This experiment was conducted to determine the relative bioavailability (RBV) of Cu in tribasic copper chloride (TBCC) to Cu in copper sulfate (monohydrate form; CuSO4·H2O) for layer diets based on egg yolk and feather Cu concentrations. A total of 252, 72-wk-old Hy-Line Brown laying hens were allotted to 1 of 7 treatments with 6 replicates consisting of 6 hens per replicate in a completely randomized design. Hens were fed corn-soybean meal-based basal diets supplemented with 0 (basal), 100, 200, or 300 mg/kg Cu from CuSO4 or TBCC for 4 wk. Results indicated that egg production, egg weight, and egg mass were not affected by dietary treatments. However, increasing inclusion levels of Cu in diets from CuSO4 decreased (P < 0.05) feed conversion ratio (FCR), whereas increasing inclusion levels of Cu in diets from TBCC did not affect FCR, indicating significant interaction (P < 0.05). Increasing inclusion levels of Cu from TBCC or CuSO4 increased (P < 0.05) Cu concentrations of egg yolk and feathers. Feather Cu concentrations were greater (P < 0.01) for hens fed diets containing CuSO4 than for hens fed diets containing TBCC. The values for the RBV of Cu in TBCC to Cu in CuSO4 based on log10 transformed egg yolk and feather Cu concentrations were 107.4% and 69.5%, respectively. These values for the RBV of Cu in TBCC did not differ from Cu in CuSO4 (100%). The RBV measured in egg yolk did not differ from the RBV measured in feather. In conclusion, the RBV of Cu in TBCC to Cu in CuSO4 can be determined using Cu concentrations of egg yolk and feathers although the values depend largely on target tissues of laying hens. For a practical application, however, the RBV value of Cu in TBCC to Cu in CuSO4 could be 88.5% when the RBV values determined using egg yolk and feather Cu concentrations were averaged.

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Pigs' feet are traditionally consumed by Korean women to increase milk production during lactation. In this study, we evaluated the perceived effectiveness and safety of consuming pigs' feet. Parous women were recruited to complete survey questionnaires in South Korea. Of the 516 respondents, 188 (36%) claimed they consumed pigs' feet. One-hundred twenty women (64%) who consumed pigs' feet reported experiencing an increase in breast milk production. Seventy-three (61%) women from this same group exclusively breastfed. In contrast, 16 (25%) of 65 respondents who did not embrace the same purported effect of pigs' feet indicated that they solely breastfed. Ninety-eight (82%) respondents who consumed pigs' feet and reported galactagoguic effects would recommend its use. Study findings reveal that the majority of women who consume pigs' feet believe in its milk-promoting effects. The results of this study suggest that further investigation of the galactagoguic effects of pigs' feet via conduction of an experimental study is warranted.