Poster Number 287
See more from this Division: C06 Forage and GrazinglandsSee more from this Session: Forage Ecology, Physiology, and Nutritive Value
Increased concentrations of non structural carbohydrates (NSC) in forages improve N use efficiency in dairy cows. We measured the changes in NSC concentration during wilting of PM- and AM-cut alfalfa. In 2008, field-grown (46�48′ N; 71�23′ W) alfalfa (cv. AC Caribou) was mown into wide swaths at the early flowering stage of development either at 18h30 (PM) of a sunny day or at 8h30 the following morning (AM). Triplicate forage samples were taken at cutting times and every 2 hours from 8h30 until the end of the second day. This 2-day experiment was conducted twice in spring and summer, and once in fall (n = 223). Concentration of NSC (glucose + fructose + sucrose + pinitol + starch) was chemically measured in a calibration set of samples and then predicted by near infrared reflectance spectroscopy.
Concentration of NSC (mg/g DM) in PM- and AM-cut alfalfa at times of cutting* and every 2 hours following the AM-cutting.
| ||||||||||
Sampling
|
| Spring growth
|
| Summer regrowth
|
| Fall regrowth
| ||||
Day
| Time
|
| PM
| AM
|
| PM
| AM
|
| PM
| AM
|
1
| 18h30
|
| 85.7*
|
|
| 106.3*
|
|
| 134.4*
|
|
2
| 8h30
|
| 87.4
| 73.4*
|
| 99.2
| 89.8*
|
| 128.7
| 110.4*
|
2
| 10h30
|
| 81.0 | 77.5 |
| 101.7
| 80.4
|
| 131.8
| 110.2
|
2
| 12h30
|
| 72.6 | 58.7 |
| 101.0
| 84.0
|
| 129.2
| 116.7
|
2
| 14h30
|
| 73.5 | 68.5 |
| 95.5
| 87.4
|
| 129.1
| 111.6
|
2
| 16h30
|
| 69.8 | 72.4 |
| 96.0
| 86.3
|
| 133.9
| 110.9
|
2
| 18h30
|
| 69.2 | 64.7 |
| 90.0
| 73.5
|
| 126.4
| 107.5
|
2
| 20h30
|
| 65.9 | 67.5 |
| 97.6
| 81.9
|
| 117.2
| 102.5
|
At cutting, NSC concentration was greater (+ 17% in spring, + 18% in summer, and + 22% in fall) in PM- than in AM-cut alfalfa. Concentration of NSC remained greater in PM- compared to AM-cut alfalfa throughout the wilting period for the summer and fall regrowth but not in spring growth; wilting conditions were poor in spring. Cutting alfalfa in PM improves forage quality.
See more from this Session: Forage Ecology, Physiology, and Nutritive Value