Processors must reward farmers for producing wether lambs, Teagasc’s Prof. Michael Diskin told a crowd of over 200 farmers at the recent Teagasc National Sheep Conference in Loughrea, Co. Galway.

Presenting key results from a Teagasc/UCD study, which looked at the differences between wether (castrate) and entire ram lambs, Diskin said: “It is refuted that there are taint issues from the meat produced from ram lambs; particularly from autumn onwards, as rams reach puberty and enter the breeding season.

“If that exists, it is to a certain degree detrimental to the sheep industry. From anecdotal information, butchers and meat processors have a preference for wether lambs; even though they don’t always reflect that preference by paying more for wether lambs.”

Despite this preference, Diskin said that the international data suggest that there is no great evidence to suggest that there is a major problem with ram taint.

However, as little Irish data was available, researchers from Teagasc and UCD developed a study to quantify the different problems and to see is ram taint an issue with Irish lambs.

The study compared ram and wether lambs fed on a short-term (36 day), all-concentrate diet prior to slaughter. 100 wether lambs (50 Texel x Scottish Blackface and 50 Scottish Blackface) and 100 ram lambs (50 Texel x Scottish Blackface and 50 Scottish Blackface) were finished as part of the study. Wether lambs were castrated within 48 hours of birth using rubber rings.

During the finishing period, the lambs were allowed tactile, olfactory and visual contact with each other through the pen partitions and also had visual and tactile contact with non-pregnant cycling ewes.

At slaughter, a number of variables were measured, including: carcass and meat composition; meat tenderness and collagen content; post-slaughter muscle pH; temperature profile; colour attributes; aroma; flavour; and texture attributes.


The current Teagasc/UCD study has confirmed the production benefits of leaving lambs entire and a low-to-modest incidence of meat samples from ram lambs with undesirable sensory attributes.

However, castration did not eliminate the problem of getting undesirable sensory traits from meat samples; although the incidence was lower in meat from castrated lambs. This would suggest that the so called ram taint issues might be due to other factors such as slaughter age, diet, consumption habits and culinary methods.

While castration reduces but does not eliminate the risk of obtaining problematic lamb meat samples, the consequences of castration are reduced production efficiency, as well as the increased likelihood of higher fatness.

Key results:
  • Ram lambs had higher growth rates, produced heavier carcasses and had lower feed conversion efficiency (FCE) than wether lambs;
  • Wether lambs had an almost 2% percentage point kill-out rate and had marginally higher confirmation score, but were much fatter;
  • Scottish Blackface lambs had higher levels of intramuscular fat (IMF) compared to Texel x Scottish Blackface, while no differences was observed between the genders for IMF;
  • Protein, ash and moisture levels did not differ between either breed or gender;
  • Neither meat from castrates or rams was deemed unacceptably tough;
  • Redness of meat colour and yellowness of meat colour was statistically higher in the meat from wether lambs compared to ram lambs. However, the differences were very small and meat from both genders was very acceptable;
  • Small differences were observed for pH at 25 hours post-slaughter in wether and ram lambs. However, in this study, no pH values of >5.8 were recorded at 25 hours post-slaughter, which would indicated that high pH was not an issue across both breed types and genders;
  • Meat from rams had higher mean scores for intensity of aroma, animal smell, rancid aroma, manure/faecal aroma, sweaty aroma, rancid flavour, fattiness/greasiness and lower mean scores for intensity of roast meat aroma;
  • Differences in soapy aroma, soapy flavour and fatty/greasy aftertaste were close to statistical significance, respectively, with rams having higher scores than castrates.

Table: Average scores for sensory attributes in grilled loin muscle from ram and wether lambs

Mean values for attributes evaluated on a 100-point unstructured line scale (0 = low intensity; 100 = high intensity). Source: Teagasc

Should Irish sheep producers castrate lambs or not?

There are undisputed efficiency advantages of leaving male lambs entire, Diskin said, which result in these lambs being ready for slaughter 10-14 days earlier than wether lambs.

Also, ram lambs are leaner which, from a consumer point of view, is desirable. However, ram lambs reach the desired target fat score of three at a heavier weight compared to wethers.

However, we must balance the advantages with the disadvantages and it can be harder to finisher rams under an all-grass system.

It’s also important, he said, to separate rams lambs from ewe lambs from autumn onwards, as ram lambs will spend significant energy following female lambs.

Whether producers castrate lambs or not will depend on their production system, time of lamb finishing, flock size, ability to separate ewe and ram lambs in the autumn as well as signals from the market place, Diskin said.

The trend toward non-castration has become well-established in recent years, he said. And, if processors require more castrate lambs, it’s probable that they will have to reward producers by paying a premium for such lambs.