M. R. Alam

Factors limiting the health of semi-scavenging ducks in Bangladesh

Duck rearing is well suited to coastal and lowland areas in Bangladesh. It is an important component of sustainable livelihood strategies for poor rural communities as an additional source of household income. An epidemiological study was conducted during January 2005–June 2006 on 379 households in Chatkhil of the Noakhali District, Bangladesh which were using the recently devised “Bangladesh duck model”. The overall objective of the study was to identify factors that significantly contributed to mortality and constrained productivity and to generate sufficient knowledge to enable establishment of a disease surveillance system for household ducks. The overall mortality was 15.0% in Chatkhil, with predation causing a significantly higher mortality compared with diseases (p < 0.001). Common diseases were duck plague and duck cholera. Morbid ducks frequently displayed signs associated with diseases affecting the nervous and digestive systems. Haemorrhagic lesions in various organs and white multiple foci on the liver were frequently observed in dead ducks. Epidemiological analysis with a shared frailty model that accounted for clustering of data by farm was used to estimate the association between survival time and risk factors. The overall mortality rate due to disease was significantly lower in vaccinated than in non-vaccinated ducks in all zones except zone 2 (p < 0.001). Only vaccinated ducks survived in zone 1. In conclusion, duck mortality and untimely sale of ducks appeared to be important constraints for household duck production in Chatkhil. Vaccination against duck plague appears to be an effective preventive strategy in reducing the level of associated duck mortality. A successful network was established amongst farmers and the surveillance team through which dead ducks, with accompanying information, were readily obtained for analysis. Therefore, there is an opportunity for establishing a long-term disease surveillance programme for rural ducks in Chatkhil of the Noakhali District of Bangladesh.

Oral administration of lysine restores food intake and ventromedial hypothalamic dopamine in chicken on a lysine-free diet

1. This study was conducted to examine whether oral administration of lysine solution affect food intake and the ventromedial hypothalamic (VMH) monoamines in chickens fed on a lysine-free diet. 2. Chickens were assigned to four treatment groups. Two groups of chickens were given two different doses of lysine solution (0·1 g and 0·07 g in 1 ml of saline) exogenously (orally) while being fed on a lysine-free diet, and these results were compared with a control diet plus saline group. Another group of chickens was fed on a lysine-free diet without lysine supplementation, and their results were compared with the lysine treated groups. The extracellular dopamine (DA), norepinephrine (NE) and serotonin (5-HT) in the VMH of freely moving chicken were measured by in vivo microdialysis. 3. There was no significant difference in food intake between the control diet and the lysine supplemented groups during the time-course of the experiments. Food intake significantly decreased at 4, 5 and 6 h in the lysine-free diet plus saline group compared with the lysine supplemented groups. Of the VMH monoamines, the DA concentration remained close to the baseline in the lysine supplemented groups. This DA concentration was significantly lower than the baseline in the lysine-free diet plus saline group at 3·5 h and thereafter. 4. No significant difference from the baseline was observed for NE in the lysine-free diet plus saline group. The 5-HT concentrations were close to the baseline for all groups throughout the experiments. 5. The findings suggest that oral administration of lysine solution to chickens fed on a lysine-free diet restored food intake which was associated with the variations of VMH DA concentration.

L-DOPA induced extracellular dopamine increases in the ventromedial hypothalamus affects food intake by chickens on a lysine-free diet

Previous work from our laboratory suggests that ventromedial hypothalamic (VMH) dopamine levels were associated with decreased in food intake by chicken on a lysine-free diet. Dopamine in the VMH started to decrease from its baseline after presenting a lysine-free diet and subsequently food intake decreased. In the present study, the dopamine levels were manipulated by perfusing L-3-4-dihydroxyphenylalanine (L-DOPA) into the VMH of chicken using the in vivo microdialysis technique and food intake was concomitantly measured when chickens received an experimental lysine-free diet. A microdialysis probe was implanted into the VMH. L-DOPA was then administered locally at 2 μg/ml through the dialysis probe into the VMH of free moving chicken for 15 min and the extracellular levels of dopamine (DA), norepinephrine (NE) and serotonin (5-HT) were measured. Hourly food intake was also measured simultaneously both for control and experimental groups. Microdialysates collected from the VMH were analyzed using high performance liquid chromatography with electrochemical detection. Local administration of L-DOPA in chicken VMH increased extracellular levels of DA, which was observed at 1-2.5h. There were no differences of NE and 5-HT levels from baseline in either group. Food intake was higher in L-DOPA treated chickens than controls at 2h. Chickens received the lysine-free diet ate as much of their diet as the controls in the subsequent 2h when the DA level was kept higher than the baseline. The findings suggest that L-DOPA induced extracellular DA increased in the VMH which was temporarily followed by the restoration of food intake in the lysine-free group.

Skin injuries identified in cattle and water buffaloes at livestock markets in Bangladesh

Skin injuries were assessed in 560 imported and local cattle and water buffaloes at two livestock markets in Bangladesh. The body of each animal was divided into 11 anatomical regions, and abrasions, lacerations, penetrations, ulcerations, bleeding, swelling, hyperkeratosis and scars were recorded for each region. Among the 560 animals studied, 501 were found to have at least one injury. The prevalence of skin injuries was 89 per cent, with 84 per cent of the cattle and 99 per cent of the water buffaloes having obvious skin injuries. The most common types of injury were abrasions that were found in 73 per cent of the animals, followed by scars (50 per cent), and lacerations (41 per cent). Buffaloes had more abrasions (95 per cent), lacerations (57 per cent), swelling (15 per cent) and hyperkeratosis (32 per cent) compared with cattle, whereas scars (60 per cent) were more common in cattle (P<0.001). Within the 11 different anatomical regions, all types of injuries were present but in different proportions. The buttock region had a higher proportion of abrasions (36 per cent) followed by the hip, hindlimb and back regions. Penetration, ulceration, bleeding and swelling were present at lower frequencies in all regions. Causes for these injuries included rubbing against the inside wall of vehicles used for transportation and stock-handler abuse (59 per cent and 13 per cent, respectively). Buffaloes sustained more transport injuries than cattle, and the number of injuries was higher in imported than local animals.

Voluntary food intake variation in chickens on lysine-free diet is attributed to the plasma lysine concentration.

Abstract 1. Growing chickens decrease their voluntary food intake when they receive a diet deficient in a single essential amino acid. Our previous studies suggest that the decreased food intake was associated with some metabolic changes. 2. In order to reveal the involvement of plasma lysine fluctuations in the reduction of food intake, we examined whether maintaining the plasma lysine concentration in chickens on a lysine-free diet (the purified diet contained no lysine) restored the food intake to that of the control (lysine hydrochloride 11.9 g/kg) group. 3. Male egg-type chickens at 21 d of age were injected with lysine at doses of 0.1 g/ml one hour after presenting the lysine-free diet. This injection increased the plasma lysine concentration one hour later and kept it similar to that of the control group for the following 2 h. Chickens ate the lysine-free diet as much as the control diet when their plasma lysine concentration was kept at a similar level to the control group. Injection of saline or alanine (0.12 g, isonitrogenous to lysine 0.1 g) into the crop of chickens on the lysine-free diet did not bring about the variations of food intake and plasma lysine concentrations as observed in those with lysine. 4. These findings show that the food intake variation was attributed to the plasma lysine concentration in the chickens on the lysine-free diet.

Local administration of l-DOPA in the chicken ventromedial hypothalamus increases dopamine release in a dose-dependent manner

L-DOPA induced extracellular dopamine (DA), norepinephrine (NE) and serotonin (5-HT) in the ventromedial hypothalamus (VMH) of chickens were measured by in vivo microdialysis. Several doses of 3,4-dihydroxy-l-phenylalanine (l-DOPA) were administered locally through the microdialysis probe into the VMH of chickens for 10 min. Local perfusion of l-DOPA increased the extracellular levels of DA. The increased DA was dose-related and was significantly higher compared to the baseline and control group. The maximal level of DA was 212% and 254%, respectively, of the baseline following administration of 1 and 2 μg/ml l-DOPA. There were no changes in NE and 5-HT levels from baseline after l-DOPA perfusion. l-DOPA (1 μg/ml) was mixed with Ca(2+)-free Ringer, tetrodotoxin (TTX) (2 μM) and high K(+) and was perfused for 30 min into the chicken VMH. TTX and Ca(2+)-free Ringers solution inhibited the effectiveness of l-DOPA in increasing DA release. The NE and 5-HT levels were significantly lower than the baseline. After administration of K(+) a significant increase of DA, NE and 5-HT was observed. The microdialysis results are consistent with our objective that l-DOPA induced extracellular DA increases in the VMH in a dose-dependent manner and the released DA, NE and 5-HT within the dialysate were related to neuronal activity.