Báo cáo Nghiên cứu khoa học Results on strengthening diagnostic capacity and control of diarrhoea in suckling pigs

Collaboration for Agriculture and Rural Development (CARD) Program 16 RESULTS ON STRENGTHENING DIAGNOSTIC CAPACITY AND CONTROL OF DIARRHOEA IN SUCKLING PIGS Project title: Diagnosis and control of diarrhoea in suckling pigs Project code: CARD 001/04VIE Authors: Do Ngoc Thuy1, Cu Huu Phu1, Au Xuan Tuan1, Nguyen Xuan Huyen1, Truong Van Dung1, Tony Fahy1, Steve Driesen2, Karen Moore2, Aileen Vanderfeen2, Darren Trott3 Collaborating organisations: 1: National Institute of Veterinary Research 2: Pig Research Unit, Victorian Department of Primary Industry, Melbourne, Australia; 3: The University of Queensland, Australia SUMMARY During the implementation time (2005-2007), three objectives of the project, including: 1) Improved field and laboratory diagnosis of preweaning diarrhoea; 2) Production and testing of locally- produced E. coli vaccines; 3) Development of a management plan for preweaning diarrhoea using a continuous improvement (CIP) model had been conducted and completed. Some achievements are: 1) A diagnostic procedure of six major causes of diarrhoea in suckling pigs has been applied successfully at Department of Bacteriology, NIVR. 2) A vaccine containing E. coli strains bearing full pathogenic factors (fimbriae, toxins) has been produced and proven safe and effective in laboratory and in the field. 3) An continuous improvement model, focused mainly on management of sows during farrowing and lactation has been developed and utilized in order to improve pig production and minimize the losses due to diarrhoea in suckling period. 1. Introduction Diarrhoea during the suckling period has been recognised as the principle health problem affecting both smallholder and commercial pig production in Vietnam. Previous research (4, 7) has confirmed the presence of a new fimbrial type in E. coli strains causing colibacillosis in Vietnam that would not be controlled by existing vaccines. Existing vaccines are currently imported into Vietnam at considerable cost. In addition, there are many other causes of suckling diarrhoea, the significance of which is currently unknown in Vietnam, which are all affected by husbandry and management during farrowing and lactation. Project 001/04VIE (Diagnosis and control of diarrhoea in suckling pigs) began with three objectives to solve this problem: 1. Improved field and laboratory diagnosis of preweaning diarrhoea 2. Production and testing of locally- produced E. coli vaccines 3. Development of a management plan for preweaning diarrhoea using a continuous improvement (CIP) model This project is designed to improve productivity of smallholder pig farmers in Vietnam through improved health management, particularly of piglets during the pre-weaning period. Through consultation and dialogue with farmers and field veterinarians, an appropriate disease management plan will be developed. This will concentrate on the pre-weaning period where greatest losses occur, but will include principles of herd health management in general. Dissemination of the plan will be through training programmes for field staff and selected farmers. CARD 001/04 VIE – Control diarrhoea in suckling pigs 17 2. Project contents and methods 2.1 Project Contents The project focuses on: 1. Improved laboratory diagnosis of preweaning diarrhoea 2. Production and testing of locally- produced E. coli vaccines 3. Development of a management plan for preweaning diarrhoea using a continuous improvement (CIP) model, training for field veterinarians 2.2 Methodology - Experimental design based on groups and compare the significant difference (1 factor, multiple factors) - Isolation and identification of bacteria (E. coli, C. perfringens) according to SOPs - Detection of virus (TGE virus, Rota virus) by ELISA (commercial kit, Institute Pourquier) - Detection of Cocci oocysts by standard faecal flotation, Cryptosporidium by modified Ziehl-Neelsen staining of faecal smears - Detection of virulence factors of E. coli (fimbriae, toxins) by PCR - Production of vaccine according to SOP 3. Research results and discussions 3.1 Development of a procedure for quick diagnose some of the most common infectious causes of diarrhoea in suckling pigs A diagnostic procedure of six major causes of diarrhoea in suckling pigs, including the infectious gastroenteritis virus (TGEV), Rota virus, E. coli, C. perfringens, Coccidiosis and Cryptosporidium have been established, in accordance with the laboratory conditions at Department of Bacteriology, National Institute of Veterinary Research. This procedure has been used for diagnosis of faecal samples collected from commercial piggeries (participated in the project) and small holder farmers in the nearby areas. Results are presented in table 1. Table 1: Prevalence of enteric pathogens in pre-weaning piglets with diarrhoea Agent(s) detected No. of positive samples (%) Commercial piggeries (n=117) Small holder farmers (n=45) Cocci 2 (1.7) Crypto 3 (2.5) RV 3 (2.5) TGEV 11 (9.3) ETEC 4 (3.4) C. per 2 (1.7) Total single infection 25 (21.2) RV ETEC 6 (5.1) RV TGEV 17 (14.4) 3 (6.7) Cocci RV 1 (0.8) 2 (4.4) Cocci Crypto 1 (0.8) 2 (4.4) Crypto ETEC 3 (2.5) 1 (2.2) Crypto C. per 1 (0.8) 1 (2.2) Crypto TGEV 6 (5.1) 2 (4.4) TGEV C. per 1 (0.8) D.N Thuy, C.H Phú, AX. Tuan, N. X.Huyen, T.V. Dung, T. Fahy, S.Driesen, K. Moore, A. Vanderfeen & D. Trott 18 Agent(s) detected No. of positive samples (%) Commercial piggeries (n=117) Small holder farmers (n=45) TGEV ETEC 7 (5.9) Cocci RV ETEC 2 (1.7) 3 (6.7) Cocci RV TGEV 4 (3.4) 3 (6.7) Cocci TGEV ETEC 2 (1.7) 2 (4.4) Cocci Crypto RV 1 (0.8) 1 (2.2) Crypto TGEV ETEC 5 (4.2) 4 (4.4) Crypto RV ETEC 1 (0.8) 3 (6.7) Crypto TGEV C. per 1 (0.8) 1 (2.2) Crypto RV TGEV 3 (2.5) RV TGEV ETEC 14 (11.9) 7 (15.6) RV TGEV C. per 1 (0.8) 1 (2.2) RV ETEC C. per 2 (1.7) 3 (6.7) TGEV ETEC C. per 2 (1.7) Crypto RV TGEV ETEC 2 (1.7) 1 (2.2) Crypto RV ETEC C. per 1 (0.8) 2 (4.4) Cocci Crypto RV TGEV 1 (0.8) 1 (2.2) Cocci Crypto TGEV C. per 1 (0.8) Cocci RV TGEV ETEC 4 (3.4) 1 (2.2) Cocci Crypto RV TGEV C. per 1 (0.8) 1 (2.2) Crypto RV TGEV ETEC C. per 1 (0.8) (36) (50) (97) (111) (76) (23) Total multiple infections 92 (78.8) 45 (100.0) 3.2 Production and testing of local produced E. coli vaccine A vaccine containing E. coli strains bearing full pathogenic factors (fimbriae, toxins) has been produced according to SOP. Specialised culture media were prepared in order to provide favourable growth conditions for the production of fimbriae. Each dose of vaccine (2 ml) contains of ~ 1.5 x 109 bacteria. Vaccine has been tested on sterility, safety and efficacy in laboratory and in the field (for small scale trial). CARD 001/04 VIE – Control diarrhoea in suckling pigs 19 Results of ELISA for efficacy testing of vaccine show that there was a significant difference between the OD levels for the treatment groups (p<0.003). There was no significant difference between the antibody response elicited (as demonstrated by OD values) by Litterguard, EcoVac or NIVR vaccines (p>0.1). All three vaccines were significantly different from the control group (p< 0.005) (Table 2) Table 2: Mean OD values of sera between treatment and control group Treatment group Mean Control 0.2260a Litterguard 0.8129b EcoVac 0.9406 b NIVR 0.8695 b * Means with different subscripts differ significantly p<0.005 Vaccine was tested in some piggeries in the North. Pregnant sows twice at 9 and 12 weeks of gestation each received 2 ml of vaccine (approximately 1.5 x 109 bacteria). Results show that under experimental conditions, the vaccine is both safe (100%) and efficacious (>85%). No local or systemic reaction to the vaccine was observed and all sows gave birth at the correct stage of gestation to an average of 9.3 healthy piglets per sow. The prevalence of pre-weaning diarrhoea in piglets born from vaccinated sows at 1, 2 or 3 weeks of age were: 16.1; 22.7 and 26.5%, compared with those of 48.1; 33.8 and 37.5%, respectively from control group (P<0.005). 3.3 Recommendations on herd health monitoring II.3.1. Sow management o Pigs must have access to feed at least daily and the diet must be nutritionally adequate to maintain health and meet the requirements for maintenance, growth, pregnancy and lactation. o When the body condition score of a pig falls below 2.5 (on the scale of 1-5, appendix 1), remedial action must be taken. o All pigs (excluding piglets) must be maintained at a body condition score of 2 or more. o Feed must be provided in such a way as to prevent undue competition or injury. o Pregnant sows should be given enough bulky or high fibre feed to satisfy hunger. The feed intake for dry sows needs to be nutritionally balanced, appropriate to the sow’s physiological needs (which vary during pregnancy) and to provide satiety without the sow becoming overweight. o Body score of breeding sows at farrowing should be 3.5 – 4. o Body score of breeding sows at weaning should be 3 or above. o Condition scoring is recommended as a way of assessing the adequacy of nutrition, along with monitoring of health and productivity. A guide to condition scoring of pigs is given in the next part. o Drinkable water and/or other wholesome liquid must be easily available to pigs in sufficient quantities to meet the physiological needs of the pigs at all times o Water provided should be fresh, palatable, and at a temperature that does not inhibit drinking. o Drinker allocation per pen group and drinker design and flow rates should be such that water requirements of different classes of pig are easily met. o Pigs should have constant access to water or other suitable wholesome liquid. The daily consumption of water (or other wholesome liquid) by a pig will vary according to environmental temperature, diet ingredients and live-weight. * Feed requirements for lactating sows The minimum feed recommended intakes for lactating sows as follows: D.N Thuy, C.H Phú, AX. Tuan, N. X.Huyen, T.V. Dung, T. Fahy, S.Driesen, K. Moore, A. Vanderfeen & D. Trott 20 Table 3: Feed requirements for lactating sows Day of lactation Daily feed requirement (kg) 1 2.5 2 3 3 3.5 4 4 5 4.5 6 5 7 5.5 8 6 9 7 10 8 11-15 9 16-20 10 21-28 10.5 * WATER REQUIREMENTS For planning purposes the following consumption estimates are provided for normal ambient temperatures: Table 4: Average water consumption (litres per day)* Boar or dry sow 12–15 Sow and litter 25–45 Grower pig: 25 kg 45 kg 65 kg 3–5 5–7 7–9 90 kg 9 – 12 Flow rates will vary depending on the number of drinking points and care should be taken to ensure adequate pump capacity and supply to maintain flow. Recommended water flow rates and maximum water pressures Class Flow Rate (litres/minute) Maximum pressure (kPa) Weaners 0.5 85-105 Growers/Finishers 1.0 140-175 Dry sow 1.0 No limit* Lactating 2.0 No limit* * Care should be made not to have excessive pressure as water wastage can occur. * TEMPERATURE REQUIREMENTS Pigs, except the very young, are able to tolerate a wide range of temperatures without detriment to their well being, provided temperature changes do not occur abruptly. During very hot weather (35°C or more) adult pigs are very susceptible to heat stress, and steps should be taken to alleviate distress and avoid deaths. Pigs may die if transported in very hot weather. The heat index in most sheds we visited was 37-38°C. CARD 001/04 VIE – Control diarrhoea in suckling pigs 21 The ranges of temperature that afford optimum comfort for different classes of pigs are: Piglets — newborn 30–35°C Piglets — 3 weeks of age 24–30°C (reducing to 26°C at 5 weeks of age) Farrowing house 16-22°C Weaners 28–30°C first week (start at 30C, reduce by 2°C per week to 22°C) Growers Aim for 20-24°C, aim to keep daily fluctuations below 6°C Finishers Aim for 20-24°C, aim to keep daily fluctuations below 6°C Sows and boars 18 – 24°C, aim to keep daily fluctuations below 6°C Table 5: Thermal comfort zone (assuming concrete floors, no drafts and 15% skin wetness) Stock Weight (kg) Lower critical temp Evaporative critical temp Weaners 5 27 30 6 25 29 7 22 28 8 21 26 9 20 25 Growers 20 16 30 50 12 28 90 9 27 Dry sows & boars 150 15 27 Lactating sows 150 10 23  At the lower critical temperature pigs will feel cold, huddle and change position to conserve heat. They will also need more feed to generate heat.  At the upper limit (evaporative critical temperature) the pigs will begin to pant in an effort to cool down. 3.3.1. Condition scoring of sows The following criteria can be used as reference for scoring sows: D.N Thuy, C.H Phú, AX. Tuan, N. X.Huyen, T.V. Dung, T. Fahy, S.Driesen, K. Moore, A. Vanderfeen & D. Trott 22 Condition scoring of sows Numerical Score Pelvic Bones, Tail Head Loin Vertebrae Ribs 1 Pelvic bones very prominent. Deep cavity around the tail head. Loin very narrow. Sharp edges on transverse spinal process. Flank very hollow. Prominent and sharp throughout the length of the backbone Individual ribs very prominent 2 Pelvic bones obvious but some slight cover. Cavity around tail head. Loin narrow. Only very slight cover to edge of transverse spinal process. Flank rather hollow. Prominent Rib cage less apparent. Difficult to see individual ribs 3 Pelvic bones covered. Edge of transverse spinal processes covered and rounded. Visible over the shoulder. Some cover further back. Covered but can be felt. 4 Pelvic bones only felt with firm pressure. No cavity around tail. Edge of transverse spinal processes felt only with firm pressure. Felt only with firm pressure Rib cage not visible. Very difficult to feel any ribs. 5 Pelvic bones impossible to feel. Root of tail set deep in surrounding fat. Impossible to feel bones. Flank full and rounded. Impossible to feel vertebrae. Not possible to feel ribs. 4. Conclusions and recommendations 4.1 Conclusions  A diagnostic procedure of six major causes of diarrhea in suckling pigs, including the infectious gastroenteritis virus (TGEV), Rota virus, E. coli, C. perfringens, Coccidiosis and Cryptosporidium have been established. This procedue can be easily applied for diagnosis in laboratory conditions in Vietnam.  A vaccine containing E. coli strains bearing full pathogenic factors (fimbriae, toxins) has been produced and proven safe and effective in CARD 001/04 VIE – Control diarrhoea in suckling pigs 23 laboratory and in the field. Vaccine can be used to vaccinate pregnant sows twice at 9 and 12 weeks of gestation, each received 2 ml of vaccine to control diarrhoea in suckling pigs.  An continuous improvement model, focused mainly on management of sows during farrowing and lactation has been developed and utilized in order to improve pig production and minimize the losses due to diarrhoea in suckling period. 4.2 Recommendations The E. coli vaccine should be commercialised as soon as possible so that it can be used for control of diarrhoea in suckling pigs in Vietnam References 1. Cu Huu Phu, Nguyen Ngoc Nhien, Do Ngoc Thuy, Au Xuan Tuan, Nguyen Xuan Huyen, Van Thi Huong, Vu Ngoc Quy. Results on investigation of diarrhoea in suckling pigs in North Vietnam, prevalence of antimicrobial resistance and virulence factors of obtained E. coli isolates. Proceedings of NIVR – 35 years of establishment and development, 1969- 2004. Agriculture Publishing House. 2004. Pp 126-136. 2. Do Ngoc Thuy, Darren Trot, Cu Huu Phu, Nguyen Xuan Huyen, Au Xuan Tuan, Van Thi Huong, Vu Ngoc Quy. Application of PCR on examination of virulence factors of E. coli strains obtained from piglets with diarrhoea in North Viet Nam. Veterinary Sciences and Techniques. Vol. XII, No5. 2005.P 13-17. 3. T-N Do, KM Townsend, AJ Frost and DJ. Trott. 2003. Pathogenicity of Vietnamese ETEC in day-old piglets. Proceedings of a combined annual scientific meeting and exhibition of the Australian and New Zealand societies for Microbiology. Auckland, New Zealand, 28 September-2 October, 2003. p. 82. 4. Ngoc Thuy Do. 2004. 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