THE MILK PRODUCTION OF REINDEER COWS AND THE SHARE OF MILK IN THE GROWTH OF REINDEER CALVES

. The milk quantities obtained from the reindeer cows in the present study are probably, due to technical difficulties in the milking, lower than the actual values. For this reason the figures on the milk producing ability, and the connection between the milk yield and other characteristics of the cpw or its calf, are bound to be uncertain. The general composition of reindeer milk is in fair agreement with results reported by other researchers (Tables 1, 4 and 5). Individual differences in the milk producing ability could clearly be detected. The correlations between the milk quantity and the constituents were usually not significant. The association between the dam’s spring weight and the protein percentage was significant (r = —0.47*»). The range of the calves’ weights at birth was to a large degree mainteined during the entire period of growth (Table 9). The weight and growth of the calves was clearly depen-dent on the weight or on the size of the dam. The results obtained did not indicate any connection between the milk production characteristics of the dams and the growth of the calves (Tables 11 and 12). The spring weight of the dam has a more decisive influence on the growth of the calf than the birth weight of the latter. The results obtained seem to indicate that in the breeding for growth capacity, selection on the basis of the weight or size of the dams os of conclusive importance. In spite of the individual variations existing in the milk producing ability ofreindeer cows, the importance ofthe quantity and composition of the milk seems to be covered by the genetically determined growth factors. As the size of reindeer can be determined more easily than the weight, the combined measure, (body length -f- chest girth), seems tobe a more suitable basis for eval-uation.

general composition of reindeer milk is in fair agreement with results reported by other researchers (Tables 1, 4 and 5).
Individual differences in the milk producing ability could clearly be detected. The correlations between the milk quantity and the constituents were usually not significant.
The association between the dam's spring weight and the protein percentage was significant (r = -0.47*»).
The range of the calves' weights at birth was to a large degree mainteined during the entire period of growth (Table 9). The weight and growth of the calves was clearly dependent on the weight or on the size of the dam. The results obtained did not indicate any connection between the milk production characteristics of the dams and the growth of the calves (Tables 11 and 12). The spring weight of the dam has a more decisive influence on the growth of the calf than the birth weight of the latter.
The results obtained seem to indicate that in the breeding for growth capacity, selection on the basis of the weight or size of the dams os of conclusive importance. In spite of the individual variations existing in the milk producing ability of reindeer cows, the importance of the quantity and composition of the milk seems to be covered by the genetically determined growth factors. As the size of reindeer can be determined more easily than the weight, the combined measure, (body length -f-chest girth), seems tobe a more suitable basis for evaluation.
Since 1965 the reindeer breeding studies, started on the initial of the Reindeer Keeper's Association in 1962 at Askankangas in Puolanka (Varo 1964), has been continued at the Reindeer Experimental Region Kaamanen in Inari. During the summer 1967, in the period June Ist to Sept. 15th, the subject of study was the milk production ability of reindeer cows and the possibly existing variation between dams in this respect, as well as the influence of these factors on the development of the reindeer calves.
During the experiment the weather conditions were relatively good. Precipitation and temperature were below average, which apparently resulted in a decreased number of mosquitoes and gadflies. Work among the reindeer was thus rather easy.
In order to catch the reindeer, small pasture fences had to be erected. When fencing new pasture areas one sometimes encountered such difficult conditions of terrain that cloth fences had to be used. This was also why the entire herd escaped in the middle of July and was lost for over a week. Later, the reindeer were herded in a 4 km 2 wide area, situated 10 km from the experimental region. The construction of a small fence, however, took so long that the herd again scattered. In spite of continuous efforts barely one half of the experimental animals could eventually be caught. This misfortune naturally seriously affected the reliability of the results. The observed quantities of milk should be regarded with great caution also because the reindeer cows were not used to such close contact with human beings as was required in the milking process. Greatly depended on the nature of cow whether the animal did or did not give milk.

Review of the literature
The literature on the milk yields of reindeer is very limited. The Norwegian research worker Skjenneberg (1965) notes that the amount produced varies between 100 and 750 g per day, the most favourable lactation period being July-August. On the other hand, information on the average composition of reindeer milk is plentiful. Table 1 shows the values, as percentages, given by different researchers. The values are reported either as averages or as changes during the lactation period.  (Tables 2 and 3). The breed in question is considerably larger than our own.
According to the present writer, R.M. Varo (1964), the average birth weight of calves, born in spring 1963, was 5.80 kg, the heaviest calf weighing 7.45 and the smallest one 4.70 kg. A small but statistically significant difference between the sexes was noted. The calves by cows of different ages did not significantly differ in weight. Own studies Material and methods. The reindeer cows of the experiment were mainly born in 1963 (Varo 1964). Some otherreindeer, also younger ones, were likewise included.
In the spring 1967 a total of 33 calves were born, of these two died immediately after the calving and two dams with calves disappeared. Thus the material consisted of 29 calf-cow pairs. Later, during the course of the experiment, three calves had to be delivered to the State Game Research Institute and one calf was lost in an accident.
Originally the intention was to do 3-4 milking rounds by milking the dams in their calving order. In this way the milk samples would have been obtained after approximately the same period after calving. This plan could, however, not be fully realized because the reindeer managed to escape. The collection of samples and the weighing of the animals was done by two students, H. Kullberg and H. Varo.
The cows to be milked, two animals each day, were in the evening separated from their calves and kept in a 2 X 3 m enclosure. The animals were given water, moistened lichen and Peura-fodder. The milking took place the following morning and evening. The calves were weighed during the same day. The milk quantities obtained were combined and from the mixture a sample of approx. 80 ml. was taken and put into a plastic flask containig formalin. The samples were kept in a nearby cold brook and were weekly sent for analysis to the Department of Dairy Science of Helsinki University. With the aid of Peurafodder the reindeer were easily caught, but the milking often took quite long. Occasionally a cow had to be released because it had damaged its developing horns.

Results
The milk production of the cows. The milk quantities obtained varied between 47 and 206 ml per milking day. In order to make the values comparable they were corrected to correspond to the amounts of milk obtained 30 and 60 days after calving. The new values obtained in this vay varied between 54 and 207 ml and between 47 and 202 ml for samples collected 30 and 60 days, respectively, since the calving. The corresponding averages were 99.8 and 96.9 ml. For reasons given above connected with the milking, it is probable that the milk quantities obtained are lower than the real ones of reindeer cows.
The general composition of reindeer milk in the present material is given in Tables 4 and 5 (Luhtala, Rautiainen & Antila 1968). Table 5 shows that the solids and fat percentages steadily increase during the experimental period, whereas the protein percentage is at its lowest in the middle of the period. In order to detect the possible individual differences in the milk production ability of reindeer cows an analysis of variance was carried out. As the milk samples were obtained at different stages of the nursing period, the measure of production capacity used was the milk yield deviation of the individual cow from the general average curve. The F-values and the coefficients of repeatability are collected in Table 6.  Table 7 shows all correlations between weight in spring, milk yield and milk composi- tion. It appears that the contents of fat and protein are independent. The correlations between milk yield and composition were not significant and were always negative. Likewise the correlations between the cow's weight in spring and the other caracteristics were in most cases nonsignificant. Only the correlation for the protein content was significant, r = -0.47 (P < 0.01).
The weight development of the calves. The calves included in the experiment were born between May 6th and 23rd. The birth weight was, on an average, 5.63 kg, the standard deviation being 0.74 kg. The lightest calf weighed 4.2 and the heaviest 7.5 kg. Female calves weighed, on an average, 5.28 and male calves 5.93.  Table 8 shows the development of the weights of the calves during the summer period.
The weight of 3 month old calves in a few cases had to be evaluated on the basis of their earlier development and the overall average growth capacity.
The individual differences with regard to the weight development of the calves were detected by means of a similar analysis of variance as in the matter of the milk production of the cows. The calculations were thus done on the basis of the deviations of the weights from the means at different ages.  Table 9 shows that the ranges in weight at birth have to a considerable extent been mainteined during the experiment, although less so in the males than the females.
When evaluating the dependence of the growth of the calves on the weight of the dams in spring, the weight differences caused by sex have been levelled. As all dams were weighed at the same time, April 24-25, 1967, the weights in spring are not altogether comparable on account of the differences in the stages of pregnancy. Moreover, the closeness of the weighing date to the calving may have increased the correlations. The correlations calculated using the weight of the dams in autumn (1967) probably give a more accurate picture of the association. Table 10 shows the dependence of the weight of the calves on the weights of the dams in spring and autumn, on the dam's body length, chest girth and on the two latter measures combined. Taking into account the inaccuracy of the spring weights of the cows when evaluating the dam, the combined measure seems quite suitable. The magnitude of the coefficients indicates that in addition to the genes also the embryonic period and the ability of the dams to take care of the calves may have had its effect on the correlations.  Table 11 shows the correlations between different milk characteristics of the dam and the growth rate of the calf. The large negative values are probably due to the fact that the correlations between the weights of the calves and the spring weights of the dams are high and positive (Table 10), while those between the weights of the dams and the milk traits are negative (Table 7). Moreover, it should be noted that already when the calves were less than one month old they consumed other nutrients beside milk, among other things Peura-fodder, which is rich in protein and trace elements. If the influence of the spring weight of the dams is eliminated from the above correlations, the coefficients get higher and become positive, with the exception of the correlations concerning the protein percentage. The values are, however, not significant, as the 5 % level is at 0.37 (Table 12). When evaluating the correlations concerning the weights and growth of the calves (Table 13), it may be noted that the influence of the birth weight on the later weights all the time decreases. The influence of the birth weight on the growth is negligible. Alunperin oli tarkoituksena suorittaa 3 -4 lypsykierrosta siten, että emät olisi lypsetty vasomisjärjestyksessä. Näin olisi maitonäytteet saatu suunnilleen yhtä pitkän ajan kuluttua vasomisesta. Tästä jouduttiin kuitenkin tinkimään porojen karkaamisen takia. Näytteiden keruun suorittivat ylioppilaat H. Kullberg ja H. Varo. Lypsettävät vaatimet, joita oli kaksi kunakin päivänä, erotettiin illalla vasoistaan n. 2 X 3 m:n suuruiseen aitaukseen. Eläimille annettiin vettä, kostutettua jäkälääja Peura-rehua. Lypsy tapahtui seuraavana aamuna ja iltana. Vasat punnittiin saman päivän aikana. Saadut maitosaaliit yhdistettiin ja seoksesta otettiin formaliinia sisältävään muovipulloon n. 80 mhn näyte. Maitonäytteet säilytettiin läheisessä kylmässä purossa ja lähetettiin viikottain Helsingin Yliopiston maitotalouslaitokselle analysoitaviksi. Peura-rehun avulla porot saatiin helposti kiinni, mutta itse lypsy venyi usein hyvinkin pitkäksi. Silloin tällöin oli vaadin päästettävä vapaaksi sen loukattua kehittyvät sarvensa.