title: Pigs weaned from the sow at 10 days of age respond to dietary energy source of manufactured liquid diets and exogenous porcine somatotropin.
abstract: Previous research indicates that the neonatal pig does not alter feed intake in response to changes in the energy density of manufactured liquid diets. Also, the limited response of IGF-I to exogenous porcine ST (pST) previously observed in young pigs may be influenced by the source of dietary energy. Our objectives were to 1) determine the effect of a high-fat (HF; 25% fat and 4,639 kcal/kg ME; DM basis) or low-fat (LF; 2% fat and 3,481 kcal/kg ME; DM basis) manufactured liquid diet on pig performance; and 2) determine whether the limited response to exogenous pST in young pigs depends on the source of dietary energy. Two replicates of 60 pigs (n = 120; barrows and gilts distributed evenly), with an initial BW of 4,207 +/- 51 g, were weaned from the sow at 10 d of age and used in a randomized complete block design. Pigs were assigned by BW to one of six pens. Diets were formulated to provide a constant lysine:ME ratio and were fed on a pen basis for a duration of 9 d. On d 5, barrows and gilts within a pen were assigned randomly to receive either 0 or 120 microg of pST.kg BW(-1).d(-1) for 4 d. Pigs gained 336 +/- 9 g/d, which resulted in an ending BW of 7,228 +/- 120 g, regardless of dietary treatment (P > 0.15). Pigs fed the LF diet consumed 17% more DM per pen daily than pigs fed the HF diet (2,777 +/- 67 vs. 2,376 +/- 67 g/d, P < 0.01), but calculated ME intake did not differ between dietary treatments (P > 0.20). The G:F was 24% greater in HF- than in LF-fed pigs (P < 0.01). Plasma urea N concentrations were higher in the HF-fed pigs (11.0 +/- 0.6 mg/dL) than in pigs fed the LF diet (6.2 +/- 0.6 mg/dL; P < 0.05). Treatment with pST increased circulating IGF-I (P < 0.01) and decreased PUN (P < 0.01) concentration 32 and 25%, respectively, regardless of dietary treatment (P > 0.30). Circulating leptin averaged 1.8 +/- 0.1 ng/mL and was not affected by dietary treatment (P > 0.35) or pST (P > 0.40). These results suggest that the ST/IGF axis is responsive in the young pig and the increase in circulating IGF-I and growth is independent of the source of dietary energy. Also, young pigs respond to a lower energy density liquid diet with increased feed intake, without altering growth performance, apparently utilizing a mechanism other than circulating leptin.
authors.affiliation: Department of Animal Science, North Carolina State University, Raleigh, 27695, USA.
authors.forename: W T
authors.initials: WT
authors.lastname: Oliver
authors.forename: K J
authors.initials: KJ
authors.lastname: Touchette
authors.forename: J A
authors.initials: JA
authors.lastname: Coalson
authors.forename: C S
authors.initials: CS
authors.lastname: Whisnant
authors.forename: J A
authors.initials: JA
authors.lastname: Brown
authors.forename: S A Mathews
authors.initials: SA
authors.lastname: Oliver
authors.forename: J
authors.initials: J
authors.lastname: Odle
authors.forename: R J
authors.initials: RJ
authors.lastname: Harrell
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001806:Blood Urea Nitrogen; D004032:Diet / Q000662:veterinary*; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000187:drug effects*; D020738:Leptin / Q000097:blood; D008297:Male; D011897:Random Allocation; D013552:Swine / Q000097:blood / Q000254:growth & development*; D013997:Time Factors; D014886:Weaning; D015430:Weight Gain / Q000187:drug effects / Q000502:physiology*
chemical_list: D004041:Dietary Fats; D020738:Leptin; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone