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Diurnal variation in forage quality affects animal preference and production

Mayland, H.F. and Shewmaker, G.E. and Fisher, D.S. and Burns, J.C. (2000) Diurnal variation in forage quality affects animal preference and production. In: Proc. Michigan Hay and Grazing Council. USA-MI-St. Johns, 2000/01/20.

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In 1993. we began to evaluate animal grazing preferences among eight tall fescue cultivars,
including HiMag which had been selected to reduce risk of grass tetany. Two years of
preference studies indicated that some cultivars were better liked by heifers than other cultivars
(Shewmaker et al., 1997). One of us (jcb) and others asked WHY. This led to quantifying
various chemical and physical characteristics of these cultivars and determining their relationship
to grazing preference. It also led to an evaluation of animal preference among these same tall
fescues when harvested in late afternoon and conserved as hay (Burns et al., 'a', submitted J.
Anim. Sci.). In the grazing study. we had found a close relationship between total nonstructural
carbohydrate (TNC) levels and animal grazing preferences among the cultivars (Mayland et al..
`c', revised for Agron. J.). However, TNC values change during the day. What effect might
variation in harvest time have on TNC concentration and ultimately animal preference?
This diurnal cycling of forage sugars had been known for many years, but had been
dismissed as not affecting feed value or animal behavior. We checked the literature (August
1996) but found no documentation of animal responses to diurnal changes in forage composition.
The challenge seemed obvious and the potential impack seemed great; so we decided to test
ruminant animals' ability to differentiate between hays harvested in afternoon and subsequent
morning. We completed several studies and will share some exciting results with you. Animals
demonstrated strong preference for afternoon-harvested compared to morning-harvested forage.
This led to questions concerning 1) animal preferences among other forage types and cultivars,
2) more detailed characterization of diurnal changes occurring in forages, 3) affects on energy
and crude protein digestibility, and 4) affects on animal production?
Could ruminants distinguish between evening- and morning-cut hay and did this occur over
a range of conditions? If they could, then we needed to know what was going on in the plant.
We would then need to determine management strategies to take advantage of possible benefits.
We first discuss the animal studies and then close with plant studies.

Item Type: Conference or Workshop Item (Paper)
NWISRL Publication Number: 1007
Additional Information: **A.K.A NWISRL PUBLICATION 1007a**
Subjects: Animal > Feed preference
Irrigated crops > Grass forage > Time-of-day harvest difference
Irrigated crops > Grass forage > Animal preference
Irrigated crops > Grass forage > Forage quality
Mass Import - autoclassified (may be erroneous)
Depositing User: Dan Stieneke
Date Deposited: 20 Nov 2010 21:56
Last Modified: 16 Nov 2016 17:37
Item ID: 934