Evaluation and Optimal Down-Stream Processing to Recycle Unfasted Stomach Spent Feed for Pig

다국어 초록 (Multilingual Abstract)

Two trials were conducted to investigate the significance of the un-fasted stomach spent feed (USSF) as either reducible or recyclable waste. Trial 1 was carried out to examine physico-chemical and microbiological properties of USSF and to develop the optimal pretreatment or processing method of wet USSF to enable recycle. Trial 2 was carried out to evaluate the feed-nutritional value of USSF upon feeding to finishing pig.

In trial 1, freshly retrieved wet USSF was mixed with pig feed then either pelleted or fermented to develop proper and cost-effective processing method to enable recycling of USSF. Moisture content of wet USSF retrieved at an abattoir was near 70% and its pH was 4.52, which was relatively acidic. Average particle size of dried USSF was 1,869 μm suggesting faster gastric emptying of finer particle.
After drying, the protein and GE content of USSF were close to those of pig feed, suggesting its potential as feed. Fermentation was able to extend storage life of USSF mixed feed. Successful pelleting of USSF + pig feed mixtures was achieved and able to improve storage life of the mixture as pellet feed. Therefore, less than 20% portion of USSF blending with pig feed was recommend to enable proper mixing, handling, pelleting and storage.
In trial 2, two levels (5 and 10%) of USSF were respectively mixed with 95% and 90% of formula feed and 100% formula feed was prepared. Three diets were designated as 0:100, 5:95 and 10:90 according to each respective blending ratio. In addition, 100% USSF was also subjected to in vitro digestion trial. In vitro, DM and OM digestibilities of USSF mixture were relatively lower (P<0.05) than those of commercial pig feed, regardless of its site of in vitro gut simulation. This decrease in digestibility was presumed to represent partial digestion of DM in the stomach.
For pig feeding study in trial 2, a total of 42 finishing pigs were allocated into three groups (seven male and seven female pigs per each group). The pigs with 81.45 kg average initial body weight were fed 28-days until marketing. Feed and water were provided ad libitum. For in vivo digestion trial, 0.3% chromium oxide was added to the test diets. The result indicated that BW and digestibility were not significantly different (P>0.05) between treatments and control. There were also no difference (P>0.05) in carcass grade among substitution levels of USSF with pig diet. Therefore, trial 2 showed that USSF can successfully replace finishing pig diet up to 5% level.
Overall, this study implied that the nutritive value USSF is almost similar to that of precedingly consumed feed before slaughter. Farm level routine practice of pre-slaughter fasting should be implemented to decrease the amount of this valuable USSF generation. Otherwise, retrieval and recycle of the USSF as pig feed could be practiced without any sacrifice on pig performance once properly processed.

목차 (Table of Contents)

• Abstract i
• Contents iii
• List of tables and figures vi
• List of Abbreviations viii
• I. Introduction 1
• II. Literature review 3
• 1. Overview on un-fasted stomach spent feed (USSF) 3
• 1.1. The definition of USSF 3
• 1.2. Pig stomach 3
• 1.3. Digestion in stomach 3
• 1.4. Microbial flora in stomach 4
• 1.5. Gastric emptying 4
• 1.6. Amount of USSF 6
• 1.7. Environmental significance of USSF 6
• 2. Recycle of feed and food waste 7
• 2.1. Fermentation 7
• 2.2. Blending and mixing 8
• 2.3. Pelleting 8
• 3. Pre-slaughter handling of pig 9
• 3.1. Advantage and disadvantage of pre-slaughter fasting 9
• 3.2. Dietary supplementation during abattoir lairages 10
• III. Trial 1. Development of optimal down-stream processing of un-fasted stomach spent feed to recycle as pig feed 12
• 1. Introduction 12
• 2. Materials and Methods 13
• 2.1. Experimental and USSF preparation 13
• 2.2. pH and chemical analyses 13
• 2.3. Blending evaluation 13
• 2.4. Angle of repose and drip water 13
• 2.5. Evaluation of storageability 14
• 2.6. Fermentation 14
• 2.7. Pelleting and pellet quality 14
• 2.8. Palatability evaluation 15
• 3. Results and discussion 16
• 3.1. Change in pH of USSF by blending 16
• 3.2. Change in moisture by blending 16
• 3.3. Storageability of USSF and its blends with pig feed 18
• 3.4. Fermentation of USSF 19
• 3.5. Pelleting of USSF 19
• 3.6. Palatability test 19
• IV. Trial 2. Nutritive value of un-fasted stomach spent feed as partial substitute of finishing pig diet 22
• 1. Introduction 22
• 2. Materials and Methods 24
• 2.1. Preparation of USSF 24
• 2.2. In vitro digestibility 24
• 2.3. Animal, diets and management 25
• 2.4. In vivo nutrient digestibility trial 25
• 2.5. Chemical analyses 26
• 2.6. Carcass grade evaluation 26
• 2.7. Statistical analysis 26
• 3. Results and Discussion 29
• 3.1. Characteristics of USSF 29
• 3.2. In vitro digestibility of USSF 29
• 3.3. Growth performance 30
• 3.4. In vivo nutrient digestibility 31
• 3.5. Carcass grade 32
• 4. Conclusion 34
• V. References 35
• Acknowledgement 46