The sci­en­tific rea­sons why chicken pro­duc­ers don’t use growth hor­mones

NZ Lifestyle Block - - Your Poultry -

One of the en­dur­ing myths about com­mer­cial poul­try is that poul­try pro­duc­ers world­wide use growth hor­mones to make broil­ers grow faster and pro­duce more meat.

The use of hor­mones for any growth pro­mo­tion pur­poses has been banned in NZ since the 1970s – and ex­ist­ing records show they were never used here be­fore then any­way – and in the EU since 1981.

Sci­en­tists at the Depart­ment of Poul­try Sci­ence in the Univer­si­dad Na­cional Au­tonoma de Mex­ico have re­cently led a re­view of the sci­en­tific rea­sons why poul­try are not fed hor­mones, with their work pub­lished in the May 2016 is­sue of Trends in Food Sci­ence & Tech­nol­ogy. They felt the world needed a sci­en­tific ex­pla­na­tion of the rea­sons why, which could then be pro­vided to pro­fes­sion­als such as pol­icy mak­ers, health providers and food in­dus­try workers to ad­dress con­sumer con­cerns.

Hor­mones sim­ply do not have time to work

Meat birds (broil­ers) grow so fast, they

WORDS ALICE MITCHELL, THE POUL­TRY SITE

reach mar­ket weight be­fore they reach sex­ual ma­tu­rity and the hor­mones have no phys­i­o­log­i­cal ef­fects.

One ex­am­ple is the hor­mone so­ma­totropin. The sci­en­tists de­scribe how a num­ber of stud­ies showed that there were only mi­nor, tran­si­tory or ab­sent growth re­sponses after pro­vid­ing this hor­mone to chick­ens.

So­ma­totropin nor­mally works by in­creas­ing the pro­duc­tion of pro­teins known as in­sulin-like growth fac­tors, which then go on to stim­u­late growth, but this in­crease was not ob­served in chick­ens.

In ad­di­tion, re­search has shown that steroid hor­mones like oe­stro­gen and an­dro­gens (and male hor­mones like testos­terone) do not stim­u­late growth in chick­ens ei­ther. In­deed, re­search sug­gests that an­dro­gens might even make rates of growth go down.

The cost of growth hor­mones is pro­hib­i­tive

Com­mer­cial poul­try farm­ers have to max­imise ef­fi­ciency and prod­uct yield while min­imis­ing costs to re­main prof­itable, and re­coup the con­sid­er­able in­vest­ment of start­ing and run­ning a farm.

The sci­en­tists showed that us­ing hor­mones would not be fea­si­ble, as the cost per chicken would rep­re­sent ap­prox­i­mately 10 per cent of the over­head cost or ap­prox­i­mately 1 per cent of the to­tal pro­duc­tion cost.

If growth hor­mone im­plants were used in poul­try, the es­ti­mated cost would be be­tween (ap­prox­i­mately) NZ$2.40$4.80 per chicken, which would be over 10 times more ex­pen­sive than the en­tire es­ti­mated to­tal cost of vac­cines, elec­tric­ity and heat­ing re­quired per chicken (NZ 20-34c/bird).

Such costs would be too high for poul­try pro­duc­ers to ab­sorb, the re­tail price of the meat would have to rise to com­pen­sate, and poul­try would no longer be the most eco­nom­i­cal meat for con­sumers.

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