TAKE HOME MESSAGES
- Finishing time for lambs can be greatly reduced by improving their nutrition.
- Quality and quantity of feed available in stubble paddocks is often unknown.
- Visual assessment of lambs is not an accurate method measure of weight.
BACKGROUND
BCG and CSIRO, with the support of a DAFF, ‘Action on the Ground’ grant, are working with four Birchip farmers comparing ways to finish lambs earlier while still fitting in with their current systems. By finishing lambs earlier, the total amount of methane (GHG) emitted by lambs is less per kilogram of meat produced compared with lambs which take longer to reach sale weight.
AIM
To trial and demonstrate farm practices and technologies to improve growth rates and reduce finishing times of lambs, thus reducing ‘whole of life’ methane emissions.
METHOD
The on-farm trials reported here were conducted with the collaboration of four commercial mixed farming (sheep and cropping) enterprises within a 25km radius of Birchip, Victoria. Various aspects of the farms’ ‘lamb finishing enterprises’ were evaluated to determine the benefits of improving nutrition, either in the paddock or feedlot, to promote earlier turnoff of lambs to market.
Table 1. Descriptions of the three feeding treatments used in this trial.
Each treatment consisted of approximately 60 lambs, selected visually then tagged and weighed. Electronic ear tags were used to track growth rates of individual lambs. Trial lambs were weighed a minimum of three times, at the start, middle and end of the trial period. The end of the trial was determined when lambs had reached market weight and were sold.
Stubble, grain feed, quantity and quality were measured throughout the trial. Stubble dry matter (kg/ ha) and spilled grain counts were measured from both the header row and inter row using five random quadrats.
Commercial pellets used were CopRice Lamb Finisher 16% formulation, sourced from CopRice, Tongala, Victoria.
RESULTS AND INTERPRETATION
Lambs were initially selected visually and allocated to the treatment groups, then electronically tagged and weighed individually. The visual selection resulted in large live weight range (15 to 20kg) within each of the treatment groups and made statistical differences between the treatment groups difficult to assess. This demonstrates how inaccurate visual assessment of lamb live weights can be, even for experienced practitioners.
Some of the problems experienced in running these trials and analysing the data collected have highlighted the many management issues that can affect the growth rate and subsequent time taken for lambs to reach sale weight. Four farms were monitored, but results from only two farms are shown in this article, due to inconsistent results and management issues experienced in 2013.
Farm 1
Treatments compared the standard practice of grazing stubbles until depleted with two high nutrition supplement regimes fed in a feedlot situation:
- Stubble/feedlot: standard practice, no supplements while grazing barley stubbles (Period 1), then moved to feedlot and fed lentil seconds and vetch/oaten hay (Period 2) as per treatment 2 (Table 1).
- Grain (lentil seconds 23% CP, 13.2 ME) and vetch/oaten hay, fed in the feedlot.
- CopRice pellets (16% CP, 11.5 ME) and vetch/oaten hay, fed in the feedlot.
The trial was conducted over a 42 day period and live weights were recorded from the three treatment groups at day 0 (17/1/13), day 23, (Period 1 = 23 days) and day 42 (Period 2 = 19 days).
Over the trial period, there was no significant difference in live weights between the treatments. However, the large range of live weights within treatments (15-20kg) made it difficult to pick up differences.
In Period 1 the Average Daily Weight Gain (ADWG, kg/d) for the pellet group was significantly lower than for the stubble group, and no other differences were observed (Figure 1). In Period 2, the lentil group had a significantly lower ADWG than the stubble and pellet groups. These results also highlighted some feed availability issues experienced by the feedlot treatment groups.
At the beginning of the trial, the grain (Treatment 2) and pellet (Treatment 3) groups went from a stubble paddock to the feedlot and were fed only vetch hay for the first 6 days before having access to the grain and pellet rations. This appears to have been detrimental to their growth. During Period 1 the stubble group (Treatment 1) grew 27% faster than the grain and pellet groups.
Figure 1. ADWG (kg/hd/day) for the three treatment groups during Period 1 and Period 2 and over the full study period.
The stubble group was moved after 23 days (Period 1) from stubble to the feedlot (Period 2) where they were fed lentil seconds and hay. Their average daily growth rate increased from 0.15 on stubble to 0.22kg/hd/day in the feedlot. At the growth rates achieved on stubble, it would have taken this group a total of 66 days to gain 10kg in weight if they had stayed on the stubble paddock (assuming stubble nutrition could be maintained). When these lambs were moved to the feedlot, they took only 45 days, (21 days less) to achieve the same weight gain of 10kg.
All groups showed major improvements in ADWG between Period 1 and Period 2. The grain group had a significantly lower daily growth rate than the stubble/feedlot and pellet groups.
The ADWG achieved in Period 2 compared with Period 1 indicates there is a considerable potential for additional growth of lambs if nutrition is maximised.
Farm 2
Treatments compared the standard practice of grazing stubbles until depleted with two high nutrition supplement regimes fed in a feedlot:
- Stubble: standard practice, grazing oat stubbles, no supplements
- Grain: (barley 60%, oats, 30%, split lentils 10%) and straw, fed in the feedlot
- CopRice pellets and straw, fed in the feedlot
The trial was conducted over a 47 day period and live-weights were recorded from the three treatment groups at day 0 (17/1/13), day 22 (Period 1 = 22 days) and day 47, (Period 2 = 25 days).
The estimated amount of stubble and spilled grain in the stubble group paddock (Treatment 1) was 0.33kg/hd/day, only 25% of the amount fed to treatments 2 and 3. Summer weeds grew in the stubble paddock for a period which was not measured so this may help account for the feed difference. The grain group (Treatment 2) was offered a total of 3800kg of grain mix, equivalent to 1.35kg/hd/day. The pellet group (Treatment 3) was offered a total of 4000kg of pellets, equivalent to 1.42kg/hd/day of pellets. This represents a 5% difference in overall feed supply for the two feedlot groups.
The amount of feed supplied to both feedlot groups (Treatments 2 and 3) in Period 2 was reduced from Period 1 as it was thought that food was being wasted. However, this appears to have adversely affected the growth rates for both groups (Table 2 and Figure 2).
Table 2. Feeding rates (kg/hd/day) and distribution (days) for Farm 2.
The range of live weights within each treatment for this farm was also large (15-20 kg) but the statistical analysis showed both the total live weight and overall ADWG for the stubble group (Treatment 1) was significantly lower (P<0.05) than the grain (Treatment 2) and pellet (Treatment 3) groups.
Figure 2. ADWG (kg/hd/day) for the two growth periods and total for the three treatment groups in Farm 2.
The ADWG for Period 1 showed that both the pellet and grain groups (Treatments 2 and 3) grew significantly faster (Figure 2, P<0.05) than the stubble group (Treatment 1). For Period 2 no significant differences were observed between the three groups. Comparisons between Period 1 and Period 2 show a decline in ADWG of 18% for the grains group and 32% for the pellet group relative to Period 1. These declines in weight gain correlate with the reductions in the amount of feed offered during Period 2 (Table 2).
COMMERCIAL PRACTICE
The trial highlights some of the inefficiencies and management issues in current prime lamb production systems. Producers have the potential to reduce production time, risk and greenhouse gas emissions while improving financial return and animal nutrition.
Growers are reluctant to feedlot animals during harvest and early January when peak stubble is available for grazing. However, the potential is there to increase nutrition earlier and improve lamb growth rates, thus reducing the time needed to bring the lambs to a marketable weight. Feed lotting or using self feeders in the paddock can improve production when pasture/stubble availability is limited, achieve rapid growth when feed prices are low, generate cash flow and value add ration components (e.g. grain).
Some factors to consider when feed lotting sheep:
- animal health considerations
- quality, quantity and supply of water
- balanced nutrition, type of feed available to be used in the feedlot
- shade
- backgrounding lambs on grain for rumen adjustment
- size of feedlot and feeding area
- mob size
Regularly weighing a selected group of lambs to accurately monitor growth is a practice producers should consider to give a better indication of whether their lambs’ nutritional requirements are being fully met.
ACKNOWLEDGMENTS
This project is supported by DAFF – Action on the Ground Grant and also by CopRice Pty Ltd, through the donation of all finisher pellets used in the completion on this trial.
