Metabolic responses to exogenous bovine somatotropin in Friesian cows of low or high genetic merit

Basal hormone/metabolite concentrations and responses to intravenous challenges of glucose, insulin and epinephrine were examined in Friesian cows from selection lines of low or high genetic merit treated with recombinantly-derived bovine somatotropin (bST) or control formulation in a 2 x 2 factorial design. Cows from the low genetic merit (low breeding index, LBI) line had previously been shown to be more responsive to the galactopoietic effects of bST (50 mg/day) than those from the high breeding index (HBI) line. Despite this, comparisons of metabolic differences were not confounded by differences in energy balance because bST treatment had also caused an increase in voluntary intake of cut pasture. Circulating levels of somatotropin, insulin-like growth factor-I (IGF-I) and insulin were greater in bST-treated than control cows but neither bST treatment nor selection line influenced basal concentrations of glucose, non-esterified fatty acids (NEFA), beta-hydroxybutyrate, urea or creatinine. Treatment with bST produced a small increase in sensitivity of cows to the lipolytic effects of epinephrine and this effect was similar in both selection lines. HBI cows had greater circulating insulin levels following the glucose challenge than LBI cows but bST treatment did not affect the insulin response to exogenous glucose. Whereas bST treatment retarded the glycogenolytic response to epinephrine and the clearance of blood glucose in response to insulin in LBI cows, it had no effect on epinephrine-stimulated glycogenolysis, and caused enhanced glucose clearance in response to insulin, in HBI cows. Results are consistent with bST altering the homeorhetic control of metabolism but do not adequately explain the greater responsiveness of LBI cows to the galactopoietic effects of bST.     

Sedimentary rock types: relative proportions as a function of geological time

Proportions of sedimentary rock types remaining today differ from period to period. These differences may be chiefly the result of differential rates of deposition and erosion of the various components of the rocks. Lower percentages of limestones and evaporites in Precambrian rocks than in post-Precambrian rocks probably represent selective loss of these more easily removable components from the original deposits.     

Preparation of an epithelium-free mammary fat pad and subsequent mammogenesis in ewes

The objective of this study was to develop a surgical procedure for the preparation of an epithelium-free mammary fat pad (cleared mammary fat pad; CFP) in ewes. At 7 to 10 d of age, ewe lambs (n = 43, mean BW 9.2 +/- .2 kg at 14 d) were sedated and one mammary gland was locally anesthetized. An incision circumscribing the base of the teat was made and blunt dissection was performed through the extraneous mammary fat pad tissue to enable the parenchyma and teat to be wholly removed. Failure to completely remove the epithelium enabled it to regenerate and grow into the mammary fat pad. Mean diameter of the parenchymal rudiment at 7 to 10 d of age was 8.9 +/- .5 mm (range of 5 to 16 mm). The excision site was closed with wound clips and recovered lambs returned to their dams. The contralateral mammary gland remained intact, allowing it to undergo normal development. Live weight gain was unaffected by this procedure. Ewes were subsequently slaughtered in groups at various stages of prepuberty, puberty, gestation, and lactation. Of 39 operated glands recovered, only one demonstrated epithelial outgrowth within the CFP. Parenchyma within the contralateral, intact gland underwent phases of rapid growth in prepuberty, puberty, and late gestation and was capable of milk synthesis after steroid induction or parturition. Change in weight of the CFP paralleled that of the intact mammary gland to 100 d of pregnancy. Sham CFP surgery was performed on four additional ewes wherein the parenchyma was completely excised and immediately replaced. Sham-operated epithelium populated the mammary fat pad and synthesized milk that could be expressed from the teat. A CFP in sheep will be a useful model for future investigations into the local growth regulatory mechanisms associated with ruminant mammogenesis.     

Influence of rearing conditions and respiratory disease on haptoglobin levels in the pig at slaughter

Associations between serum concentrations of haptoglobin, pathological lung lesions indicative of Mycoplasma hyopneumoniae (EP) or Actinobacillus pleuropneumoniae (PL) infection at slaughter and previous rearing environment were investigated in 510 pigs (90-100 kg live weight) from 17 farms in England. Haptoglobin concentrations were significantly higher in pigs showing pathological signs of EP infection compared to those without signs of this disease (EP positive median 0.43 mg ml(-1) vs. EP negative median 0.26 mg ml(-1), p<0.01). However, there were no significant associations between serum haptoglobin concentrations and pathological signs of PL. The presence of solid partitions compared with barred or similar open partitions was associated with a decrease of 0.44 mg ml(-1) farm mean haptoglobin concentration, whilst an increase in pen size of 10 m(2) was associated with a decrease of 0.08 mg ml(-1) farm mean haptoglobin concentration. The findings indicate that pathological signs of EP were associated with increased serum haptoglobin at slaughter, which in turn was influenced by components of the farm environment.     

Magnetic field-tuned quantum criticality in the metallic ruthenate Sr3Ru2O7

The concept of quantum criticality is proving to be central to attempts to understand the physics of strongly correlated electrons. Here, we argue that observations on the itinerant metamagnet Sr3Ru2O7 represent good evidence for a new class of quantum critical point, arising when the critical end point terminating a line of first-order transitions is depressed toward zero temperature. This is of interest both in its own right and because of the convenience of having a quantum critical point for which the tuning parameter is the magnetic field. The relationship between the resultant critical fluctuations and novel behavior very near the critical field is discussed.