W. A. Dewar

The digestibility of acetic, propionic and butyric acids by the fowl

Synopsis Acetic, propionic and butyric acids, fed as the calcium salts at a level so that the diet contained about 2.5 per cent of the fatty acid ion, were completely digested. Examination of the contents of gut sections indicated that each acid was completely removed from the ingesta before this reached Meckels diverticulum.

Effect of dietary fat on mineral retention in the chick

Synopsis Chicks were fed seven experimental diets to determine whether the level or type of dietary fat affected the retention of calcium, iron, magnesium or zinc. It was found that the presence of any type of fat at or above the 5 per cent level decreased the retention of all four. Retention decreased with increasing dietary fat concentration and increased with increasing absorbability of the fat. For fats of similar absorbabilities, minerals were more poorly retained when the fat was present as free fatty acid. Lowest mineral retention occurred with poorly absorbed free fatty acid.

Effect of stocking density on performance of broiler chicks.

Synopsis In two experiments space allowances of 0.143, 0.122, 0.105 and 0.093 m2/bird and 0.093, 0.078, 0.064 and 0.047 m2/bird were used and their effects on live‐weight, food consumption and food conversion of Cobb broilers up to 10 weeks old were measured. When the space allowance was greater than 0.093 m2/bird there was no effect on any of the characters studied. At 10 weeks old a decrease in space allowance from 0.093 to 0.047 m2/bird was accompanied by reduced final live‐weight and food consumption and increased efficiency of food conversion; the effect on live‐weight was smaller at 9 weeks and was not significant at 8 or 7 weeks. It was concluded that in broiler experiments ending at 8 weeks a space allowance of 0.078 m2/bird (0.8 ft2/bird) is more than adequate.

Sodium toxicity resulting from feeding hen egg albumen powder to turkey poults

Synopsis Purified diets, containing spray‐dried egg albumen powder as the source of protein, caused cardiovascular symptoms, reminiscent of the “oedema syndrome “, resulting in high mortality when fed to turkey poults from 1 d of age. This was found to be due to the amount of sodium contributed by the albumen to the diets. Use of a reprecipitated albumen of low sodium content produced satisfactory growth and low mortality.

The transfer of minerals from the egg to the chick embryo from the 5th to 18th days of incubation

Synopsis The amounts of copper, iron, magnesium, manganese, potassium, sodium and zinc in the embryo and in the rest of the egg were determined daily from the 5th to 18th days of incubation. For all minerals the relationships between the amounts present in the embryo and the embryo dry weight were allometric over this period. There were significant, positive, within‐day correlations between the amounts of copper, manganese, sodium and potassium and between iron, magnesium and zinc present in the embryo. Only in the cases of iron and sodium was there evidence to suggest that the total amount of the element present in the egg was correlated with the amount transferred to the embryo.

Monocytosis in experimental zinc deficiency of domestic birds

Differential and total white cell counts on the peripheral blood of chickens, turkeys and quails maintained from hatching on an experimental zinc-deficient diet, revealed a severe monocytosis. In chickens the increase in monocytes was first detected on the 3rd day after hatching and was maintained until 18 days of age. The relationship of this monocytosis to the zinc-associated factors which affect mammalian leucocytes and to the damaged epithelium in zinc-deficient birds is discussed.

Sodium supplementation of broiler rations

Synopsis Broiler chickens were fed on diets containing 0.1 to 0.5% sodium from 0 to 8 weeks. During the 0‐ to 4‐week period the best combined growth rate and efficiency of food conversion was obtained when the diet contained 0.2% sodium; for the period 0 to 8 weeks 0.2 and 0.3% were equally good. The treatments had no effect on carcass moisture retention.

Effect of dietary sodium levels on the incidence of testicular cysts in the chick

Synopsis Testicular cysts have been recognised as a new sign of sodium toxicity in chicks. Practical diets containing different sodium levels were fed to chicks of three different strains and the occurrence of testicular lesions was noted. The strains varied in their susceptibilities, but cysts were found in birds fed diets whose sodium contents would have been regarded as satisfactory by all other criteria.

Some histochemical observations on zinc deficiency in chickens.

Histochemical examination of tissues from chickens maintained from hatching on experimental zinc-deficient diets, showed that enlargement of the nucleoli of the crop epithelium was associated with increased amounts of RNA in that organelle. The layers of mucosubstance-coated prickle cells near the lumen of the crop were reduced in number and this pericellular, PAS-positive and colloidal iron-staining material was sometimes less distinct round the remaining prickle cells. Ten enzymes were examined in various tissues but only alkaline phosphatase in the stratum basale of the crop and oesophagus and in the tarsometatarsal epiphyseal cartilage, and alcohol dehydrogenase in similar regions of the crop and oesophagus, were severely depleted. The reaction for NADH diaphorase was moderately less intense in the crop and oesophageal epithelium.

Morphological changes seen at sexual maturity in experimentally induced cystic testes of broiler fowls.

It has been shown previously that a proportion of chicks fed on a high salt diet from hatching developed a severe diffuse cystic dilation of their seminiferous tubules. In an effort to determine whether such testes could produce spermatozoa, birds with cystic testes were selected by direct inspection of their gonads at laparotomy and then maintained until sexual maturity when they were killed and their testes examined histologically. A variety of pathological features was found in the seminiferous tubules but spermatogenesis could be demonstrated in the majority of gonads, thus indicating that although severely damaged at 4 weeks of age considerable epithelial recovery is possible, even though these birds were maintained on a high salt diet for the entire experimental period of 40 weeks.