Growth and compositional changes of fetal tissues in pigs

• Published in: Journal of animal science 2004-09, Vol.82 (9), p.2534-2540
• Main Authors: McPherson, R.L, Ji, F, Wu, G, Blanton, J.R. Jr, Kim, S.W
• Format: Article
• Language: English
• Subjects: Animal Feed; animal growth; Animal Nutritional Physiological Phenomena; Animal productions; Animals; Biological and medical sciences; Body Composition - physiology; diet; Energy Metabolism - physiology; feeding methods; Female; fetal development; Fetal Development - physiology; fetus; Fetus - metabolism; Fundamental and applied biological sciences. Psychology; Gestational Age; gilts; lipid content; maternal nutrition; nutrient requirements; Organ Size; Pregnancy; protein content; Swine - embryology; Swine - physiology; swine feeding; Terrestrial animal productions; tissue distribution; tissue weight; Vertebrates
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/2004.8292534x

Three hundred twenty fetuses were obtained from 33 pregnant gilts (Camborough-22, Pig Improvement Co.) to determine rates of nutrient deposition in fetal tissues and to estimate nutrient requirements for fetal growth. Pregnant gilts were fed an equal amount of a gestation diet (2.0 kg/d; as-fed basis), and were slaughtered at d 0, 45, 60, 75, 90, 102, or 110 of gestation (n = 3 to 6 per day). Fetuses were dissected into carcass and individual tissues (including gastrointestinal tract, liver, lung, heart, kidney, spleen [greater than or equal to d 75]), and partial placental collection was made for chemical analysis. Fetal tissues were weighed and analyzed for DM, ash, CP, and crude fat. Regression equations were obtained to explain the weight and compositional changes of individual tissues during gestation. Weights of the fetus, carcass, gastrointestinal tract, liver, heart, lung, and kidney increased cubically (P < 0.001), whereas brain weight increased linearly (P < 0.001) as gestation progressed. Fetal protein and fat contents increased quadratically (P < 0.001) as gestation progressed (R2 = 0.906 and 0.904, respectively). Changes in fetal protein and fat contents fit a multiphasic regression that consisted of two linear equations (P < 0.001, R2 = 0.988 and P < 0.001, R2 = 0.983, respectively), indicating that protein and fat growth accelerated after d 69 of gestation. Fetal protein and fat accretions were 0.25 and 0.06 g/d (P < 0.001) before d 69 of gestation, and increased to 4.63 and 1.09 g/d (P < 0.001) after d 69 of gestation. Protein needs for tissue protein gains increased 19-fold after d 69 of gestation. Results of this study indicate that the growth of the fetus and fetal tissues occurs at different rates during gestation and support the practice of a two-phase feeding strategy (before and after approximately d 70 of gestation) for pregnant gilts.