30 October 1998

Phase feeding has potential

By Simon Wragg

PHASE feeding trials at Easton Lodge have been completed and show the principle of reducing protein:energy ratio in feed as liveweight increases has proved sound. However, putting research into practice has highlighted a need for tighter management and better pig health to achieve consistent results.

Easton Lodge unit manager Jasper Renold has taken three batches of pigs from 73kg liveweight to finishing at 95kg – the period where MLC suggested lysine was being significantly overfed – on a ration which adheres to phase feeding research.

"I have no doubt that theres an argument for reducing protein:energy ratios in pig diets," says Mr Renold. "But I am not convinced MLC recommendations are entirely right for pigs on a commercial unit."

As protein requirement is dictated by liveweight, lysine levels were pegged at the average weight of pigs between starting and finishing weights for each ration as suggested by phase feeding research. But in a commercial environment, pig liveweight varies in pen groups and lighter pigs can start a new ration being underfed lysine. This can reduce growth rate, suggests Mr Renold.

This concern is shared by Caroline Bevan, Easton Lodges nutritionist. But she says in this trial disease had a greater effect on growth rate than reducing lysine level in feed. In a commercial situation, Mrs Bevan says its necessary to set nutrient levels to meet requirements of lighter pigs.

From the outset, MLC pig scientist Pinder Gill has said response to phase feeding in a research environment is potentially better because of a tighter control on weight variation and health status. "In phase feeding we are tailoring a diet to a specific liveweight. If theres a 35kg variation in live-weight, as seen at Easton Lodge, it is not surprising performance varies," says Dr Gill (see table 1).

Mr Renold acknowledges that a reduction in weight variation would require significant sorting and mixing of pigs. "In a commercial unit I dont believe we can get weight difference below about 10kg, even by mixing pigs as they go through the system which is undesirable."

Improving health has helped Easton Lodge improve performance in the final batch of trial pigs. Treated with tilmicosin (Pulmotil) at weaning against APT, pigs achieved daily liveweight gains of over 900g/head compared to daily gains of about 700g/head for unmedicated groups (see table 2).

According to Mrs Bevan, this highlights the greater effect of health status on growth rate than differences attributed to feeding two levels of lysine.

Analysis by Dr Gill (see table 3) – adjusting Easton Lodge results for variation in start and finishing weights – shows a feed saving of 43p/pig, worth £3311 for Easton Lodge which finishes 7700 pigs annually.

While feed savings are encouraging, Mrs Bevan says the trial doesnt show the effect of phase feeding on carcass quality. "The MLC acknowledges in trials that carcass fat increased for pigs fed a low lysine ration. That could have a significant effect on payments for finished pigs and would need to be set against possible savings in feed, partic-ularly in todays economic climate."

Mr Renold was unable to obtain carcass grades on an individual basis from the abattoir for pigs fed the lower lysine and commercial finisher ration to compare MLC and Easton Lodge findings.

Mrs Bevan adds that producers mustnt associate low lysine rations with low quality, however it is important to establish what is the energy to lysine ratio of the ration. "The quality of ingredients and digestibility of low lysine rations must be taken into consideration or pig performance will be affected."

Mr Renold says trial results provide food for thought. Although pigs grew better on the higher lysine diet, theres a useful saving in the cost of the low lysine ration which could be exploited, particularly if health status improved.

"There was a predicted saving for Easton Lodge and although what has been achieved falls short of that, we dont know how much can be attributed to the way pigs are housed and fed on a commercial unit compared to a research environment," says Mr Renold. &#42

PHASEFEEDING

&#8226 Principle works on-farm.

&#8226 Some predicted savings made.

&#8226 Weight and health dependent.

&#8226 Check protein:energy ratio.

&#8226 Copies of MLCs phase feeding booklet are available free (01908-844271).

Table 3: Performance

and feed costs

Lo Pro Grow/Fin

diet diet

Feed intake

(kg/day) 2.22 2.28

Growth (g/day) 766 779

FCR 2.93 2.97

Feeding costs

(p/kg gain) 40.0 42.7

Source: MLC

Table 1: Start weight ranges by diet and batch

Batch Number Low protein diet Grow/Finish diet

of pigs (0.7g lysine/MJ DE) (0.86g lysine/MJ DE)

lightest heaviest lightest heaviest

(kg) (kg) (kg) (kg)

1 144 61 98 61 92

2 152 56 92 51 88

3 144 57 90 61 101

Source: MLC

Table 2: Growth performance

Trial 1 Trial 2 Trial 3

Lo Pro* Grow/Fin Lo Pro Grow/Fin Lo Pro Grow/Fin

No. of pigs 72 72 76 76 72 72

Start weight (kg) 76.7 77.4 70.9 69.4 74.5 75.8

Finish weight (kg) 90.3 90.6 86.0 85.7 93.3 95.0

Growth (g/day) 748 737 648 692 894 914

FCR 3.01 3.07 3.04 3.04 2.74 2.71

Feed/pig/day (kg) 2.25 2.26 1.97 2.10 2.45 2.48

Source: Bevan C *Lo Pro = low protein diet