Luận án Utilization of cassava forages for goat production in An Giang province, Vietnam

eld in the present study ranged from 0.53 to 0.83 tonnes ha-1 about 11 months of growth. The differences in results are probably due to the differences in the variety, soil fertility, harvesting time, climate (Moore, 1976; Khang et al., 2004). 
3.1.6. The fresh and dry yield of cassava proportion with different variety 
In the present study, after root harvesting, there was cassava plant remains. Cassava plants were divided into two parts: hard stems (one third above the soil of cassava plant) and cassava forages (two third of aerial part of cassava plant). It was described in Figure 2.1 & 2.2). The fresh and dry weight proportion of cassava plant is shown in table 2.6. The cassava forage was differences between two varieties of cassava. The proportion of sweet cassava forage was higher than the bitter cassava. The reason is that the harvesting time of bitter cassava was a long time after planting (10 – 12 months) while, the harvesting time of sweet cassava was 6-8 months, the plant has more leaves, shorter and softer stems. The mean dry leaf proportion of sweet cassava forage was high (51.7%) similar to an earlier study by Meyrelles et al. (1977), the leaf propostion of cassava forage on DM basic was almost 52%, but it was slightly lower than found in study result of Khang et al. (2004) (59%). These results were different due to the differences in variety, farming conditions, regions, soil, and fertilization and cutting time. 
Table 2.6: Yield of cassava proportion with different variety 


Sweet cassava (tons/ha)
Proportion %
Bitter cassava (tons/ha)
Proportion
 %
Fresh cassava plant




Hard stems
13.2 ± 3.6
33.5
17.2 ± 4.5
54.0
Cassava forage
26.2 ± 7.2
66.5
14.7 ± 3.8
46.1
 Cassava stems
8.7 ± 2.4
22.1
4.9 ± 1.3
15.3
 Leaves + petiole
17.5 ± 4.8
44.4
 9.8 ± 2.5
30.7
DM cassava plant




Hard stems
5.5 ± 1.5
49.1
6.4 ± 1.6
62.1
Cassava forage
5.7 ± 1.6
50.9
3.9 ±1.0
37.9
 Cassava stems
2.1 ± 0.5
18.4
1.2 ± 0.3
11.3
 Leaves + petiole
3.6 ± 1.0
32.5
2.7 ± 0.76
26.6
CP of cassava forage in DM (tons/ha)
0.79 ± 0.23
-
0.52 ± 0.15
-

3.2. GOAT PRODUCTION IN AN GIANG PROVINCE
3.2.1. Ruminants population in An Giang from 2014- 2017
Goat production in An Giang increased 3.2 times from 2014 to 2017. The reasons for this increase were that goat are easy to raise, are a low investment, there is an increasing price and increasing consumption of goat meat, in not only An Giang but also in the whole country. 
Table 2.7. Population of ruminants in An Giang from 2014- 2017 
 Unit: heads
Ruminants
Year
2014
2015
2016
2017
Goat
4,325
7,876
11,905
13,950
Cattle
109,306
111,709
96,040
81,543
Buffalo
4,181
4,013
3,876
3,265
 Source: Statistical yearbook of An Giang 2018
In recent years, goat production in An Giang is shown in table 2.7. Based on the survey, the climate, weather and natural conditions were suitable for developing goat raising. The total area of hilly land in An Giang is about 29,320 ha, accounting for 8.6% of the total land area of the province. There are natural grass and agricultural by-products all year round, there is a clean water source, farmers love raising and goat raising, therefore, goats were raised a long time ago in An Giang. However, goat raising is still not much developed, because goats were raised by traditional farming, farmers did not utilize by-product efficiency. 
Goats were raised and concentrated in the Phu Tan - Tan Chau districts to the mountainous areas of Tri Ton and Tinh Bien. Currently, the goat production in 2017 was 13,950, the most was in Tinh Bien (2,428); Tri Ton (2,245) (Statistical An Giang yearbook, 2018). The number of goats in 2017 increased by 3.2 times compared to 2014, because the price of goats in the market increased sharply, while households with more than 20 heads / household accounted for 49.2%. 
3.2.2. Goat farm size and purpose raising in An Giang province
Base on the survey results, the farm size and structure of goats in the Tinh Bien and Tri Ton districts are presented in table 2.8.
The goat farm size were divided into three groups: the group of raising households below 10 accounts for the lowest percentage, the number of households raising over 20 heads accounts for a high percentage (59%), this result was higher than the research results of Nguyen Binh Truong (2016) goats raised in Tinh Bien district were 26.7% with households raising more than 20 heads per household. Thus, Goat breeding in An Giang, especially Tinh Bien area developed and increased clearly.
Table 2.8. Farm size and purpose raising 
 
Items
Tri Ton
Tinh Bien
Total
percentage %
Number
percentage %
Number
percentage %
Farm size (Household)






1-<10 heads/farm

14
23.3
5
8.3
19
15.8
10-20 heads/farm
27
45
15
25
42
35.0
> 20 head/farm
19
31.7
40
66.7
59
49.2
Purpose raising (Heads)






 Meat
691
62.9
1,163
95.1
1,854
79.8
  Breeding
408
37.1
60
4.9
468
20.2
 Total
1,099
 
1,223
 


The purpose of raising goats here was mainly to sell meat at 79.8%, in addition to raising goats with the purpose of selecting good ones in the herd to sell goats for local market, or neighbourhood; but account for a smaller percentage (20.6%). In addition, markets for goat production (eg: milk, cheese, ...) are in the cities providing farmers with better income and opportunities for further development (Nguyen Van Thu, 2016). There is a high demand for goat meat in many different areas of Vietnam from the North to the South and the rate of increase in the number of goats annually is not sufficient to meet the demand. Therefore, many farmers and companies are preparing to build large commercial farms with the importation of dairy goat breeds for both milk and meat.
3.2.3. Goat prodution systems in An Giang
The results in Table 2.9 showed that goats were raised intensive, semi- intensive and extensive systems and intensive was highest (55%).
Table 2.9. Goat production systems in Tri Ton and Tinh Bien district

Number of farms in district
Total
Percentage, %
Management 
Tri Ton
Percentage, %
Tinh Bien
Percentage, %
Intensive 
31
51.7
35
58.3
66
55.0
Semi-intensive
27
45.0
25
41.7
52
43.3
Extensive 
2
3.33
0
0.00
2
1.67
	Intensive systems are the main method of goat raising in An Giang, this result was similar to the results of Nguyen Binh Truong (2016) who found raising goats by intensive systems was 66.7%. This systems of complete confinement helps the farmers manage each individual, can detect disease or manage oestrus in a timely manner, but feed had to controled actively, while semi- intensive systems help goats have time to graze, develop the right features and reduce the reserve of food. According to the study of Bounmy and Nguyen Xuan Trach (2010) in Laos, semi-grazing is the most common farming method, accounting for 100% of the surveyed households. By- products, storage or processing of goat feed reserves have not been considered. Goat grazing is restricted in farming areas because goats are destructive, eating a variety of foods affecting other households' crops. Although raising by completely captive raising methods, the farmers in the surveyed areas still raise their livestock in the traditional way, around the farming area, there were any kind of edible plants that can be used, not interested in the demand. Nutrition for goats, how to coordinate, reserve feed sources for goats to ensure nutritional needs according to each stage of their development are not of interest in this system. In addition, extensive farm is causing increase green house gas (GHG) emissions as Alexandra and Irene (2015) reported that GHG emissions were particularly high in the extensive farm, because of its low productivity and the excessive use of pastures in livestock feeding. Therefore, intensive systems can manage feed and limite methane emissions from ruminants. 
3.2.4. Feed and feeding systems
Goat feed is very diverse in Tinh Bien and Tri Ton district, beside natural grass, there are many kind of leaves, eg: jackfruit leaves, magic vegetables, banana leaves, peanuts, and sweet potatoes, but limited in quantity. In the survey area, the main feed is natural grass, 100% of the households use natural grass and a source of locally available by-products except cassava leaves. Few households (21.7%) among surveyed households grew grasses: elephant grass, VA06 grass to supplement feed in the dry or flooding season or at harvest time. In addition to the main feed source of natural grass and seasonal byproducts, a few households had supplied salt (38.3%), rice bran (18.3%); very few households used concentrate supplement, all fewer households (35%) did not supply supplements. The farmers did not care about quaities or chemical composition of grass or by-product, so they did not supply enough nutrition for their goats, especially in the dry season (from February to May). The results were slowly growth rate, and low production. Beside that, the nutritional supplement, especially protein sources, mineral, visibly improve productivity of goats (Phengsavanh, 2003; Keopaseuht et al., 2004; Bounmy Phiovankham and Nguyen Xuan Trach, 2011). 
Table 2.10. Feed and feeding systems for goats in Tri Ton and Tinh Bien district

Tri Ton
Tinh Bien
Items
Household
percentage, 
%
Household
percentage, 
%
Feed 




 Natural grass
60
100
60
100
 Natural grass + Leaves (except CL)
9
15
4
6.67
 Natural grass + by-products 
28
46.7
36
60
 Natural grass + cassava forage
4
6.67
2
3.33
 Natural grass + Grass growing
13
21.7
13
21.7
 Natural grass + Commercial concentrate
6
10
5
8.33
Supplements




 Salt
15
25.0
23
38.3
 Rice bran
9
15.0
11
18.3
 Commercial Concentrate
5
8.3
5
8.33
 No supplement
31
51.7
21
35.0
Note: CL: cassava leaves




3.2.5. Diseases and diseases management
The survey results of 60 households raising goats in 2 districts (Table 2.11) show that 50.8% of total households have never used vaccines for goats. The most common disease for goats was often diarrhea (26.9%), other disease eg: coughing, sneezing and rumen bloating, accounting for 23.4%. Although there are veterinary facilities in the communes of the two districts surveyed for animals welfare, the farmers used less vaccine to prevent diseases. Farmers often bought drugs for injection those diseases such as diarrhea, fever and cough. In recent years, there have been occasional illnesses such as mouth ulcers. People often used traditional method such as finding some leaves to apply to ulcers. For other diseases such as rumen bloating, and mastitis most farmers have not found any cure for goats. This is causing low goat production. 
Table 2.11. Diseases and diseases management of goats 
Diseases and management
Tri Ton
Tịnh Bien
Total
Percentage, %
Household
percentage, 
%
Household
percentage,
%
Diseases






Parasites 
4
4.9
5
5.6
9
5.3

Mouth ulcer
15
18.3
13
14.6
28
16.4

Diarrhea 
25
30.5
21
23.6
46
26.9

Infectious diseases
15
18.3
14
15.7
29
17

Difficult birth
5
6.1
14
15.7
19
11.1

Others (cough, Sneeze, rumen bloating;,...)
18
22
22
24.7
40
23.4
Diseases management






Vaccine
17
28.3
28
46.7
45
37.5

No vaccine
37
61.7
24
40.0
61
50.8
 
Deworming
6
10.0
8
13.3
14
11.7
4. CONCLUSIONS 
In An Giang province, goat production is developing with promising conditions of abundant feed resources, good government policies, improved research results, good markets and efficient development strategies. However, some constrains for production development such as low breed quality, lack of large farms and improving nutrient of feed, limited knowledge, poor marketing and less international co-operation should be improved for a sustainable goat production and dairy goat production also. Beside that, cassava forage has potential in An Giang. The average of dry matter cassava forages was 5 ton/ha in 2017. They can be used as a protein source, as a replacement for grass for ruminants but farmers did not use because it is high HCN content. How to use and preserve cassava (including the stems) as feed ruminants and against toxicosis by reducing HCN content. The other thing, after a few days root harvesting, leaves will fall down, cassava stems were only remaining. Based on that situation, the study of utilizing is not only cassava forage, but also cassava stems necessary and practically by alkaline method. Therefore, the interest in using urea treated cassava stems could be improved with improved nutritive value and preservation. 
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CHAPTER 3
USING UREA TO TREAT CASSAVA STEMS AND EFFECT OF WATER SPINACH AND BIOCHAR ON FEED INTAKE, DIGESTIBILITY AND N-RETENTION IN GOATS FED UREA TREATED CASSAVA STEMS
Abstract
The specific objectives were to determine what level of urea treated cassava stems would facilitate the storage, improving nutritive value and the same time improve its digestibility. Then, determining the synergistic effect of biochar and water spinach on growth of goats fed urea treated cassava stems. There were two experiments: Treated cassava stems with 5 levels of uera (0; 1; 2; 3; 4 % in DM) as treatments and 4 replications. All treatments were kept in anaerobic conditions. Treated cassava stems appearance characteristics were observed, pH value, HCN, tannin content and chemical composition were measured at the storage times (0; 2; 4; 6 and 8 weeks). The results were that with 8 weeks storage, urea treated cassava stems were preserved of high quality in the evaluation of color, ammonia, mold appearance, and pH. Cassava stems treated with 3% urea level in DM had improved nutrient value. Urea treatment of the cassava stems increased the crude protein from 5.5 to 11.7% in DM and urea treatments were effective in delignifying HCN content of cassava stems. Moreover, this level of urea is needed to prevent mould in cassava stems ensiled with urea. The 3 % level of urea in DM was the best treatment and chosen for the next experiment.
 Four “Bach Thao” goats (LW 14 ± 2 kg) were fed urea-treated cassava stems alone (UCS) or with a supple