Browsing by Autor "P. Hutton"

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Investigating Eremophila glabra as a bioactive agent for preventing lactic acidosis in sheep
(CSIRO Publishing, 2010) P. Hutton; Z. Durmic; Philip E. Vercoe
The Australian native plant Eremophila glabra was tested as a potential agent for preventing lactic acidosis in sheep after it was observed to be effective against acidosis in vitro. Ruminally fistulated wethers were infused via rumen cannula with single doses of kibbled wheat (14 g/kg bodyweight) and either virginiamycin (Eskalin500; AB, 80 mg/kg of wheat plus 100 g milled oaten hay/kg of wheat, n = 6), E. glabra (EG, 100 g freeze-dried and milled leaf material per kg of wheat, n = 10) or milled oaten hay (Control, 100 g milled oaten hay/kg of wheat, n = 16). Rumen samples were collected immediately before infusion and then 2, 4, 6, 8, 12, 16 and 24 h after the infusion. The samples were analysed for pH, D-lactate, volatile fatty acids (VFA) and osmolality. Rumen pH and D-lactate values indicative of acidosis were detected in the Control and EG groups. The pH nadir of the rumen was 12 h after the wheat infusion, at which time the values in the EG (pH = 4.87) and Control (pH = 5.09) groups were lower (P &lt; 0.05) than in the AB group (pH = 5.63) and the D-lactate concentrations were higher (P &lt; 0.05) in the EG and Control groups (24 mmol/L and 15 mmol/L, respectively) than in the AB group (0.9 mmol/L). At the same time, total VFA concentration was higher (P &lt; 0.05) in the AB group (102 mmol/L) than in the Control (65 mmol/L) and the EG (14 mmol/L) groups. Rumen osmolality did not differ between groups. Virginiamycin was effective at preventing lactic acidosis. However, the inclusion of dried leaves from E. glabra at a similar level that was effective in vitro did not prevent lactic acidosis in vivo, and the reasons behind this remain unclear. The study demonstrates the difficulty in converting in vitro results to in vivo and highlights the need to test the plant at higher doses in vivo.
Mixed herb and legume pasture improves the growth of lambs post-weaning
(CSIRO Publishing, 2011) K. P. Golding; E. D. WILSON; Peter Kemp; Sarah J. Pain; P. R. Kenyon; Stephen T. Morris; P. Hutton
The potential of mixed herb and legume pastures to increase post-weaning growth rates of lambs in comparison to ryegrass-based pastures was evaluated. Unrestricted allowances of pasture treatments were offered to weaned, Romney lambs in consecutive autumns of 2007 and 2008. In Experiment 1 (2007), 300 ewe lambs were allocated for 64 days to one of four permanent sward mix treatments; chicory, plantain, red clover and white clover [herb/clover (n = 75)]; plantain, perennial ryegrass and white clover [plantain/pasture (n = 75)]; tetraploid perennial ryegrass and white clover [new pasture (n = 75)]; or diploid perennial ryegrass, other grass species and white clover [old pasture (n = 75)]. In Experiment 2 (2008), the first three pasture treatments from Experiment 1 were re-used (‘old pasture’ not used) with 168 wether lambs allocated for 35 days; herb/clover (n = 56); plantain/pasture (n = 56); and new pasture (n = 56). Unfasted liveweights of all lambs were recorded at weekly intervals and before slaughter. A sub-sample of 78 lambs from Experiment 2 was slaughtered to obtain the carcass weights, tissue depth (11 cm from the spine over the 12th rib) and commercial meat percentages. At the conclusion of Experiment 1 the herb/clover treatment lambs were heavier than the new pasture and plantain/pasture treatment lambs, which were heavier than the old pasture treatment lambs (47.4 vs 41.5 vs 41.5 vs 39.6 ± 0.4 kg, respectively) (P &lt; 0.05). At the conclusion of Experiment 2 the herb/clover treatment lambs were heavier than the new pasture treatment lambs, which were heavier than the plantain/pasture treatment lambs (35.6 vs 32.8 vs 28.8 kg ± 0.4, respectively) (P &lt; 0.05). In Experiment 1 a higher percent of herb/clover treatment lambs grew faster than 200 g/day (P &lt; 0.001) than of the pasture/plantain, new pasture and old pasture treatment lambs (87 vs 4 vs 3 vs 0 percent, respectively). In Experiment 2 only the herb/clover lambs (71%) grew faster than 200 g/day (P &lt; 0.05). In Experiment 2 herb/clover treatment lambs had heavier (P &lt; 0.05) final carcass weight (15.7 ± 0.20 vs 14.8 ± 0.38 vs 14.6 ± 0.27 kg) compared with the plantain/pasture and new pasture lambs, respectively. It was demonstrated that a herb/clover mixed sward can increase post-weaning lamb liveweight gains during unrestricted feeding conditions compared with traditional perennial ryegrass-based pastures.