|Lay Jr, Donald|
Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/2005
Publication Date: 10/14/2005
Citation: Koch, J.M., Moritz, J.S., Lay Jr, D.C., Wilson, M.E. 2005. Effect of melengestrol acetate (MGA) as an alternative to induce molting on egg quality. Journal of Animal Science. 83(2):22.
Technical Abstract: Inducing hens to molt increases egg quality, egg production and extends the productive life of hens. Molting is normally accomplished by feed withdrawal, which has received criticism, and alternatives described thus far have resulted in poor post-molt performance. Previous studies have shown that MGA at a dosage of 4 or 8 mg MGA/day, when incorporated into a balanced layer diet, leads to reversible regression of the reproductive tract. However, this alternative must also result in an increase in egg quality post-molt to be considered an adequate method by the industry. Hy-Line W-36 (n=72) laying hens at 67 weeks of age were randomly assigned to receive a diet containing, 0 mg MGA (control) throughout the experiment, or 4 or 8 mg MGA/ day, for, 2, 4 or 6 weeks. Eggs were collected daily to determine percent lay throughout the experiment. Upon reaching 50 and 70 percent lay, following removal of MGA, eggs were collected for four days and measurements of egg quality, including haugh units (i.e., internal egg quality), as well as shell thickness and breaking strength (i.e., measures of external egg quality) were determined. Egg quality measured by haugh units was greater (p<.05) for those eggs laid by hens molted with a diet containing 8 mg of MGA for four or six weeks compared to controls (81.2 +/- .7 vs. 78.4 +/- .5). Following MGA induced molt, shell thickness was greater (p<.05) when hens were treated with 4 mg for six weeks and 8 mg MGA for four and six weeks compared to control (.341 +/- .004, .334 +/- .0047, .358 +/- .004 vs. .320 +/- .002 mm). Egg breaking strength was greater (p<.05) than controls for all hens fed MGA regardless of dosage or duration of feeding (4.48 +/- .06 vs. 3.88 +/- .04 kg). When utilized as an alterative MGA, leads to an increase in both the internal (i.e., haugh units) and external (i.e., shell thickness and breaking strength) egg quality compared to non-molted hens.