title: Consequences of different patterns of feed intake during the estrous cycle in gilts on subsequent fertility.
abstract: The impact of different patterns of feed restriction between d 1 and 15 of the estrous cycle on subsequent reproductive performance of 23 trios of littermate gilts was tested. Some gilts were fed a high plane of nutrition (HH gilts) throughout the cycle, in contrast to HR gilts, which were restricted from d 8 to 15, and RH gilts, which were restricted from d 1 to 7. During feed restriction, weight gain in RH gilts (2.5 +/- .7 kg) was lower (P = .006) between d 1 and d 7 than in their HH and HR littermates (5.6 +/- .7 and 5.6 +/- .8 kg, respectively) and it was lower (P = .0001) in HR gilts (5.5 +/- .5 kg) between d 8 to d 15 than in their HH and RH counterparts (8.5 +/- .4 and 9.4 +/- .5 kg, respectively). There were no differences in backfat changes among groups. Embryonic survival in HR gilts at d 28 of gestation (68.3 +/- 4.8%) was lower (P < .05) than in HH and RH gilts (83.6 +/- 4.3 and 81.7 +/- 4.5%, respectively). Plasma progesterone concentrations in HR gilts were lower (P < .05) at 48 and 72 h after onset of standing estrus (.82 +/- .2 and 3.6 +/- .5 ng/mL, respectively) than in HH and RH gilts (1.44 +/- .2 and 1.24 +/- .2 ng/mL, 5.0 +/- .4 and 5.0 +/- .5 ng/mL, respectively at 48 and 72 h). No differences in ovulation rate were observed among treatments. Placental area was positively correlated to embryo size at d 28 (embryo size = .0003 x (area) + 18.35; r = .28, P = .03) but placental volume was negatively correlated to the number of embryos in utero (placental volume = -4.317 x (number) + 207.55, r = -.39, P = .002). These data demonstrate that the timing of feed restriction during follicular development has important consequences for subsequent embryo survival, possibly mediated by differences in progesterone concentrations in early pregnancy.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada.
authors.forename: F R
authors.initials: FR
authors.lastname: Almeida
authors.forename: R N
authors.initials: RN
authors.lastname: Kirkwood
authors.forename: F X
authors.initials: FX
authors.lastname: Aherne
authors.forename: G R
authors.initials: GR
authors.lastname: Foxcroft
mesh_terms: D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D005314:Embryonic and Fetal Development; D002149:Energy Intake / Q000502:physiology*; D004971:Estrus / Q000502:physiology*; D005260:Female; D005298:Fertility / Q000502:physiology*; D005508:Food Deprivation; D008297:Male; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D013552:Swine / Q000196:embryology / Q000502:physiology*
chemical_list: D011374:Progesterone