title: The impact of diet and arginine supplementation on pancreatic mass, digestive enzyme activity, and insulin-containing cell cluster morphology during the estrous cycle in sheep.
abstract: To determine the effect of feed intake and arginine treatment during different stages of the estrous cycle on pancreatic mass, digestive enzyme activity, and histological measurements, ewes (n = 120) were randomly allocated to 1 of 3 dietary groups; control (CON; 2.14-Mcal metabolizable energy/kg), underfed (UF; 0.6 × CON), or overfed (OF; 2 × CON) over 2 yr. Estrus was synchronized using a controlled internal drug release device for 14 d. At controlled internal drug release withdrawal, ewes from each dietary group were assigned to 1 of 2 treatments; Arg (L-Arg HCl, 155-μmol/kg BW) or Sal (approximately 10-mL saline). Treatments were administered 3 times daily via jugular catheter and continued until slaughter on d (day) 5 and 10 of the second estrus cycle (early luteal phase, n = 41 and mid-luteal phase, n = 39; yr 1) and d 15 of the first estrus cycle (late luteal phase, n = 40; yr 2). A blood sample collected from jugular catheters for serum insulin analysis before slaughter. The pancreas was then removed, trimmed of mesentery and fat, weighed, and a sample snap-frozen until enzyme analysis. Additional pancreatic samples were fixed in 10% formalin solution for histological examination of size and distribution of insulin-containing cell clusters. Data were analyzed as a completely randomized design with a factorial arrangement of treatments. Diet, treatment, and diet × treatment were blocked by yr and included in the model with initial BW used as a covariate. Day of the estrous cycle was initially included in the model but later removed as no effects (P > 0.10) were observed for any pancreatic variables tested. Overfed ewes had the greatest (P < 0.001) change in BW, final BW, change in BCS, and final BCS. A diet × treatment interaction was observed for change in BW and final BW (P ≤ 0.004). Overfed and CON had increased (P < 0.001) pancreas weight (g) compared with UF ewes. Protein concentration (g/pancreas) was the lowest (P < 0.001) in UF ewes, whereas protein content (mg/kg BW) was greater (P = 0.03) in UF than OF ewes. Activity of α-amylase (U/g, kU/pancreas, U/kg of BW, and U/g protein) and trypsin (U/pancreas) was greater (P ≤ 0.003) in OF than UF ewes. Serum insulin was the greatest (P < 0.001) in OF ewes. No effects were observed for pancreatic insulin-containing cell clusters. This study demonstrated that plane of nutrition affected several measurements of pancreatic function; however, the dosage of Arg used did not influence pancreatic function.
authors.affiliation: Department of Animal Sciences, North Dakota State University, Dept. #7630, PO Box 6050, Fargo, ND 58108-6050, USA.
authors.forename: F E
authors.initials: FE
authors.lastname: Keomanivong
authors.affiliation: Department of Animal Sciences, North Dakota State University, Dept. #7630, PO Box 6050, Fargo, ND 58108-6050, USA.
authors.forename: A T
authors.initials: AT
authors.lastname: Grazul-Bilska
authors.affiliation: Department of Animal Sciences, North Dakota State University, Dept. #7630, PO Box 6050, Fargo, ND 58108-6050, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Redmer
authors.affiliation: Department of Animal Sciences, North Dakota State University, Dept. #7630, PO Box 6050, Fargo, ND 58108-6050, USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Bass
authors.affiliation: Department of Animal Sciences, North Dakota State University, Dept. #7630, PO Box 6050, Fargo, ND 58108-6050, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Kaminski
authors.affiliation: Department of Animal Sciences, North Dakota State University, Dept. #7630, PO Box 6050, Fargo, ND 58108-6050, USA.
authors.forename: P P
authors.initials: PP
authors.lastname: Borowicz
authors.affiliation: Department of Animal Sciences, North Dakota State University, Dept. #7630, PO Box 6050, Fargo, ND 58108-6050, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Kirsch
authors.affiliation: Department of Animal Sciences, North Dakota State University, Dept. #7630, PO Box 6050, Fargo, ND 58108-6050, USA. Electronic address: kendall.swanson@ndsu.edu.
authors.forename: K C
authors.initials: KC
authors.lastname: Swanson
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology*; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D004063:Digestion / Q000502:physiology; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D007328:Insulin / Q000378:metabolism*; D010179:Pancreas / Q000033:anatomy & histology* / Q000187:drug effects; D012756:Sheep / Q000502:physiology*
chemical_list: D007328:Insulin; D001120:Arginine
keywords: Arginine; Enzymes; Feed intake; Pancreas; Sheep