Livestock Husbandry: Pig Feed Improvement

		Pig Feed Improvement through Enhanced Use of Sweet Potato Roots and Vines in Northern and Central Vietnam
		Contents:
		INTRODUCTION
		PART I -SELECTING AND GROWING SWEET POTATO FOR LIVESTOCK
		1	Technology for growing dual-purpose and forage-purpose sweetpotato in the Northern Midlands of Vietnam
		2	Technology for growing dual-purpose and forage-purpose sweetpotato in the Red River Delta of Vietnam
		3	Technology for growing dual-purpose and forage-purpose sweetpotato in North-Central Vietnam
		PART II - SWEETPOTATO ROOT AND VINE PROCESSING AND FEEDING TO PIGS
		1	Sweetpotato vine and root ensiling methods and use of silage as pig feed
		2	Feed crops and their processing and storage methods
		3	Composition of concentrate feed mixtures (basal feed) and the rations for pigs for various weight categories
		Technical supplement: Some principles of pig nutrition in the tropics

3. Technology for growing dual-purpose and forage-purpose sweetpotato in North-Central Vietnam

3.1 Characteristics of North-Central Vietnam

3.1.1 Soils

North-Central Vietnam was deposited by the Ma River and the Huong River, resulting in infertile coastal-sandy soils with some alluvial characteristics.

3.1.2 Climatic conditions

North-Central Vietnam is commonly hit by storms from the east sea and by hot wind currents from the west part of the Truong Son mountains. It is, therefore, often plagued by floods and drought. During the heavy rainy season, the whole rainfall comes down from the east side of the Truong Son mountains and creates floods immediately. The two distinct seasons are the rainy season from May to October when the average temperature hovers around 25-35 °C, and the dry season from November to April. The average rainfall is 264.7 mm/month, mainly concentrated in three months during the rainy season (September to November), with common flooding between June and October every year.

3.13 Population and density

Population of North-Central Vietnam is 10,007,200, of which 87.7 % reside in rural areas. Average agricultural land per capita is higher than that of the Red River Delta, averaging 910.3 m2, of which rice cultivation area occupies 75%.

3.14 Crops and production systems

In North-Central Vietnam main rotation formulas between sweetpotato and other crops are as below:

- Only subsidiary crops:

Winter/Spring sweetpotato - Rice - Bean
Soybean - Sesame or autumn ground nut - Winter/Spring sweetpotato

- One rice crop with two subsidiary crops:

Winter/Spring sweetpotato - Main winter rice
Spring sweetpotato - Early winter rice - Potato
Spring sweetpotato - Early winter rice - Winter sweetpotato
Spring groundnut - Early winter rice - Winter sweetpotato

- Two rice crops with a winter crop:

Late spring rice - Early winter rice - Winter sweetpotato

3.2 Geographical location

North-Central Vietnam consists of the following provinces: Thanh Hoa, Nghe An, Ha Tinh, Quang Tri, Quang Binh, Thua Thien Hue. The following recommendations also apply to some neighbouring provinces that share similar topographical, soil, and cropping characteristics.

3.3 Recommended sweetpotato varieties suitable for root and vine dual-purpose and their characteristics

3.3.1 The characteristics of yield, agronomic performance, and growing period

Distinguishing characteristics	Varieties
	K51	K4	KL5	Cuc nhanh	Chiem dau
Root yield (ton/ha)	20-30	15-20	13-20	12-15	8-12
Vine yield (ton/ha)	15-20	17-22	15-25	15-20	10-15
Root DM yield (ton/ha)	3.15-4.25	5.6-7.3	3.8-6.5	4.8-6.4	3.3-5.0
Root starch yield (ton/ha)	1.2-2.3	3.5-5.0	3.0-5.5	3.5-4.0	2.0-3.0
Season suited to planting	Winter, spring	Winter, summer	Winter, spring	Winter, spring	Winter, spring
Tolerance performance:
Drought tolerance	Good	Good	Medium	Medium	Fair
Submergence tolerance	Fair	Fair	Fair	Medium	Medium
Cold tolerance	Good	Good	Fair	Fair	Fair
Leaf insect tolerance	Good	Good	Medium	Fair	Medium
Weevil tolerance	Good	Fair	Medium	Medium	Fair
Growing time (days)	80-90	90-120	90-120	120-180	120-180

3.3.2 The characteristics of utilization, vine, root and storage

Distinguishing characteristics	Varieties
	K51	K4	KL5	Cuc nhanh	Chiem dau
Root palatability
For humans (boiled)	Low DM	High DM	High DM	High DM	High DM
For pigs (cooked)	Good	Acceptable	Fairly good	Fairly good	Good
Vine palatability
For humans (boiled)	Sweet	Bitter	Sweet	Acceptable	Bitter
For pigs (fresh)	Sweet	Bitter (Should be cooked)	Sweet	Acceptable	Bitter (Should be cooked)
Method of root storage
Time (months)	3-4	2-3	3-4	4-5	2-3
Way to store	Fresh, dried	Fresh, dried	Fresh, dried	Fresh, dried	Dried
Root morphobgy
Color of skin	Light yellow	Yellowish	Red	Red	Yellow
Color of root flesh	Red	White,yellow	White,yellow	White,yellow	White-yellow
Shape of root	Elliptical	Roundish	Slender	Slender	Elliptical
Vine morphology
Shape of leaf	Round heart	Long heart	Dentate	Serrated	Round heart
Color of tender leaf	Green	Violet	Green	Green	Light green
Color of adult leaf	Dark green	Light green	Green	Dark green	Light green
Color of stem	Green	Purple green	Green	Green	Purple green

3.4 Sweetpotato varieties suitable for forage purpose and their characteristics

3.4.1 The characteristics of yield, agronomic performance, and growing period

Distinguishing characteristics	Varieties
	K51	KL1	KL5	H.1.2	Cuc nhanh
Fresh vine yield (ton/ha)	6-8.7	6.3-11.34	7.2-12	8.4-13	6.8-10.2
Vine DM yield (ton/ha)	1.93	2.20	2.69	2.78	2.30
Leaf protein yield (ton/ha)	0.39	0.40	0.51	0.56	0.41
Season suited to planting	Winter, spring	Winter, spring	Winter, spring	Winter, spring	Winter, spring
Tolerance performance:
Drought tolerance	Good	Good	Medium	Medium	Fair
Submergence tolerance	Fair	Fair	Fair	Medium	Medium
Cold tolerance	Good	Good	Fair	Fair	Fair
Leaf insect tolerance	Good	Good	Medium	Fair	Medium
Weevil tolerance	Good	Fair	Medium	Medium	Fair
Branching re-growing	Strong	Strong	Strong	Strong	Strong

3.4.2 The characteristics of utilization, vine, root and storage

Distinguishing characteristics	Varieties
	K51	KL1	KL5	H.1.2	Cuc nhanh
Vine palatability
For humans (boiled to eat)	Sweet	Sweet	Sweet	Sweet	Sweet
For pigs (fresh)	Sweet	Sweet	Sweet	Sweet	Sweet
Method of vine storage
Time (months)	34	2-3	34	4-5	4-5
Way to store	Dried	Dried	Dried	Dried	Dried
Vine morphology
Shape of leaf	Long heart	Round heart	Dentate	Round heart	Serrated heart
Color of tender leaf	Light green	Light green	Green	Green	Light green
Color of adult leaf	Dark green	Light green	Green	Dark green	Green

3.5 Technologies that can be applied to increase vine and root yield

3.5.1 Selecting the appropriate variety

Using purpose	Spring crop	Winter crop
Dual purpose	K51.K4.KL5	K51.K4.KL5
Forage purpose	K51,KL5,KL1	K51,H.1.2,KL5

3.5.2 Planting season

Spring crop

Winter crop

Planting season

15 February- 30 March

15 September-30 October

Favorable conditions

Unfavorable conditions

Due to low moisture require ment, sweetpotato can grow where groundnut and sesame cannot.
There usually are early rains. It has negative impact on root growth.

Sweetpotato is planted between crops to increase land use efficiency.
The cold in the beginning and drought at the end of season both have adverse effects on root growth.

3.5.3 Soil characteristics

	Spring crop	Winter crop
Proper soil type	Mixed sandy, light loamy, river side, along canals and dikes, sandy soils on seaside.	Mixed sandy, light loamy, river side, along canals and dikes, sandy soils on seaside.
Land type	Highland, upland, well drained	Highland, upland, middle land.

3.5.4 Soil preparation

	Spring crop	Winter crop
Requirements	Dry, airy, deeply ploughed.	Deeply ploughed for moisture retention.
Size of beds	1.2 - 1.5m wide, 0.35-0.5m high	1 - 1.5m wide, 0.3 - 0.45m high
Distance between beds	30-35 cm	25-30 cm
Direction of beds	West- East	West - East

3.5.5 Planting method

	Spring crop	Winter crop
Vegetative multiplication	The stems from winter crop or garden crop can be multiplied. Choose the stems that are not infested with viruses or insects. No nitrogen fertilization before cutting	Multiplication season is the end of June and beginning of July Plant in mounded beds or flat beds. Irrigate, cut tops early to promote multiple branches.
Multiplication method of planting material from root	Choose the small or medium roots with no scratches, no virus, or insect infestation Prepare the soil well, the soil clods must be as fine as for vegetables. The top of the bed is flat, with 1 .2 m width, 20 cm height, fertilize 10 tons of manure/ha before planting as basic fertilizer. Planting density: 40 x 40 cm/hole, the big root should be cut into parts then dipped into ash, planting depth is about 3 cm, cover the surface of the bed with chopped rice straw, water them to keep the plants and soil moist. After the shoots have grown out of the soil surface about 5cm, cut off weak shoots, leave only 2-3 shoots in a hole. When the shoots are 20-25 cm long, cut the top to allow branching, 50 - 60 days later cut the stem to plant.
Preparation before cutting planting material	7-10 days before cutting, apply additional P and K fertilizer (1 -2 kg K/sao), do not water or apply nitrogen
Standards of good planting material	Adult stem, thick and hard, with no root, no virus and insect infestation
Method of cutting planting material	Cut the Island the 2nd section, avoid damaging the stems and leaves. In late afternoon when it is less sunny. Do not dip the stems in water just after cutting
Length of stem (cm) Node number/stem	25-30 6-8	20-25 5-7
Planting method	Put the stem horizontally in the direction of the bed, exposing the top 3-5 cm, cover it with soil from both sides and pat down the soil next to the stem. Lay the stem down flat and no need to leave space between plantlets. Keep the stem fresh. Better plant in the evening. In winter, avoid planting during the northeast windy days.
Direction of beds	North east-South west	North east-South west
Density (stem/m of bed)	5 stem/m	4-5 stem/m

3.5.6 Fertilizer

	Spring crop	Winter crop
Ratio and amount of fertilizers (kg/sao)	300-400 kg manure 2-4 kg urea (N) 12-14 kg phosphate (P) 2-4 kg potassium chloride (K)	300-400 kg manure 3-5 kg urea (N) 12 -14 kg phosphate (P) 2-4 kg potassium chloride (K)
Basic fertilization	Mix manure with P, put in the furrow and cover with soil from the bed. Apply additional 1-1.5 kg urea and 1-1.5 kg potassium chloride, cover with soil. Avoid stems touching fertilizer.	Mix manure with P, put in the furrow and cover with soil from the bed. Apply additional 1-1.5 kg urea and 1-1.5 kg potassium chloride, cover with soil. Avoid stems touching fertilizer.
First additional fertilization Timing Amount (kg/sao)	At 15-25 days after planting 1-1.5 kg urea mixed with 1-1.5 kg potassium chloride	At 10-20 days after planting 1-1.5 kg urea mixed with 1-1.5 kg potassium chloride
First additional fertilization Timing Amount (kg/sao)	At 30-35 days after planting 1-1 .5 kg urea 1-1.5 kg potassium chloride	25-30 days after planting 1-1.5 urea 1-1.5 potassium chloride

3.5.7 Cultivation technology

	Spring crop	Winter crop
Pinching off young shoots	At 25-30 days after planting (several days before or after the 1 st additional fertilization) cut the tops to help branching and optimize vegetative development.	At 25 days after planting (several days before or after the 1 st additional fertilization) cut the tops to help branching and optimize vegetative development.
Re-mount the bed for weed control	At 25-30 days after planting, hoe deeply into soil, turn up the bed slightly linking this activity with the 1 st additional fertilization. At 10-15 days after the 1 st additional fertilization, hoe, turn up soil slightly. Keep soil moist for 2-3 days after planting so that the stems can re-grow.	At 25 days after planting, hoe soil deeply, turn and earth up the bed slightly, in combination with the 1 st additional fertilization. At 10 - 15 days after the 1 st additional fertilization, hoe, turn slightly and earth up the bed highly. Keep soils moist for 2-3 days after planting so that the stems can re-grow.
Irrigation	Irrigate 2-3 days after turning up the bed and additional fertilization application.	Irrigate, flood 1/2-1/3 of the furrows, keep soil moist when weather is dry.
Vine lifting	At 45-50 days after planting if too much vine during the first period, some stems should be cut and stems should be lifted to break excessive roots.	At 45-50 days after planting if too much vine during the first period, some stems should be cut and stems should be lifted to break excessive roots.

3.5.8 The vine-cutting method for forage varieties

	Spring crop	Winter crop
First vine harvest Time to start harvest	At 30-40 days after planting when the bed is covered by vine	At 35-45 days after planting when the bed is covered by vine
Harvesting criteria	Leave a section of 10-15 cm on the bottom.	Leave a section of 10-15 cm on the bottom.
Subsequent vine harvests	Nitrogen should be added after each harvest (0.5 - 1.0 kg/sao urea). Cut stems every 10-15 days until the last harvest. Depending on vegetative growth, cut 2-3 longest stems, up to 4 stems if much growth, leaving 15- 20cm. More stems can be cut near the end harvest	Nitrogen should be added after each harvest (0.5 -1.0 kg/sao urea). Cut stems every 10-15 days until the last harvest. Cut 2-3 longest stems of a plant, leaving 15-20 cm. Irrigate while applying additional fertilizer after cutting.

3.5.9 Main insects and protection

	Spring or winter crop
Weevil	Use traps (For example: chopped sweetpotato pieces) to lure adult weevils to come to lay eggs, then get the traps to kill larvae. Mound high beds and keep soil moist to reduce weevil damage. Use biological control such as introduction of natural enemies, manipulation of habitat, conservation of natural enemies through avoidance of pesticide use or trap weevils to eliminate them.
Sweetpotato Hornworm (Agriusconvolvuli)	Sweetpotato rotating with paddy rice helps eliminate insects. Leaf-eating caterpillar can be caught by hand
Scrap	Planting tolerant varieties is the best protection from scrap. Check and eliminate the attacked plants.
Black rot	Restrict irrigation during the final period. Rotate sweetpotato with other crops in paddy fields, or plant on highlands.

3.5.10 Harvest

	Spring crop	Winter crop
Root harvesting Time to harvest Date of harvest Method of harvest	105-120 days after planting End of May-Start of June -Avoid damaging roots - Process, store vine, make dried chips	80-90 days after planting End of January-Start of February - Avoid damaging roots - Process, store vine, make dried chips
Vine harvesting Time to harvest	Vines can be harvested 45-50 days after planting.	Vines can be harvested 45-50 days after planting.
Subsequent harvests	Every 10-15 days after the first vine harvest.	Every 10-15 days after the first vine harvest.

3.5.11 Storage

	Spring crop	Winter crop
Method of root storage	Clean soil or sand from roots, keep in dry, airy, and cool places	Clean soil or sand from roots, keep in dry, airy, and cool places
Some remarks during storage	Check regularly to eliminate rotting roots	Check regularly to eliminate rotting roots
Storage duration	3-4 months	3-4 months
Method of vine torage	Drying or ensiling	Drying or ensiling
Storage duration	3-4 months	3-4 months
Some remarks during storage	After 14 days ensiled feed can be fed to pigs. It can be stored for at least 4-5 months. It has the typical smell and taste of ensiled feed. Check the bags regularly to make sure of anaerobic condition to avoid rot and mould	After 14 days ensiled feed can be fed to pigs. It can be stored for at least 4-5 months. It has the typical smell and taste of ensiled feed. Check the bags regularly to make sure of anaerobic condition to avoid rot and mould

3.5.12 Recommended utilization

	Spring crop
Vine	The soft and sweet vine can be used as vegetable for humans or forage for animals
Root	Roots can be boiled or dried for human consumption or animal feed