Seroprevalence of small ruminant lentivirus infection in goats in Thailand.

Small ruminant lentivirus (SRLV), which causes caprine arthritis encephalitis in goats and ovine progressive pneumonia (maedi-visna disease) in sheep, is classified in genus Lentiviruses belonging to Retroviridae family. It persists in infected goats and sheep, which mostly are sub- clinical. A serological survey was conducted to determine the prevalence of small ruminant lentivirus infection in Thai goat population. Serum samples were taken from 1,925 goats distributed throughout the country, then they were tested for the presence of SRLV antibodies using commercial indirect enzyme-linked immunosorbent assay (ELISA) test kits. Results revealed that a total of 68 goats were found seropositive, representing the apparent prevalence and true prevalence of 3.57% and 2.60%, respectively. The seroprevalence, revealed in this study, was lower than in the previous reports. The decreasing of seroprevalence might be caused by successful control strategies from Department of Livestock Development (DLD).

Diagnosis of Caprine Arthritis Encephalitis Virus infection in dairy goats by ELISA, PCR and Viral Culture.

For preventive and control strategies of Caprine Arthritis Encephalitis Virus (CAEV) infection in dairy goats, performance of the available diagnostic tests was described as one of the most important and necessary aspects. The study aimed at evaluating the diagnostic test performance, including PCR, ELISA and viral culture, for CAEV infection in dairy goats in Thailand. Blood samples of 29 dairy goats from five low- to medium-prevalence herds and one very low-prevalence herd were collected for PCR and ELISA methods. The performance of these two diagnostic methods was evaluated by comparing with cytopathic effects (CPE) in the co-cultivation of CAEV and primary synovial cells. Results indicated that sensitivity, specificity were, respectively, 69.6%, 100%, for PCR; and 95.7%, 83.3% for ELISA. The PCR assay tended to have lower sensitivity and higher specificity than ELISA. When multiple tests were applied, parallel testing provided sensitivity and specificity of 98.7% and 83.3%, while series testing showed sensitivity and specificity of 66.6% and 100% respectively. These results indicated that combination of ELISA and PCR provided some advantages and possibly offered optimal methods to detect CAEV-infected goats. Kappa value of the agreement between PCR and ELISA test was 0.34, indicating fair agreement. Regarding the possibility of antigenic variation between CAEV strains used in both PCR and ELISA assays, the actual circulating CAEV strain should be reviewed in order to develop and enhance the diagnostic tests using the CAE viral antigens derived from specific local strains of Thailand.

Financial Impacts of Priority Swine Diseases to Pig Farmers in Red River and Mekong River Delta, Vietnam.

A study was conducted between May 2013 and August 2014 in three provinces of Vietnam to investigate financial impacts of swine diseases in pig holdings in 2010-2013. The aim of the study was to quantify the costs of swine diseases at producer level in order to understand swine disease priority for monitoring at local level. Financial impacts of porcine reproductive and respiratory syndrome (PRRS), foot and mouth disease (FMD), and epidemic diarrhoea were assessed for 162 pig holders in two Red River Delta provinces and in one Mekong River Delta province, using data on pig production and swine disease outbreaks at farms. Losses incurred by swine diseases were estimated, including direct losses due to mortality (100% market value of pig before disease onset) and morbidity (abortion, delay of finishing stage), and indirect losses due to control costs (treatment, improving biosecurity and emergency vaccination) and revenue foregone (lower price in case of emergency selling). Financial impacts of swine diseases were expressed as percentage of gross margin of pig holding. The gross margin varied between pig farming groups (P < 0.0001) in the following order: large farm (USD 18 846), fattening farm (USD 7014) and smallholder (USD 2350). The losses per pig holding due to PRRS were the highest: 41% of gross margin for large farm, 38% for fattening farm and 63% for smallholder. Cost incurred by FMD was lower with 19%, 25% and 32% of gross margin of pig holding in large farm, fattening farm and smallholder, respectively. The cost of epidemic diarrhoea was the lowest compared to losses due to PRRS and FMD and accounted for around 10% of gross margin of pig holding in the three pig farming groups. These estimates provided critical elements on swine disease priorities to better inform surveillance and control at both national and local level.

Social network analysis for assessment of avian influenza spread and trading patterns of backyard chickens in Nakhon Pathom, Suphan Buri and Ratchaburi, Thailand.

The aim of this study is to explain the social networks of the backyard chicken in Ratchaburi, Suphan Buri and Nakhon Pathom Provinces. In this study, we designed the nodes as groups of persons or places involved in activities relating to backyard chickens. The ties are all activities related to the nodes. The study applied a partial network approach to assess the spreading pattern of avian influenza. From 557 questionnaires collected from the nodes, the researchers found that the degree (the numbers of ties that a node has) and closeness (the distance from one node to the others) centralities of Nakhon Pathom were significantly higher than those of the others (P<0.001). The results show that compared with the remaining areas, this area is more quickly connected to many links. If the avian influenza virus subtype H5N1 was released into the network, the disease would spread throughout this province more rapidly than in Ratchaburi and Suphan Buri. The betweenness centrality in each of these provinces showed no differences (P>0.05). In this study, the nodes that play an important role in all networks are farmers who raise consumable chicken, farmers who raise both consumable chicken and fighting cocks, farmers' households that connect with dominant nodes, and the owners and observers of fighting cocks at arenas and training fields. In this study, we did not find cut points or blocks in the network. Moreover, we detected a random network in all provinces. Thus, connectivity between the nodes covers long or short distances, with less predictable behaviour. Finally, this study suggests that activities between the important nodes must receive special attention for disease control during future disease outbreaks.

Interrelation of fatty acid composition in adipose tissue, serum, and liver of dairy cows during the development of fatty liver postpartum.

We investigated the composition of fatty acids in adipose tissue, serum, and liver of cows that were fed at restricted energy intake or were overfed during the dry period. Overfed cows had higher concentrations of serum nonesterified fatty acids and consequently accumulated greater amounts of triacylglycerols in the liver than did cows that were fed at restricted energy intake. The percentages of the different fatty acids present in adipose tissue were similar for both groups and did not change during sampling intervals. Before parturition, concentrations of the individual fatty acids present in serum were similar between groups. After parturition, concentrations of major fatty acids in serum, including palmitic, stearic, oleic, and linoleic acids significantly increased in both groups and were higher in overfed cows than in cows that were fed at restricted energy intake. The shift of concentrations of the different fatty acids present in the liver--as a result of increased lipolysis-was observed in palmitic, oleic, and linoleic acids but not stearic acid, suggesting that stearic acid is used by the liver (i.e., oxidation) or is considerably secreted through the milk, thereby not increasing in accumulation in the liver. In conclusion, different feeding regimens during the dry period do not influence the composition of fatty acids in adipose tissue. More intensive lipolysis results in increased concentrations of palmitic, stearic, oleic, and linoleic acids in the blood; subsequently, these fatty acids, excluding stearic acid, greatly accumulated in the liver.

Relationship between overfeeding and overconditioning in the dry period and the problems of high producing dairy cows during the postparturient period.

In dairy cows, overfeeding during the dry period leads to overcondition at calving and to depression of appetite after calving. As a consequence, at calving overconditioned high-producing dairy cows inevitably go into a more severe negative energy balance (NEB) postpartum than cows that have a normal appetite. During the period of NEB, the energy requirements of the cow are satisfied by lipolysis and proteolysis. Lipolysis results in an increased concentration of non esterified fatty acids (NEFA) in the blood. In the liver, these NEFA are predominantly esterified to triacylglycerols (TAG) that are secreted in very low density lipoproteins (VLDL). In early lactation in cows with a severe NEB, the capacity of the liver to maintain the export of the TAG in the form of VLDL in balance with the hepatic TAG production is not always adequate. As a result, the excess amount of TAG accumulates in the liver, leading to fatty infiltration of the liver (hepatic lipidosis or fatty liver). The NEB and/or fatty liver postpartum are frequently associated with postparturient problems. In general, a severe NEB induces changes in biochemical, endocrinological, and metabolic pathways that are responsible for production, maintenance of health, and reproduction of the postparturient dairy cow. These changes include a decrease in blood glucose and insulin concentrations, and an increase in blood NEFA concentrations. High NEFA concentrations caused by intensive lipolysis are accompanied by impairment of the immune system, making the cows more vulnerable to infections. Metabolic diseases such as ketosis, milk fever, and displaced abomasum are related to overcondition at calving. The changes in biochemical, endocrinological, and metabolic pathways are associated with delay of the first visible signs of oestrus, an increase in the interval from calving to first ovulation, a decrease in conception rate, and a prolonged calving interval. It is possible that the increased blood NEFA concentration directly impairs ovarian function.

Effect of overfeeding during the dry period on the rate of esterification in adipose tissue of dairy cows during the periparturient period.

The in vitro rate of esterification of fatty acids in adipose tissue was compared between cows that were fed at restricted energy intake and cows that were overfed during the dry period. Subcutaneous adipose tissue was biopsied at -1, 0.5, 1, and 3 wk from parturition. The basal in vitro rate of esterification was quantified, as well as the rate of esterification after the addition of glucose or glucose plus insulin. The basal rate in adipose tissue from overfed cows at -1 wk was higher than in adipose tissue from cows that were fed at restricted energy intake and indicated enhanced storage of triacylglycerols in adipose tissue of overfed cows at that time. The rate of esterification after the addition of glucose or glucose plus insulin was increased in both groups at each sampling time, but the mean rates, expressed as a percentage of the basal rates, were lower for overfed cows than for cows that were fed at restricted energy intake at 0.5 and 1 wk. Although the addition of glucose or glucose plus insulin increased esterification rates in adipose tissue from both groups of cows, adipose tissue from overfed cows was less sensitive to the addition of these compounds. In conclusion, overfeeding during the dry period predisposed cows to accumulate fat in adipose tissue during the prepartum period. The smaller increase in esterification rate after the addition of glucose or glucose plus insulin in adipose tissue of overfed cows indicates a lower ability of the adipose tissue to esterify circulating fatty acids or to reesterify mobilized fatty acids, which, combined with higher rates of lipolysis postpartum, contributes to continuously elevated concentrations of circulating nonesterified fatty acids postpartum, leading to a more severe hepatic lipidosis in overfed cows.

Effect of fatty liver on hepatic gluconeogenesis in periparturient dairy cows.

The purpose of this study was to compare the hepatic enzyme activities of gluconeogenesis between control cows and experimental cows that had been overfed during the dry period to induce fatty liver postpartum. Blood and liver samples were collected 1 wk before and 0.5, 1, 2, and 3 wk after parturition. Before parturition, neither the serum nonesterified fatty acid nor the liver triacylglycerol concentration differed between the two groups. After parturition, these variables were higher in experimental cows than in control cows. Liver glycogen was higher at 1 wk before parturition in experimental cows; sharply decreased after parturition in both groups; and, at 1 wk after parturition, was lower in experimental cows than in control cows. In the liver, activities of phosphoenolpyruvate carboxykinase were significantly lower at 1 wk before and at 0.5 and 2 wk after parturition in experimental cows; in addition, the activities tended to be lower at 1 wk after parturition. Activities of fructose 1,6-bisphosphatase tended to be lower, but activities of glucose 6-phosphatase tended to be higher, at 0.5 wk after parturition in experimental cows than in control cows. Our results suggest that, in fatty infiltrated liver, the rate of gluconeogenesis is not optimal, which results in prolongation of lipolysis, particularly during the first weeks after parturition.

Hepatic fatty acid composition in periparturient dairy cows with fatty liver induced by intake of a high energy diet in the dry period.

The present study compared the hepatic fatty acid composition of cows that were fed a high energy diet during the dry period to induce fatty liver after parturition with that of control cows. Treated cows had higher concentrations of plasma nonesterified fatty acids as a result of greater lipolysis after parturition than did control cows; consequently, the treated cows accumulated greater amounts of triacylglycerols in the liver. Before parturition, treated cows had lower percentages of oleic acid and higher percentages of linoleic acid than did control cows, but percentages of other fatty acids were similar for both groups. After parturition, percentages of each fatty acid were changed substantially, particularly the four major fatty acids (palmitic, stearic, oleic, and linoleic acids). For treated cows, the percentages of palmitic and oleic acids were higher at 0.5 wk after parturition than at 1 wk before parturition; percentages of stearic and linoleic acids decreased. Unlike treated cows, the percentages of both oleic and linoleic acids in the control cows did not change during that time. Moreover, we found that when lipolysis decreased, as indicated by lower plasma nonesterified fatty acid concentrations, the percentages of each fatty acid gradually rebounded toward the concentrations measured before parturition; this observation indicates that the shift in hepatic fatty acid composition is influenced by lipolysis. The increased lipolysis after parturition led to a vast increase in the hepatic triacyglycerol concentration and to a shift in hepatic fatty acid composition.

Relationship between triacylglycerol concentration in the liver and first ovulation in postpartum dairy cows.

The relationship between accumulation of triacylglycerols in the liver and first ovulation post partum was studied in an experiment with 32 dairy cows. During the dry period, 16 treated cows were fed a high energy diet to induce overconditioning, while 16 control cows were fed a recommended diet. After parturition, the treated cows entered deeper negative energy balance state, required more days to reach the nadir of negative energy balance, required more days to regain positive value of energy balance, and lost more body weight than the control cows. The treated cows also accumulated greater amounts of triacylglycerols in the liver and had higher concentrations of nonesterified fatty acids and 3-hydroxybutyrate post partum than the control cows. Although the number of days to first ovulation did not differ significantly between the 2 groups, the results of pooled data demonstrated that the liver triacylglycerol concentration was positively correlated with the number of days to first ovulation. In conclusion, negative energy balance caused the body fat of cows to mobilize. As a consequence, the cows accumulated greater amounts of triacylglycerols in the liver, and this accumulation was associated with an increase in the interval from parturition to first ovulation.

Effect of overfeeding during the dry period on regulation of adipose tissue metabolism in dairy cows during the periparturient period.

During the dry period, cows were either fed restricted amounts or were overfed to study lipolytic rates in adipose tissue. Higher lipolytic rates can result in greater accumulation of triacylglycerols in liver and, subsequently, hepatic lipidosis. Adipose tissue was biopsied at -1, 0.5, 1, 2, and 3 wk from parturition. The basal in vitro lipolytic rate was measured as well as the lipolytic rate as affected by the addition of noradrenaline, 3-hydroxybutyrate, or glucose. Liver was biopsied to quantify triacylglycerol concentrations. Blood was collected to determine insulin and nonesterified fatty acid concentrations. Basal in vitro lipolytic rates at -1 and 0.5 wk were lower in overfed cows. Lipolytic rate was enhanced in both groups of cows when noradrenaline was added, but rates at -1 and 3 wk tended to be higher in overfed cows than in cows that were fed restricted amounts. After the addition of 3-hydroxybutyrate or glucose in vitro, lipolytic rates tended to be higher in overfed cows. Liver triacylglycerol concentration was higher in overfed cows at 0.5 and 1 wk. Plasma insulin concentration tended to be higher in overfed cows at -1 wk. Plasma nonesterified fatty acid concentration was higher in overfed cows at 0.5 and 1 wk. Although overfeeding compared with restricted feeding did not significantly alter the in vitro lipolytic response to 3-hydroxybutyrate or glucose, adipose tissue from overfed cows tended to be less inhibited by these substances, which may contribute to higher lipolytic rates in vivo and a greater triacylglycerol accumulation in the liver after parturition.