Frothy Bloat (primary ruminal tympany) Potential and Nutrient Content of Forage Kochia (Bassia prostrata L.)

Abstract

Forage kochia (Bassia prostrata L.) has been used extensively by grazing animals in Central Asia. Forage kochia was introduced into the U.S.A. in 1966 from a Stavropol Botanical Gardens (USSR) planting, and released as a cultivar (Immigrant) in 1984. It has been included in fire and rangeland rehabilitation seed mixes and planted on at least 200,000-400,000 ha in the USA. However, in central Nevada (USA), it has been linked to cattle mortality by frothy bloat (primary ruminal tympany) under specific ecological site conditions. In order to assess its potential to cause frothy bloat in free roaming cattle, we investigated the nutritive value of forage kochia across a grazing season (September-January), and compared in vitro gas production, and foam production and strength with fresh alfalfa. Crude protein values were highest in October-November (23.3 and 21.5%, respectively), while NDF was lowest during the same period (38.8 and 39.3%, respectively). Gas and foam production were higher for alfalfa than kochia over a 12 h incubation period. In general, alfalfa produced twice as much gas and foam as forage kochia (P<0.001). However, forage kochia foam strength (g/DM) was double that of alfalfa (P<0.002), and by 6 h incubation time, foam height of forage kochia was twice that of alfalfa (P<0.001). Forage kochia when used as the sole forage in the diet has the potential to cause frothy bloat in cattle. Fresh alfalfa produces more gas in the rumen; however, foam from forage kochia digestion is likely to be more persistent, potentially leading to frothy bloat development.

Full text

Frothy Bloat (primary ruminal tympany) Potential and Nutrient
Content of Forage Kochia (Bassia prostrata L.)
Teshome SHENKORU 1), Antonio FACIOLA 1), Brad SCHU LTZ 2) and Barry PERRYMAN*1)
Abstract: Forage kochia (Bassia prostrata L.) has been used extensively by grazing animals in Central Asia. Forage kochia was
introduced into the U.S.A. in 1966 from a Stavropol Botanical Gardens (USSR) planting, and released as a cultivar (Immigrant) in 1984. It
has been included in fire and rangeland rehabilitation seed mixes and planted on at least 200,000-400,000 ha in the USA. However, in
central Nevada (USA), it has been linked to cattle mortality by frothy bloat (primary ruminal tympany) under specific ecological site
conditions. In order to assess its potential to cause frothy bloat in free roaming cattle, we investigated the nutritive value of forage kochia
across a grazing season (September-January), and compared in vitro gas production, and foam production and strength with fresh alfalfa.
Crude protein values were highest in October-November (23.3 and 21.5%, respectively), while NDF was lowest during the same period (38.8
and 39.3%, respectively). Gas and foam production were higher for alfalfa than kochia over a 12 h incubation period. In general, alfalfa
produced twice as much gas and foam as forage kochia (P<0.001). However, forage kochia foam strength (g/DM) was double that of alfalfa
(P<0.002), and by 6 h incubation time, foam height of forage kochia was twice that of alfalfa (P<0.001). Forage kochia when used as the
sole forage in the diet has the potential to cause frothy bloat in cattle. Fresh alfalfa produces more gas in the rumen; however, foam from
forage kochia digestion is likely to be more persistent, potentially leading to frothy bloat development.
Key Words: Bassia prostrata, Foam strength, Frothy bloat.
1. Introduction
Forage kochia (Bassia prostrata L.) has been used
extensively by grazing animals for millennia in Central Asia
(Harrison et al., 2000; Waldron et al., 2005). It has high
crude protein content during the critical fall/winter grazing
period (Davis and Welch, 1985; ZoBell et al., 2003; Waldron et
al., 2006), non-toxic levels of oxalates (Davis, 1979), and
acceptable digestibility and relatively high preference (Welch
and Davis, 1984; Stevens et al., 1985; ZoBell et al., 2003).
In 2005, some ranchers in central-Nevada, USA began
reporting problems with frothy bloat in cattle, which can be
fatal. After a large mortality incident in October 2005,
necropsies were performed on several head of cattle and the
cause of death was asphyxiation related to frothy bloat
(primary ruminal tympany). Frothy bloat is defined as the
entrapment of the normal gases of fermentation in a stable
foam within the ruminant animal foregut (Irsik, 2007).
Unlike free gas bloat where large pockets of gas accumulate, in
frothy bloat gases are retained within the forage digesta
creating foam or froth that cannot be belched since a free
pocket of gas never develops.
Upon further investigation, it was determined that the
deceased animal rumens contained large quantities of forage
kochia, and that the animals had been grazing in a location
where forage kochia had been established as a fire
rehabilitation seeding. A subsequent mortality incident, in
October 2012, lead to the same conclusions.
Because of the seasonality of forage kochia, it is often the
only available, green, high crude protein source during the fall
and early winter grazing period. Forage kochia also has very
small leaves that increase the potential for gasses and foam to
be retained in the rumen digesta. Mortality of cattle translates
into lower profitability for ranchers. Economically marginal
operations like many in Nevada cannot afford mortality losses
from grazing related incidents that can be easily corrected or
eliminated.
The primary goal of this study was to assist Nevada
ranchers in dealing with a rangeland management problem
associated with cattle consuming forage kochia. In order to
achieve this goal, our specific objectives were: 1) investigate
the nutritive content of forage kochia harvested during the
fall/winter grazing season period, by chemical analyses; and 2)
compare kochia (October sample) with fresh alfalfa for frothy
bloat potential by measuring gas production, foam production,
and strength, using in vitro digestion.
2. Materials and Methods
The nutritive content of forage kochia was assessed in
fall/winter of 2011-12 by one-way ANOVA using months as
treatments (Sept., Oct., Nov., Dec. and Jan.). Variables of
interest included: dry matter (DM) (AOAC, 2000), crude
protein (CP), neutral detergent fiber (NDF), acid detergent
fiber (ADF), acid detergent lignin (ADL), ether extract (EE)
沙漠研究 25-3, 177 -180 (2015)
Journal of Arid Land Studies
‐ICAL 2 Refereed paper‐
* Corresp onding Author: bperryman@cabnr.unr.edu
Mail Stop 142, University of Nevada-Reno, Reno, Nevada 89557, USA
1) Department of Agriculture, Nutrition, and Veterinary Sciences, University of Nevada-Reno 2) College of Extension, University of Nevada-Reno
（Received, July 22th, 2012; Accepted, November 29th, 2012
）

and in vitro dry matter digestibility (IVDMD) (Jeraci et al.,
1988).
Gas production (Min et al., 2005a, 2005b) was assessed
with a 2 × 7 factorial ANOVA using forage kochia (October
samples), fresh alfalfa, and seven incubation times (1, 2, 3, 4, 5,
6 and 12 h). Gas production was modeled according to
Ørskov and McDonald (1979) using the model:
Y = b (1 - e-ct)
Where:
Y = volume of gas produced within time (t).
b = potential extent of gas production.
c = gas production rate, expressed in percent/h.
The intercept is not included in the model with the
understanding that no gas is produced from unfermented feed.
Foam production characteristics were assessed using a 2 ×
3 factorial ANOVA that included both forage kochia (October
samples), fresh alfalfa, and three incubation times (0, 2 and 6
h). Response variables included foam production (height in
cm per g of DM) and foam strength (Mangan, 1959; Pressey et
al., 1963; Min et al., 2005a, 2005b). Foam strength was
calculated using the formula: foam strength = 100 × time of
fall/distance of foam drop (Mangan, 1959). Forage kochia
used in the gas and foam assessments was collected only in
October of 2011.
Data were analyzed with Statistical Analysis Software
version 9.2 (SAS, 2010) and differences determined at P <
0.05 for all analyses. Post-hoc comparisons were performed
using least significant difference (LSD).
3. Results and Discussion
3.1. Nutritive content of Bassia prostrata
Actual values are presented in Table 1. The highest CP
content (P<0.0001) was observed on samples collected in Oct.
and Nov. of 2011 (23.3 and 21.5%, respectively); while the
lowest value was recorded in Jan., 2012 (10.1%). Values for
NDF, ADF and ADL fractions were the lowest during Oct. and
Nov. (P<0.02), while their values were higher during Sept. and
Jan. Value of EE was significantly (P< 0.0001) higher in
November than the rest of the assessment period. IVDMD
was highest (P<0.003) in October, and lowest (P<0.05) in
December and January.
CP levels reported here are higher than those reported by
Schauer et al. (2004) and Waldron et al. (2006). Differences
between trials may be the result of differences among climates,
soils or stand maturity. Values of CP declined as plants
matured and senesced between Oct. (23.3%) and Jan. (10.1%).
However, the CP content was above the minimum of 7%
required to maintain rumen function (NRC, 2000). This
characteristic indicates that forage kochia has great potential as
Tab le 1. Mean nutritive content (% of DM) and standard error (SE)
of Bassia prostrata across the grazing season 2011-2012.
Means in the same row with different letters are significant at P<
0.05.
Fig. 1. Cumulative, in vitro gas production from forage kochia
(Bassia prostrata) and fresh alfalfa for seven incubation periods,
2011. Vertical axis = Gas production (ml/gDM); Horizontal axis
= incubation time (h).
a fall/winter protein source for grazing beef cows in the
western USA.
3.2. Gas production
The cumulative in vitro gas production from forage kochia
and alfalfa are displayed in Figure 1. With the exception of
1h, alfalfa gas production was continuously greater than forage
kochia (P<0.001). This is due in part to its lower NDF
content (27.5 vs. 38.6%), and greater amounts of fermentable
products, relative to forage kochia.
3.3. Foam production and strength
Foam production (measured as height in cm per g of DM)
by time responses are shown in Table 2. An interaction was
observed between forage species and incubation time (P<0.05).
The interaction is an artifact of comparatively low foam height
at 6 h versus 2 h fermentation time. Alfalfa foam production
was higher at 0 and 2 h fermentation time than forage kochia
(P<0.001). However, the lowest foam production observed
for alfalfa was at 6 h fermentation time.
Kochia had significantly higher foam strength than alfalfa
(P<0.002; Fig. 2). This is most likely due to the smaller
bubbles observed for kochia during fermentation process.
Smaller bubbles have higher internal pressure than larger
bubbles, which provides greater resistance against collapse
%Sept Oct Nov Dec Jan SE
DM 93.4 95.2 94.5 96.2 95.8 0.24
CP 15.9b 23.3a 21.5a 16.8b 10.1c 1.02
NDF 45.4b 38.8c 39.3c 42.3c 54.6a 1.85
ADF 27.8ab 19.1c 20.4c 26.3b 31.6a 1.66
ADL 7.3a 6.2b 5.9b 7.2a 7.5a 0.21
EE 1.5e 2.6c 5.6a 3.3b 2.1d 0.17
IVDMD 54.0ab 57.9a 48.8b 42.8c 41.1c 2.12
0
20
40
60
80
100
12345612
Kochia
Alfalfa

Tab le 2. Effect of time (h) by species on in vitro ruminal foam height
(cm per g of DM) for forage kochia (Oct. samples and fresh
alfalfa, 2011. Means in the same row with different letters are
significant at P< 0.05 (SE: 15.1).
Fig. 2. Foam strength of fresh alfalfa and Bassia prostrata.
(Busaryev et al., 2012).
Since movement in the rumen is fairly continuous,
persistent foam would be expected to provide considerable
resistance to mechanical stress, and a greater ability to retain
entrapped gases. Alfalfa produced more gas and foam than
forage kochia; however, the larger bubbles associated with it
disappeared at a much faster rate than with forage kochia.
Another factor leading to the more substantial foam of
forage kochia could be the attraction between soluble proteins
that are negatively charged, and positively charged mineral
ions present in the rumen fluid. This can increase the stability
and strength of foams (Moeller et al., 2012), the authors stated
that divalent and trivalent ions can form bonds with two or
three negatively charged protein particles, thereby creating a
more stable foam when compared to sodium, a monovalent ion.
Although we did not determine mineral contents of the test
forages, according to Karimi et al. (2005) mineral analysis of
forage kochia showed 39 mg/g potassium, and 7.3 mg/g
magnesium, while alfalfa contains only 26 mg/g potassium and
2.8 mg/g magnesium (NRC, 2000). The high concentration
of these minerals in forage kochia likely contributed to its
greater foam stability. Additionally, high concentrations of K
and Mg are associated with occurrence of bloat in cattle (Stifel
et al., 1968).
4. Conclusions
Results of this study indicate that forage kochia (Bassia
prostrata) when consumed as the sole forage in the diet has the
potential to cause frothy bloat in ruminant animals. Even
though alfalfa produced more fermentation gases, forage
kochia produced more persistent foam in terms of strength and
residence time. Given this potential, we can offer some
simple guidelines for producers that utilize forage kochia as a
fall grazing resource: 1) When possible, do not introduce
ruminants into forage kochia seedings when it is actively
growing during the fall; 2) If animals must be placed in these
areas, offer grass hay or other dry forages to buffer the bloat
effects; and 3) Offer anti-bloat supplements before moving and
after arrival into forage kochia seedings.
Acknowledgements
This research was funded by the University of Nevada-Reno
Agriculture Experiment Station and the College of Agriculture,
Biotechnology, and Natural Resources.
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