Crossbred steers (n = 20; 235 ± 4 kg) were fed for 53 d during a receiving period to determine if supplementing chromium (Cr; KemTRACE Chromium Propionate 0.04%, Kemin Industries, Des Moines, IA) would alter glucose or lipid metabolism of newly received cattle. Chromium premixes were supplemented to add 0 (Con) or 0.2 mg/kg of Cr to the total diet on a DM basis. Cattle were fitted with jugular catheters on d 52. A glucose tolerance test (GTT) and an insulin sensitivity test (IST) were conducted on d 53. Blood samples were collected from -60 to 150 min relative to each infusion. Serum was isolated to determine glucose, insulin, and NEFA concentrations. Throughout GTT, no differences were detected in glucose concentrations, glucose clearance rates (k), or preinfusion insulin concentrations (P > 0.50), but insulin concentrations postinfusion tended (P = 0.06) to be greater for the Cr-supplemented steers. This caused an increase in the insulin to glucose ratio (I:G) from 0 to 150 min postinfusion for the Cr-supplemented steers (P = 0.03). In addition, NEFA concentrations during GTT were lower (P ≤ 0.01) for Cr-supplemented steers both preinfusion and postinfusion. During IST, there was no treatment effect on glucose concentrations preinfusion (P = 0.38), but postinfusion glucose concentrations were greater (P< 0.01) in the Cr-supplemented steers. The k of Cr-supplemented steers tended (P = 0.06) to be faster than Con steers from 30 to 45 min postinfusion. During the same test, there was no treatment effect detected for insulin concentrations (P > 0.33). The I:G were not affected by treatment (P > 0.40).Concentrations of NEFA were reduced (P < 0.01) both preinfusion and postinfusion during IST for Cr-supplemented steers. Results of this study indicate that supplementation of Cr can significantly alter lipid metabolism. This suggests that these steers had less dependence on lipid metabolism for energy or sensitivity of adipose tissue to antilipolytic signals was reduced. Results of glucose and insulin metabolism were inconsistently modified after a GTT and an IST.

MuciNs are produced from three morphologically distinct types of cell in the mammalian stomach, viz. the superficial epithelium which forms a continuous covering, the mucoid neck cells of the fundal glands, and the pyloric glands. Possibly the cardiac glands, which consist of mucus-producing cells, and are a conspicuous feature in some species, represent a fourth type of mucous cell.The duodenal or Brunner's glands are composed of mucous cells, although in some species, for instance the rabbit and horse, "serous" cells are present in addition.Goblet cells, which produce mucin, are found throughout the small and large intestines. In the small intestine they occur both in the crypts of Lieberkuhn and on the villi. The colon contains large numbers, most closely packed in the crypts but also scattered among the surface epithelium. They are relatively scarce in the csecum of the rabbit and guinea-pig, where they are found principally at the bases of the shallow crypts.Some of the mucins secreted by these various cells contain sulphur, probably in the form of ester sulphate groups. The present experiments have been concerned with observations on the incorporation and excretion of 35S, administered intravenously either as Na235SO4 or as [35S] methionine, by the various types of mucous cell. EXPERIMENTALComparative observations were made on mice, rats, guinea-pigs, rabbits and cats. Material was obtained from 6 mice, killed 1, 21, 3, 6, 12 and 24 hrs. respectively after the injection of radioactive sodium sulphate; from 9 rats killed 1 hr. 10 min., 2 hrs. (2 animals), 3 hrs. (4 animals) and 24 hrs. (2 animals) after sulphate; from 3 rabbits killed at 21, 61 and 24 hrs.; 2 guinea-pigs killed at 2 and 61 hrs.; and 2 cats killed at 21 and 6 hrs. after sulphate.Two of the mice (killed at 1 and 21 hrs.) and two of the rats (killed at 2 and 24 hrs.) had dilute mustard oil inserted into a loop of the colon for 4 hours to empty and stimulate the goblet cells, as previously described [Jennings and Florey, 1954]; the oil was removed immediately before sulphate was given.131

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Crossbred steers (n = 180; 230 ± 6 kg) were fed during a 56-d receiving period to determine if supplementing chromium (Cr; KemTRACE Chromium Propionate 0.04%, Kemin Industries) would improve feedlot performance and health of newly-received cattle. A completely randomized block design (36 pens; 9 pens/treatment; 5 steers/pen) was used. Chromium premixes were supplemented to add 0 (Con), 0.1, 0.2, or 0.3 mg/kg of Cr to the total diet on a DM basis. No differences were detected on d 0 or after the first 14 d on feed. From d 0 to d 28, DMI (P = 0.07) and ADG increased linearly (P = 0.04) as Cr concentrations increased. From d 0 to d 56, BW (P = 0.08) displayed a tendency to increase linearly, and consequently ADG and G:F increased linearly (P ≤ 0.05) as Cr concentrations increased. The number of steers treated at least once for respiratory symptoms tended (P = 0.07) to linearly decrease as Cr concentrations increased. Twenty additional steers (235 ± 4 kg) were fed 56 d to determine if supplementing Cr (Con or 0.2 mg/kg Cr) would alter the metabolic response of newly-received cattle to a lipopolysaccharide (LPS) challenge. Cattle were fitted with jugular catheters on d 52. On d 55, blood samples were collected at 0.5-h intervals from -2 to 8 h, and again at 24 h relative to a LPS challenge (0.5 μg/kg BW) at 0 h. Serum glucose, insulin, and NEFA concentrations were determined from blood samples. Steer BW was also measured at cannulation, and 24 h and 8 d post-LPS. Steer BW did not differ at cannulation (P = 0.37), but 24 h post-LPS, Cr-supplemented steers had lost less BW (P = 0.03). Pre-LPS glucose concentration did not differ (P = 0.97). Post-LPS, there was a time × treatment interaction (P < 0.01) such that glucose concentration peaked earlier (0.5 h) and at a greater concentrations in Cr-supplemented steers (P < 0.01). Insulin concentration did not differ between treatments pre- or post-LPS (P > 0.13). Concentration of NEFA did not differ pre-LPS (P = 0.54); but 0.5 h post-LPS Cr-treated steers produced a greater peak NEFA concentration (P < 0.04). Results of this study indicate that supplementation of Cr to the basal diet can have beneficial effects on the performance and health of newly-received steers. These data also suggest that supplementation of Cr attenuated BW loss and allowed for a quicker recovery after a LPS challenge.

The ErbB-1 tyrosine kinase receptor plays critical roles in regulating physiological functions. This receptor-mediated signaling in astroglia has been implicated in controlling female sexual development via activating neurons that release LH-releasing hormone (LHRH), the neuropeptide required for the secretion of LH. It remains unknown whether astroglial ErbB-1 receptors are necessary for maintaining normal adult reproductive function. Here we provide genetic evidence that astroglia-specific and time-controlled disruption of ErbB-1 receptor signaling by expressing mutant ErbB-1 receptors leads to compromised reproduction due to alteration in LHRH neuron-controlled secretion of LH in adult female mice. Therefore, astroglial ErbB-1 receptors are required for controlling LHRH neuronal function and thus maintaining adult reproduction, suggesting that compromised astroglial ErbB-1 signaling may also contribute to reproductive abnormalities in aging females.