Bryan K A, Hagen D R
Department of Dairy and Animal Science, Pennsylvania State University, University Park 16802.
Growth Dev Aging. 1991 Spring;55(1):27-33.
Fifty-four Duroc gilts (mean wt = 88 kg, mean age = 164 d) were fed a 15% protein diet either ad libitum (F) or at a rate of approximately 50% of ad libitum daily (1.8 kg: L) prior to mating at either second (Exp. 1) or first (Exp. 2) observed estrus. Gilts were checked for estrus twice daily with a mature, active boar, mated at the appropriate estrus, and fed 1.8 kg of the prebreeding diet per gilt daily until slaughter between 42 and 49 days of gestation, mated gilts were slaughtered and measurements taken on fetuses and reproductive organs. In Exp. 1, fetal weight per day of gestational age (FetWDA), placental weight (PLW), crown-to-rump length (CRL) and uterine space per fetus (SP) were greater for fetuses from L gilts than F gilts (all P less than .05) with no difference in number of fetuses (P greater than .05). In Exp. 2, FetWDA was greater for fetuses from F gilts than L gilts (P less than .05), however there was no difference due to level of feeding for PLW, CRL and SP (all P greater than .10). Fetal weight (FW) was highly correlated with CRL indicated that a cubic relationship existed (both r = .97). In both studies, male fetuses grew more rapidly than female fetuses (P less than .05). These studies indicate that pre-breeding nutritional status and sexual age of the dam at conception have differential effects on fetal growth rate, but relationships among FW and CRL are not readily altered by pre-breeding level of feeding or sexual age of the dam at conception.(ABSTRACT TRUNCATED AT 250 WORDS)
