Influence of Premolt Production on Postmolt Performance with Explanation for Improvement in Egg Production Due to Force Molting

Abstract

Performance of force-molted hens as influenced by premolt production was determined in two experiments using 720 Babcock hens. Hens selected to be laying at a low (41%), average (59%), and high (75%) rate of production were divided into two groups. One half of the hens were force molted (FM) and the other half served as controls (CON). On completion of the fasting period, blood was collected for chemical analyses from 10 hens per group. These hens were then necropsied and weights of the ovary, oviduct, liver, and fat pad determined. During the last 4 weeks of the postmolt period, dietary calcium was increased from 3.5 to 4.5% in half of each group.Postmolt production was directly related to premolt production. The hens laying the highest rate premolt showed no improvement, whereas those laying at the lowest rate showed the greatest improvement. The"FM hens exhibited a lower incidence of shell-less eggs than CON hens. Premolt production appeared to have little influence on postmolt egg weight, organ weights, and blood constituents. However, shell weight and egg specific gravity were significantly improved by force rnolting^ Increasing dietary calcium had no significant influence on shell weight and specific gravity in FM hens in either experiment but significantly increased specific gravity and shell weight of CQN hens during Experiment 2.It >Kas^concluded that most of the improvement in production in force-molted hens was caused by a reduction in shell-less eggs and"not by an increase in ovulation. Also, only a portion of the improvement in shell quality could be explained by an increase in feed intake (calcium intake) after molting due to the increase in production. An improvement in calcium metabolism was postulated to be a major cause of improved shell quality. (

Eggshell quality and calcium utilization in feed of hens in repeated laying cycles

“…After moulting the calcium metabolism in hens, and especially its absorption in the intestine, calcium transport to the oviduct for the shell synthesis in the uterus and also calcium deposition in medullary bones are improved. A correct complex diet, especially a mineral diet during moulting and at the start of a new reproductive cycle, decides on the effectiveness of the consumer egg production (Roland and Brake, 1982). It can be stated that the above information has been confirmed by our observations.…”

Biochemical Parameters and Histopathological Findings in the Forced Molt Laying Hens

“…Gildersleeve et al (1983) found the Ca and P levels in the control and molting groups as 26.6-5.1 mg/dL and 6.9-4.43 mg/dL respectively. Roland and Brake (1982) also determined the serum, Ca and P levels in the control and molting groups to be 23-4.6 mg/dL and 14-4.4 mg/dL respectively. Hens in a long term fasting program (10 days) had lower Ca and P levels than the short term fasting Ca-P levels (Yalçın, 1998).…”

Use of nicarbazin, salinomycin and zinc oxide as alternative molting methods for commercial laying hens

“…Forced molting is defined as a set of management practices to promote stress, inducing birds to stop producing eggs and the partial molting of the feathers (Roland & Brake, 1982). The objective of forced molting is to rest the reproductive system of layers for some time in order to recover their production capacity and to increase the longevity of layers for further 25 to 30 weeks, as well as to improve egg quality, reducing losses caused by poor eggshell quality (Berry, 2003).…”