520 APPENDIX 



TABLE A-3. Daily Nutrient Requirements of Dairy Cattle* 



(Based on Air-dry Feed Containing 90 Per Cent Dry Matter) 



Body 



Weight, 



lb. 



Daily Gain 



Small 



Breeds, 



lb. 



Large 



Breeds, 



lb. 



Vita- 

 min 

 D, 

 I.U. 



Normal Growth of Dairy Heifers 



Maintenance of Mature Cows' 



Reproduction (Add to Maintenance during Last 2 to 3 Months) 



2.0 



2.0 



(') 



Lactation (Add to Maintenance for Each Pound of Milk) 



(«) 



Maintenance of Breeding Bulls 



1,200 

 1,600 

 2,000 

 2,400 



* Committee on Animal Nutrition, National Academy of Sciences, National Research Council, revised 

 1956. 



'Thiamine, riboflavin, niacin, pyridoxine, pantothenic acid, folic acid, vitamin B12, and vitamin K are 

 synthesized by bacteria in the rumen, and it appears that adequate amounts of these vitamins are furnished 

 by a combination of rumen synthesis and natural feedstuffs. Manganese, magnesium, iron, copper, and 

 cobalt are essential, and the amounts needed are discussed in the text. 



- DE (digestible energy) was calculated on the assumption that 1 g. of TDN (total digestible nutrients) 

 has 4.45 kcal. of digestible energy. DE may be converted to metabolizable energy by multiplying by 82 

 per cent. The therm equals 1,000 large cal. 



' Calves should recei.e colostrum the first few days after birth, as a source of vitamin A and other essen- 

 tial factors. 



•• While vitamin D is known to be required, the data are inadequate to warrant specific figures for older 

 growing animals and for maintenance, reproduction, and lactation. 



5 When calculating the intakes for lactating heifers that are still growing, it is recommended that the 

 figure for growth rather than maintenance be used. 



* When adequate amounts of vitamins A and D are fed for normal reproduction, extra amounts will not 

 timulate milk production but will increase the vitamin content of the milk. 



