Effect of season on the immunity of newly hatched broiler chicks reared in arid-hot climate.

This study was conducted to investigate the effect of the environmental temperature on the immune response of exotic broiler chicks reared in arid-hot climate zone (the Sudan). Twenty eight broiler chicks (Lohman) were challenged with 1 mL of 10% sheep red blood cells suspension (10% SRBCs) at day 2 and day 13 during summer (June) and winter (January) seasons. At day 13 and day 20 sera were harvested and subjected to hemagglutination test to measure antibody titers against 10% SRBCs for primary and secondary immune response, respectively. In winter season the antibody titers (GMT) against 10% SRBCs for the secondary immune response was so high compared to that in summer season. Nevertheless, the antibody titers for primary immune response during winter and summer seasons were, somehow, identical although it was a little bit higher during winter season. The weights of the lymphoid organs (spleen, thymus and bursa of Fabricius) were significantly higher in the winter season compared to summer season irrespective of the age.

Effect of residual yolk sac on growth, liver total lipids and serum total lipids in broiler chicks.

Two experiments were conducted to investigate the effect of the residual yolk sac on growth and total lipids in serum and liver of newly hatched broiler chicks. In each experiments 36 one day old broiler chicks (Lohmann) were allocated to three groups according to the status of the residual yolk sac; deutectomized (surgical ablation of the residual yolk sac, Y), sham operated (S) or intact chicks (I). Y chicks, when compared to S or I chicks, exhibited significant reduction in body weight gain during the 1st week of age. Feed intake was not significantly affected by removal of residual yolk sac. Removal of the residual yolk sac had no effect on serum total lipids and serum cholesterol during 8 days post-hatch and dietary fat absorption for 15 days. Significant interaction between age and removal of residual yolk sac was observed for liver total lipids. Furthermore, the results showed that the liver total lipids, serum total lipids and serum cholesterol were significantly lower at day 8 compared to day 2. The results of this study indicated that removal of the residual yolk sac had no effect on serum total lipids, serum cholesterol, dietary fat absorption and liver weight. However, it reduced the growth of the chicks for the first week of age, after which the chicks compensate for this reduction. The removal of the residual yolk sac showed significant interaction with age for liver total lipids.

Growth and apparent absorption of minerals in broiler chicks fed diets with low or high tannin contents.

Sorghum grains with low (0.28 per cent catechin equivalent (%CE) or high (1.36%/DCE)) tannin contents were used to study the effect of tannin on growth and on the apparent absorption of Ca, P, Mg, Na, K, Fe and Co by chickens. High-tannin sorghum caused a highly significant (p < or = 0.01) reduction in the weight gain and feed intake of broiler chicks compared to low-tannin sorghum and increased the feed conversion ratio (p < or = 0.01). The amount of tannin did not affect mortality. The apparent absorption of Ca, P, Mg, Na, K, Fe and Co was reduced (p < or = 0.01) by feeding sorghum grains with a high tannin content.

Mineral deficiencies in grazing dairy cattle in Kordofan and Darfur regions in western Sudan.

The seasonal changes in mineral profiles in serum of grazing dairy cattle and the concentrations of nutrients available from forages were determined in western Sudan. Blood samples were collected seasonally from dairy cows, Kenana and Botana breeds, in 6 locations in Kordofan and Darfur. Data were analysed as a split-plot design with repeated measures. The results indicated there were significant seasonal changes in concentrations of P, Cu and K, Ca, Mg, Na, Co, and Zn in blood serum of grazing cows. Concentrations of P, Ca and Na in serum were lowest during the late dry season (4.5 mg/dl, 8.21 mg/dl and 129 mEq/L respectively), while concentrations of Cu, deficient throughout the year, were lowest during the rainy season (0.35 microgram/ml). The interaction of location x season was significant for serum P, Ca, Cu, Mg, Na, Co and K. Kenana cattle had lower Zn in serum (0.96 microgram/ml) than Botana cattle (1.13 microgram/ml). During the dry season, forages had very low CP (3.5 +/- 0.5%), high neutral detergent fibre (NDF) (67.5 +/- 1.8%) and high acid detergent (ADF) (38.5 +/- 1.2%) content. Calcium, P and Na levels in forages were deficient during the dry season (0.38 +/- 0.03%, 0.08 +/- 0.03% and 0.047 +/- 0.01% respectively). Copper also was deficient in forages during the dry season, but adequate during the mid-rainy season (3.0 +/- 2.4 and 26.1 +/- 1.5 mg/kg respectively). In conclusion, the low Cu concentration in sera of cattle indicated a possible nutritional deficiency throughout the year, while P, Ca, and Na were low in sera during the late dry season. Thus, seasonal deficiencies of minerals may affect productivity of cattle in the Kordofan and Darfur regions of Sudan.

Reduced selenium status in chicks given diets low in sulphur-containing amino acids and containing sodium nitroprusside as a source of cyanide.

1. Two experiments were carried out to study the effect of dietary cyanide, given in the form of sodium nitroprusside (SNP), on the growth and selenium status of chicks fed on diets low in sulphur-containing amino acids. 2. In experiment 1, SNP (0.3 g/kg) depressed growth rate and food intake when included in diets low in total sulphur-containing amino acids. It also reduced plasma and liver glutathione peroxidase activity (GSH-Px) and kidney selenium concentration. These latter variables also showed increases in response to supplements of selenium of 0.1 and 0.2 mg selenium/kg (as sodium selenite) although growth was not affected. 3. In experiment 2, SNP did not affect growth when reduced to 0.1 g/kg in diets low both in methionine and total sulphur-containing amino acids. It did, however, reduce plasma GSH-Px activity, which again increased in response to similar dietary supplements of selenium. 4. It is concluded that dietary cyanide effectively increases the requirement for selenium and could induce deficiency in diets only marginally adequate in selenium, particularly when the supply of sulphur-containing amino acids was marginal or inadequate.

Effect of dietary sodium nitroprusside as a source of cyanide on the selenium status of chicks given diets of varying selenium concentration.

1. The interaction between dietary cyanide, given in the form of sodium nitroprusside (SNP), and selenium has been studied in two experiments with growing chicks from 14 to 38 d of age. 2. In experiment 1, dietary selenium at 10 mg Se/kg reduced growth, food intake and efficiency of utilisation, and increased relative liver size and selenium content. All of these effects were eliminated by the addition of 0.1 g SNP/kg except for liver selenium content, which progressively declined towards control values as SNP was increased to 0.4 g/kg in increments of 0.1 g/kg. At 0.3 g SNP/kg, cyanide toxicity, as judged by decreased growth, reached significance. 3. In experiment 2, similar effects were observed with selenium at 10 mg Se/kg and SNP at 0.3 g/kg, but selenium deficiency was not evident from growth indicators when selenium supplementation of the diet was omitted completely, nor did these indicators suggest that deficiency was induced by cyanide. 4. In both experiments, plasma and liver glutathione peroxidase activity reflected the dietary selenium content. There was an interaction with dietary SNP content. With selenium intake at a toxic level, SNP increased enzyme activity, further evidence of alleviation of selenium toxicity, but when selenium intake was low and normal, SNP decreased activity in liver, an indication that cyanide could induce deficiency. 5. A possible mechanism for alleviation of selenium toxicity is proposed.

Sodium nitroprusside, a convenient source of dietary cyanide for the study of chronic cyanide toxicity.

1. The suitability of sodium nitroprusside (SNP) as a source of dietary cyanide has been tested with growing chicks and with hens by measuring plasma or urinary thiocyanate; the major detoxication product of cyanide. 2. Growth and food intake were depressed and plasma thiocyanate concentration was increased in chicks in a progressive manner as the dietary concentration of SNP was increased from 0 to 0.5 g/kg. 3. In laying hens, urinary excretion of thiocyanate was increased fivefold by including SNP in the diet at 0.3 g/kg. 4. It is concluded that SNP is a suitable and convenient source of dietary cyanide for the investigation of chronic cyanide toxicity.

Nutritional and biochemical factors influencing the biological effects of cyanide.

Investigation of the dietary interaction between cyanide and selenium in the chick, whereby cyanide alleviates selenium toxicity, suggests that cyanide alters metabolic reductive potential. Cyanide enhances the elimination of selenium as dimethyl selenide, the formation of which requires both reducing equivalents and methyl groups. Even when the methionine supply is adequate, meeting the need for the methyl groups, the interaction can be lost if there is a deficiency of certain micronutrients or an excess of vitamin K. Cyanide reduces liver glycogen, implying greater emphasis on anaerobic metabolism through inhibition of cytochrome oxidase. This may increase reductive potential but may also result in increased free radical production, processes that can be modified by levels of micronutrients. There is no evidence that an excess of sulphur amino acids can markedly enhance cyanide detoxification, although, for reasons that are not yet clear, cystine may be beneficial. However, the balance of dietary amino acids may be more critical than had been realized, because an excess of alanine appears to exacerbate cyanide toxicity.