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INTRODUCTION
1. BACKGROUND
Though the commercial pig production is an obvious trend at present and in the future, one of the biggest chanllenge for the development of the production is the environmental pollution from waste (dung + urine). Pig production emits NH3, ordorous and green house gases (GHG) into the air and releases N, P into land and water. Therefore, how to reduce the evironmental pollution from pig production is a research topic getting much attention from scientists, policy makers, producers as well as farmers.
In Vietnam, there have been studies on how to reduce the environmental pollution from pig raising. However, these studies are not systematic and mainly focus on investigating the situation of pollution and applying methods to handle waste effectively though. As a result, there is a shortage of significantly systematic research programs on how to reduce the evironmental pollution from pig production through nutritional approach while nutritient intake is the main cause leading to pollution in pig production.
With the above reasons, we choose the research topic: Study on several nutritional solutions to reduce the environmental polution in commercial pig production.
2. OBJECTS
- To determine the effectiveness of dietary supplementation of enzyme, organic acids and bentonite on performance of growing pigs, nitrogen, photporous excreted in feaces, emission of H2S and NH3 from slurry of pigs from 20 kg to selling weight.
- To determine the effectiveness of dietary supplementation of phytase on performance of growing pigs, nitrogen, photporous excreted in feaces, emission of H2S and NH3 from slurry of pigs from 20 kg to selling weight.
- To evaluate achievement of application of research results in farm conditions.
3. SCIENTIFIC AND PRACTICAL VALUES
- In scientific meanings: the obtained results from this thesis will be used as an initial scientific base for formulating and balacing diets of growing pigs to ensure that pig production was both environmental benefit and friendly environment. The obtained results also was a scientific base for further studies on diffrent kinds of pig such as swine and boar as well as valuable scientific reference documents in teaching, research and management.
- In practice meanings: the obtained results from this thesis were good recommendation for the development of commercial pig production in Vietnam to guarantee environmental and sustainable benifits for traders, pig producers and farm owners in formulating and balacing suitable diets of growing pigs at different stages.
4. NEW CONTRIBUTION OF THE THESIS
This was one of the first studies on reducing environmental pollution through dietary supplementation. The obtained results of the thesis showed that dietary supplementation of enzyme Kenzyme (300g/MT of feeds) or organic acids and or phytase were succesfull alternatives for unchanged performance and FCR and economic efficiency of growing pigs and at the same time, reduction in pollution (N and P excreted in faeces, NH3 and H2S gases emitted into the air).
5. CONTENT OF THESIS
The thesis consisted of 160 pages, 04 chapters, 51 tables, 13 pictures, 223 reference documents (14 in Vietnamese and 207 in English). There are 03 published articles related to this thesis.
Chapter 1: LITERATURE REVIEW
1.1. THE SITUATION OF PIG PRODUCTION IN VIETNAM IN RECENT YEARS
Pig production in Vietnam is changing from a small scale system in household farms to a large industrial scale in concentrated farms to meet a higher demand of food for consummers day by day.
According to the report of Animal Production Department (2015), it was estimated that in 2016, the total number of pig in Vietnam was 28,78 millions and will be about 30 millions in 2020.
1.2. PIG PRODUCTION AND ENVIRONMENTAL POLLUTION
Pig production can caused different kinds of environmental pollution such as: emission of green house gases (GHG), bad smell and ammoniac gases in to the air; changes of the quality of land due to N, P and heavy metals in waste; changes of the quality of the underground and surface water; potential of risks to the health of human and other animals.
Due to the fact that pig waste went into drainage systems and then went into underground water and soil, pathogens in pig waste can infect human and another animals and cause a local infection (Fisher và cs., 2000)
1.3.THE SCOPE OF THE THESIS
While nutrion intake has been studied intensively over the world to solve environmental pollution such as N and P pollution, smell and green house gases emision caused by pig raising, in Vietnam there has been a very few of studies of this kind, or there has been even none. Therefore, this study was undertaken to contribute to sold an existing knowlege shortage.
Chapter 2: MATERIAL AND METHODS
The thesis had 3 different parts: the 1st part contained 3 experiments, the 2nd part included one experiment and the 3rd part was the application of new findings in 03 pilot model farms of commercial pig production representing 3 climatic regions (North, Central and South). Materials and methods, therefore, were presented for each experiment.
2.1. STUDY ON THE EFFECT OF DIETARY SUPPLEMENTATION OF ENZYME, ORGANIC ACIDS AND BENTONITE ON COMMERCIAL PIGS IN THREE DIFFERENT STAGES
2.1.1. Experiment 1: The effect of dietary supplementation of enzyme, organic acids and bentonite on productivity, nitrogen, phosphorous excreted, H2S and NH3 emission from pig slurry of pig from 20-50 kg
2.1.1.1. Animal and the experimental design
The experiment was carried out on 30 hybrid Duroc x F1 (Landrace x Yorkshire) pigs with the initial weight of 20 kg. The experiment was in 2012 March-April (3-4/2012). Because the initial weight of pigs was not equal, RCBD designed experiment with 01 experimental factor was used. Experimental factor was ingredients supplied and included enzyme, organic acids, bentonite or a combination of the above. There were five treatments in this experiment as follows:
- The controlled group (BD): the basal diet (no enzyme, organic acid or bentonite supplement);
- The experimental group: the basal diet with enzyme supply (BD + enzyme (BD+ E) with 500 g/MT of feed (supplied enzyme: Kemzyme V Dry of Kemin (US); Xylanase (minimum 1875 U/g) and Cellulase (minimum 2500 U/g);
- The experimental group: the basal diet with organic acids (BD + organic acids (BD + A) with 3 kg/MT of feed; organic acid supplied: Biotronic SE of Biomin contained Propionic and Fomic acids;
- The experimental group: the basal diet with combined enzyme and organic acids supply (BD + Kemzyme V Dry, 500 g/MT of feed + Biotronic SE with 3 kg/MT of feed (BD + EA);
- The experimental group: the basal diet with bentonite supply (BD + bentonite (BD + B) with 2 kg/MT of feed (bentonite: Mycofix Secure of Biomin company), bentonie contained a special mineral: Smectite/ Montmorilonite - (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2·nH2O.
Six blocks was used in this experiment, each animal was one experimental unit.
2.1.1.2. Experimental diet and pig raising
Experimental diets was formulated on available materials such as maize, soya bean cake, fish meal, rice brain and cassava bagasse. ME, Ca, P and amino acids was supplied to meet the nutrient requirement of pigs as recommended by NRC (1998). Pigs were raised individualy in cages with an area of 0.8m x 2.2 m per cage. Each cage was equipped with a separated feeder, no automatic drinking water system. A hole of a size of 110cm x 50cm x 40cm, was put beneath each cage to store pig slurry from each animal. Pigs experienced 07 days of adaptation with a free access to feeds and water. During the eperimental period, the amount of feeds supplied to pigs equaled to 4.0% live weight (Feeding Standard of Japan, 1993, cited by National Institute of Animal Husbandry, 2001). This intake was calculated on estimated diary growth rates. Pigs had a limited water supply by mixing feed with water of a ratio of 1 to 4. No additional water supplied to make sure that the amount of feed and water given to each individual was similar to restrict the effect of waste dilution level on volume and surface of emission, which may cause environmental pollution and characteristic of waste (Le et al., 2005). Pigs were fed twice a day at 8:30 AM. and 15:30 PM. The amount of feed given and eaten was recorded every day. Pigs were weighed in morning before feeding at the beginning and the finishing of the experiment to calculate the ADG and FCR.
2.1.1.3. Sample collection and analyzing
After 07 days of adaptation, the waste hole was cleaned and the experimental period officially started. Dung and urine were continuously stored in the waste hole. Parameter measurements included N and P excreted in P in slurry, NH3, H2S - greenhouse gases emitted from surface of slurry and characteristics of slurry as well.
NH3 sample collection and the amount of NH3 emission calculation:
To determine NH3 emission, the sample of gases was directly taken from the air on the surface of waste hole according to the method of Le et al. (2009). Total of 30 gas samples was taken from 30 holes of waste for determining NH3 emission. After 26 experimental days, one cylinder tank without bottom was put in the waste hole. The bottom of the tank contacted with the bottom of the waste hole. The size of the tank surface was 312 cm2. Air went into the cylinder tank from the roof of the raising cage, and the input air sample was also taken to determine the amount of NH3 in input air . Air moved out of the cylinder tank though a suck up pump and an air speed controlling system of 1.0 littre/minute. This system was operated throughout the sample taking process in order to imitate the system of emission of gas NH3 from the waste hole. The output air went into two impingers contained 15 ml of 0.5M HNO3. NH3 gas was kept in impingers contained acid. This sample system was operated within 60 minutes.
H2S sample collection and the amount of H2S emission calculation:
The principles of sample collection and calculation of H2S emission were similar with NH3. Sample to determine H2S emission was collected by using a sample system, and the amount of H2S emission was estimated as in formula. HNO3 was replaced by Cadimi Sulfat 0.1M (CdSO4). H2S was absorbed in Cadimi Sulfat 0.1M. The volume of absorbed solution was 30 ml.
Slurry collection (dung + urine):
After 29 days, dung and urine in the waste hole were well-mixed, then 1 kg of sample was taken from every waste hole. Chemical parameters measured in slurry samples were: DM, total of N, P and pH.
After being mixed, feed samples were taken and analyzed for: DM, N, crude fiber, minerals, P and Ca. When the experiment finished, all of feed samples of different mixing times of each treatment were mixed together before sending to the Lab. for analysis
Analyzing method
Dried matter (TCVN 4326-2001), total of N (TCVN 4328-2007), P (TCVN 1525-01), Calcium (TCVN 1526-07), crude fiber (TCVN 4329 - 93), mineral (4327 - 93) were analyzed according to standard methods (TCVN). NDF and ADF were analyzed according to AOAC (973.18.01). pH level in feaces samples was measured by using pH meter HI 8424 HANNA (Made in Mauritius). All of these parameters were analyzed in the Lab. of Animal Feeds and Animal Product Analysis, belongings to National Institute of Animal Sciences.
2.1.1.4. Data analysis
The effects of experimental factors on ADG, FCR and of pig, N, P excreted, NH3 and H2S emission…were analyzed using ANOVA in Minitab 14.0 software. A mathematical model for ANOVA as follows: yij =μ+αi+ρj+ eij
Where: yij = dependent variable; αi = effect of experimental factor; ρj = effect of block; eij = random error.
The value of dependent variables was checked for identically characteristic of variation and normal distribution. When the value p of ANOVA was <0.05 (H0 hypothesis was rejected), comparison of post variation (post hoc) was used using Planned Ontological Contrast technique (Kuehl, 2000) with 04 ontological contrary coefficients as presented in Table 2.1.
Table 2.1. Four orthogonal contrary coefficients (C)
Experiment treatmen (group) / Contrary coefficient (C)C1 / C2 / C3 / C4
BD + Enzyme / 1 / 1 / 1 / 1
BD + Organic acids / 1 / 1 / 1 / -1
BD + Enzyme + Organic acids / 1 / 1 / -2 / 0
BD + Bentonite / 1 / -3 / 0 / 0
BD (control) / -4 / 0 / 0 / 0
Among them, C1 was used to compare the experimental groups with controlled group, C2 was used to compare the experimental group with bentonite with 03 other experimental groups with enzyme, organic acids and enzyme + organic acid; C3 was used to compare the experimental group with enzyme + organic acids with the experimental group with only enzyme or organic acids; C4 was used to compare experimental group with organic acids with experimental group with enzyme. p<0,05 (significant difference) was used to compare experimental group differences.
2.1.2. Experiment 2: The effect of dietary supplementation of enzyme, organic acids and bentonite on nitrogen, phosphorous excreted, H2S, and NH3 emission from pig slurry of pig from 40-70 kg
2.1.2.1. Animals and experimental design
This was similar to experiment 1. Only one different thing was that the initial weight was higher (0.5 ± 1.6 kg/head (Mean ± SD).
2.1.2.2. Experimental diet and pig raising
This was similar to experiment 1. Only one different thing was that analysed crude protein and ME in diets was lower. They were 15%; and 13.6 MJ/kg DM of feed.
2.1.2.3. Sample collection and analyzing
This was similar to experiment 1.
2.1.2.4. Data analysis
This was similar to experiment 1.