The number of sheep processed amounted to 173,000 head for the week, which represented a decrease of 7% from the previous week.
The AHDB said that this puts slaughter figures to date, this calendar year, at 4.23 million head, which is around 325,000 head more than at the same point last year.
Deadweight prices fell during the week ending May 21, also. The GB old season lamb (OSL) standard quality quotation (SQQ) averaged 598.5p/kg, down 6.6p from the week before, and the NSL SQQ was 4.4p lower at 672.0p/kg, the AHDB said.
Looking at the liveweight trade, for the week ending May 25, the AHDB said that liveweight lamb prices were a mixed bag compared levels the week earlier.
The OSL SQQ price averaged 249.14p/kg, a drop of 6.5p, while the NSL SQQ price incrased by nearly 4.5p, to 327.74p/kg.
Market throughput stood at 89,500 head (OSL and NSL combined) during the week, down 9% from the previous week and a further 9% lower than throughputs the week before that.
Meanwhile, cull ewes gained £5/head to average £115 in GB marts, the AHDB concluded.