Recently completed research* funded by the US Poultry
& Egg Association studied the effects of dietary sulfur amino acids and
trace minerals on feather cover in laying hens.
Importance of the study
Feather cover is important for its insulation value and protection from scratches and injury to the hen's skin. In commercial settings, surveys indicate a rapid deterioration in feather cover after the hens are about 40 weeks of age, with some recovery after molt and then again a rapid deterioration during the second cycle of egg production. The United Egg Producers Animal Husbandry Guidelines also note the importance of adequate feather cover for the welfare of the laying hen.
The objectives of the research were to test the level of cystine and methionine supplementation necessary to optimise feather cover during the first and second cycles of egg production, and to investigate the effects of supplemental selenium (Se) or zinc (Zn) on feather cover through the first and second cycles of egg production.
Egg production (EP) was significantly affected by dietary amino acid treatment during all three phases of production. During Phase 1, EP was greatest for hens on the control diet (low methionine and basal cystine) or high cystine diets. During Phase 2, EP was greatest for hens fed the highest level of methionine supplementation. There was no benefit to cystine supplementation during Phase 2. During Phase 3, positive effects of high levels of methionine or cystine supplementation were quite apparent for improved egg production. Trace mineral supplementation had a transitory effect on egg production during Phase 2 of the study, showing improved EP when hens were fed inorganic Se combined with 100 ppm Zn from Bioplex.
Egg weights were only significantly affected during Phase 2, at which time hens fed the highest level of methionine had the greatest egg weights. Cystine and methinionine supplementation inconsistently improved egg weights during Phase 3 whereas trace mineral supplementation had no effects on egg weight.
Feather scores by both feather quality scales (Webster and Hurnik's for overall or Tauson's for five different areas of the body) did not show any dietary amino acid or trace mineral treatment effects. Age significantly affected feather scores as one might expect. After 46 weeks of age, feather scores significantly decreased by both scales, reaching a low point by 64 weeks of age. Feather scores significantly rebounded following the molt but were not positively influenced by the dietary treatments.
High levels of methionine or cystine supplementation had positive effects on egg production and egg size. Cystine was as effective as methionine at the highest treatment levels. Unfortunately, the levels of methionine and cystine supplementation used in this trial were not able to prevent normal age-related feather loss in this population of white leghorn hens. The practice of non-restriction molting did improve feather quality and scores for a period of time following the molt regime.
* Effects of Dietary Sulfur Amino Acids and Trace Minerals on Feather Cover in Laying Hens, by Sheila E. Scheideler, Ph.D., Department of Animal Science, University of Nebraska, Lincoln, NE 68583-0908
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