ANNUAL REPORT, 1937 23 



element in the milk is being followed in a manner similar to that outlined for cal- 

 cium in last year's report. 



The Effect of Artificial Light on Milk Production. (J. G. Archibald, V. A. Rice, 

 and C. H. Parsons.) This project was seriously interfered with during the latter 

 half of the winter of 1936-37, by the repeated burning out of the special 1000-watt 

 lamps installed for the purpose. The trouble was finally located by the manu- 

 facturers of the lights and they are hopeful that the defect has been remedied. 

 Due to partial destruction by fire in September of the building in which the stalls 

 and equipment were located, there has not been an opportunity as yet to test out 

 the improved lights. It is hoped that sufficient repairs will be made before the 

 end of the calendar year to allow the work to proceed. 



The small amount of data available shows approximately one percent greater 

 milk production during the 30-day periods when the cows were exposed to the 

 strong light than when they were kept under ordinary conditions as regards 

 lighting. The results need further confirmation before any significance can be 

 attributed to this small increase. 



Studies in the Chemistry of Pasture Grass. (J. G. Archibald.) Chemical 

 studies of the grasses grown on the series of plots established in 1930 have been 

 brought to completion with the analysis of the samples obtained in 1936, but the 

 final interpretation of results has not yet been made. 



This series of plots was used for palatability tests with cows during the early 

 summer of 1937. The plots were enclosed with a temporary wire fence, and two 

 Jersey cows were turned into the enclosure from about 8:30 a. m. until about 12 

 noon on each of two successive days at three different times during May and 

 June. The time interval between grazings was determined by the growth of the 

 grass and averaged about 17 days. 



A reliable attendant was stationed to watch closely the movements of the 

 cows and to record the time when they started to graze on any given plot and 

 when they left it for another one; also to record any time when they were not 

 grazing. A complete record of each cow's grazing activity and preferences was 

 thus obtained, approximately seven hundred individual observations being 

 recorded. It was planned originally to make further tests in the fall but the 

 growth on the plots did not warrant it. The work will be repeated next year and 

 extended to the second series of plots established in 1934. 



While final conclusions cannot be drawn at this time, it is of interest to note 

 that our judgment of the nutritive value of the several species of grasses based 

 on their chemical composition as determined by actual analyses of a large number 

 of samples, is confirmed by the preference shown by these cows. Invariably the 

 cows grazed much more heavily those species having a relatively high content 

 of moisture, protein, and soluble ash, and a relatively low content of crude fiber; 

 they showed scant liking for species relatively high in fiber and relatively low in 

 moisture, protein, and soluble ash; they refused almost entirely one species which 

 has been characterized by a high fiber content over a period of years. 



Chemical studies of grasses from the second series of plots referred to above, 

 which was established in 1934 on a very different soil type from the 1930 series, 

 have been continued this year, but at date of writing the analytical work has 

 not been completed. 



The Vitamin Content of Certain Pasture Grasses. (W. S. Ritchie and J. G. 

 Archibald. Cooperative with Chemistry.) The laboratory and field work on this 

 project has been completed. (See report of Chemistry Department for details.) 



