UDC 613.6 : 371.386.8 : 637.11 + 371.386.8 : 613.6 : 637.11

Hygienic Assessment of Schoolchildren’s Practical Training on Dairy Farms

Yu. V. Spechus and E. P. Sasnauskayte, Candidates of Medical Sciences

Research Institute of Epidemiology, Microbiology and Hygiene, Ministry of Health of the Lithuanian SSR, Vilnius

Many collective and state farms in the Lithuanian SSR have established facilities for schoolchildren’s practical training. At these facilities, pupils in grades 9 and 10 of general education schools receive theoretical and practical instruction throughout the school year in the occupation of mechanized livestock worker. In the spring, after the end of the school year, pupils in the same grades undertake 18 days of practical work according to an established program. The program includes, among other activities, milking cows.

At present, only 36% of dairy farms in the republic are mechanized, so cows are milked mainly by hand. Using this method, adult milkmaids milk 16–18 cows three times a day in summer. No standards, however, have been established for adolescents. We therefore conducted a series of studies to determine the optimal workload for adolescent milkmaids.

In 1962–1963, during the schoolchildren’s summer practical training, studies were conducted on two dairy farms in the Ukmergė district. Eleven schoolgirls aged 16–18 years in grades 9 and 10 were observed. All participants underwent a medical examination and were found to be healthy. During the observation period, the girls lived in school premises, where a school work camp had been organized for them.

The girls did not take part in the morning milking, which began at 5 a.m. The ninth graders participated only in the daytime milking, while the tenth graders participated in both the daytime milking, at noon, and the evening milking, at 6 p.m. For six days, the ninth-grade girls were assigned to milk 2–6 cows by hand, with the number of cows changing daily. During the first week, the tenth-grade girls were to milk 2–7 cows by hand and, during the following week, 7–12 cows by machine.

Each day before and after work, we measured the girls’ pulse rate, arterial blood pressure, hand muscle strength, speed of visuomotor reactions, and errors on proofreading tests, expressed as a percentage; we also performed ergography using Leinik’s method. Each pupil underwent the battery of tests described above 24 times during the week of hand milking and 24 times during the week of machine milking. For comparison, four adult milkmaids were also examined.

Among the ninth graders, pulse rate increased by 20% after milking the fifth cow, while right-hand dynamometry readings declined, particularly after five cows had been milked. The latency of visuomotor reactions to white and red light increased considerably after six cows had been milked. Errors on the proofreading tests increased after only two cows had been milked; after five cows, they rose from 0.37% to 1.5% of the letters examined, that is, almost threefold.

Of the ergographic measures, fatigability showed the most pronounced change: it was 20% after two cows had been milked and rose to 64% after six.

Among the tenth graders milking by hand, pulse rate after the daytime work increased to an average of 95 beats per minute; pulse pressure also increased, with the maximum pressure rising to 106 mm and the minimum falling to 51 mm. By the beginning of the evening milking, blood pressure had nearly returned to baseline. After the evening milking, some slowing of the pulse and a reduction in pulse pressure were observed. The most pronounced changes in the functional state of the tenth graders’ cardiovascular system occurred when 21–30 liters of milk were obtained, corresponding to the milking of seven cows. During machine milking, the cardiovascular response was moderate and increased somewhat when a pupil had to milk 12 cows.

The latency of visuomotor reactions to white and red light increased after evening hand milking; the most statistically reliable changes were observed after seven cows had been milked.

Of the ergographic measures, the greatest changes were recorded in fatigability and resistance to fatigue during hand milking, particularly in the evening. Fatigability during evening work had increased by 9% after the third cow was milked by hand and reached its highest level, an increase of 18%, after six cows. Resistance to fatigue decreased after the evening work, with a sharp decline observed after six cows had been milked. No substantial post-work changes in ergographic measures were observed with machine milking. Hand and back dynamometry readings were within the normal range for the pupils’ age.

The workload of milkmaids is limited by the time required to milk a given number of cows. The schoolgirls took 80 minutes to milk 7 cows by hand, whereas adult milkmaids completed the same work in 42 minutes, i.e., twice as fast. Thus, a schoolgirl took an average of 11.3 minutes to milk one cow, compared with 6 minutes for an adult milkmaid. The schoolgirl made 1,140 hand movements, whereas the adult made only 700.

Time-and-motion observations showed that work occupied an average of 64.6% of the schoolgirl milkmaids’ working day, compared with 71.4% for adult milkmaids. The intervals between milking cows averaged 4.7 minutes for the schoolgirls and 2 minutes for the adults.

Conclusions

1. In 16-year-old schoolgirls, noticeable fatigue appears after milking 6 cows.
2. Given the inadequate training of girls of this age, their permissible workload for hand milking should be limited to no more than 5 cows.
3. The milking workload of 17–18-year-old schoolgirls should not exceed 6 cows. Individual workloads may, however, range from 5 to 7 cows.
4. Mechanized milking does not cause substantial fatigue in adolescent schoolgirls, so they can milk up to 12 cows. This workload is limited by the duration of milking (more than 1½ hours).

Received February 3, 1964.