Cumulative reproductive performance effect on overall lifetime productivity in Merino sheep

2018 ◽  
Vol 58 (8) ◽  
pp. 1470
Author(s):  
J. S. Richards ◽  
M. A. Sladek ◽  
G. J. Lee

Reproduction is an important driver of profitability in commercial sheep flocks. Historically, Merino flocks have been run with a fixed age structure, ignoring individual merit and casting for age at a specific age. More recently, research has focussed on utilising the variation within age groups by keeping productive older ewes longer and culling less productive ewes earlier. Previous studies have also examined the effect of age on reproduction and the impact of reproduction status on productivity, but little research has been conducted on cumulative effects of reproductive performance on later productivity, reproduction and health. The present study examined the impact of higher lifetime reproduction on other key production and fitness traits in older ewes run under commercial conditions. Data were collected from two commercial wool-producing properties in the South West Slopes and the Central West Plains of New South Wales during 2009–2011. Reproduction, fleece measurements, bodyweight and condition and dental health were recorded during the study. The results showed that age had a bigger effect on productivity and dental health than did cumulative lifetime reproduction. Environment and genetics determined the level of impact, with minimal loss in productivity from increased age of animals occurring in the South West Slopes flock, whereas the Central West Plains flock would appear to require closer monitoring of productivity as ewes aged. The data collected did not allow separation of the genetic and environmental influences within the study. Retaining animals with a higher reproductive performance past normal culling age does not necessarily result in reduction of productivity or ewe health, but this must be monitored.

1989 ◽  
Vol 29 (2) ◽  
pp. 201 ◽  
Author(s):  
MK Conyers ◽  
BJ Scott

The aim of this study was to establish whether surface incorporated liming materials could reduce subsurface acidity. Three sites on the southwest slopes of New South Wales, between Wagga and Albury, were sampled at 2 cm depth increments to 16 cm, 5 years after the liming materials were applied. Limestone and dolomite had been applied at 0,2 and 8 tlha in 3 replicates. At 2 t/ha the effect of the liming materials on pH was largely confined to the depth of incorporation. At 8 t/ha substantial pH increases occurred to 6 cm or more below the depth of incorporation. In general, the movement of Mg>Ca> HCo3 (pH), and was consistent with the soil's ability to hold those cations and to neutralize alkalinity respectively. Agriculturally realistic liming rates are not likely to ameliorate subsurface soil acidity on the south-west slopes of New South Wales.


1992 ◽  
Vol 5 (1) ◽  
pp. 1
Author(s):  
RJF Henderson

The genus Amperea Adr. Juss. contains eight species, six of which are confined to the south-west of Western Australia. The seventh occurs only in central Australia while the eighth ranges from central Queensland to Tasmania and extends to the south-east of South Australia. A. simulans, from Western Australia, is described as new, and A. xiphoclada var. papillata and A. xiphoclada var. pedicellata from New South Wales are recognised as new varieties; A. xiphoclada var. pedicellata is probably now extinct. Lectotypes are chosen for A. micrantha and A. volubilis. All species are described in detail and a key to identify them is provided. The diagnostic relevance of a range of attributes of the genus is reviewed as is its classificatory history.* The first of a projected series of revisions of genera traditionally included in Stenolobeae Benth., and others related to them, which are intended to form the basis of future Flora of Australia accounts.


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