In Class Activity: Heifer Nutrition
Instructions:
Table 1 presents ration ingredients, nutrient composition, and intake for four dairy replacement rations. Unfortunately, the table contains missing cells. Using the information presented in the reading and your nutrition-related critical thinking skills, answer the 9 multiple-choice questions listed here. Some of the questions may be ambiguous Your explanation is really what counts!
| Ration Composition | D | C | A | B |
|---|---|---|---|---|
| Ration Ingredients, % of ration dry matter | ||||
| Corn silage | 32.0 | 28.0 | 28.0 | 31.0 |
| Legume silage, bud | 66.0 | 71.0 | 48.0 | 61.0 |
| Shelled corn | ... | ... | 14.4 | 7.3 |
| Soybean meal | ... | ... | ... | ... |
| Expeller soybean meal | 1.3 | ... | 8.9 | ... |
| Salt | 0.3 | 0.3 | 0.3 | 0.3 |
| Mineral & Vitamin premix | 0.5 | 0.5 | 0.5 | 0.5 |
| Total | 100 | 100 | 100 | 100 |
| Ration Nutrient Composition, % ration DM (unless noted otherwise) | ||||
| Crude Protein (CP) | 13.0 | 13.5 | 16.5 | 15.0 |
| Rumen undegraded protein (RUP) | 3.0 | 3.0 | 5.9 | 3.5 |
| Total Digestible Nutrient (TDN) | 59.0 | 60.0 | 67.0 | 62 |
| Metabolizable Energy (ME), Mcal/lb | 1.0 | 1.0 | 1.1 | 1.0 |
| Neutral Detergent Fiber (NDF) | 48.0 | 48.4 | 39.2 | |
| Non-Fiber Carbohydrate (NFC) | 30.4 | 29.8 | 35.8 | 31.2 |
| Dry Matter Intake | ||||
| DMI, lb/day | 26.5 | 21.2 | 8.5 | 14.7 |
Question 1: TDN of ration D is about:
a. 55%
b. 60%
c. 65%
Explain:
Correct answer is b. 60%; TDN of D must be almost the same as for diet C because NDF and NFC are almost identical.
Question 2: CP of ration A is about:
a. 14.5%
b. 15.5%
c. 16.5%
Explain:
Correct answer is c. 16.5%; Much greater than ration B (15%) because t includes 9% expeller soybean meal (which would more than make-up for the lower afalfa (the two sources of protein in the diet).
Question 3: NDF of ration A is about:
a. The lowest compared to the other rations
b. About equal to ration B
c. More than in ration D
Explain:
Correct answer is a. The lowest compared to the other rations; Most NDF comes from forage (corn silage and alfalfa silage), all rations other than ration A includes more than 90% forage (and more than 45% NDF. Thus with only=78% forage, ration A must have a lower NDF than any other ration.
Question 4: What is the percent of RDP in ration B?
a. Unknown
b. 11.5%
c. 12.5%
d. 13.5%
Explain:
Correct answer is b. 11.5%; CP - RUP = RDP. Thus, 15.0 - 3.5% = 11.5%
Question 5: Which of the rations would be appropriate to feed a 900-lb heifer:
a. Ration A or B
b. Ration B or C
c. Ration C or D
d. Ration D or A
Explain:
Correct answer is c. Ration C or D; An 18 month old 900 lbs heifer should be fed the highest forage diets.
Question 6: Ration A is most likely the best ration for:
a. 300-kb heifer
b. 600-kb heifer
c. 900-kb heifer
d. 1200-kb heifer
Explain:
Correct answer is a. 300-kb heifer; Ration A is the highest energy diet, which should be fed to the youngest heifers.
Question 7: Which of the rations would be appropriate to feed a 600-kb heifer?
a. Ration A
b. Ration B
c. Ration C
d. Ration D
Explain:
Correct answer is b. Ration B; Ration C and D must be forolder, heavier heifers (> 1 yr) because of their low CP. Ration A is to high in CP for a 600-lb heifer.
Question 8: Assuming the same dry matter intake, which of the rations would result in the least amount of manure excretion per day?
a. Ration A
b. Ration B
c. Ration C
d. Ration D
Explain:
Correct answer is a. Ration A; The ration with the highest TDN would yield the least manure.
Question 9: Assuming the same dry matter intake, which of the ration would contribute least to global warming through enteric methane production
a. Ration A
b. Ration B
c. Ration C
d. Ration D
Explain:
Correct answer is a. Ration A; CH4 production is closely associated with NDF fermentation in the rumen. Ration A with the least NDF will yield the least CH4.