influenced by nitrogen fertilization and date of cutting in that both the 

 nutrient yield and digestibility are enhanced (5, 15). 



The purpose of this experiment was to study the effects of different 

 nitrogen levels on the yield, chemical composition, and digestibility of 

 the first cutting of two varieties of timothy, Commercial and Essex, 

 grown under different climatic conditions and harvested at different 

 dates. The yields of the second cuttings were recorded in order to deter- 

 mine total yield. The acceptability of some of the first cuttings was 

 determined in feeding trials with sheep. The investigation also included 

 the determination of complete energy balances of each hay by means of 

 an open-circuit indirect calorimeter, direct determinations of the metab- 

 olizable and net energy, in addition to the conventional digestible energy 

 and total digestible nutrients methods. 



Material and Methods 



Pure stands of two varieties of timothy, one early-maturing Com- 

 mercial and the other late-maturing Essex were grown in two different 

 locations of the state, Groveton, New Hampshire which is in the north- 

 ern part and Northwood, New Hampshire which is located in the south- 

 eastern part. The plots established at Northwood were on Paxton loam, 

 a brown Podzolic soil which is one of the better agricultural soils in 

 southern New Hampshire. While surface drainage is good, the soil has a 

 slow internal drainage due to a compact layer which occurs at about 24 

 inches. The plots established at Groveton were on Hadley, very fine 

 sandy loam, an alluvial soil with a higher-than-average fertility and 

 good moisture-holding capacity. At Northwood the Commercial was 

 grown under three levels of nitrogen, 50, 100 and 150 lb. per acre and 

 the Essex under 100 lb. per acre only. At Groveton, both the Essex and 

 Commercial were grown under 100 lb. nitrogen fertilization per acre. 

 The nitrogen was applied in a split application with half before and 

 half after the first harvest. All plots received the same rate of phos- 

 phorus and potassium. 



The dates of cutting in both localities were June 1, 15 and 30. All 

 resulting crops were artificially dried with heat for uniformity. The 

 aftermath of each cutting was harvested two months after the initial 

 cutting. 



The animals used during the three-year study were as follows: one 

 pair of twin Holstein steers H 509 and H 510 and two other unrelated 

 Holstein steers H 906 and H 907 the first year, (1960-1961) ; the same 

 four animals plus two males from a set of Holstein quadruplets H 559 

 and H 560 the second year, (1961-1962) : and one pair of identical twin 

 Ayrshire steers A 554 and A 556 and the set of Holstein quadruplets. 

 H 559, H 560, H 557 and H 558, two male and two female, the third 

 year, (1962-1963) . Also three Shropshire wethers were used to determine 

 the acceptability of some of the hays, and also the digestibility of three 

 hays, the yields of which were not sufficient to carry the digestion bal- 

 ances with cattle. Table 1 shows the schedule of experiments. 



Analyses of variance were constructed to assess the importance of 

 the various factors (location, variety, date of cut, and fertilizers) on the 

 nutritive value of the hay. Since the data were not balanced, the method 



