Regular readers of our farm diary will recall that last month we left the lambing shed with all but one of our ewes nursing their lambs – we knew that ewe number 20, a maiden ewe, had scanned for twins, and her belly certainly looked like she was expecting twins, but her udder wasn’t ‘bagging up’ in the way that it ought to be for a ewe about to lamb. She had obviously missed the first cycle with the ram and so would be at least another 2 weeks before she lambed, so we decided to turn all the ewes and lambs out into the field – the weather was glorious and at this time of year outdoor lambing for the final ewe should not be a problem.
Typically, the temperature suddenly dropped and strong easterly winds brought torrential rain on the night number 20 delivered her lambs. On my late night patrol I found one strong ewe lamb whose full tummy confirmed that she’s already been sucking, and one smaller, perfect, but cold and lifeless, ram lamb. Of course, the usual self-recriminations follow such an event, “if only I’d gone out an hour earlier”. Sadly, each year the national average lambing losses are between 15-16% of which 24% is due to the ewe aborting (usually caused by an infection), 18% is due to the pre-parturient death of the ewe (mostly due to poor body condition at tupping or nutritional imbalance during pregnancy), and a staggering 49% is accounted for at lambing (source: EBLEX). So, having recently been shown by our vet how to carry out a post-mortem (PM) examination, and with a copy of the latest EBLEX ‘Better Returns’ Bulletin and my favourite vet book Sheep Flock Health by Neil Sargison, I decided to see if I could find out why the lamb had failed to thrive – and to try to establish whether the lamb breathed, walked and sucked. Don’t worry, I will spare my readers the really icky bits (though I found carrying out a PM considerably simpler than skinning, gutting and jointing a rabbit for the first time!), but the process is both interesting and informative – so here’s a clinical description of the PM and what I discovered:
Firstly, the external examination (my findings in bold):
- Birthweight? Anything under 3kgs will be less viable, and a big lamb (6kgs and over) is likely to suffer from birthing stress – this lamb weighed 3.9kgs, small for the breed, but a viable weight
- Is the lamb’s coat stained? A yellowing would indicate the lamb expelled meconium (see photo) – the first faeces, which would suggest birthing stress – none present
- Is the head and/or tongue swollen? Either of these could indicate birth stress, or, possibly Schmallenberg Disease (SBv) – head normal
- Is the navel swollen? Occasionally a rupture can occur, allowing intestines to protrude (in an older lamb, you’d also check that the cord had dried properly) – navel normal
- Eyes – bloodshot? Again, indicating birth stress – eyes normal (interestingly, I also learned that in cases of entropion, the ram is often implicated)
- Anus missing – an odd one, but more common than many people realise, and without an anus the lamb would become congested with faeces – anus normal
- Feet – lambs are born with a membrane on the soles of their feet, often called ‘slippers’ – if this is still present, it means the lamb never stood or walked – slippers present, so it’s likely that this little lamb never stood
Having got so far without finding any obvious reason for the lamb’s death, it was now time for me to steel myself, and pick up the scalpel, something I hadn’t done since dissecting rats in school biology lessons!
- With the lamb lying ‘spread-eagled’ on its back, the first four cuts are through the lamb’s armpits and groin (No's 1-4 on diagram), so that the lamb will rest on its back without the legs getting in the way. This enabled me to inspect the ribs, feeling for any fractures that may have been caused by a difficult birth – there were none as far as I could tell.
Next, a deep cut all along the midway of the lamb (No 5 on diagram), cutting from the pelvis, through the midribs, and up to the top of the throat so that I could see and access the internal organs. By this stage my curiosity had banished all thoughts of this being a gruesome act.
- After a bit of searching, I found the thyroid gland in the throat – if enlarged, it would indicate iodine deficiency - although I’m not familiar with what a normal thyroid looks like, this one looked like the healthy one in my book.
- Working down to the chest, the lungs were easy to find: they should be pink and spongy – but these looked more like liver – this is a typical sign that the lamb never breathed, to be absolutely sure, I cut away the lung and placed it in a bowl of water: it sank, confirming that there was no air inside.
Well, it looked as though I had found the reason for the lamb’s death; he’d never drawn breath. The ewe was a maiden (a shearling ewe, we don’t lamb from ewes in their first year), so it is quite likely that she was so preoccupied with her first lamb, she’d simply ignored this one, or, perhaps the birth membrane had covered his nose and prevented him from drawing breath. That was certainly a theory, but having gone this far, I decided to continue and try to rule out any other cause.
- ‘Brown fat’ is present in all newborn lambs; it’s found around the heart and kidneys and has a grey-white appearance – this all appeared normal in my lamb.
- The liver is just below the ribs, and I checked for any sign of bleeding from damage caused by a difficult birth – all looked well, no sign of bleeding.
The final thing to check, though by now I was confident that the lamb was, to all intents and purposes, still-born, was the gut (specifically the abomasum, or fourth stomach) to see whether it contained any clotted milk – there was no sign, which, together with my other findings more or less confirmed that the lamb sadly didn’t breath, stand or suck.
So how does this help me prevent such deaths in the future? Well, my first lesson is to be more vigilant with maiden, inexperienced ewes – however inconveniently late they chose to lamb! And secondly, I learned some interesting anatomy first-hand, while at the same time overcoming my natural reticence about carrying out the post mortem procedure.
On a much brighter note, our 24 lambs are growing well, and have already had their first Heptavac-P vaccination (to protect against clostridial diseases and pasturella); a prophylactic dose of white drench as the time of year and weather conditions increased the risk of Nematodirus (resistance by this species to BZ wormers is uncommon).
The ewes are all looking well – apart from my favourite ewe, Meggie, whose lack of condition was sadly even more apparent following shearing. If you recall from last month’s diary, I’d noticed her ‘quidding’, dropping food from her mouth as her teeth were too warn to enable her to cud satisfactorily. However, the sheep sheared very well this year. We sheared them (14 ewes and 3 rams – that’s the current working ram, his elderly companion and one of last year’s ram lambs) on the 25th – a swelteringly hot day, which gives the fleeces a good ‘rise’ which helps the sheep shear well. Following lambing, all the sheep, including lambs, were treated with a ‘pour-on’ – in this case ‘CLIK’ an IGR (insect growth regulator, that inhibits development from fly egg to maggot) and provides up to 16 weeks protection from flystrike.
And finally, following last year’s drought, which impeded grass growth, this year’s sun and rain has produced a bumper crop of grass … but it’s still raining and the forecast is … more rain! So now we’re hoping for a few day’s of guaranteed fine weather and life at Green Farm will be perfect!