THE EFFECT OF DIFFERENT ALLOWANCES OF FEED ON THE LEVELS OF BLOOD GLUCOSE,LACTIC ACID,FFA AND THE AMOUNT OF URINARY NITROGEN IN THE PIG

Zhou Da-cheng Qi Shun-zhang Zhang Huan-rong Niou Wen-biao Zeng Bing-ji Chen Qiao Xie Chang-mian Sun Cun-xiao Department of Veterinary Science,Beijing Agricultural University,Beijing

This trial was carried out during 1963—1964 and was a part of our research work on the effect of feed allowance on digestion and meta- bolism in the pig.In the beginning,16 young boars of the Jilin-Black breed similar in birth date and birth weight were used.They were castrated at 3 months of age and kept in good health condition during the whole test period. The pre-feeding period was arranged when the animals were 4—8 months of age.During this period of time they were kept under similar conditions and their blood glucose,lactic acid and FFA levels were analyzed once every two weeks,and the urinary nitrogen was also analyzed.At 8 months of age 6 pigs were selected from these 16 pigs and divided into 2 groups.In each group there were 3 pigs.In grouping, the average levels of blood glucose,lactic acid and FFA and the aver- age amount of urinary nitrogen of each group were made similar,so that the difference resulting from the difference of individuals could be eliminated. After grouping at 8 months of age,the 2 groups of pigs were kept in the same condition but the amount of essential feed of one group (the more feed group)was twice as much as that of the other group (the less feed group).So we could find the effect of different allo- wances of feed by comparison of these two groups. In the experimental period after grouping,i.e.at 8—12months of age,the blood samples were taken from the pigs' carotid vein before feeding in the morning once every two weeks and the levels of glucose, lactic acid and FFA of the blood were analyzed.In the same period, the urinary nitrogen of the pigs was also analyzed 4 times.After this,i.e.at 13 months of age,the fast test was carried out.From the experimental results the conclusions are as follows. 1.When the other conditions were common,the increase in feed allowance might increase the levels of blood glucose,lactic acid and the amount of urinary nitrogen and decrease the level of plasma FFA. Those phenomena were found either in the normal feeding period or in the fasting period of 4 days. 2.During the period of fasting,the change in metabolism of the 2 groups showed the same regular tendency.That is,after the beginning of fasting,the levels of blood glucose and lactic acid and the amount of urinary nitrogen tended to decrease while the level of plasma FFA tended to increase,and at about 36 hours after feeding,the levels of blood glucose and lactic acid and the amount of urinary nitrogen reach- ed the minimum values and then rose again.At the same time,that is,at about 36 hours after feeding the level of plasma FFA reached the maximum value and then decreased again.These suggest that at about 36 hours after feeding,a turn in the metabolism of the pigs happened to adapt the animals to the physiological needs of fasting. 3.Although the tendency of the changes in metabolism of the 2 groups of pigs was the same in the process of fasting,the activities in metabolism of the 2 groups appeared not the same.These were expressed in the fact that the rates of change in some metabolites' levels were not the same.The rates of both the increase and decrease in blood glucose and lactic acid level and in the amount of urinary nitrogen of the pigs ingesting more allowance of feed all were quicker than those of the pigs ingesting less allowance of feed during the process of fasting.These were induced by the different allowances ingested by the 2 groups of animals. 4.What differences were meant by the above differences in the metabolic activities between these 2 groups of pigs could not yet be ex plained completely from the results of this trial.But we already could see:(1)the regulatory mechanism of the pigs ingesting more allowance of feed could maintain the blood glucose in a higher steady level,and thus promoted the utilization of carbohydrate by their tissues;(2)their glycolytie activity was more intensive while the mobilization of trigly- ceride was lower than that of the pigs ingesting less allowance of feed; and(3)when it was necessary,the animals ingesting more allowance of feed could mobilize more body protein to convert it into carbohy- drate,that is,their activity of gluconeogenesis was more intensive. 5.The difference between these 2 groups of pigs also appeared in the response to the ingesting of food.Although the ingesting action induced the sudden rise in the level of blood glucose in both groups and the sudden decrease in the level of plasma FFA,(these were consistent with the well known theory now,)the extent of the increase in blood glucose of the pigs ingesting more allowance of feed was greater and the decrease in plasma FFA smaller than that of the pigs ingesting less allowance of feed.This phenomenon can not yet be well explained.