Nautakarjan kivennäisaineiden syönnistä laitumella. II

Authors

• Irja Uotila Maatalouden tutkimuskeskus, kotieläinhoidon tutkimuslaitos, Tikkurila

DOI: https://doi.org/10.23986/afsci.71478

Abstract

In the investigation the voluntary mineral matter consumption of milk cows and heifers on pasture has been studied. The investigation is a continuation of the tests performed in 1957 (3), Two tests were performed with cows in the summer of 1958, their duration being 30 days (4. VI— 4. VII, test No. I) and 40 days (14. VII—23. VIII, test. No. II), respectively. The experimental animals were of Ayrshire breed. The mean live weight of the cows was 502 kg and their mean age 5,8 years. The average number of cows was 41,5 in test No. I and 42,3 in test No. II, the corresponding milk yields being 12,2 and 10,3 kg per animal and day. Table 1 (p. 151) shows the distribution of the animals according to milk production class and Table 2 (p. 151) their distribution according to the time left before the next calving. The pasture grass was meadow fescue-cocksfoot-timothy-dominated. It was largely the same pasture as in the tests in 1957. The cows were given as additional fodder in connection with milking, in test No. I, oats - wheat bran mixture (50/50) in an average quantity equivalent to more than 7 food units for lactation; in test No. II, oats-barley mixture (50/50) in an average quantity equivalent to more than 6 food units for lactation and furthermore green fodder in a total quantity of 400 kg per day. In the 1957 experiments the additional fodders were the same except that in test No. I the concentrate administered to the animals was oatmeal. The cows were absent from pasture on an average 2 1/2 hours in the morning and in the evening as in the 1957 experiments. Similarly, the animals were not allowed to eat mineral fodders anywhere except on the pasture. One case of parturient paresis occurred during test No. I (no other cows calved) and another case during test No. II (4 calvings). In test No. I the cows were given ground lime stone, dicalcium phosphate, monosodium phosphate, disodium phosphate and common salt separately ad lib. The cows consumed hardly any lime stone (5 g per animal and day) or dicalcium phosphate (7 g per day), whereas disodium phosphate and particularly monosodium phosphate were accepted very willingly (28 and 63 g per day, respectively). The consumption of common salt was small (11 g per day) while the animal sobtained abundant quantities of sodium in the Na-phosphate. On an average the cows obtained: Ca 3.6 g, P 16.2 g, Na 17.4 g, and Na calculated as NaCl 44 g per animal and day (Table 3, p. 152), In test No. II fodder salt mixtures I (53 % dicalcium phosphate + 42 % lime stone), II (55 % dicalcium phosphate + 10 % disodium phosphate + 20 % common salt), III (94 % monosodium phosphate), fodder bone meal and common salt were made available for the animals (see p. 150). The consumption of the two first mentioned mixtures was very small (I: 4 g, II: 5 g per animal and day), whereas bone meal and particularly mixture III were accepted very willingly (31 and 61 g per day respectively). The consumption of common salt was not abundant (28 g per day) while the animals obtained sodium in Na phosphate. On an average the cows obtained: Ca 10.8 g, P 16.5 g, Na 20.5 g. and Na calculated as NaCl 52 g per animal and day (Table 4, p. 153). If sodium phosphates are kept at the disposal of the cows while no bone meal is available (although lime stone + dicalcium phosphate is available), the quantities of substances taken by the cows will be remarkably phosphate-dominated. With bone meal and sodium phosphates available the phosphorus quantity is abundant and calcium quantity will be of medium magnitude. The cows eat little lime stone and dicalcium phosphate, particularly if sodium phosphates are available. If there is bone meal in addition to mixtures mainly containing lime stone and dicalcium phosphate (test No. II in 1957, 3), the Ca quantity consumed by the cows is abundant and the P quantity of medium magnitude. When the cows are given lime stone and dicalcium phosphate only, the Ca quantities and particularly the P quantities consumed by them are comparatively small. Two tests were performed with heifers in the summer of 1958,their duration being 30 days (4. Vl— 4. VII, test No. I) and 40 days (14. VII—2. IX, test No. II), The number of heifers was 8 in test No. I and 11 in test No. II, the corresponding mean ages being 1,4 and 1,2 years, the live weights 359 and 303 kg and the number of covered heifers 3 and 2, respectively (Table 5, p. 154). The pasture consisted of clover-meadow fescue-cocksfoot-timothy being the same as in the summer of 1957 (3). In test No. I the heifers were given ground lime stone, dicalcium phosphate, monosodium phosphate and common salt separately ad lib. They consumed a markedly greater quantity of lime stone and dicalcium phosphate (35 and 24 g per animal and day, respectively) than the cows in the corresponding test (No. I). Monosodium phosphate was accepted very willingly (117 g per day). The heifers consumed hardly any common salt (5 g per day) while they obtained abundantly sodium in Na phosphate. On an average the heifers obtained: Ca 18.8 g, P 27.3 g, Na 18.9 g, and Na calculated as NaCl 48 g per animal and day (Table 6, p. 155). In test No. II, fodder salt mixtures II (55 % dicalcium phosphate, 10 % disodium phosphate, 25 % common salt) and III (94 % monosodium phosphate), bone meal and common salt were made available for the heifers (see p. 150). The consumption of the first mixture was very small (4 g per day), whereas bone meal and particularly mixture III were taken willingly (33 and 109 g per day, respectively). The consumption of common salt (11 g per day) was higher than in test No. I. On an average the heifers obtained: Ca 10.4, g, P 25.4 g. Mg 3.7 g, Na 20.5 g, and Na calculated as NaCl 52 g per animal and day (Table 7, p. 155). In both tests the heifers consumed monosodium phosphate abundantly. In addition to this they took considerable quantities of bone meal (test No. II). Since no bone meal was available in test No. I, they consumed considerable quantities of lime stone and dicalcium phosphate, which the cows were very unwilling to eat in the corresponding test. Heifers prefer to eat mineral fodders with a higher Ca content than do cows. The phosphorus quantities, too, were higher than those taken by the cows. The higher requirement of mineral fodder with the heifers is obviously due to the fact that the quantities of pasture grass eaten by the heifers are smaller than those in the case of the cows, while on the other hand the growing heifer has a high requirement of mineral substances. If monosodium phosphate is available, the phosphorus quantities consumed are high; if in addition also bone meal or lime stone + dicalcium phosphate is available, the calcium quantities consumed are fairly high. The heifers take bone meal more willingly than a mixture containing mainly lime stone and dicalcium phosphate (test No. I, 1957). They also take it more willingly than a mixture containing dicalcium phosphate (test No. II, 1958). If bone meal is not available, they take lime stone and dicalcium phosphate more willingly (test No. I, 1958). Comparing the tests of 1957 and 1958 (Table 8, p. 157) we note that although the heifers in the tests of 1958 had a lower mean age (nearly one year younger) as well as live weight (nearly 100 kg less), and most of them were not covered (while those in the test of 1957 were in the latter stages of pregnancy), the consumption of mineral matter was at least equal in level to that in the test of 1957. This is obviously due to the fact that, on account of the small size of their stomachs and of their smaller nutrient requirements, smaller heifers cannot eat as much pasture grass and consequently receive less minerals in the grass. On the other hand, however, the growing heifer has a high requirement of mineral matter. Probably it is due also to the fact that they eat monosodium phosphate more willingly than other mineral matter of the tets. In the tests in 1957—1958 both with the cows and with the heifers it can be noted that the consumption of common salt (or sodium) is slightly higher in the middle of the summer than in its early part.