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Publisher: PVNR TVU
Type: Thesis
Series/Report no.: D;442
Agrotags: biological phenomena, livestock, eggs, zinc, proteins, layering, productivity, minerals, concentrates, enzymes
Abstract: Zinc (Zn) is one of the dietary essential minerals which exerts various metabolic functions by influencing various enzymatic activities in the biological system. It is required for normal growth, skeletal development, immune system function as well as egg production. NRC (1994) recommended 35 ppm of Zn for White Leghorn (WL) layers. These recommendations were established two decades ago, considering the egg production as principal criterion, the relevance of which is questionable for the current genetically improved WL layers which prone to more stress. It is mostly supplemented from inorganic sources like zinc sulphate (ZnSO4), zinc oxide (Zn0), etc. The lower retention coupled with higher levels of mineral salts supplementation results in excess of mineral excreted in poultry manure. Organic sources are gaining attention in poultry • due to better bioavailability than their inorganic sources. An experiment was conducted with an aim to study the effect of organic Zn supplementation on performance, antioxidants status, immune response and retention of Zn in WL layers. Seventy two WL layers at thirty eight weeks age were randomly allotted to 72 replicates considering each bird as a replicate. The hens were reared in individual California type cages having the provision of individual feeding. A corn-soybean meal, deoiled ricebran basal diet (BD) was prepared for layers to meet the nutritional requirements, as recommended by NRC (1994) except Zn. Experimental diets were viz., BD with 35 ppm Zn supplementation from ZnSO4 (inorganic) and BD with Znbioplex (organic) at 35, 70 and 105 ppm. Each diet was allotted to 18 replicates and fed ad libitum from 38 to 50 weeks of age. Body weights, feed intake and feed conversion ratio (FCR) were measured period wise. At the end of each 28 days period, eggs were collected during the last 5 days from all the birds to record egg weight and egg quality parameters. The Zn content in egg was measured using Atomic Absorption Spectrophotometry. The cell mediated immune (CMI) response was assessed by measuring cutaneous basophilic hypersensitivity to phytohemagglutinin P (PHA-P) and humoral immune response (HI) by log2 titre against New castle Disease vaccine was measured after 10 weeks from the starting of experiment. At the last week of feeding trial, blood samples were collected from 8 birds of each dietary treatment to collect serum and measure antioxidant enzyme activities. Increasing the concentration of organic Zn from 35 ppm to either 70 or 105 ppmin diets of WL layers had no further advantage on feed intake, FCR, hen day egg production, egg weight and body weight gain, which were comparable to those fed 35 ppm inorganic Zn. Similarly, the organic Zn supplementation at 35ppm level and two fold increase in dietary concentration did not influence the egg quality parameters significantly (P>0.05). However, serum ,total protein concentration was significantly (P<0.05) higher (3.44 01) in layers supplemented with 70 ppm organic Zn compared to other dietary treatments. Serum Ca and P values were not effected by source and level of Zn. Lipid peroxidation (nmol MDA/mg protein) (TBA concentration) was highest (P<0.05) in WL layers with 35 ppm Zn supplemented as Zn-bioplex compared to 70 and 105 ppm Zn as Znbioplex and 35 ppm as ZnSO4. The antioxidant enzymes measured in present study were uperoxide dismutase (SOD) and catalase. Significantly (13<0.05) highest and lowest SOD activity was observed with 70 and 35 ppm Zn supplementation, respectively. The catalase activity was comparable among all dietary groups and the activity varied from 39.91 to 55.91 units/mg protein. Humoral and cell mediated immune responses were not affected by source and levels of Zn supplementation. Similarly, the Zn deposition (ppm) in eggs was not increased though increasing the Zn supplementation from 35 to 105 ppm as organic Zn and these values were statistically comparable with birds fed with control group.Based on the results, it is concluded that dietary Zn concentration of 35 ppm is optimum in the diets of WL layers for egg production and proper egg quality. For better performance and stress alleviation, inorganic Zn of 35ppm (NRC recommended) can be replaced with organic Zn at the same level.
Subject: Poultry Science
These Type: M.SC
Issue Date: 2015-12-02
Appears in Collections:Thesis

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