By consultant Heddwyn Owen
Are you harvesting one tonne of eggs from two tonnes of feed?
There are a number of ways of measuring and recording output from a flock of free range laying hens—Hen Housed production, Hen Day production, egg weight, egg gradings, seconds etc. Arguably, the most important measure of all is the return on the initial financial investment, but that is a subject outside the scope of this article. This article makes a case for recording and plotting egg mass output (EMO).
We measure yield of a potato crop in tonnes per hectare and we sell tomatoes by weight. Although we sell eggs by the dozen we measure the main input, feed, in tonnes. Turkey and chicken growers put great emphasis on feed conversion efficiency (Kg of feed per Kg live weight) but Kg of feed per dozen eggs does not have the same meaning. Kg of feed per Kg of egg is more meaningful.
EMO is measured in terms of Kg of egg mass output per day, for the flock. For example, about 600 Kg/day for a 10,000 bird flock, or if expressed as grams/bird/day, birds laying at 94% with a 64 gm egg weight are producing a daily EMO of 60 gm/bird/day.
Why is EMO important? Egg mass output is by far the best measure for matching nutrient intake to egg output and therefore for deciding which diet to feed, when to change diets in mid-lay etc.
Several scientific researchers have produced equations that calculate the daily nutrient requirement of laying birds at different egg mass output levels. These equations take into account temperature, growth (live weight gain), maintenance and daily egg mass output. For example, at 15ºC (average 24 hour temp for the bird) and a daily egg mass output of 60 grams, the daily nutrient requirement of one bird is 1.5 MJ of energy, 1.05 grams of lysine and 490 mg of methionine. To provide that energy the bird must eat 125 grams of a diet containing 12 MJ/Kg of metabolisable energy and in order to supply the amino acids mentioned the diet should contain 0.84% lysine and 0.39% methionine (as constituents of the Crude Protein content).
It is important to realise that, although peak egg numbers occur around 26/28 weeks, egg mass output continues to increase beyond this stage, peaking at around 32/34 weeks. Diets should be chosen for a specific EMO range, for example 60+, 58 to 60 and below 58 gm/bird/day.
A flock I just visited was producing at 59 EMO at 42 weeks. This particular flock was on a diet designed for an EMO of 58 to 60 gm/bird/day. The egg mass curve is much flatter than it used to be as a result of better persistency in all breeds. The feeding programme must reflect this fact.
I recommend that a random sample of 180 eggs (6 trays) from each flock is weighed on the same day every week to obtain the average egg weight. This can later be compared with the calculated packing centre egg weight if desired. The egg weight is then multiplied with the % Hen Day production figure to obtain the EMO. The breeding company will provide a card for plotting the EMO which will enable an ongoing comparison with the breed target.
If the nutrient content of the feed is well matched to flock performance there will be a period around peak EMO when the flock feed conversion is around 2:1 ie two tonnes of feed for one tonne of eggs. This is the period when the birds are at their most efficient in terms of feed utilisation.
The practice of weighing eggs weekly has other benefits—egg weight, and changes in egg weight, can be a quicker indicator than egg numbers of disease challenges or management problems. This could enable action to be taken sooner to investigate possible reasons for and thus avoid potential production drops.
A specific EMO can be the product of fewer but larger eggs or vice versa. Depending on market requirements it may be possible to manipulate size versus numbers by making changes to management practices and feed nutrient content without affecting the total egg mass output of the flock.
You will need to decide your plan of action before the birds come into lay e.g. if you want egg numbers, stimulate the birds with light earlier and quicker and feed lower linoleic acid diets. But if you want egg size, delay the lights, start with a heavier bird and feed higher linoleic. Thus two different flocks might have different feeding regimes but have the same egg mass output.
