1 / 18

The Demand Day

The Demand Day. A Unit for Adaptive Stocking Rate Management Austin Sewell Agren Inc., Carroll, IA. What is a Demand Day?. Definition: The Demand Day (DD) is a standard unit of measure of forage demand for large wild or domestic herbivores.

ramona
Download Presentation

The Demand Day

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Demand Day A Unit for Adaptive Stocking Rate Management Austin Sewell Agren Inc., Carroll, IA

  2. What is a Demand Day? Definition: • The Demand Day (DD) is a standard unit of measure of forage demand for large wild or domestic herbivores. • 1 DD equals 12 Megacalories (Mcal) per day intake of net energy for maintenance and gain.

  3. Legitimacy Meets criteria for a standard unit of measure (Hinnant 1994) • The standard should be readily and widely accessible. • The standard should be easy to use. • The standard should be invariable.

  4. NEm (Mcal) + NEg (Mcal) 12 Formula Demand Unit Equivalent* = = *Where NEm is net energy for maintenance, NEg is net energy for gain or loss, W is average animal bodyweight in pounds, and ADG is average daily gain or loss of animal bodyweight in pounds. Demand Days = Demand unit equivalent multiplied by No. of days

  5. Example • 1150 lb. cow with calf, 2 months old, gaining 1.1 lbs. per day • Average cow weight = 1150 lbs. • Calf born at 80 lbs, 160 lbs at 2 months, ADG = 1.1

  6. Example (cont.) • Cow demand equivalent: = =

  7. Example (cont.) • Calf demand equivalent: = =

  8. Example (cont.) • Cow-calf pair demand equivalent: 0.7 + 0.4 = 1.1

  9. Example • Computer applications (TGM)

  10. Animal Unit • Ambiguous past • Should be defined as 26 lbs Dry Matter intake per day (Scarnecchia 1985) • Meets Hinnant’s criteria as a standard unit of measure

  11. DD vs. AUD • Similarities • Both model forage intake. • Both standard units of measure for forage demand. • Differences • DD directly tied to animal production, AUD not. • DD considers forage quantity AND quality, AUD only considers quantity. (IES an example).

  12. Demand Side vs. Supply Side

  13. Pasture Use

  14. PDR (Cum. DD used/Cum. DD produced) Pasture Use Rating (%PDR) 10-40 40-60 60-90 0-10 90-100 Light Moderate Heavy None Sev. Pasture Use Curve based on Hart (1986)

  15. System of Use

  16. Stocking rate needs to be managed more adaptively – more responsively and proactively For this, we need quicker turnover of management phases. Demand side methods have faster turnover Adaptive SR Management

  17. Why the Demand Day? • Advantages over AUD • Accounts for forage quality • Directly related to animal production • Better suited for demand side approach to stocking rate management • Better suited to Productivity-Stocking Rate theoretical model • Demand side better suited to forage balance simulation (Rittenhouse and Bailey 1996) • Demand side stocking rate management better suited to adaptive management

  18. References • Hart, R. H. 1986. How important are stocking rates in grazing management? In. P.E. Reece and J.T. Nichols (Eds.). Proceedings, The Ranch Management Symposium, November 5-7, 1986, North Platte, Nebraska. Univ. Neb. Ext. Serv., Lincoln, Neb., pp. 77-87. • Hinnant, R. T. 1994. What is an animal-unit? A time to conform. Rangelands: 16(1) pp 33-35. • Rittenhouse, L. R. and D. W. Bailey. 1996. Spatial and Temporal Distribution of Nutrients: Adaptive Significance to Free-Grazing Herbivores. Proc. Grazing Livestock Nutrition Conf. 3:31-61.

More Related