Andrew Burtt, chief economist of Beef and Lamb's economic service, said the record lambing percentage and more lambs from hoggets offset fewer breeding ewes.
"The report provides further evidence of sheep and beef farmers doing more with less," he said.
North Island lamb numbers were a major factor behind the overall lift in the New Zealand lamb crop with growth of 4.9 per cent (551,000 head) to 11.7 million head.
In the North Island, the average ewe lambing percentage for 2017 was 128.0, up 8.6 percentage points on last year.
"This was a record high, and was due to good climatic conditions and ewe condition at both mating and lambing for most regions," Burtt said.
"However, after autumn and winter conditions were generally good, but wet, lamb growth rates were lower than normal due to a lack of sunshine, cool damp weather and more lambs. This has had a negative impact on lamb growth.
"On a positive note, there were no adverse weather events during lambing," he said.
According to the survey, the number of breeding ewes declined 1.9 per cent to 17.8 million at 1 July 2017.
Beef and Lamb's crop survey is drawn from its Sheep and Beef Farm Survey, which covers a statistically representative sample of over 500 commercial sheep and beef farms.
-- Staff Reporter
