Are you really getting value by flushing your ewes?

This case study demonstrates the power of the StockCARE® programme. An opportunity was identified in 2009. A confident decision for change was made, the plan put in action and the outcomes were assessed the following year.

 
This case study involves one our high performance ewe flocks (Fig 1) with a consistent 150% lambing and 300g/day pre-weaning lamb growth rate. Note the kg lamb weaned per ewe in 2008 is down because lambs were weaned early due to drought conditions.
 
The case study is used to demonstrate the value of flushing only the ewes that are likely to respond to the extra feed. In this case there weren’t any other stock to utilise the extra feed, but it could have been saved to take into the winter.
 

Ewes in condition score 3 & better do not respond well to flushing

 
  
Figure 1. Between Year Ewe Flock Performance

 

Scanning results for the MA ewes has been close to 170% with a record 178% in 2009 (Table 1). Drought conditions in summer 2009 meant early exit of the sale lambs and ewes lambs grazed off.
 
Table 1. Scanning results for mixed age ewes
 

 
2006
2007
2008
2009
Ewes scanned
3459
3449
3450
3421
Average mating weight
69
71
70
73
Scanning %
170
173
173
178
Scanning Index
2.47
2.43
2.48
2.43

The drought broke before mating so the ewes were offered as much as they could eat over the next 4 weeks leading up to mating. At Pre-Mating the average liveweight was 63kg with 20% of the ewes condition score 2. By mating about half the ewes were condition score 4 and about 10% score 5. The average weight gain going into mating was 10kg (Fig 2.)
 
 
Figure 2. Liveweight and condition score curves for mixed age ewes in 2009

   

  Pre- mating (Average 63kg)  Mating (Average 73kg)  Ram Removal (Average 67kg)

Feed started getting short so after the second cycle the ewes were tightened up. They lost 6kg between start of mating and ram removal, but because of the timing it has had little impact on mating performance.
 
The main outcome was low pasture covers going into winter. This meant the single ewes had to be tightened up so more than half of them went into lambing at score 2 and by tailing more than half the singles and multiples were score 2. It is most likely this could have impacted on the lamb growth rates.
 

So what did it cost to get the record scanning?

2009 Scanning up by 5% = 4% lambing potential

Over 3400 ewes = 140 lambs, at $70 = $9,800

Weight gain 10kg over 30 days = 300 g/day

Require about 37MJME = 2.8kgDM at 13MJME
Feed eaten
3400 ewes x 2.8 x 30 = 285,600 kgDM
 

But research says ewes in good condition score don't respond to flushing. If the score 2 ewes in this flock were taken out and flushed to gain 5kg and the rest fed to gain 2kg:

CS 2 fed to gain 5kg over 30 days = 170g/day
Need 27MJME/day = 2.1kgDM/day
680 ewes x 2.1 x 30 = 42,840kgDM
 
CS 3 ewes feed to gain 2kg over 30 days = 70g/day
Need 17.5MJME/day = 1.35kgDM
2720 ewes x 1.35 x 30 = 110,160kgDM
 
Feed eaten = 153,000kgDM
 
Feed saved = 132,600kgDM
 

The feed saved is equivalent to 265ha of pasture grazed from 1500kgDM/ha down to 1,000kgDM/ha – a fair bit of feed to take into the winter.

 
Mating plan for 2010
Ewes were managed to ensure they were close to score 3 at Pre-Mating and then to gain about 2kg going into and during mating (Fig. 3).
 
 
Figure 3. Liveweight and condition score curves for mixed age ewes in 2010
 
 

   

  Pre-Mating (Average 70kg)  Mating (Average 69kg)  Ram Removal (Average 64kg)

Again the weight loss during mating occurred during the third cycle. Scanning was back to 173% (Table 2). 
 
 
Table 2. Scanning results for mixed age ewes 2010 compared to previous years

 
2006
2007
2008
2009
2010
Ewes scanned
3459
3449
3450
3421
3425
Average mating weight
69
71
70
73
69
Scanning %
170
173
173
178
173
Scanning Index
2.47
2.43
2.48
2.43
2.47

Note in 2007 & 2009 the scanning index was lower. In both years 60% of the ewes were score 4 & 5 at mating. Research shows that excessive body condition can compromise mating performance. So the extra feed required to put weight onto very good conditioned ewes adds very little value in terms of more lambs.

What happened?
Weight of lamb weaned per ewe was the same as 2009 (Fig 4). In 2010 lambs were weaned 7 days earlier which is equivalent to 2.1kg.
 
The lambing was 152% and lamb growth rate 307g/day.
 
 
Figure 4. Ewe Flock Performance Between Years
 

 

 Summary

StockCARE® has been able to add value to this high performance ewe flock. That value came from being able to make a decision to decrease the amount of feed to the ewes before mating. 
 
The combination of the monitoring information, research and more than 10 years of StockCARE® experience enabled a confident decision for change. StockCARE® has shown that decision was a very good one.