Yesterday was the last day I could set aside to process chickens for some time. It was also their 11 week age mark. Actually they could have gone on for another few weeks without problems but I've got a busy time coming up, so despite wanting them to have a longer life I just couldn't delay it.
Processing went fine. I caught them singly with a handful of feed and made sure the area was cleaned completely between dispatch. This stops them seeing any sign of what's to come — chickens are quite visual and, despite what some people believe, they do watch and will show signs of distress when another member of their flock is culled.
After dispatch each bird was singly processed by skinning, eviscerating and then washing down. The parson's nose was removed at the start of evisceration (I don't use it in most recipes anyway) and this made removal of organs much easier and cleaner. Livers and gizzards were cleaned and put aside for further use such as making paté. Hearts, spleens, legs (I already have a freezer full for use in stock), a few gizzards, and anything that slipped out of my hands and touched another surface were fed to the dog, who hovers nearby at dispatch time.
I found the birds had a wide variety of weights, from 1kg up to 1.8kg dressed weight. These weights are far lighter than meat hybrids I've raised to similar age in the past, but it must be remembered that they weren't fed synthetic methionine as a bulking agent and also had a cocci setback. They're still a lot heavier than my other crossbreds at the same age. Indeed my malay-leghorns didn't reach this weight range until week 16. Remember too that skin + parson's nose probably add an extra 150-250g.
Now for a couple of evident health problems. The smallest bird appeared to have two issues: one was a flaccid gizzard with signs of a couple of ulcers in the gizzard wall and an enlarged proventricular attachment (possible runting/stunting); the other was a pea-sized tumour inside the cavity (possible marek's).
Three of the next smallest birds also had flaccid gizzards, one or two erosion sites, and lax proventriculus with enlarged attachment (again, possible runting/stunting). Two of these also had faintly streaky livers, though no liver enlargement.
All the other birds (there were 21 in total) had good solid gizzards and digestive systems, but about half had faintly streaky livers. Again they had no liver enlargement (the way to tell this is to look at the edge of the liver, which should come to a sharp line; enlarged livers tend to have a plumped, pillow-like edge) and all other organs appeared normal. Remember I'm not an expert in any of this, and can't do close pathology, so these are 'gross' observations at best. However I do know that there should be no streakiness in the liver. My guess is that the naturally-occuring toxins in the lupins were a little hard on the birds' livers (when fed raw); or else that the grains were mildly affected by mould toxins. As the feed was all properly stored and very fresh (none older than a few weeks), and the sprouting was all carefully managed, such mould would have most likely been present at purchase. The third guess would be that the livamol and/or meat meal (both fed in small quantities up to about week 4 or 5) contained toxic amines (as noted in earlier research on runting/stunting syndrome) and these toxins had some liver impact.
Oddly, of the three birds with possible runting/stunting, all were smaller-framed than their counterparts, but equally well if not better fleshed. This may suggest that whatever had caused the earlier stunting had begun to disappear or improve.
Possibilities seem to include a virus (they were raised in the same tractor as the earlier sussex, one of which also showed runting/stunting symptoms), genetics (the sussex may have had broiler genes), amino acid imbalance (a strong possibility, though I can't find sufficiently detailed information on how amino acid ratios affect the gizzard if the birds are well-muscled and feathered and show no other symptoms), or something like mould or other toxins in the feed.
There is simply no way to decide between these possibilities, even given the observation that the runted birds began to improve after a certain point. For instance, if it was to do with an adenovirus, perhaps their immune systems improved as the birds aged. An amino acid imbalance (if there was one) may have been corrected by adding soured milk in greater quantities, as I did after about week 5. Removal of soy meal, meat meal and livamol (any of which may have contained toxic amines) may alone explain the improvement in the grower stage. Lastly (if this isn't complicated enough) I began cooking the lupins at about week 6 or 7, out of a concern about naturally-occurring toxins in the legume being perhaps higher than generally believed.
Next part of the project is, of course, to taste-test the results. I'm not concerned that the streaky livers imply anything wrong with the carcasses; in fact even the couple of stunted birds are well fleshed and appeared basically healthy inside (with the exception of the one with a small tumour, which I don't like to keep for eating). However I did only keep the well-coloured livers for paté; the rest will also be dog food.
If I find the meat to be absolutely delicious, I might fine-tune the diet and keep going with the earlier plan to crossbreed the meat hybrids with layers to develop a stronger, healthier, better foraging, tastier meat bird that does well without synthetic inputs. After all, none of the birds appeared to be in any discomfort despite those very faint liver streaks or the couple that weren't growing as well as the rest. Only the cocci bout left me feeling unhappy with my own management, and if I raise these birds under hens in smaller numbers (and don't put them in the tractor just as it starts to sheet with rain) I believe I can reduce the likelihood of it.
The biggest change if I did this again would be to do only what I've done in the second half of this project: i.e. include no meat meal or livamol, but do include more soured milk and cooked rather than raw lupins. The mealworms may well have bred in sufficient quantities to provide some more protein as well. If I do this without changing much else, but still see birds with gizzard/proventricular issues and/or streaky livers, I'll be in a better position to decide on a probable cause (e.g. mould toxins from faulty feed). But that's for down the track.
Meanwhile, on to the next part of this long and fairly arduous project: finding tasty ways to honour the meat that those birds gave their lives for...