The effects of decreasing the calcium (Ca) level of the diet during the growing and early laying period were investigated with Single Comb White Leghorn pullets. In the first experiment, lowering the dietary Ca level from 3.2 to 2.0 or 1.0% between 154 and 182 days of age or to 2.0% between 183 and 211 days influenced egg specific gravity (P<.001) and shell weight at 177 and 205 days but had no effect (P>.05) on subsequent measurements. Dietary Ca level had no effect on feed intake and efficiency, egg production and yield, egg weight, and Haugh units during the laying period from 154 and 439 days. In a second experiment containing chicks from each of four 2-way crosses, three commercial and a control strain, the dietary Ca level was lowered during the rearing (1 to 143 days) and laying (144 to 354 days) period. Mortality was higher and body weight lower (P<.001) for chicks reared on diets containing .51% Ca than those given the control diets containing .78% Ca. In the laying period, egg production, feed intake and efficiency, and egg specific gravity were lower and mortality, Haugh units, and blood spots were higher for pullets given a diet containing 2.2% Ca between 144 and 242 days or 144 and 340 days than for those receiving a 3.2% Ca laying diet. The hens given the 2.2% Ca laying diet previously had received the .51% Ca diets during the rearing period. There were differences (P<.05) among strains for the aforementioned variables, except feed intake and efficiency, but there were few strain X dietary Ca interactions. These results indicate that egg shell quality was only temporarily improved when the dietary Ca was decreased and subsequently increased during the laying period. (
1. Sialidase digestion resulted in a decreased electrophoretic mobility of pig transferrins without destroying their ability to bind iron.2. The decrease in electrophoretic mobility occurred in two distinct steps.3. The migration rates of the final sialidase digestion products of TfA and TfB suggest that the difference in mobilities of TfA and TfB is not due to a difference in the amount of sialic acid which each contains.4. The mobility differences between the three zones observed for both TfA and TfB under high voltage Tris–citrate gel analyses do not appear to be due to the amount of sialic acid possessed by each.
Crystalline ethyl and propyl l,2-orthoacetates of or-D-glucopyranose triacetate were prepared. Conclusions are drawn regarding the chemical properties and configurations of these compounds which are based on the conformation of the l,2-cyclic carboxoni~~m ion believed to be formed when the substances are treated with acetic acid.
An experiment was made to investigate the possibility that reported differences in egg specific gravities, associated with time of oviposition, may in part be due to the duration and/or method of egg storage. It was confirmed that eggs laid in the afternoon had higher specific gravities than those laid in the morning. This effect could not be explained by differences in the duration and conditions of storage. The evident cause was the increased thickness of the egg shell and of its mass relative to egg size.
The effect of vitamin D on the components of epiphyseal cartilage was investigated. Three-week-old rachitic chicks were pooled into two groups, one of which received vitamin D3, while the other served as a control. The epiphyseal cartilage from these two groups was subjected to comparative study which is described in detail. Two distinct effects that resulted from the vitamin D3administration were the significant increases in the hexosamine content and in the amount of acetone-extractable solids.
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