The ability of the skeletal musculature to use amino acids to build or renew constitutive proteins is gradually lost with age and this is partly due to a decline in skeletal muscle insulin sensitivity. Since long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) from fish oil are known to improve insulin-mediated glucose metabolism in insulin-resistant states, their potential role in regulating insulin-mediated protein metabolism was investigated in this study. Experimental data are based on a switchback design composed of three 5 week experimental periods using six growing steers to compare the effect of a continuous abomasal infusion of LCn-3PUFA-rich menhaden oil with an iso-energetic control oil mixture. Clamp and insulin signalling observations were combined with additional data from a second cohort of six steers. We found that enteral LCn-3PUFA potentiate insulin action by increasing the insulin-stimulated whole-body disposal of amino acids from 152 to 308 µmol kg −1 h −1 (P = 0.006). The study further showed that in the fed steady-state, chronic adaptation to LCn-3PUFA induces greater activation (P < 0.05) of the Akt-mTOR-S6K1 signalling pathway. Simultaneously, whole-body total flux of phenylalanine was reduced from 87 to 67 µmol kg −1 h −1 (P = 0.04) and oxidative metabolism was decreased (P = 0.05). We conclude that chronic feeding of menhaden oil provides a novel nutritional mean to enhance insulin-sensitive aspects of protein metabolism.

No abstract

-Eight calves between 16 and 18 weeks of age that were seronegative to bovine viral diarrhea virus (BVDV), bovine leucosis virus and bovine immunodeficiency-like virus were infected (day 0) intranasally with the type 2 noncytopathogenic Canadian 24515 field isolate of BVDV in order to evaluate the effect of BVDV infection on certain clinical, hematological and immunological parameters. All virus-exposed animals developed fever and showed a significant (P < 0.05, 0.01 or 0.001) drop in the number of circulating leucocytes (neutrophils, lymphocytes and monocytes) by day 3 or 5 post-exposure (PE), which continued to the end of the experiment at day 12 PE. BVDV was consistently isolated from the peripheral blood buffy coat cells from day 5 PE, and also from selected tissues (spleen, thymus, mesenteric and submaxillary lymph nodes, small intestine, lungs and thyroid gland) that were collected at the time of euthanasia of the animals at day 12 PE. Diminished significant (P < 0.05) percentages of peripheral blood mononuclear cells (PBMCs) expressing at their surface either B7 and MHC II molecules were observed in virus-exposed calves at days 7, 10 and/or 12 PE, when compared to virus-nonexposed control calves (n = 5). However, no changes in the percentages of PBMCs expressing either B4 or MHC I molecules were observed throughout the experiment. Finally, a significant (P < 0.05 or 0.01) enhanced phagocytic capability of the PBMCs, as analyzed by flow cytometry, was observed in virus-exposed animals at days 3, 5, 7, 10 and 12 PE, when compared to control calves. These results demonstrated the virulence of the 24515 isolate of BVDV in 4 to 4.5 month-old calves, and suggest that type 2 BVDV infection in calves is associated with dysregulation of certain immunological functions. bovine viral diarrhea virus type 2 / clinical response / immunomodulation Vet. Res. 31 (2000) 215-227 215

This study was undertaken to evaluate the biological potency of two synthetic human growth hormone-releasing factors, hGRF (1-44)NH2 and hGRF (1-29)NH2, on growth hormone (GH) release in young dairy heifers (n = 10) and pigs (n = 10). In each species, the GH response to an iv injection (0, .067, .2, .6 and 1.8 nmol.kg-1 body weight) of each peptide was evaluated in a double 5 X 5 Latin square design. In each square, there were five animals injected with either hGRF (1-44)NH2 or hGRF (1-29)NH2. Main effects were doses (n = 5) of hGRF and days (n = 5) of injection. In both species, data indicated that hGRF (1-44)NH2 and hGRF (1-29)NH2 equally stimulate GH secretion at all doses. In dairy heifers, average peak concentrations (81.7, 94.7, 84.5 and 93.7 ng.ml-1 vs 91.5, 81.0, 94.3 and 91.6 ng.ml-1) and area under the GH response curve (3,661, 4,541, 7,196 and 6,788 ng.ml-1.min vs 3,000, 3,982, 5,639 and 6,724 ng.ml-1.min) were not different (P greater than .05) between hGRF(1-44)NH2 and hGRF(1-29)NH2 at .067, .2, .6 and 1.8 nmol.kg-1, respectively. Similarly, in pigs, average peak concentrations (35.6, 38.6, 76.5 and 73.8 ng.ml-1 vs 28.7, 30.0, 41.3 and 80.8 ng.ml-1) and area under the GH curve (1,576, 1,567, 3,299 and 3,622 ng.ml-1.min vs 1,115, 1,658, 1,482 and 2,528 ng.ml-1.min) were not different (P greater than .05) between both peptides. A biphasic release of GH after hGRF (1-44)NH2 and hGRH (1-29)NH2 injection was observed at the highest dose in heifers. The GH response to hGRF injection was much more variable in pigs as compared with dairy heifers. In conclusion, hGRF (1-44)NH2 and its (1-29)NH2 fragment are equipotent in stimulating GH release in dairy heifers and pigs.

The records of 14 cases of bovine hypokalaemia observed between 1983 and 1996 were reviewed. The most common history included a protracted, often infectious, disease. All age groups were represented. Although previously reported as a risk factor, isoflupredone acetate had not been administered to five of the cases. The following clinical signs were recorded in 10 cases: abnormal position of the head and neck, severe weakness, rumen hypomotility or atony, abnormal faeces, anorexia and tachycardia. Cardiac dysrhythmia was observed in six cases. Acid-base imbalance (alkalosis in 10 cases), hyperglycaemia and increased activities of aspartate aminotransferase and creatine kinase were associated with hypokalaemia ranging from 1.35 to 2.49 mmol/litre. Treatments included symptomatic treatment, supportive care and potassium chloride given intravenously and orally at an average total daily dose of 42 g/100 kg bodyweight (26 g by mouth and 16 g intravenously) for an average of five days. Eleven cases recovered after an average of three days.