The effects of non-genetic factors on the morphometric parameters of sheep placenta and the birth weight of lambs
The objective of this paper was to determine morphometric parameters of sheep placenta and the birth weight of lambs and their relationship with the type of pregnancy, litter sex and age of ewes. Placenta was obtained directly after delivery from Pomeranian sheep (n=128), including single (n=99) and multiple (n=29) pregnancies. For twin pregnancies, dichorial and monochorial placement classification has been taken into account. The following were determined: lamb birth weight (BWL), placental weight (PW), placental length (PL), placental width (WP), cotyledons number (CN), cotyledons weight (CW), mean diameter of cotyledon (MDC), umbilical cord diameter (DUC). For statistical comparisons, one-way ANOVA variance analysis was used, correlation analysis was calculated by determining the Pearson and / or Spearman’s correlation coefficient. The elements were shown to have significantly lower PW and MDC (p<0.05) compared to older sheep. On the other hand, in the case of PL (p<0.05) and CN (p<0.01), which were significantly higher in the element compared to multi-family. A significantly higher BWL was found in the ram-lambs than in the caves (p<0.05). Significantly higher PW, MDC (p<0.01) and CW (p<0.05) were found in the placenta from which ram-lambs were born. There was also a significantly higher BWL in ram-lambs (p<0.05) born from dichorial twin pregnancy. CW was significantly higher in the dichorial placenta from which the ram-lambs were born (p<0.05). Comparing the placenta from single and twin dichorial pregnancies, it was shown that litter size had a significant impact on the development of placental indices and the birth weight of lambs. Significantly heavier lambs were born from single pregnancy (p<0.01). Also PW and PL (p<0.01) and CN (p<0.01) were significantly higher in single pregnancy placentas. In turn, MDC (p<0.05) was significantly higher in twin placental dichorial pregnancies. Monochorial placenta were characterized by significantly larger PW and CW (p<0.05) from which the lamb-rams were born. The obtained results showed that morphometric parameters of sheep placenta and birth weight of lambs depend on the type of pregnancy, litter sex and age of ewes. These results should be helpful in assessing postpartum placenta in this animal species. In addition, recorded differences in placenta parameters and birth weight of lambs may be useful in ultrasound assessment of placental and fetal development during pregnancy.