decreased birth weights and decreased body temperatures at birth. Piglets born in first 25% of the birth order had the highest levels of immunoglobulin-G, with decreased levels as birth order increased.
birth order, birth weight, pigs, pre-weaning mortality
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign