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Cavendish, Australia

Hunter T.E.,University of Melbourne | Suster D.,Jobs Transport and Resources | DiGiacomo K.,University of Melbourne | Dunshea F.R.,University of Melbourne | And 3 more authors.
Small Ruminant Research | Year: 2015

The introduction of East Friesian (EF) genetics into commercial sheep milking herds has the potential to improve milk yield and offer a robust dam for meat lamb production systems. This study was conducted to measure the milk production, feed intake and longitudinal changes in body composition of EF×Romney (EFR) and Border Leicester×Merino (BLM) ewes over the first nine weeks of lactation. Sixteen seconds parity single-bearing EFR (n =8) and BLM (n =8) ewes that had been mated to a purebred EF ram were housed in individual pens from 2 weeks prior to, and until 9 weeks after, lambing and fed a commercial pelleted diet with additional chaff. Milk yield was measured twice a week using the four-hour milking interval technique after injection of oxytocin and body composition was determined by dual energy X-ray absorptiometry (DXA) at 1, 3, 5 and 9 weeks of lactation. Potential milk production was higher in EFR than BLM ewes (2.57 vs. 1.92kg/d, P =0.028) and declined as lactation advanced. Similarly, the yields of milk fat (P =0.015), protein (P =0.018) and lactose (P =0.062) were all higher in EFR than BLM ewes and declined as lactation advanced. Energy intake increased over the first 4 weeks of the study, before reaching a plateau for the remaining 5 weeks of the study. However, there was no significant difference in energy intake or energy balance between EFR and BLM ewes. Changes in tissue energy between DXA scans were highly correlated (R 2 =0.51, P <0.001) to average estimated energy balance over the same periods. There was no effect of breed on birth weight of lambs nor was there any effect of dam breed on average daily gain of lambs. In conclusion, EFR ewes have greater potential milk yield than BLM ewes but this was not realized as an increased average daily gain in the single lambs possibly due to insufficient milking pressure failing to produce a difference in actual milk yield. It is likely that this difference would be expressed in response to a greater milking demand (i.e. from a milking machine or twin/triplet lambs). The EFR ewes ate more than BLM ewes during lactation and mobilized less fat than BLM ewes to maintain similar nursing lamb growth. However, a greater milking demand of twins or triplets may allow the greater potential milk yield of EFR to be expressed. Alternatively, machine milking EFR would most likely allow the expression of their full milking potential. Finally, DXA was able to predict body tissue mobilization and accretion in lactating ewes and these changes in body composition were related to estimated energy balance indicating that DXA can be used to serially determine body composition in lactating sheep. © 2015 Elsevier B.V.. Source


Harrison M.T.,University of Tasmania | Jackson T.,Australian Department of Primary Industries and Fisheries | Cullen B.R.,University of Melbourne | Rawnsley R.P.,University of Tasmania | And 3 more authors.
Agricultural Systems | Year: 2014

Greenhouse gas (GHG) emissions from livestock constitute the largest proportion of Australian agricultural GHG emissions, necessitating development of strategies for mitigating GHG emissions from the livestock sector. Here we simulate a self-replacing prime lamb enterprise to examine the effect of increasing ewe genetic fecundity on whole farm GHG emissions, animal production and emissions per animal product (emissions intensity; EI).Breeding ewes were a cross-bred genotype containing the Booroola (FecB) gene with average lambing rates of 1.5-2.0 lambs per ewe. Lambs were born in winter on pastures of phalaris, cocksfoot and subterranean clover, and were sold at the beginning of summer. Flock dynamics were simulated using the model GrassGro and whole-farm GHG emissions were computed using equations from the Australian National Greenhouse Gas Inventory. Increasing ewe fecundity from a baseline of 0.96-1.54 lambs per ewe reduced EI from 9.3 to 7.3t CO2-e/t clean fleece weight plus liveweight (CFW+LWT) and GHG emissions per animal sold by 32%. Increasing fecundity reduced lamb sale liveweights and increased lamb mortality rates at birth, but this was offset by an increase in total liveweight turnoff. Greater ewe fecundity increased whole-farm productivity without increasing GHG emissions. For the same stocking rate as an enterprise running genotypes with lower fecundity, high fecundity genotypes either increased annual production from 449 to 571kg CFW + LWT/ha with little change in net emissions, or reduced emissions from 4.2 to 3.2t CO2-e/ha for similar average productivity. In both cases, EI decreased by ca. 2.1t CO2-e/t CFW+LWT.A foremost advantage of using high fecundity breeds is greater intra-annual variation in flock number, because such genotypes give birth to more lambs. This necessitates a reduction in the number of adult breeding ewes to maintain average annual stocking rate and benefits whole farm emissions, because breeding ewes contribute the largest proportion of farm emissions (77-80%), particularly enteric methane. We conclude that increasing ewe fecundity offers a win-win opportunity for the sheep industry by allowing sustainable intensification through greater production and lower emissions intensity, without adversely affecting net farm emissions or increasing stocking rate. High fecundity genotypes also present an opportunity for sheep producers to reduce stocking rates while maintaining current levels of farm production, thereby reducing labour and flock nutritional requirements. © 2014 Elsevier Ltd. Source


Hunter T.E.,University of Melbourne | Suster D.,Jobs | DiGiacomo K.,University of Melbourne | Dunshea F.R.,University of Melbourne | And 3 more authors.
Small Ruminant Research | Year: 2015

The introduction of East Friesian (EF) genetics into commercial sheep milking herds has the potential to improve milk yield and offer a robust dam for meat lamb production systems. This study was conducted to measure the milk production, feed intake and longitudinal changes in body composition of EF×Romney (EFR) and Border Leicester×Merino (BLM) ewes over the first nine weeks of lactation. Sixteen seconds parity single-bearing EFR (n =8) and BLM (n =8) ewes that had been mated to a purebred EF ram were housed in individual pens from 2 weeks prior to, and until 9 weeks after, lambing and fed a commercial pelleted diet with additional chaff. Milk yield was measured twice a week using the four-hour milking interval technique after injection of oxytocin and body composition was determined by dual energy X-ray absorptiometry (DXA) at 1, 3, 5 and 9 weeks of lactation. Potential milk production was higher in EFR than BLM ewes (2.57 vs. 1.92kg/d, P =0.028) and declined as lactation advanced. Similarly, the yields of milk fat (P =0.015), protein (P =0.018) and lactose (P =0.062) were all higher in EFR than BLM ewes and declined as lactation advanced. Energy intake increased over the first 4 weeks of the study, before reaching a plateau for the remaining 5 weeks of the study. However, there was no significant difference in energy intake or energy balance between EFR and BLM ewes. Changes in tissue energy between DXA scans were highly correlated (R 2 =0.51, P <0.001) to average estimated energy balance over the same periods. There was no effect of breed on birth weight of lambs nor was there any effect of dam breed on average daily gain of lambs. In conclusion, EFR ewes have greater potential milk yield than BLM ewes but this was not realized as an increased average daily gain in the single lambs possibly due to insufficient milking pressure failing to produce a difference in actual milk yield. It is likely that this difference would be expressed in response to a greater milking demand (i.e. from a milking machine or twin/triplet lambs). The EFR ewes ate more than BLM ewes during lactation and mobilized less fat than BLM ewes to maintain similar nursing lamb growth. However, a greater milking demand of twins or triplets may allow the greater potential milk yield of EFR to be expressed. Alternatively, machine milking EFR would most likely allow the expression of their full milking potential. Finally, DXA was able to predict body tissue mobilization and accretion in lactating ewes and these changes in body composition were related to estimated energy balance indicating that DXA can be used to serially determine body composition in lactating sheep. © 2015. Source


Reed K.F.M.,Reed Pasture Science | Vaughan J.L.,Cria Genesis | Cummins L.J.,Ivanhoe | Moore D.D.,Biomin Australia Pty. Ltd. | Moore D.D.,University of Queensland
Animal Production Science | Year: 2010

Liveweight gain, animal health and the effectiveness of a mycotoxin deactivator were studied on an old pasture that contained 61% perennial ryegrass. Sixty-seven percent of the ryegrass population was infected with endophyte (Neotyphodium spp.). The pasture was fenced into two halves and two groups of 28 alpaca male weaners were rotated between the two plots. Nine to 10 Suris and 1819 Huacayas were allocated to each group. One group was fed a concentrate supplement (100 g/head per day) and the other was fed the same supplement to which was added the toxin deactivator, Mycofix Plus (5 g/100 g). Mean liveweight gain on the low-quality pasture over late summer and early autumn was not significantly (P 0.05) different between the groups. For the control group it was 41 g/day but individual rates of gain ranged from 67 to 0 g/day, depending on the severity of signs of perennial ryegrass toxicosis (r ≤ 0.82, P 0.001). Liveweight gain was independent of neurotoxic signs in the Mycofix Plus treated group. Ergovaline concentration in perennial ryegrass varied from 0.43 to a peak in early autumn (March) of 1.05 mg/kg. Mean urine lysergol alkaloid concentration peaked in mid-summer (January) at 109 ng/mg creatinine (control group) and was consistently lower in the Mycofix Plus group, although the difference approached significance (P ≤ 0.06) only in March. Lolitrem B concentration in perennial ryegrass varied from 0.78 to 1.57 mg/kg. Neurotoxic signs in alpacas were observed throughout the study and peaked in early autumn, coinciding with peak lolitrem B concentration; at this time, 84% of alpacas exhibited neurotoxic signs. Over the 145-day study, the Mycofix Plus treated group exhibited a lower mean rating of perennial ryegrass toxicosis signs (P 0.05). Variation in liveweight gain and signs of toxicosis were not associated with significant differences in liver enzyme activity. © CSIRO 2010. Source


Hunter T.E.,University of Melbourne | Suster D.,Australian Department of Primary Industries and Fisheries | Dunshea F.R.,University of Melbourne | Cummins L.J.,Ivanhoe | And 2 more authors.
Small Ruminant Research | Year: 2011

An Hologic QDR4500A dual energy X-ray absorptiometer (DXA) was used to measure live body composition in 15 second-cross wether lambs ((Border Leicester×Merino)×Poll Dorset) aged 6-8 months (17-50kg) and 13 mature ewes (composite terminal sire line based largely on Poll Dorset, White Suffolk and Texel breeds) (44-71kg). After slaughter, DXA scans were also performed on the whole carcasses. Values determined by DXA including total tissue mass (TTM), lean tissue mass (LTM), fat tissue mass (FTM) and bone mineral content (BMC) for the half carcass were evaluated by comparison with chemically determined composition. In the case of BMC the relationship was with chemically determined ash content. Live weight and chemically determined lean, fat and ash were strongly related to DXA-derived values for whole body TTM, LTM, FTM and BMC, respectively (R2=0.999, 0.988, 0.980 and 0.977, respectively). Carcass weight and chemically determined lean, fat and ash were strongly related to DXA-derived values for carcass TTM, LTM, FTM and BMC, respectively (R2=0.998, 0.984, 0.986 and 0.906, respectively). However, because DXA estimates were different from chemically determined values in this sample of carcasses, they needed to be adjusted with the use of appropriate regression equations to correct the in-built algorithms used to predict human body composition. These data demonstrate the efficacy of DXA as a non-destructive method for determining the composition of the whole body and carcasses of sheep. © 2011 Elsevier B.V. Source

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