G. Bouchard et al., RETROSPECTIVE EVALUATION OF PRODUCTION CHARACTERISTICS IN SINCLAIR MINIATURE SWINE - 44 YEARS LATER, Laboratory animal science, 45(4), 1995, pp. 408-414
Three hundred seventy-one litter records collected between 1985 and 19
93 from 156 Sinclair S-l miniature sows, a Hormel-derived strain of mi
niature swine, were retrospectively analyzed and compared with publish
ed records for 1950 to 1952 and 1963 to 1965. The effect of several va
riables such as season and month of parturition, age of sow, parity, a
nd litter size on reproductive parameters of the Sinclair miniature sw
ine were evaluated. The mean and standard error of the mean for litter
size, number of liveborn, number of stillborn, and litter size at wea
ning of the Sinclair S-1 miniature swine were 7.20 +/- 0.12, 6.57 +/-
0.12, 0.63 +/- 0.06, and 5.75 +/- 0.12 piglets respectively. From a to
tal of 2,436 liveborn piglets, 2,133 (87.56%) were weaned. The litter
size at birth was similar to that previously reported for this strain
of swine, whereas the litter size at weaning increased (P < 0.001) fro
m 4.7 piglets during 1963 to 1965 to 5.8 piglets in our study. The ave
rage birth weight decreased (P < 0.001) from 0.90 kg in 1950 to 1952 a
nd 0.72 kg in 1963 to 1965 to 0.59 kg in our study. Reproductive varia
bles that had a considerable effect on the miniswine reproduction incl
uded month of parturition, age of sow, parity, and litter size. Primip
arous sows had the smallest litter size and lowest number of weaned pi
glets. Sows during their second and third parity or sows between 2 and
4 years old had the best reproductive performances. Litter size and n
umber of stillborn increased with parity and age of sow, resulting in
fewer piglets weaned in older sows. Litter size had a curvilinear effe
ct on preweaning mortality, with the highest mortality in small and la
rge litters. Overall, production efficiency of the Sinclair miniswine
has been stable or has improved since 1950, and all reproductive varia
bles evaluated, except season, were found to have a profound effect on
miniswine reproduction.