BVDV and BHV-1 Infections in Dairy Herds in Northern and Northeastern Thailand

Bulk milk samples from 220 dairy herds were collected at 9 public milk collection centres in the northeastern and northern Thailand, and a subset of 11 herds was selected for individual testing. The samples were tested for presence of antibodies to BVDV and BHV-1 using an indirect ELISA. The results from the bulk milk testing demonstrated a moderate level of exposure to BVDV and BHV-1 (73% and 67%, respectively). However, the low proportion of herds with high BVDV antibody-levels (13%) and the low within-herd seroprevalence of BVDV and BHV-1 in the 11 herds (24% and 5%, respectively), particularly among the young stock (15% and 0%, respectively), demonstrated a low prevalence of active BVDV infection and a low rate of reactivation of latent BHV-1. The presence of a self-clearance process was also indicated by the results from the individual testing. Moreover, a surprisingly low prevalence of BVDV and BHV-1 antibody-positive herds at one of the milk centres was found. This centre was established 5–10 years before the others. Our impression is that this reflects the self-clearance process, where consecutive replacement of imported infected animals without further spread has resulted in a nearly total elimination of the infections. Based on our experiences and on these results we are convinced that this process can continue if there is awareness of herd biosecurity. This is especially important in the context of a future intensification of the dairy production

Peripheral and placental immune responses in sheep after experimental infection with "Toxoplasma gondii" at the three terms of gestation

P. 1-9Although it is known that gestation could infuence the clinical course of ovine toxoplasmosis, the precise efect of the term of gestation when sheep are infected are yet mostly unknown. The aim of this study was to evaluate the peripheral and placental immune responses developed in pregnant sheep after experimental infection with Toxoplasma gondiiat diferent times of gestation. Thirty‑six pregnant sheep were allocated in diferent groups, orally inocu‑lated with sporulated oocysts of T. gondiiat early, mid and late gestation and culled within 30 days post‑infection. The peripheral humoral and cytokine responses were evaluated, as well as the transcription of cytokines at the placenta. Serological analysis revealed that, regardless the term of gestation when infected, specifc IgG against T. gondiiwere detected from day 8 post‑infection and there was an early peripheral release of IFN‑γ at the frst week post‑infection followed by a short peak of IL10 and TNF‑α at the second week post‑infection. There were no signifcant diferences in this response between infected groups. At the placenta, a similar increase in transcription of IFN‑γ, and TNF‑α was found at the three terms of gestation, while IL‑4 increased mainly at the frst and second terms and IL‑10 transcription was higher at the last term. While these fndings show that both Th1 and Th2 cytokines play a key role in the patho‑genesis of ovine toxoplasmosis and that placental and peripheral immune responses do not closely correlate, there seems to be no clear modulation of these responses along the gestation.S

Effect of high cassava ration on insulin sensitivity and clinical signs of laminitis in dairy heifers

The relationship between high intake of rapidly fermentable carbohydrates and the subsequent response on plasma glucose, insulin sensitivity and clinical signs of laminitis in dairy heifers was studied. Ten dairy heifers with a mean body weight of 275 kg (SD 13.8 kg), were parallelly subjected (n=5/treatment group) to either a total mixed ration (TMR) low (LC, 130 g DM/kg) or high (HC, 480 g DM/kg) in cassava (starch). Results showed that mean DM intake, rectal temperature, heart rate, respiration rate and rumen contractions were not affected by the dietary treatments. All heifers fed the HC-TMR had diarrhea while all the heifers fed the LC-TMR had a pasty, soft consistency of feces. Three of the 5 heifers fed the HC-TMR displayed clinical signs of acute laminitis compared to none in the LC-TMR group. Mean postprandial rumen pH values of heifers fed the HC-TMR, but not the LC-TMR, were lower than 6.0 at all the time points measured. The reduction in rumen pH was associated with 49% greater concentration of total VFA and a concomitant shift from acetic to propionic acid and increased rumen lactic acid concentrations. Moreover, the HC-TMR caused greater plasma insulin levels and insulin resistance. The three laminitis animals had 1.9 greater basal plasma insulin values and a 46% lower insulin sensitivity values, respectively compared to their non-laminitis counterparts fed the HC-TMR. Insulin sensitivity was shown to be associated with clinical signs of laminitis in heifers only when plasma insulin concentrations were greater than ~ 700 pmol/L

Effect of high cassava ration on insulin sensitivity and clinical signs of laminitis in dairy heifers

The relationship between high intake of rapidly fermentable carbohydrates and the subsequent response on plasma glucose, insulin sensitivity and clinical signs of laminitis in dairy heifers was studied. Ten dairy heifers with a mean body weight of 275 kg (SD 13.8 kg), were parallelly subjected (n=5/treatment group) to either a total mixed ration (TMR) low (LC, 130 g DM/kg) or high (HC, 480 g DM/kg) in cassava (starch). Results showed that mean DM intake, rectal temperature, heart rate, respiration rate and rumen contractions were not affected by the dietary treatments. All heifers fed the HC-TMR had diarrhea while all the heifers fed the LC-TMR had a pasty, soft consistency of feces. Three of the 5 heifers fed the HC-TMR displayed clinical signs of acute laminitis compared to none in the LC-TMR group. Mean postprandial rumen pH values of heifers fed the HC-TMR, but not the LC-TMR, were lower than 6.0 at all the time points measured. The reduction in rumen pH was associated with 49% greater concentration of total VFA and a concomitant shift from acetic to propionic acid and increased rumen lactic acid concentrations. Moreover, the HC-TMR caused greater plasma insulin levels and insulin resistance. The three laminitis animals had 1.9 greater basal plasma insulin values and a 46% lower insulin sensitivity values, respectively compared to their non-laminitis counterparts fed the HC-TMR. Insulin sensitivity was shown to be associated with clinical signs of laminitis in heifers only when plasma insulin concentrations were greater than ~ 700 pmol/L

The effects of high levels of rumen degradable protein on rumen pH and histamine concentrations in dairy cows

An experiment was conducted to test the hypothesis that the supplementation of crude protein (CP) results in rumen acidosis and increased histamine concentrations in dairy cows. Six ruminally fistulated, non-pregnant dry cows were fed three experimental rations in a replicated 3 × 3 Latin square design. The CP contents in the low-CP, the high rumen undegradable protein (high-RUP) and the high rumen degradable protein (high-RDP) rations were 112, 259 and 266 g/kg dry matter (DM) respectively. The cows were fed 7.7 kg DM of the concentrates and 2.7 kg DM of rice straw. High levels of RDP in the ration significantly increased the ammonia, total volatile fatty acid (VFA) and histamine concentrations in the rumen fluid. However, supplemental CP, whether degradable or undegradable, did not significantly affect the pH of rumen fluid. Plasma urea nitrogen concentration was higher in both high-RDP and high-RUP in relation to cows fed the low-CP ration. The rise in ruminal histamine concentrations was physiologically non-relevant, most likely because rumen pH was not affected by supplemental CP at the installed level of DM intake. Therefore, it can be concluded that the issue of supplemental CP, rumen pH and ruminal histamine concentrations has not yet been settled. Further research is warranted to understand these relationships

Diet factors and subclinical laminitis score in lactating cows of smallholder dairy farms in Thailand

The objective of this study was to evaluate the importance of dietary crude protein (CP) content, dietary neutral detergent fiber (NDF) content and feeding regime as well as other factors related to management and demographics on the occurrence of (subclinical) laminitis under practical Thai feeding conditions. Hemorrhage of the white line and the sole, sole ulcer and white-line fissure of all four claws of milking cows (n=119) on 25 farms (selected based on the occurrence of lameness) were macroscopically assessed to calculate the prevalence of subclinical laminitis (SCL) on each farm. Data were collected on farm characteristics, feed and feeding management, floor type and hoof care. Dry matter intake was assessed on each farm and feed ingredients collected and analyzed for dry matter (DM), CP and NDF. No significant differences were found for farm characteristics such as herd size, number of milking cows, parity and body condition scoring between farms with a low (25%) of SCL. Percentages of DM and CP content of the rations did not differ, whereas mean NDF content in the ration was significantly higher in the low compared to the high prevalence farms. Multiple regression analysis of the data showed that a ration low in NDF content and/or in combination with the separate feeding of roughage and concentrate was associated with a high SCL prevalence. The results suggest that mixing concentrate with a substantial part of the roughage is an important strategy to prevent SCL in smallholder dairy farms under Thai feeding conditions. In addition, the dietary NDF content but not the dietary CP level is associated with SCL prevalence in dairy cows under Thai feeding conditions

Starch source in high concentrate rations does not affect rumen pH, histamine and lipopolysaccharide concentrations in dairy cows

The replacement of ground corn by cassava meal on rumen pH, lipopolysaccharide (LPS) and histamine concentrations under typical Thai feeding conditions (high concentrate diets and rice straw as the sole source of roughage) was investigated. Four rumen-fistulated crossbred Holstein, non-pregnant, dry cows were randomly assigned to the four experimental rations in a 4×4 Latin square design with 21-d periods. Each period consisted of a 14-d run-in/wash out period, followed by a 7-d experimental period. During the run-in/wash out period, the cows were offered 5.4 kg DM of concentrate containing 4.6% cassava meal and rice straw was provided ad libitum. During the 7 day of each experimental period, cows were offered 10.5 kg DM of concentrate containing either 4.6% or 18.3% or 32.4% or 46.2% cassava meal and 1.5 kg of rice straw. Irrespective of dietary treatments, rumen total VFA and lactate concentrations were significantly affected by sampling day, which were significantly higher on day 1 versus days 3 and 7 of the experimental periods. Mean postprandial rumen pH was reduced to value