i920] 



DAIRY FARMING DAIRYING. 



875 



(E. S. R.. 39, p. 75), and many of tlic results are restated In a new form in the 

 present publication. The foUovvinj? table summarizes some of the main results 

 of the two trials : 



luJliK ncc of the protein plane of dairy cotvs on protein metabolism and utiliza- 

 tion of feeds. 



' Uriiiary nitrogenX6.25. 



2 Cow at end of lactation. 



The substantial equality of the urinary nitrogen excreted by the two cows 

 on the low protein ration, de.spite the fact that they were in different stages of 

 lactation and one was losing and the other gaining in flesh, is held to indicate 

 that 0.34 lb. of digestible protein per day is sufficient for body maintenance 

 provided only 1 lb. of digestible protein is required to offset a pound of milk 

 protein. The fact that cows on the high protein rations secreted more fat in 

 the milk than they derived from their feed confirms previous conclusions that 

 such rations promote the formation of milk fat from carbohydrates or proteins. 

 It is also pointed out that cows on such rations required a considerable amount 

 of drinking water due to the excess of nitrogen in the urine. 



" These experiments indicate that when a cow begins her lactation period with 

 a lack of digestible protein and excess of energy or even a sufficiency of energy 

 in her ration her digestion coetlicients fall, she loses flesh rapidly, and her 

 milk flow continues to fall, at first rapidly, later more slowly, until she can 

 support the flow of milk. When the flow of milk has become so small that she 

 can begin to gain weight, generally near the end of the lactation period, her 

 digestion coefficients begin to rise again, but this results in an increased gain 

 in flesh and has no markeil effect on the milk flow." 



A table gives the proximate composition of the feeding stuffs supplied to the 

 animals in the 1917 trial. 



Feeding dairy cattle, A. C. McCaxdltsh {lotva Sta. Circ. 64 {1920), pp. 32, 

 fig. 1). — This circular includes definitions of feeding stuffs and suggestions 

 for feeding dairy cows, calves, and bulls. 



The efTiciency of milk substitutes in calf feeding, G. Spitzkr and R. H. 

 Caek (Indiana Sta. Bui. 21,6 \1920), pp. 8, figs. 2).— A group of 36 grade Hol- 

 stein calves, varying in age from 10 to 20 days and in weight from 85 to 126 

 lbs., were fed for 140 days. A lot of 12, receiving whole milk throughout, 

 made an average daily gain of 1.91 lbs. per head. A similar lot fed skim milk 

 after the first 10 days made an average daily gain of 1.73 lbs., and a third 

 lot fed Purdue calf meal gained 1.18 lbs. Ground corn and oats (1:1) was 

 fed as a dry mash to eacli lot, and for part of the time the calves had access to 

 blue grass pasture or clover hay. The calf meal lot were thrifty and remained 

 in good condition, and during six months of pasture following the feeding 

 period they made about the same gains as the other lots. 



