The Distribution of Carbohydrase Activities in the Small Intestine in Early Weaned Calves

Toshikazu MIYASHIGEand Shigefusa YAHATA

Chugoku National Agricultural Experiment Station, Oda-shi 694-01

(Received December 8, 1980)

Abstract 1. The carbohydrase activities of the small intestine of early weaned calves were compared with those of nursing ones at 26 weeks of age. 2. In the early weaned calves, the pH value of content of the caecum was observed to be lower than that of the nursing ones, suggesting that more soluble carbohydrates would have escaped from ruminal fermentation and reached the caecum. 3. The values of maltase and iso maltase activities of the early weaned calves were not different from those of the nursing ones. However, maltase activity of the early weaned calves distributed more constantly with relatively high level all over the small intestine. Lactase activity of the early weaned calves was almost the same as that of the nursing ones. Dextranase and amylase activities were also found in the small intestine of the early weaned calves. Jpn. J. Zootech. Sci., 52 (7): 532-536, 1981

In the previous study1) with nursing calves, it was shown that intestinal maltase activity was very low and did not increase with age. But the pattern of the distri- bution of maltase activity in the small intestine apparently changed with age and higher activity of maltase was found in the lower part of the small intestine at 26 weeks of age. Although the meaning of this change is not known, it is supposed that the change of the pattern would be correlated with the increase of solid food intake. The purpose of the present study is to observe the effect of early weaning of beef calves on the activities of intestinal carbohydrases, especially those related to break- down of starch, and their distributions.

Materials and Methods

Four calves of Japanese Black Cattle were used. The calves were removed from their dams at one week of age and then were offered milk substitute until 6 weeks of age. Concentrates (25.2% crude protein, 4.5% crude fiber and 47.8% crude starch in dry matter) and hay (7.2% crude protein, 38.3% crude fiber and 13.8% crude starch in dry matter) were offered ad libitum at 9 a.m. every day. All calves were killed at 26 weeks of age. The time of killing was fixed at 1 p.m. The mucosa of the small intestine for enzyme assay were taken exactly from the middle of each quarter of the whole length. These sampling sites were at 13, 38, 63 and 88% of the whole length of the small intestine measured from the pylorus. The contents of each part of the small intestine and the caecum and colon were

Jpn. J. Zootech. Sci., 52 (7): 532-536 532 1981 Intestinal Carbohydrase of Early Weaned Calves taken for pH measurement. The procedure of preparation of mucosal homogenate was the same as described previously1). Enzyme activities of lactase (EC 3. 2. 1. 23), maltase (EC 3. 2. 1. 20), isomaltase (EC 3. 2. 1. 10), dextranase (EC 3. 2. 1.

11)and α-amylase (EC 3. 2. 1. 1) were measured by the methods of DAHLQVIST2,3).

One unit of activity of the former three is defined as that which hydrolyses 1μmol

disaccharide in one minute at 37℃. _One unit of activity of the latter two is that

which liberates reducing groups corresponding to 1mg of maltose in one minute at

37℃. The protein contents of homogenates were assayed by the method of LOWRY

et al.4).

Table 1. Body weights and relative tissue weights of the reticulo- rumen, abomasum, small intestine and large intestine to the body wei- ghts in early weaned calves and nursing ones1)

1) Mean±S. E. 2) taken from our earlier work1)

Results

Table 1 shows the body weights and the relative tissue weights of the reticulo- rumen, abomasum, small intestine and large intestine to the body weights in early weaned calves, and also in nursing ones taken from our earlier work1). The tissue weight of the reticulo-rumen of the early weaned calves was significantly greater than that of the nursing ones (P<0.01). However, there were no significant differences between those calves in other tissue weights. The enzyme activities of mucosa and the pH values of contents from different sites of the small intestine and from the caecum and colon are shown in Table 2. Lactase activity of the early weaned calves seemed to be quite similar to that of the nursing ones. Much differences were not observed between the calves of early weaning and of nursing in the activities of maltase and isomaltase. In the early weaned calves, however, maltase activity with relatively high level was distributed more constantly all over the small intestine. It was apparent that the activities of dextranase and amylase were also found in the small intestinal mucosa. Amylase activity showed a tendency to increase in the lower part of the small intestine, although there were great variations among individuals. The change of pH in the small intestine of the early weaned calves was similar to that of the nursing ones.

533 MIYASHIGE and YAHATA

Table 2. Carbohydrase activities of mucosa and pH values of contents from different. sites of the small intestine and from the caecum and colon in early weaned calves and nursing ones at 26 weeks of age1)

1) Mean±S. E. of four and three animals for early weaning and nursing, respectively.

2) taken from our earlier work1)

However, the pH in the caecum of the former was significantly lower than that of the latter (P<0.05).

Discussion In our early weaned calves, the tissue weight of the reticulo-rumen showed remarkable development compared with that of nursing ones and a large quantity of intake of solid food, especially concentrates, was observed. Our finding of distinctly lower pH value of the caecal content in the early weaned calves suggests that there would be more soluble carbohydrates bypassed the ruminal digestion and reached the caecum. However, the values of maltase and isomaltase activities of the early weaned calves were not much different from those of the nursing ones, suggesting almost no dietary effect. SIDDONS5)also reported a similar result, in which no marked differ- ences were observed in carbohydrase activities including maltase and lactase at ages of 101 and 114 days between calves that had been fed solely on milk and those that had been given a concentrate-hay diet from weaning at 6 weeks of age. But, there

534 Intestinal Carbohydrase of Early Weaned Calves was also our finding that in the small intestine, more constant distribution of maltase activity with relatively high level, which seemed to be rather similar to that of fattening steers reported earlier1), was observed in the early weaned calvescompared with that in the nursing ones. This pattern of the distribution of the activity in the early weaned calves seemed to be dependent on much larger intake of concentrates and suggests probably some change of the digestive and absorptive regions of starch or its products of hydrolysis in the small intestine, although much increase of the digestive capacity by this enzymecould not be expected. It was reported that the activities of disaccharidases in the small intestine of rats exhibited circadian fluctuationswhich were closelyrelated to the cycle of feed intake6). In early weaning system, calves would show a different eating habit compared with those in nursing system. But a perfect shift of time eating feed in day cannot be considered between those calves under the same feeding system of concentrates and hay. The early weaned calves possessedalmost the same activity of lactase in the small intestine as the nursing ones did, suggesting that lactose from dam's milkis notvery important to regulate intestinal lactase activity. The mucosal homogenates of the small intestine showed the activities of dex- tranase and amylase, as also reported by SIDDONS5)and TOOFANIANet al.7). However, it is known that there is an adsorption of pancreatic amylaseonto the mucosa in all areas of the small intestine, where a process of membrane-digestiontakes place8). It would be predicted, therefore, that these activities originated from adsorbed enzyme.

References 1) MIYASHIGE,T. and S. YAHATA,Jpn. J. Zootech. Sci., 51: 58-68. 1980. 2) DAHLQVIST,A., Anal. Biochem., 7: 18-25. 1964. 3) DAHLQVIST,A., Biochem. J., 78: 282-288. 1961. 4) LOWRY, O.H., N. J. ROSEBROUGH,A. L. FARR and R. J. RANDALL,J. Biol. Chem., 193: 265- 275. 1951. 5) SIDDONS,R. C., Biochem. J., 108: 839-844. 1968. 6) SAITO, M., E. MURAKAMI,T. NISHIDA, Y. FUJISAWAand M. SUDA, J. Biochem., 78: 475-480. 1975. 7) TOOFANIAN,F., D. E. KIDDERand F. W. G. HILL, Br. vet. J., 130: 19-21. 1974. 8) SHREEVE, W. W., Physiological Chemistry of Carbohydrates in Mammals. 38-52. W. B. Saunders Company. Philadelphia. 1974.

535 MIYASHIGE and YAHATA

早 期 離 乳 子 牛 に お け るcarbohydrase活 性 の 小 腸 内 分 布

宮 重 俊 一 ・八 幡 林 芳

中国農業試験場,大 田市694-01

早 期離 乳 に と も な う飼料 採 食 量 の 増 加 が 子 牛 の小 腸 粘 を示 してい る.し か し,早 期 離乳 子 牛 のmaltaseやiso- 膜carbohydrase活 性 にお よぼ す影 響 を 調 べ た.用 い た maltaseの 活性は 哺 乳 子 牛 と あ ま り変わ らな かっ た.た 4頭 の 子牛(黒 毛和 種)は6週 齢 で 離 乳 し,26週 齢 で 屠 だ,maltase活性 の 小 腸 内 分 布 を み る と哺 乳子 牛 で は小 殺 した.こ の間,毎 日午前9時 に 濃 厚 飼 料 と乾草 を十 分 腸 下 部 で 高 くな る傾 向 が認 め られ た の に,早 期 離 乳 子牛 な 量 給 与 して 自由 に採 食 させ,ま た,屠 殺 は午 後1時 か で は 比較 的高 い活 性 が小 腸 全 体 に 一 様 に 観 察 され た.小 ら実 施 した.酵 素 活 性 測 定 の た め の粘 膜 は,小 腸 を 四 等 腸 に流 入 す るで ん ぷ ん や そ の 加水 分解 産 物 の増 加 に と も 分 してそ の 各 中 央 部 か らそれ ぞ れ 採 取 した.ま た,小 腸 な い,そ の 消 化 吸収 部位 の 変 化 を 示 唆 す る も の で あ ろ 各 部位 か ら と盲 腸 お よび 結 腸 か らpH測 定 の た め 内 容 物 う.早 期 離 乳 子 牛 のlactase活 性 は 哺 乳 子 牛 と変わ らず, を 採 取 した.得 られ た 分 析結 果 は 同 週 齢 の3頭 の 哺乳 子 離 乳 の影響 は ま った く認 め られ な か った.ま た,小 腸 粘 牛 の結 果(既 報)と 比 較 した.早 期 離 乳 子牛 の 盲腸 内容 膜 に は低 い な が らもdextranaseお よびamylaseの 活性 物 のpHは 哺 乳 子 牛 に比 べ て 明 らか に低 く,ル ー メ ン発 が認 め られ た.

酵 を免 れ て盲 腸 に達 した可 溶 性 炭水 化 物 が 多か った こ と 日 畜 会 報,52(7):532-536,1981

日 畜 会 報,52(7):532-536 536 1981