An appraisal of moulting on post-moult egg production and egg weight distribution in white layer hens; meta-analysis.

1. The aim of this study was to establish how different moulting methods and body weight losses influenced post-moult performance and USDA egg weight distribution. 2. Data on 5 laying flocks (#34-38) of the North Carolina Layer Performance and Management Test were used in this meta-analysis. 3. The moulting methods were non-fasted moulted (NF), short feed restricted (SF), 13-d feed restricted (FR), non-anorexic moult programme (NA), non-anorexic moult programme with low sodium (NALS) as well as non-moulting programme as control treatment. The percentages of targeted body weight loss during the moulting period were 20, 24, 25 and 30% of body weight at the end of the first egg production cycle. 4. Post-moult egg production and egg mass were influenced by all moulting methods. Maximum increase in post-moult egg production rate and egg mass occurred with FR and NF programmes, respectively, at 30% of body weight loss, compared to non-moulted hens. Non-fasting methods reduced mortality rate more effectively than fasting methods. 5. Moulting resulted in increases in percentage of grade A and decreases in percentage of grade B eggs. Non-fasting methods increased percentage of grade A eggs more effectively than fasting methods. Percentage of cracked eggs decreased in moulted rather than non-moulted hens and the lowest rate was associated with the NA programme. 6. Post-moult egg weight was not significantly influenced by moulting methods. However, percentage of body weight reduction affected egg weight. The optimum increment in egg weight was achieved by 24% body weight reduction. 7. Overall, non-fasting methods resulted in similar egg production compared with fasting methods. Considering post-moult mortality and USDA egg weight distribution, non-fasting methods, especially NF and NA programmes, performed much better than fasting methods, indicating that non-fasting moulting methods, which are better for animal welfare, are effective alternatives to fasting methods.