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| Author(s): |
Aline Mondini Calil Racanicci
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2000-06-21 |
| Advisor: | José Fernando Machado Menten |
| Abstract | |
Meat and bone meal (MBM) is an important animal by-product used as a feed ingredient in poultry diets because it is a source of calcium, phosphorus, essential amino acids and energy. However the lipid fraction of MBM is very susceptible to oxidation because it contains hight amounts of unsaturated fatty acids, especially oleic and linoleic acids. The objectives of this study were to assess the variation in quality of MBM during an extended storage period (10 weeks), evaluate the effects of the antioxidant BHT on MBM and the performance of broilers fed diets containing these MBM. A fresly produced batch of commercial MBM was divided into six portions: one was stored with no BHT added and the others were treated with 500 mg BHT/kg at different times (day 0, 7, 14, 21 and 28 begining on the day of production). The quality of MBM was evaluated through weekely samplings, and peroxide value (PV) was the main parameter analysed. After that, a feed trial was carried out using 1,440 male Ross X Ross day-old chicks raised in floor pens in an experiment with six treatments and six replicates. Treatments were CONTROL (diet containing MBM without BHT), BHT/0, BHT/7, BHT/14, BHT/21 and BHT/28 (diets with MBM treated with BHT on d 0, 7, 14, 21 and 28). The birds were fed ad libitum cornsoy diets formulated to contain aproximately 4% MBM and 22.0, 21.0 and 19 % CP and 3,000, 3,050 and 3,100 kcal ME/kg in the 1-21 d, 21-35 d and 35-42 d periods, respectively. Results of 42 d liveweight (LW), feed intake (FI), feed:gain ratio (F/G) and mortality + culling (Me) in the overall period were submitled to analysis of variance; treatment means were compared to CONTROL using Dunnet's test at 5% probability leveI. There was an increase in the PV of untreated MBM during the storage period, reaching levels above the accepted by industry (10 meq/kg) after the second week. When BHT was added up to 7 d of storage, it was effective in preserving the quality of MBM and PV maintained at zero until the end of the experiment. When the oxidation process was already started (BHT/14 through BHT/28), the addition of BHT did not prevent PV from increasing. Although rancidity was observed in MBM after storage, the levels of PV found (maximum 80 meq/kg) did not adversely affect bird performance. The results indicated that, although there was a significant difference (P<.05) on LW and FI of BHT/28 relative to CONTROL, in general it appears that the addition of the antioxidant BHT in the MBM used in this study did not affected the performance of the broilers. The additions of 500 mg BHT/kg in MBM was effective in preventing oxidative rancidity when done on the fresh product or after seven days. Under the conditions of this study, MBM with no antioxidant added maintained PV below the maximum allowed (10 meq/kg) for one week only. MBM with PV around 80 meq/kg, when added to broiler diets at rate of aproximately 4% and fed from O to 42 days, did not appear to be detrimental to the performance of the birds. (AU) | |