29 March 1996

Lamb castration not such a good idea – MLCstudy

Concern over financial cutbacks in research was highlighted alongside technical papers at the British Society of Animal Science annual winter meeting at Scarborough, Yorks. Jonathan Riley reports

CASTRATING lambs reduces growth rates and is more of a tradition than a sound management practice.

This is the finding of MLC-sponsored studies at the University of Newcastle, reported at the BSAS meeting last week.

Researcher Jennifer Anderson said: "Castrating lambs is a time consuming task. It also raises blood cortisol levels indicating that the process which has been banned in Sweden and Finland is stressful."

Ms Anderson said that tradition, concern over meat quality and managment of male and female lambs after puberty were the reasons why most producers castrated lambs.

In the study lambs were reared to 11 months. Half the male lambs, entire and castrated, were kept in flocks with females. The other half were separated from females. Entire lambs were found to be more active and aggressive particularly after 20 weeks and the onset of puberty. They had higher growth rates, finishing with liveweights 4.5kg above castrated lambs.

Meat quality was affected in entire males with meat less tender. But when entire males were kept separate from females, tenderness improved. This meat was preferred overall by a taste panel.

"It would be possible to finish male and female lambs separated by as little as a field of crops without castrating and gaining the extra growth.

"However, most male lambs are killed before hormonal changes have any affect on behaviour or meat quality anyway. So leaving lambs entire saves time and gives growth benefits even for early finished lambs," said Ms Anderson.

&#8226 Reduces growth rates.

&#8226 Raises stress.

&#8226 Takes time.