Calcium supplementation in low nutrient density diet for meat ducksimproves breast meat tenderness associated with myocyte apoptosisand proteolytic changes

摘要

To define the relationship between dietary nutrient density, calcium (Ca), and meat quality in meatducks. A total of 288 male Cherry Valley SM3 medium ducklings were fed a common standard starter dietuntil d 14. At 15 d of age, ducks were randomly divided into 2 treatment groups and fed either a conventionaldiet or a low nutrient density (LND) diet. Compared with the conventional diet, the energy wasreduced in the LND diet by 8.6% and 16.8% in grower (15 to 35 d) and finisher (36 to 56 d) phases,respectively, while other essential nutrients were kept proportionate to energy. The LND diet decreasedthe shear force (P < 0.05) and increased the lightness values of the pectoralis muscle when compared tothe conventional diet, suggesting that LND diet exerted a beneficial role in meat quality. Subsequently,the effects of grated Ca in the LND diet on meat quality of pectoralis muscle were evaluated. A total of 576male ducklings were fed a common starter diet until d 14, followed by feeding 4 LND diets with 0.5%,0.7%, 0.9%, and 1.1% Ca. The results show that LND diets with 0.7% or more Ca decreased the shear force ofpectoralis major muscle in 42-d-old meat ducks (P < 0.05). To explore the mechanism underlying Ca andtenderness, data from birds fed either 0.5% or 1.1% Ca in the LND diet indicated that birds fed 1.1% Caexhibited lower shear force, upregulated calpains 1 expression, and higher calpains activity compared tothose fed the LND diet with 0.5% Ca (P < 0.05). Moreover, the 1.1% Ca LND diet induced a higher myocyteapoptosis (P =0.06) and upregulated mRNA expression of caspase-3 (P =0.07) in breast muscle. Our datasuggest that LND diets with 0.9% or 1.1% Ca had a positive role in the tenderness of breast meat,particularly the enhancing effect of 1.1% Ca LND diet on tenderness seems to be associated with proteolyticchanges of myofibrillar proteins and myocyte apoptosis in meat ducks.