Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 15, 1997
Publication Date: N/A
Interpretive Summary: Increasing litter size as a means of improving efficiency of production and profitability will have to be accompanied by increased management in the farrowing house due to the increased numbers of light weight, weak pigs born. To evaluate the developmental aspects of light weight fetuses, fetal and placental weights were monitored at 30, 70 and 104 days of gestation to ocorrelate with metabolic and endocrine markers. Differences of fetal weights and placentas were detectable as early as 30 days of gestation age for light weight fetuses. Cholesterol concentrations were lower in light weight fetuses. Concentrations of IGF-I increased with fetal weights. Such information indicates complex endocrine and metabolic interactions play an important role in growth and health of developing porcine fetuses and understanding this regulation may improve animal production.
Technical Abstract: With emphasis on increasing litter size to improve productivity and profitability, light weight pigs born will increase in numbers as litter size increases and may be problematic due to reduced neonatal survival of light weight piglets. To study developmental aspects of light weight fetuses, fetal and placental weights were evaluated at three stages of pregnancy (30, 70, and 104 d) from white composite gilts (n = 88, 123, and 135, respectively) in relation to uterine position of light and heavy weight fetuses. Fetal cholesterol concentrations were analyzed at the beginning (d 70) and end (d 104) of the in utero growth phase. At 30 d of gestation, no differences were noted in relation to fetal weight and position within the uterine horn; but at 70 d and 104 d of pregnancy, heavy weight fetuses were found at the tubal end and light weight fetuses at the cervical ends of the uterus. Using the criteria of +/- 1SD or +/- 2SD of the population mean and lower and upper 10 or 20% of fetal weights for eac gestational age, light and heavy weight fetuses in conjunction with their placentas were different from population means at all stages of gestation. Cholesterol concentrations were lower in light weight fetuses (d 104) and increased in heavy weight fetuses. In 28 litters (d 104) selected for extremes in within litter fetal weights, concentrations of IGF-1 increased with fetal weight (P < .01) and suggest growth and development in light weight pigs may be limited by critical endocrine components.