Animal Type

Fecal N

Urine N

Fecal S

Fecal C

Layers

0.44

1.55

0.063

7.4

Meat-Type Chickens

 

Broilers (avg. for 7 wks)

0.46

1.51

0.008

6.4

Roasters (avg. for 9 wks)

0.70

1.91

0.019

10

Meat-type laying hens

0.47

1.82

0.13

8.7

Meat-type breeder roosters

0.29

0.80

0.10

7.6

Turkeys

 

Growing males (avg. for 24 wks)

1.77

7.3

0.095

27

Growing females (avg. for 20 wks)

1.22

5.0

0.061

17

Laying hens

0.34

0.59

0.14

19

Breeder males (22 kg)

0.29

1.63

0.52

38

aGrams per day per animal.

bRHA = rolling herd average, average lactating cow’s milk production per 305-day lactation.

cBW = body weight.

by up to 30 percent in either direction for specific animal feeding operations, depending on feeding and management practices.

Dairy

Dry matter intake and protein feeding requirements for typically managed animals were determined (NRC, 2001a). Mature body weight was assumed to be 454 kg for small breeds (e.g., Jersey) and 680 kg for large breeds (e.g., Holstein and Brown Swiss). Heifer growth rates were assumed to be 0.5 kg/d for 100-300-kg body weight and 0.6 kg/d for 300-450-kg body weight for small breeds. Growth rates were assumed to be 0.8 kg/d for large breeds. An average lactating cow was defined for each level of herd milk production. The average cow was assumed to be multiparous and 90 days in milk. Milk from small-breed cattle was assumed to be 4.5 percent fat and 3.5 percent true protein, and milk from large-breed cattle was assumed to be 3.5 percent fat and 3.0 percent true protein. Average DMI (dry mater intake) was assumed to be in accordance with National Research Council predictions (NRC, 2001a). Crude protein was assumed to be fed at 8 percent above the average cow’s requirement because producers feed for a higher level of production than the average to avoid the risk of lost milk production from higher-producing cows. At 8 percent above the average cow’s requirements, protein should be sufficient for the 82nd percentile cow. In addition, protein in excess of requirements is fed to account for variation in feed composition. Nitrogen intake was equal to crude protein intake divided by 6.25.



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