[Agr. Biol. Chem., Vol. 34, No. 9, p. 1314•`1319, 1970] Availability of Energy in Ester and Ether Derivatives of Glycols by Growing Chicks By Minoru YOSHIDA, Hiroshi MORIMOTO,* Masanao MATSUI** and Ryohei ODA*** National Institute of Animal Industry *Japan Scientific Feeds Association **Faculty of Agriculture, University of Tokyo ***Faculty of Technology, Kyoto University Received March 4, 1970 Biological availability of 33 esters, 17 ethers and 2 acetals of ethanediol, 1,2-propanediol, 1,3-butanediol and 1,4-butanediol was compared by mini-test with chicks. Chicks can utilize esters of ethanediol, 1,2-propanediol and 1,3-butanediol with acetic acid and fatty acids of carbon chain length from 5 to 12 with more improved palatability than that of free acids, while availability of esters of these glycols with propionic and butyric acids was low. Esters of 1,4-butanediol and ether derivatives of these glycols was not available, except ethyl ether of di-ethanediol which was partially available. Acetacetal of ethanediol was partially available but n-butyracetal was not. This is the third paper of the studies on fore, it is suspected that chicks have enough the possibility of various chemicals as energy enzyme system or systems to utilize energy sources of poultry feed. In the previous in these acids readily. papers,1,2) biological availability of 54 aliphatic While Ozaki reported about 40 years ago4) mono-, di- and tri-carboxylic acids, 23 alcohols, that rats on acetic, butyric, capric acids died 16 aldehydes and 2 ketones was compared by within 40 days of experimental period, bioassay procedure, mini-test, developed speci Ashida's recent works5) revealed that growth fically for this purpose.3) rate of rats on acetic, propionic and valeric It was observed in the first paper of this acids was satisfactory but none of them series of studies that chicks can not utilize exceeded that of the control rats. energy in volatile fatty acids of carbon chain Since in these previous works volatile fatty less than 6, when the acids were mixed in acids were mixed in the diet and fed to the diet and fed to chicks. These findings chicks and rats, some physiological activities were unexpected, since these acids were of free fatty acids, such as influence on pH known as energy source for ruminants, being in digestive canal, may possibly depress the produced by the fermentation in rumen, and utilization of the acids. To avoid any such at the same time, various metabolic pathways detrimental physiological influence of free of these acids were published already. There acids, it was planned to study the availability of these volatile acids, in the form of ester 1) M. Yoshida, H. Morimoto and R. Oda , Agr. with four diols, i.e. ethanediol, 1,2-propanediol, Biol. Chem., 34, 1301 (1970). 2) M. Yoshida, H. Morimoto, M. Matsui and R. Oda, ibid., 34, 1308 (1970). 4) J. Ozaki, Nippon Nogeikagaku Kaishi , 8, 1286 3) M. Yoshida and H. Morimoto, ibid., 34, 684 (1932). (1970). 5) K. Ashida, private communication (1969). Availability of Energy in Ester and Ether Derivatives of Glycols by Growing Chicks 1315 1,3-butanediol and 1,4-butanediol. As for the EXPERIMENTAL moiety of the esters, initial three diols were Test material. Ethanediol di-laurate, ethanediol found available by chicks when mixed in the acetal and n-butyracetal, 3-ethoxy-, 3-propoxy- and diet at a level of 5%, but the last one, 1,4- 3-n-butoxy-1,2-propanediols were synthesized in Oda's butanediol, was observed unavailable by Laboratory, Kyoto University. Eleven esters of 1,2- chicks.6) Therefore, in the experiments propanediol, 13 esters of 1,3-butanediol and 7 esters planned, it was also attempted to confirm of 1,4-butanediol were synthesized in Matsui's Labora whether chicks can utilize 1,4-butanediol tory, University of Tokyo. when fed as esters of fatty acids. Cellosolve (ethanediol mono-ethyl-ether) and its 6 It was also found in the previous papers1) derivatives, carbitol (di-ethanediol mono-eth)-lether) that availability of free fatty acids with carbon and its 6 derivatives were all purchased as reagent, chain longer than 14 was low, mainly because of which grade were given in Note in Table I. Ethanediol mono-methyl ether, methyl cellosolve, was of low digestibility of these acids. Therefore, a highly special reagent to be used for amino acids esters of these higher fatty acids with various autoanalyzer. diols were included in these experiments to Gross energy of the test materials was determined find whether these higher fatty acids are by automatic bomb calorimeter, CA-1, manufactured available when fed in the form of ester. by Shimadzu Seisakusho. Gelatin capsule, of which Natural fat is an ester of these fatty acids caloric value was 4,371 cal/g with standard deviation with glycerol. Therefore, esters of these fatty of 197 cal, was used in the determination of volatile acids with diols, analogous to natural fat in materials. chemical construction, might be utilized by chicks better than the free fatty acids. Bioassay. Details of the procedure of bioassay was On the other hand, various ethers of exactly the same as those reported in the previous two papers.'.') All of the test materials were mixed ethanediol or its dimer, known as cellosolve in the diet at the level of 5%. Special care was and carbitol, respectively, and their derivatives taken to feed the diet containing cellosolve derivatives are readily available as solvents, so that to chicks in the smallest amount as possible at a. nutritive values of these solvents were also time, to avoid loss by evaporation. Standard dose studied by the procedure of mini-test. response curve was prepared so that available energy In the previous paper,2) it was revealed of the test material was estimated directly on the that acetal, which is a compound of acetal curve. dehyde with two molecules of ethyl alcohol, Procedure of the determination of digestibility was looked like partially available by chicks. also the same as that reported in the previous paper.1) Therefore, the analogous compounds of acetal dehyde or n-butylaldehyde with one molecule RESULTS AND DISCUSSION of ethanediol were prepared and tested for their availability by chicks. The data on ester and ether derivatives of The derivatives of 1,2-propanediol, having ethanediol were presented in Table I. ethoxy, propoxy, or n-butoxy groups at 3 Chicks could utilize energy in ethanediol position by ether bond, were also prepared di-laurate efficiently, but they could not utilize and tested. none of ether derivatives of ethanediol and In this paper, results of these mini-tests on of di-ethanediol, except ethyl ethers of di- esters and ethers of various diols were ethanediol. Methyl ethers of ethanediol summarized. were all toxic, and those of di-ethanediol retarded growth of chicks and palatability of 6) M. Yoshida, H. Hoshii and H. Morimoto, all of these ethers was low. Three ethyl Japan. Poultry Sci., 6, 73 (1969). ethers of ethanediol retarded growth of chicks 1316 M. YOSHIDA, H. MoRIMOTO, M. MATSUI and R. ODA TABLE I. GROSS ENERGY, AVAILABILITY AND PALATABILITY OF DERIVATIVES OF ETHANEDIOL a) See text. b) Special: special grade reagent; Fi c) D rst: first grade reagent; Reagent: reagent grade . ead/total. d) Can not be estimated because chicks died . but the corresponding ethers of di-ethanediol already reported6) that chicks can utilize part could be partially utilized by chicks , although of energy in dimer of ethanediol . Data on available energy of these ethers was not more ethyl ether of di-ethanediol agrees with the than one-third of their gross energy . Three previous observation. butyl ethers tested were all toxic , either A derivative of ethanediol with acetaldehyde retarding growth rate or killing the chicks . seemed to be utilized partially as shown by These findings suggested that ethyl moiety possitive available energy. Since only 5 g of of the ethers can be utilized partially by the sample was obtained and was fed to one chicks, but methyl and butyl moieties of the chick, no determination was carried out on ethers were rather detrimental . caloric value of the sample . It is supposed As discussed in the previous paper ,6) low to be about 5.8 kcal/g , which is the caloric availability of ethers of ethanediol suggested value of n-butyric acid having the same that chicks apparently lack the ability to molecular formula as that of ethanediol cleave the ether bond of these compounds , acetacetal. Therefore , the availability of the since moieties of these ethers after the cleav sample was expected to be about 200o . An age, i.e. methyl or ethyl alcohols and ethane other derivative of ethanediol with n-butyral diol, were known to be partially available dehyde was unavailable by chicks . These by chicks.2,6) On the other hand , it was two derivatives are acetal in nature showing Availability of Energy in Ester and Ether Derivatives of Glycols by Growing Chicks 1317 TABLE II. GROSS ENERGY, AVAILABILITY AND PALATABILITY OF DERIVATIVES OF PROPANEDIOL a) See footnotes of Table I, masked carbonyl function, and no detrimental clearly by carbon skeleton of the ester, the change in the diet was observed due to free data with this ester suggested very low carbonyl function, as discussed in the previous availability of propionic acid. paper.2) However, here again were obtained The data with derivatives of 1,3- and 1,4- the data indicating that ethyl moiety of the butanediols were summarized in Table III. compound can be partially available by chicks Again, chicks could utilize energy in esters but butyl moiety can not as in the case of of 1,3-butanediol with acetic acid and fatty ethers mentioned above.