1346
With the objectives of: 1) to develop a model of subclinical zinc (Zn) deficiency in sheep, and 2) to estimate the relative bioavailability (RBA) of Zn from a Zn amino acids complex relative to Zn sulfate (ZnSO4) in lambs, two trials were carried on.\nIn the first experiment, 10 Corriedale lambs wit...
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| Formato: | Tesis doctoral acceptedVersion |
| Lenguaje: | Español |
| Publicado: |
Universidad de Buenos Aires. Facultad de Ciencias Veterinarias
2016
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| Acceso en línea: | http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=avaposgra&cl=CL1&d=HWA_1346 https://repositoriouba.sisbi.uba.ar/gsdl/collect/avaposgra/index/assoc/HWA_1346.dir/1346.PDF |
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| Sumario: | With the objectives of: 1) to develop a model of subclinical zinc (Zn) deficiency in sheep, and 2) to estimate the relative bioavailability (RBA) of Zn from a Zn amino acids complex relative to Zn sulfate (ZnSO4) in lambs, two trials were carried on.\nIn the first experiment, 10 Corriedale lambs with an average weight of 10.09 kg were randomly assigned to two groups: Basal (B) and Supplemented with Zn (Z). Diet B contained 10 ppm of Zn, dry matter (DM) basis, and the Z diet was supplemented with ZnSO4, to provide an extra level of 30 ppm Zn. The trial lasted for five months, during which the animals were weighed monthly. Also with this periodicity, they were bled from the jugular vein for subsequent measurement of hematological parameters and Zn, Cu and alkaline phosphatase (ALP) concentration in plasma. At 45 days and at the end of the experimental period, Zn, Cu and nitrogen (N) balance assays were performed. Subsequently, we proceeded to the slaughter of animals and samples of muscle (longissimus dorsi, suprascapular and semimembranosus), liver, pancreas, testis, kidney, lung, bone (metacarpus and metatarsus) and wool were collected for Zn and Cu determination. In addition, skin samples (flank and belly zones), bone (metacarpal and metatarsal distal thirds), testis, pancreas and epithelium of tongue, esophagus, rumen and bladder were also taken to be histologically processed. Weight gain and wool quality were similar in both groups, while wool production was higher in the Z group. Plasma Zn levels were significantly higher in the Z group than in the B group, but ALP plasma levels, hematocrit, hemoglobin concentration, and erythrocytes, leukocytes and lymphocytes in blood did not differ between groups. The plasma Cu tended (p <0.10) to be higher in group B. According to the first trial balance, Zn and N retention were significantly higher in the group Z. The percent retention of Zn in group B was increased and it showed the activation of homeostatic mechanisms. Cu retention tended (p <0.10) to be higher in group B. In the second trial balance the results (Zn, Cu and N) were similar.\nIn the second experiment, 20 Corriedale lambs, weighing 15.3 kg, were randomly assigned to five groups: Basal (diet with 10 ppm Zn), supplemented with ZnSO4 and a Zn-amino acid complex to provide, in either case, additional levels of 10 and 20 ppm. With animals, we worked with a methodology similar to the first experiment. For the determination of the RBA of Zn from Zn amino acid complex compared to ZnSO4 were chosen five variables linearly respondents, in the two sources, to increasing doses of Zn. They were apparently digested Zn (periods 1 and 2), Zn retention (periods 1 and 2) and liver Zn. Although in all five cases the slope of Zn amino acid complex was numerically greater than that of the standard source (RBA between 105 and 125), the differences were not statistically significant.\nTaken together, the results of both studies demonstrate the validity of Zn deficiency model, in which various indicators can be used in assays of RBA. Under the conditions of our assay, the RBA of Zn from Zn amino acid complex does not appear to be higher than that of ZnSO4. |
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