The amount and ratio of protein and energy fed during rearing and laying might influence the growth curve, body composition and laying persistency of hens. We studied the influence of a low or high apparent fecal digestible (AFD) Lys level in all rearing diets and constant or reduced ME level and source during laying (reducing energy over time high oil = REHO; constant energy high oil = CE; reducing energy over time low oil = RELO) on growth and laying persistency in a 2 × 3 factorial arrangements. Per treatment, 240 one-day-old Dekalb White pullets were divided over 8 pens and housed until 110 wk of age. Body weight was measured every 4 wk, feed intake and egg weight weekly, eggs were collected daily. Data were subjected to mixed model analyses. The egg production curve was modelled using a non-linear regression function. In general, there were no interaction effects (P > 0.05). Feeding a low AFD Lys diet during rearing reduced feed intake and therefore AFD Lys and ME intake (P < 0.001), resulting in lower BW long-term (wk 5 to 24, 48, 56 to 72, 96 and 110; P < 0.05). Egg mass production of pullets fed low AFD Lys was slightly higher in wk 44 to 72 (P = 0.038) and 72 to 100 (P = 0.056), while laying persistency was reduced, indicated by a longer peak production phase but a higher slope of decline (modelled data; P < 0.001). During laying, hens fed CE diets had the lowest feed and AFD Lys intake from wk 20 onwards (P < 0.05), but a similar ME intake. Egg weights of hens fed RELO diets were lighter from wk 20 onwards (P < 0.001). The peak production phase was 3 wk shorter for hens fed CE diets (P < 0.001), while the slope of decline after wk 85 was steeper for hens fed RELO diet (P < 0.001). Feeding higher AFD lysine during rearing and optimizing energy source during laying can improve BW, feed efficiency, and laying persistency, emphasizing the long-term impact of early nutrition.
Eck et al. (Tue,) studied this question.