Factors affecting placental size in beef cattle: Maternal and fetal influences

Our objectives were to determine the effects of dam body condition score (BCS), age dam, and calf sex on placental size relationships between weight (BW) with size. Expelled placentas at birth collected from crossbred beef heifers cows during four experiments (n = 22 39/experiment). Placentas deemed complete by visual inspection dissected; dry weights determined for cotyledonary intercotyledonary tissues. Mixed linear models used individually main peripartum BCS category [Thin (<5), Moderate (=5), or Fleshy (≥6)], [Primiparous (2 yr), Young (3–4 Mature (≥5 yr)], measures. Correlations characteristics prepartum BW, gestation length, Thin dams had lower (P ≤ 0.05) cotyledonary, total placental, average cotyledon greater efficiency (calf BW/placental weight) than moderate fleshy dams. Intercotyledonary was < 0.01) in thin compared smaller 0.04) BW Primiparous young mature dams, yet unaffected 0.17). Male calves heavier females, there no differences ≥ 0.59) weights. Calf heart girth positive correlations shoulder rump length abdominal weak all Dam flank a correlation BW. Gestation 0.02) weight. Number cotyledons not correlated 0.28) any offspring characteristics. In conclusion, these data suggest that both maternal affected positively correlated, but it is still unknown which controls signals growth other.