RI-ERP-FINALACTION-Recommendations

6350

HIGGS ET AL.

Table 8. Parameters used to specify program evaluation and review technique (PERT) distributions (mean, minimum, and maximum) and SD for the digestion rates of carbohydrate and protein fractions of feeds in the reference diet used to analyze model sensitivity

Carbohydrate and protein fractions 1

Item

CA1 CA2 CA3 CA4 CB1 CB2 CB3 CC PA1

PA2 PB1 PB2

PC

Corn silage Mean Minimum Maximum Alfalfa silage Mean Minimum Maximum Grass hay Mean Minimum Maximum Corn grain Mean SD SD SD

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

7.8 3.5 0.2

5.6 22.3 35.7 33.5 2.5 10.0 16.1 15.1

3.8 0.0 200.0 50.0 20.0

3.8 0.7 1.9 5.7 7.0 1.4 3.4 4.5 1.0 1.9 7.1 6.0 1.2 2.8 9.1 6.0 1.2 2.8 9.2 0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

0.7 0.0

15.1

6.6

5.2 6.8

0.1

0.2

0.6

0.7

1.9 0.0 161.1 32.8 5.6 0.0 238.4 66.8 33.4

18.2 13.0 52.4 82.8 78.6

7.0 1.4 3.4

5.0 20.0 30.0 35.0

7.0 0.0 200.0 45.0 16.0

1.0 2.5

4.0

6.0

7.0

1.4 0.0

15.1

6.0

5.0 3.3

9.9 14.6 17.1

3.5 0.0 161.3 29.7

10.5

7.6 30.1 45.2 52.8 10.5 0.0 238.9 60.2 28.6 10.5

7.0 1.4 3.5

5.0 40.0 30.0 30.0

4.5 0.0 200.0 20.0 14.0

1.0

8.0

6.0

6.0

1.0 0.0

15.1

2.7

5.1 0.7

2.4 19.8 14.6 14.8 7.6 60.7 45.3 45.3

1.9 0.0 161.4 13.2 7.1 0.0 238.9 26.8 27.1

10.6

7.0 2.4 0.8

5.0 40.0 15.0 20.0

6.0 0.0 200.0 16.0

9.0 2.8 1.9

SD

1.7 14.0

5.2 1.6

7.0 2.3

1.2 0.0

15.1

2.1

Minimum Maximum

0.4

4.1

2.8 0.0 161.0 10.6 9.2 0.0 238.8 21.4 16.1

13.2

9.5 76.7 28.6 38.0

Soybean meal Mean

7.0 2.2 1.4

5.0 40.0 25.0 30.0

6.0 0.0 200.0 24.0 11.0

SD

1.6 12.5

7.8 5.2

9.4 5.8

1.2 0.0

15.1

3.2

2.7 4.2

Minimum Maximum Blood meal Mean Minimum Maximum SD

1.0

7.9

2.9 0.0 161.3 15.9 9.1 0.0 238.8 32.1 17.8

12.5

9.0 71.9 45.3 53.9

0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0

0.0 0.0 200.0 13.5

3.7 1.9 0.0 9.7

0.0 0.0

15.1

1.8 8.9

0.0 0.0 161.4

0.0 0.0 238.4 18.1 0.0 1 CA1 = acetic + propionic + butyric + isobutyric; CA2 = lactic; CA3 = other organic acids; CA4 = WSC; CB1 = starch; CB2 = soluble fiber; CB3 = digestible fiber; CC = indigestible fiber; PA1 = ammonia; PA2 = soluble true protein; PB1 = insoluble true protein; PB2 = fiber-bound protein; PC = indigestible protein.

match the AA profile of the RUP fraction (Macgregor et al., 1978). However, Tedeschi et al. (2001) investi- gated this hypothesis and found no differences in AA profiles of feeds analyzed with or without extraction of the soluble fraction. Furthermore, the soluble fraction of feeds has been shown to contribute 10 to 20% to the flow of AA to the small intestine (Velle et al., 1997; Volden et al., 1998; Choi et al., 2002). Extracting the insoluble protein residue requires soaking samples in borate-phosphate buffer to remove the soluble fraction (Krishnamoorthy et al., 1982) and adds another step to AA analysis. Therefore, it was decided using AA profiles determined on a whole-feed basis was simpler, more feasible for commercial laboratories, biologically more relevant, and provided access to much larger data sets than using profiles from the insoluble residue. Revision of the Feed Library The process of evaluating and updating the feed library was designed specifically to pool data from vari-

ous sources and combine it to estimate likely values. Al- though the data set used in our analysis encompassed a large number of samples from a wide range of situations, information on environmental and management factors implicit in the composition of individual samples were not available. Many external factors affect the nutrient composition of feeds both pre- and postharvest. When considering forages, preharvest environmental factors such as temperature, light intensity, nitrogen availabil- ity, water, and predation affect quality and composition (Van Soest et al., 1978). Postharvest, management fac- tors such as packing density, particle size, silo type, silo filling rate, and the way in which the face of the silo is managed can affect ADF, NFC, ADICP, SP, ammonia, pH, surface temperature, and aerobic instability (Rup- pel et al., 1995). Furthermore, biological processes dur- ing ensiling such as plant respiration, plant enzymatic activity, clostridial activity, and aerobic microbial ac- tivity will affect levels of rapidly fermentable CHO, AA, and NPN and can lead to heating and Maillard reactions (Muck, 1988). Analytically, elevated levels

AOAC Research Institute ERP Use Only

Journal of Dairy Science Vol. 98 No. 9, 2015