| 1. | Besides the calorie, in what other units is energy measured? |
| 2. | What two terms are used to represent energy losses that are not of dietary origin? |
| 3. | When we talk about protein digestibility or energy digestibility it is understood that we are talking about “apparent” digestibility even though “apparent” is normally not spoken. Why do we use the word “apparent?” |
| 4. | Define heat increment. What two components make up heat increment? |
| 5. | Where does TDN fit in the net energy scheme? |
| 6. | Under what conditions is the heat increment not wasted heat? |
| 7. | According to the feed composition tables, a feed has an NEm value of 0.92 Mcal/lb and an NEg value of 0.61 Mcal/lb. What do these values tell us about how the feed is used by the animal? |
| 8. | You look in the requirement tables and find that a 700-lb heifer requires 5.79 Mcal/day for maintenance and requires 4.63 Mcal NEg to gain 2.0 lb/day. What effect would a cold rain have on the NEm requirement of the heifer (assuming she does not have shelter to get under)? What effect would the cold rain have on the NEg required to gain 2 lb/day? How much NEg is C. M. Russell's "Last of 5,000" receiving? (Painting also known as "Waiting for a Chinook") |
| 9. | Does the TDN system over-estimate or under-estimate the nutritional value of forages? What is the explanation for this effect? |
| 10. | Explain the statement, “One pound of grain TDN does not equal one pound of hay TDN.” |
| 11. | When does THP = NEm? |
| 12. | Which has the greatest heat loss relative to its size, a rabbit or a cow? How do we put smaller animals and larger animals on an equivalent basis? (i.e., Why do we use weight raised to the 3/4 power?) |
| 13. | The feed tables give us the DE, ME, NEm, NEg values of a feed in Mcal/kg, and the TDN, CP, Ca, and P values as a percent. If you know how much feed an animal is eating (e.g., 15 lb), you can calculate the quantity (amount) of DE, ME, TDN, CP, Ca, and P that the animal is eating. (For example, 15 lb x 1.3 Mcal ME/lb = 19.5 Mcal ME; 15 lb x 12% CP = 1.8 lb CP) However, you can NOT multiply 15 lb times the NEm value of the feed and obtain the total NEm consumed nor can you multiply 15 lb times the NEg value of the feed and obtain the total NEg consumed. Explain why these are NOT valid calculations for NEm and NEg. (You may want to do question 21 first and proved to yourself why this is true.) |
| 14. | Why do we have two values for NEm and NEg for a feed but only one value for NE lactation? |
| 15. | What is “comparative slaughter” and how do we use it to determine the NEg value of a feed? |
| 16. | Be able to use the net energy system to (1) determine the amount of a given feed or diet that is needed to achieve a desired daily gain, and (2) given the amount of a feed or diet an animal is eating, determine the expected daily gain of the animal. |
| 17. | Maintenance energy needs (kcal/day) of humans, beef cattle, and dairy cattle are estimated by multiplying 70, 77, and 80, respectively, times weight in kg raised to the 0.75 power. While these factors are relatively close considering the differences in humans and cattle, they still are different. Explain why there are three different numbers for humans, beef cattle, and dairy cattle. |
| 18. | A pig consumed 2,500 gm of a feed having 3.71 kcal GE/gm. There were 340 gm feces collected having a GE content of 3.0 kcal/gm. The urine contained 330 kcal of energy and the heat increment was 270 kcal. Gas losses were negligible. Calculate the ME content of the feed as it would be reported in the feed tables (i.e., kcal ME/gm feed). (Your answer should be 3,170 kcal/gm.) |
| 19. | The GE values of carbohydrate, protein, and fat are approximately 4.15, 5.65, and 9.4 kcal/gm, respectively. How do we get from these values to the physiological fuel values of 4, 4, and 9 kcal/gm for carbohydrate, protein, and fat, respectively? |
| 20. | Assume an animal gaining 2.5 lb/day requires 19 Mcal ME daily of a diet containing 80% concentrates. If the proportion of roughage in the diet were increased, would the Mcal ME required for the same rate of gain increase, decrease, or remain the same at 19 Mcal? Explain your answer. |
| Shown below is a diagram of the net energy scheme followed by the energy values for well-eared corn silage. All energy values are Mcal/lb silage DM. Do the necessary calculations and answer the questions in #21 below. | |
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| 21. | A 700-lb large-framed steer is eating 18 lb of corn silage DM daily. (Refer to
the above information and diagram.) a. Calculate how many Mcal of DE and ME the steer receives daily from the corn silage. (25.2 Mcal DE and 20.7 Mcal ME) b. How many pounds of silage DM does the steer need daily for maintenance? (7.82 lb) c. How many Mcal are deposited as gain? (4.78 Mcal) What is the steer's expected daily gain? (2.78 lb/day) After answering parts a, b, and c you have the necessary information to answer parts d and e. d. What is the steer's total heat production (THP) from 18 lb of silage DM? (15.92 Mcal) e. What is the estimated heat increment (HI)? (10.13 Mcal) |
