Gabrielle M. Ellinger

The Influence of Diet on the Nitrogenous Components Passing to the Duodenum and through the Lower Ileum of Sheep

Analyses of the alimentary contents flowing to the duodenum of sheep during 24 h show that when the sheep are consuming a low-nitrogen diet more total nitrogen and amino nitrogen pass to the duodenum than are eaten daily in the food whereas when the sheep are eating high nitrogen diets, less total nitrogen and less amino nitrogen pass to the duodenum. The disparity between the total nitrogen and amino nitrogen content of the diets largely disappeared by the time the alimentary contents reached the terminal part of the ileum. From 64 to 68% of the nitrogen entering the duodenum and 54 to 64% of the nitrogen in the ileal contents was in the form of amino nitrogen. Proportionately more of the amino nitrogen was in solution in the ileal contents than in the duodenal contents. Losses of amino acids in the stomach when a high-nitrogen diet was consumed were especially large for glutamic acid, aspartic acid, proline, arginine and leucine. They were least for cystine and threonine. Gains of amino acids in the stomach when low nitrogen diets were consumed were all substantial except for proline, where a loss was found when hay and flaked maize were given. When these changes are considered as proportions of the quantities eaten then trends are similar for all acids. Changes in the molar proportions of the amino acids present in hydrolysates of the duodenal and ileal contents are discussed together with the significance of these changes in relation to the nutrition of the sheep.

Skeletal changes during pregnancy and lactation in the rat: effect of different levels of dietary calcium.

It is now well known that the skeleton serves as a store of calcium and phosphorus, and that a part of the mineral requirements of lactation is met by bone resorption. In an earlier communication (Warnock & Duckworth, 1944) the literature was surveyed and the role of the spongiosa as a source of minerals for lactation in the rat was studied under conditions of adequate calcium intake. Certain interesting questions about the resorption of bone in lactation and its subsequent repair after lactation remain unanswered. In the first place, the extent to which the response of the skeleton to lactational needs is modified by differences in the level of calcium intake is unknown. Secondly, the extent to which cancellous and compact bone are individually resorbed in lactation and the degree to which these changes can be modified by alterations in calcium intake have not been studied. Thirdly, the extent to which calcium intake affects the capacity of cancellous bone and compact bone to recover after depletion does not seem to have been examined. Fourthly, it is not clear whether resorption of bone is the only process by which minerals are released from skeletal stores to meet the needs of lactation in the calciumdeficient animal. The possibility of demineralization of bone, that is of extraction of the mineral component without resorption of the organic matrix, must also be considered. Finally, it seems that no study has been made of changes in physical dimensions of bone in pregnant and lactating animals receiving diets differing in their calcium content. The present experiment was designed to answer these questions and to afford an opportunity to study the effects of different dietary calcium levels on the reproductive performance of rats and their ability to rear their young. The diets were composed of natural feeding-stuffs, selected for their low calcium content. Most earlier investigators in this field used synthetic diets.

Amino acid composition of some fish products and casein.

It has been shown that when vacuum-dried cod muscle is heated under controlled conditions of temperature and moisture the value of the protein as a supplement to cereal proteins diminishes (Carpenter, Ellinger, Munro & Rolfe, 1957). After heat treatment of the cod muscle, lysine was found to be the limiting amino acid in the gross protein value (GPV; Heiman, Carver & Cook, 1939) chick test and quality could be related to the available lysine content of the material. Yet, the supplementation of heated cod muscle with free lysine did not raise the GPV to the level obtained with the unheated cod muscle. Analyses were carried out to determine whether damage by heat treatment was reflected in the amino acid composition of acid hydrolysates prepared from heated cod muscle. Analyses are also reported for two other protein concentrates. Casein was chosen as the standard used in the GPV determinations and for comparison with other analyses in the literature. A sample of white-fish meal of known history and GPV was chosen as a protein used as standard in practical feeding trials, and for comparison with the cod-muscle preparations.

Economies in the use of animal by-products in poultry rations: II. Vitamin and amino-acid provision for laying hens

1. Birds fed on rations devoid of animal byproducts from hatching until 18 months of age were equal in laying performance and health to those that had received animal supplements. 2. The stimulation of early growth by feeding aureomycin did not affect the final weight of pullets, their egg production or the incidence of broodiness. 3. The ‘animal protein factor(s)’ was of limited importance for egg production. There was a suggestive indication of an effect of a deficiency of the factor(s) when birds on an all-plant ration had been laying for 6 months without access to their droppings. Limited access to ‘unfermented’ droppings, which provided the only dietary source of the factor(s) during both rearing and laying periods, was sufficient to meet the need of the birds for sustained egg production.