A slaughterhouse survey of lung lesions in slaughtered stocks at Arusha, Tanzania.

An abattoir survey was conducted on clinically healthy 115,186 cattle, 61,551 sheep and 37,850 goats slaughtered in Arusha municipality, Tanzania, between 2005 and 2007. The objective was to determine the prevalence of disease conditions affecting the lungs. Routine meat inspection procedures were used to detect the presence of the pathological lesions. A total of 15,245 (13.2%), 4668 (7.8%) and 3192 (8.4%) lungs of cattle, sheep and goat, respectively, were condemned due to nine diseases/conditions namely pneumonia, hydatidosis, emphysema, abscesses, anthracosis, pleurisy, calcified cysts, melanosis and bovine pulmonary tuberculosis. Pneumonia was the leading cause of condemnations as it was responsible for 4594 (30.1%), 1495 (31.4%) and 1072 (33.6%) of all the condemned lungs in cattle, sheep and goats, respectively. Anthracosis, pleurisy, melanosis and pulmonary tuberculosis were only recorded in cattle attributing to 7.3%, 6.4%, 2.9%, and 0.7% of lung condemnations, respectively. The percentages of lung conditions recorded in 2005, 2006 and 2007 were not statistically different (P>0.05) among cattle, sheep and goats. The different lung lesion percentages recorded in cattle were significantly higher (P<0.05) compared to sheep and goats. There were no significant (P>0.05) variations between lung condemnation percentages due to various diseases during the rainy and dry seasons. Because of their zoonotic nature, occurrence of hydatidosis and tuberculosis may pose a public health risk. The study showed that different lung diseases/lesions in domestic ruminants are prevalent in Tanzania. Thus, there is a need to introduce appropriate control measures of diseases affecting lungs to minimize the rate of infection and reduce the ensuing economic losses. The data obtained from this survey cannot be wholly relied upon as accurate, but it can be used as a baseline for more extensive epidemiological investigations.

Theileria parva infection in calves causes massive lymphocyte death in the thymus, spleen and lymph nodes without initial proliferation.

In a study of trends and magnitudes of lymphocytes proliferation, destruction or apoptosis eleven 3-month-old healthy calves were experimentally infected with the protozoan parasite Theileria parva, which is reported to cause lymphocyte proliferation. Four control calves were not infected. Infected and non-infected calves were sacrificed on days 9, 12, 16, 19, 23, 24 and 25 to examine lymphoid tissue changes and lymphocyte proliferation, apoptosis or necrosis in the thymus, spleen and lymph nodes. All infected calves developed severe East Coast fever, with enlargement of lymph nodes, dyspnoea, high fever and pulmonary oedema. Lymphocyte proliferation was not observed in lymph nodes, thymus and spleen; instead there were massive deaths of lymphocytes and other cells. The terminal severe disease caused massive lymphoid parenchyma coagulation terminating with caseation, organs and cells being undeterminable histologically. Tissues surrounding the lymph nodes were oedematous. Lymph node and thymus parenchyma were caseated and cortices and medulla indistinguishable because of severe lymphocyte and accessory cell deaths. The lymph node fibrous reticular stroma was necrotic and caseated. Lymphoid follicles in lymph nodes degenerated and lacked germinal centres. Lymph nodes, spleen and thymus were grossly enlarged, hardened, potato or cheese like, but microscopically very hypocellular and in the terminal disease acellular because of massive lymphocytes destruction. In the thymus there was extensive thymocyte and epithelioid cell necrosis and loss of distinction between cortex and medulla. The spleen white and red pulps were indistinguishable because of extensive lymphoid cell necrosis. The white pulp degenerated more than the red pulp. The massive lymphocyte deaths in the lymph nodes, thymus and spleen, without lymphocyte proliferation in this T. parva infection in calves leads to a conclusion that this parasite is lympho-destructive and lympho-degenerative in vivo rather than lympho-proliferative.

Effect of anionic salt and highly fermentable carbohydrate supplementations on urine pH and on experimentally induced hypocalcaemia in cows.

The objective of this experiment was to determine the effect of dietary grain on calcium homeostasis. Six rumen-fistulated dairy cows with 3 or more previous lactations and no history of parturient paresis were randomly assigned to a sequence of diets in a crossover study with 4 periods of 10 days each. Dietary treatments were: A control ration consisting of wrap grass silage alone (1), the control ration supplemented with ammonium chloride and ammonium sulphate salt solution (2), control ration following a period with supplementation (3) and control ration supplemented with increasing amounts of barley from 4 to 10 kg/cow per day, expected to produce subclinical rumen acidosis (4). Daily intake of the diets was adjusted to 14 kg DM/cow per day. On day 11, the calcium-regulating mechanisms in cows were challenged until recumbency by a standardized intravenous EDTA infusion and cows were left to recover spontaneously. Anion supplementation and the feeding of highly fermentable carbohydrate lowered urine pH below 7.0 due to subclinical acidosis. During spontaneous recovery from EDTA induced hypocalcaemia, the cows more quickly regained a whole blood free calcium concentration of 1.00 mmol/L if they had most recently been supplemented with either anionic salts or with increasing amounts of barley, as compared to the basic ration. It is concluded that so-called slug-feeding or 'steaming up' with highly fermentable carbohydrates before parturition in milk fever susceptible cows enhanced calcium homeostasis similar to the effect seen in cows on anionic diets.

The effect of subclinical hypocalcaemia induced by Na2EDTA on the feed intake and chewing activity of dairy cows.

The effects of induced subclinical hypocalcaemia (SCHC) on feed intake and chewing activity during eating and rumination were studied in dairy cows. Two non-lactating and non-pregnant cows were subjected to three different treatments, with one test per day, such that the plasma free (ionized) calcium (FCa) concentration was maintained at the eucalcaemic level or at one of two constant SCHC levels. The cows and test days followed a 2 x 3 crossover design. SCHC was maintained for 7 h by repeatedly infusing 5% Na2EDTA so that constant FCa concentrations of 0.8 mmol/L or 0.6 mmol/L in plasma were achieved. Control conditions were achieved by infusing isotonic saline. Feed intake and the number of the rumination periods were recorded during test days. The proportion of feed eaten during each test meal (EatPro) was related to the mean plasma FCa. An almost linear decrease in EatPro was observed when the plasma FCa was 0.6-0.9 mmol/L. The cows showed no other clinical signs of hypocalcaemia during Na2EDTA-infusion. The time spent chewing during eating and rumination, and the number of rumination periods during a test day, decreased with a decline in plasma FCa concentration. It was concluded that induced SCHC depresses the feed intake and ruminative activity of dairy cows.

The influence of short-term anion salt exposure on urine pH and on resistance to experimentally induced hypocalcaemia in cows.

The objective of this experiment was to induce acidification by anion salt supplementation for 2 days or 10 days and to study the prophylactic effects of such supplementation in preventing hypocalcaemia in cows. It was further attempted to monitor the extent to which any effect on the calcium-regulating mechanisms would persist following a 10-day period of acidification with anion salts. Study animals were three untreated control cows and three cows supplemented with ammonium chloride and ammonium sulphate in their ration for 2 days or 10 days through the rumen cannula. The basic ration of hay was dominated by Urochloa spp. The pH of the urine of the control cows was around 8.00 throughout the experiment and was considered normal. Anion-supplemented cows produced urine with a daily mean pH between 5.5 and 7.0, possibly due to anion salt exposure. The ability to withstand hypocalcaemic challenges was tested by a standardized intravenous infusion of disodium ethylenediaminetetraacetate (Na2EDTA). The calcium regaining time (CRT), expressed as time spent to reach 1.00 mmol/l of ionized calcium during recovery from the EDTA-induced hypocalcaemia, was used to compare cow responses. In the control cows the unexpectedly short CRT, especially during the weekly EDTA tests, could be a result of the repeated induced episodes of hypocalcaemia caused by the EDTA infusions. The improved CRT in the anion-supplemented cows may thus be interpreted as the combined effect of the repeated hypocalcaemic episodes due to EDTA infusions and probably the effect of anion-induced metabolic acidosis on endocrine-regulated calcium homeostatic mechanisms. The effect of anion salt exposure for 10 days on the improvement of calcium-regulating mechanisms was not clear due to the unexpected improvement of CRT that was exhibited by the untreated control cows as well. An on-farm trial of the effect of a 2-day or 10-day anion exposure of dry cows on calcium-regulating mechanisms is suggested.