The effects of dietary calcium and phosphorus level, and feed form during rearing on growth performance, bone traits and egg production in brown egg-type pullets from 0 to 32 weeks of age

In a 3 × 2 factorial arrangement, effects of feed form (crumbles (CWS), mash (MWS), both with inclusion of 3% finely ground wheat straw, or crumbles with inclusion of 3% oat hulls (COH)), and dietary Ca and P (high and low Ca-P) from 0 to 16 wk of age were studied on growth performance, bone characteristics, and gizzard development of egg-type pullets. The cross-over effect of feeding strategy during rearing on laying performance and egg shell quality was studied from 19 to 32 wk of age. From 0 to 16 wk, ADG, ADFI, and feed conversion ratio (FCR) were improved with CWS and COH compared to MWS, but ADG and FCR were improved with MWS compared to CWS and COH from 11 to 16 wk. Uniformity of BW till 11 wk, and tibia breaking strength at 6 and 16 wk were higher with CWS and COH compared to MWS. Tibia ash content at 11 wk and relative empty proventriculus + gizzard weight (EPG) were lower with CWS and COH compared to MWS, also relative EPG at 11 and 16 wk was higher with COH compared to CWS. At 25 wk BW was lower with MWS compared to CWS and COH, but BW was equal for all treatments at 32 wk. The FCR for egg production was improved with COH compared to MWS. Egg shell parameters were not affected by feed form during rearing. Low Ca-P decreased BW uniformity at 6 wk, relative keel bone weight and ash content at 11 wk, tibia ash content at 11 and 16 wk, increased relative EPG at 6 wk, and improved egg shell quality at 32 wk of age. It was concluded that feeding CWS and COH compared to MWS increased growth performance, but had no clear cross-over effect on egg production. Low dietary Ca-P led to a lower bone mineralization during rearing, nevertheless improved egg shell quality at 32 wk.