Preliminary Study Of The Supply Plan: Optimization Of Copper, Iron, Zinc, And Manganese In Laying Hen’s Diet

The study was conducted to investigate the effects of trace minerals(copper, iron, zinc, and manganese) on laying hens’ production performance, egg quality, and the apparent utilization of nutrients, and therefore seek to rationalize the supply plan for laying hens by optimizing the effective dosage of trace minerals. A single-factor completely random design was adopted in this study: 540 Lohmann brown shell laying hens(25-week old) were randomly divided into 5 treatments(see the schematic figure), with 6 replicates per treatment and 18 feathers per replecate. Five batches of basal diet were prepared during the whole experimental period, with the ingredients from the different batch of feed product; meanwhile, five groups of basal diet were prepared in each bacth, with the ingredients from the same batch of feed product. In particular, these five groups include:(i) group B – without any trace minerals and feeding basal diet;(ii) group B + N – with trace minerals according to NRC(1994), regardless of those in the basal diet;(iii) group B-MN – three of the trace minerals were increased according to the other trace mineral, which had the highest ratio in basal diet to the NRC recommended one;(iv) group 30% B- MN – the concentration of trace minerals in the basal diet was conversed into effective concentration(assuming that the biological titer of trace minerals in the basal diet was 30%, and the NRC recommends were seen as effective ones), with each minerals complemented according to the NRC standards;(v) group 30% B-ON – the concentration of trace minerals was conversed into effective concentration in the diet and then complemented with methionine chelate salt according to the NRC recommends(we assumed that the biological titer of methionine chelate salt was 150% of the sulfate. The feeding experiment lasted for 15 weeks, duiring which time the hens was fed ad libitum, after which the production performance, egg quality, nutrient apparent utilization rate were measured and recorded.The results showed that there was no significant difference in mineral concentration amongst different diet groups from the same batch, whilst a significant difference was observed between those diet groups from different batches(P < 0.01); the feed intake, feed/egg ratio, egg rate, broken egg rate, and egg weight were not notedly affected between different treatment groups; it is interesting that during 6-10 week, the death rate of group B-MN was prominently lower than those of group B(P < 0.01) and group B + N(P < 0.05); there were no substantial differences in the eggshell color, egg-shaped index, hartz unit, and egg yolk color between different treatment groups, as well as the content of four trace minerals in egg yolk and egg white; during week 6-10, the eggshell intensity of group B-30% MN was significantly increased, compared with group 30% B-ON(P < 0.01) and group B(P < 0.05); during week 1-5, the shell thickness of group B was appreciably lower than those of the other groups(P < 0.01). The energy and the apparent utilization of crude protein and phosphorus showed no significant differences. Nevertheless, the apparent utilization of calcium was notebly higher than those of the other groups(P < 0.05).Overall, the results obtained in this study indicated that:(i) the basal diet batch determined the diet content of trace minerals;(ii) the complementation method of trace minerals according to the largest ratio of trace minerals to the NRC ones decreased the death rate;(iii) the supplementation method of the concentration of trace minerals in the basal diet was conversed into effective concentration(assuming that the biological titer of trace minerals in the basal diet was 30%, and the NRC recommends were seen as effective ones), with each minerals complemented according to the NRC standards improved the egg quality and the apparent utilization of calcium.