1,023 research outputs found
Preference by sheep and goats among hay of eight tall fescue cultivars
Grazing ruminants use both visual cues
and taste in selecting their diet. Preference during grazing
may not be the same when forage is dried for hay
and cut into lengths prior to feeding in confinement.
Eight cultivars of tall fescue (Festuca arundinacea
Schreb.), previously evaluated for preference while
grazed, were harvested three times over a period of 2
yr. The hays were air-dried, baled, and passed through
a hydraulic bale processor prior to feeding. Five experiments
were conducted. All three harvests were evaluated
with sheep and the last two also with goats, using
six animals each time. During an adaptation phase,
hays were offered alone as meals. In the experimental
phase, every possible pair of hays (28 pairs) was presented
for a meal. Data were analyzed by multidimensional
scaling and by traditional analyses. Preference
was significant among cultivars in all experiments.
Multidimensional scaling showed that selection was
based on two criteria with two dimensions being significant.
Sheep preferred KENHY followed by KENTUCKY
31 and STARGRAZER but preferenced against
BARCEL. HIMAG, MO-96, and C1 were intermediate
and MOZARK was variable. Goats were similar to
sheep in preferring KENHY followed by STARGRAZER
and selected against MOZARK and BARCEL. KENTUCKY
31, HIMAG, MO-96, and Cl were intermediate.
In all five experiments, the general association was
positive for available carbohydrate fractions and negative
for fiber fractions that contribute to cell wall rigidity
Diurnal shifts in nutritive value of alfalfa harvested as hay and evaluated by animal intake and digestion
Forages accumulate nonstructural carbohydrates
during the day, with animals showing
preference and improved daily responses from
afternoon compared with morning cut hays. This
study evaluated alfalfa (Medicago sativa L.) hay
harvested at 0700, 1000, 1300, 1600, and 1900
h to determine how nutritive value changes during
the day and to assess the impact of these
changes on animal preference using cattle (Bos
taurus L.), sheep (Ovis aries L.), and goat (Capra
hircus L.) responses. Total nonstructural carbohydrates
were altered by time of cut (cubic contrast,
P < 0.01) ranging from 85 g kg?1 at 0700 h
to 83 g kg?1 at 1000 h, then increasing to 97 g
kg?1 by 1600 h with little change at 1900 h (96 g
kg?1). Fiber fractions also varied diurnally, with a
quadratic decrease from 418 g kg?1 at 0700 h to
387 g kg?1 by 1900 h in neutral detergent fiber. A
combined analysis of three animal trials showed
a linear increase in dry matter intake (DMI) with
later hay harvest, a cubic response for dry matter
digestion (DMD), and a linear increase in
digestible DMI. Mean DMI increased from 27.5
g kg?1 body weight at 0700 h to a maximum
of 30.8 g kg?1 body weight at 1600 h, whereas
DMD decreased from 658 g kg?1 at 0700 to 647
g kg?1 at 1300 h and peaked at 664 g kg?1 at
1600 h. Digestible DMI increased from 18.1 g
kg?1 body weight at 0700 h to a maximum of
20.5 g kg?1 body weight at 1600 h. No additional
advantages in animal responses were noted by
cutting after 1600 h
Dry matter uptake and digestion of alfalfa harvested at sunset and sunrise
The preference exhibited by animals in selecting one feed over another is important only if the preferred diet is consumed daily in larger quantities, digested to a greater extent, or both. Six alfalfa (Medicago sativa L.) hays were harvested in pairs at sunset (PM) and sunrise (AM) on consecutive days at three harvest dates. A previous study of these hays demonstrated differences in ruminant preference favoring PM harvests. This study evaluated the effects of time of cutting and harvest date on voluntary DMI and nutrient digestibility. The hays were field-cured, baled, and chopped before evaluation for intake and digestibility. Studies were conducted for sheep (Ovis aries), goats (Capra hircus), and cattle (Bos taurus). Goats, but not steers or sheep, demonstrated differences in nutrient digestibility between PM- and AM-cut hays. Goats consumed more PM than AM hay (2.97 vs. 2.83 kg/100 kg of BW; P = 0.07) and digested it to a greater extent (0.710 vs. 0.696; P = 0.03), resulting in greater digestible DMI (2.11 vs. 1.97 kg/100 kg of BW; P = 0.03). Sheep consumed (mean = 2.52 kg/100 kg of BW; P = 0.59) and digested (mean = 0.681; P = 0.25) PM- and AM-cut hays similarly. Steers consumed larger quantities of PM-than AM-cut hay (2.90 vs. 2.62 kg/100 kg of BW; P = 0.11), but digestion did not differ with cutting time (mean = 0.660; P = 0.75). Difference values (composition of fed hay minus composition of orts) indicated that sheep and goats selected from the feed offered similarly, whereas steers selected differently. Difference values for CP averaged 94 and 101 g/kg for goats and sheep and 32 g/kg for steers (P < 0.01), and difference values for NDF averaged 185 and 196 g/kg for goats and sheep and 73 g/kg for steers (P <or= 0.01). Steer DMI and digestible DMI were associated with preference (r = +0.83, P <or= 0.05; and r = +0.89, P <or= 0.05) and with coordinates for preference criteria (dimension 1; r = +0.90, P <or= 0.05; and r = +0.89, P <or= 0.05) from a previous preference trial. Intake and digestion responses for goats and sheep showed no relationship with the previous preference trial measurements. For cattle and goats, the management strategy of mowing in the afternoon seems to take advantage of small, but influential diurnal changes in the soluble carbohydrate fraction and offers the potential to improve forage quality
Ruminant selection among switchgrass hays cut at either sundown or sunup
As a result of photosynthesis, plants typically have greater concentrations of nonstructural carbohydrates at the end of the photoperiod. The preference of ruminants for hays harvested within the same 24-h period can be greater for plants harvested late in the photoperiod with increased soluble carbohydrate. To test for variation in ruminant preference for afternoon versus morning harvested hays in a C4 grass harvested in the humid east, established fields of 'Kanlow' and 'Alamo' switchgrass (Panicum virgatum L.) were used to produce hays in 1998, 1999, and 2000 near Raleigh, NC. Harvests were paired so that each cutting in the evening (PM) was followed by a cutting the next morning (AM). We harvested in this manner three times in 1998 to produce six Kanlow hays; twice with Kanlow and once with Alamo at two levels of nitrogen fertility in 1999 to produce eight hays; and three times in 2000 to produce six Alamo hays. The hays were field-dried, baled, and passed through a hydraulic bale processor. Hays from each year were tested with cattle (Bos taurus L.), goats (Capra hircus L.), and sheep (Ovis aries L.). During an adaptation phase, hays were offered individually. In the experimental phase, all possible pairs of hays were presented. Data were analyzed by multidimensional scaling and by traditional analyses. Multidimensional scaling indicated that selection was based on multiple criteria. The suite of improvements associated with PM-harvested hays in fiber content, digestibility, and nonstructural carbohydrate observed for alfalfa and fescue hays in the western USA was difficult to reproduce with switchgrass hay in the southeastern USA. This difficulty is likely related to the less favorable environment for haymaking as well as the physiology, anatomy, and morphology of this C4 grass
Magnetic Ordering and Superconductivity in the REIrGe (RE = Y, La-Tm, Lu) System
We find that the compounds for RE = Y, La-Dy, crystallize in the tetragonal
Ibam (UCoSi type) structure whereas the compounds for RE = Er-Lu,
crystallize in a new orthorhombic structure with a space group Pmmn. Samples of
HoIrGe were always found to be multiphase. The compounds for RE = Y
to Dy which adopt the Ibam type structure show a metallic resistivity whereas
the compounds with RE = Er, Tm and Lu show an anomalous behavior in the
resistivity with a semiconducting increase in as we go down in
temperature from 300K. Interestingly we had earlier found a positive
temperature coefficient of resistivity for the Yb sample in the same
temperature range. We will compare this behavior with similar observations in
the compounds RERuGe and REBiPt. LaIrGe and
YIrGe show bulk superconductivity below 1.8K and 2.5K respectively.
Our results confirm that CeIrGe shows a Kondo lattice behavior and
undergoes antiferromagnetic ordering below 8.5K. Most of the other compounds
containing magnetic rare-earth elements undergo a single antiferromagnetic
transition at low temperatures (T12K) while GdIrGe,
DyIrGe and NdIrGe show multiple transitions. The
T's for most of the compounds roughly scale with the de Gennes factor.
which suggests that the chief mechanism of interaction leading to the magnetic
ordering of the magnetic moments may be the RKKY interaction.Comment: 25 pages, 16 figure
Morning and evening harvest effects on animal performance
Plants vary diurnally in concentrations of nonstructural carbohydrates (TNC). Delaying forage
harvest until mid to late afternoon could result in increased TNC in forage. Ruminants can
differentiate between PM-harvested and AM-harvested grass and alfalfa hays and eat more PM-harvested
versus AM-harvested hay. In a related study, dairy cows ate about 10% more total
mixed ration containing 40% PM-harvested alfalfa hay versus the same ration containing AM-harvested
hay, produced more milk, and gained rather than lost body weight. Afternoon harvest
management could add $15/ton of alfalfa compared with morning harvesting
Diurnal variation in forage quality affects animal preference and production
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
Near infra-red measurement of nonstructural carbohydrates in alfalfa hay
Recently documented benefits from afternoon versus
morning cut forage have encouraged laboratory reporting of
total nonstructural carbohydrate (TNC) values as part of
forage quality testing. Our objective was to determine if
infra-red spectroscopy (NIRS), which is being used in many
forage testing labs, could be reliably used to quantify forage
sugars in hay samples. We used two alfalfa (Medicago sativa
L.) sample populations that were analyzed by wet chemistry
for sugars and scanned by NIRS. The first set consisted of
field-dried hay samples that were oven dried at 70°C and the
second consisted of fresh, freeze-dried samples. TNC values
were determined more precisely with NIRS than by wet
chemistr
Forage volatiles as cues for ruminants
Forage volatiles may provide cues that affect animal food choices. Collecting and
identifying these compounds is challenging. The authors briefly describe the methodology
and report several volatile compounds that relate to animal preference
Herbivore preference for afternoon- and morning-cut forages and adoption of cutting management strategies
Photosynthesizing forage plants accumulate total
nonstructural carbohydrates (TNC) during daylight, but then
TNC concentrations are reduced during the night. Afternoon-cut
forage (PM) has greater TNC value and thus economic
value, than morning-cut (AM). Livestock prefer PM-cut hay
and this can be readily demonstrated by offering animals a
choice of hays cut in PM and AM. Alfalfa growers in the
western United States are readily adopting PM-cutting
technology to increase profits
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