Download 58 their normal flora. Phages are highly specific for their bacterial

Published March 4, 2016
their normal flora. Phages are highly specific for their bacterial
targets at the species or strain level, reducing collateral damage
to beneficial members of the microflora. Finally, resistance to
phages is generally unlinked to AMR, and phages are able
to infect and kill even highly resistant bacteria. Phages have
been shown to be effective in controlling a wide variety of
pathogens in various systems, including Salmonella in poultry
and swine, pathogenic E. coli in cattle and sheep, and Listeria
monocytogenes in foods. A limited number of phage-based
products targeting these pathogens are available for food
safety applications. One of the reasons phage technology was
abandoned in the 1940s was a generally poor understanding
of what phages were and how they worked; modern research
efforts are increasingly addressing basic aspects of phage
biology to maintain and increase the efficacy of these
promising antibacterial agents.
Key words: phage biology, antibacterial agents,
antimicrobial resistance, AMR
doi: 10.2527/ssasas2015-118
Mn and Co. However, the amounts to be supplemented will
depend on the specific mineral requirements and the forage
supply of the minerals. Consequently, the development of
free choice mineral supplementation programs is a moving
target. Generally, this entangled mess is sorted by taking one
mineral at a time into considerations. However, in doing so,
one has to be cognizant of the many interactions that occur
when changing intake of just one mineral in the supplement
with respect to the amount supplied in the base forage. Often
times, mineral nutrition problems of one or more minerals
are created when trying to correct a deficiency of another
mineral. This paper will address the specific mineral-mineral
interactions that are important to consider when developing
and delivering mineral supplementation programs in pasturebased production systems.
Key words: minerals, supplementation,
pasture-based, beef cattle
doi: 10.2527/ssasas2015-119
120 Mineral nutrition of forage-fed beef cattle—
Impacts on reproduction.
SYMPOSIUM ABSTRACTS:
BILL E. KUNKLE INTERDISCIPLINARY
BEEF SYMPOSIUM
L. W. Greene*
Auburn University, Auburn, AL
J. D. Arthington*
UF/IFAS, Range Cattle Research and Education
Center, Ona, FL
The importance of mineral nutrition on the reproductive
function of beef cows has been a topic of investigation for
many years. As levels of production increase and management
systems evolve, so do the requirements of nutritionally
essential minerals. For example, increased emphasis on
rearing heifers to conceive as yearlings has brought attention
to the importance of P nutrition in developing diets. For microminerals, the increased utilization of high-S supplements,
such as distillers grains, have impacted Cu and Se nutrition
of cattle. In addition, advancing technologies have introduced
new mineral sources, such as organic and hydroxy trace
minerals, and also new forms of supplementation, such as
boluses and injectable trace minerals. Each of these impacts
and technical advances present opportunities to improve the
reproductive performance of cowherds. Among the essential
macro-minerals, P is the most commonly deficient among
forage-fed beef cows. A large focus on P nutrition of the cow/
calf herd in the 70’s and 80’s has resulted in formulation of
high-P supplements. Currently, pressures related to elevated
cost and environmental impacts have caused scientists to
rethink and refine the P nutrition of beef cattle. Among
essential micro-minerals, Cu and Se are the most commonly
deficient and each have been linked to reproductive function
in beef cattle. The direct role of Se on reproduction is likely
a secondary response to reduced immune competence due
to suppressed antioxidant capacity as a result of impaired
activity of the Se-dependent enzyme, glutathione peroxidase.
Studies linking Cu to reproduction in cattle have been highly
119 Assessing the current mineral supplementation
needs in pasture-based beef operations in the
Southeastern United States.
Macro and micro minerals are required for all physiological
processes in beef cattle. When mineral deficiencies occur in
pasture-based production systems a multitude of deficiency
symptoms will occur and most often these deficiencies result
in reduced production potential, reduced immunity and/or
reproductive failure. More severe deficiencies will result in
more specific deficiency symptoms depending on the specific
mineral deficiency. In pasture-based beef operations, forage
mineral supply is highly variable and dependent on the forage
type, stage of forage growth, and soil fertility. Additionally,
grazing cattle mineral requirements change throughout the
production cycle. With the variability of forage mineral
supply and the changing mineral requirements, care must be
taken when developing mineral supplementation programs
for grazing cattle. The macro minerals function in nerve
transmission, bone development, metabolism and as
electrolytes. These are Ca, P, Mg, Na, K, Cl and S. The micro
minerals function in various areas of metabolism, immune
responsiveness, reproductive efficiency and many other
functions. These minerals are Zn, Cu, Fe, I, Mn, Se, Mo and Co.
Of these minerals, those that are important for supplementation
to pasture-based cattle include Ca, P, Mg, Na, Cl, Zn, Cu, I,
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variable. Evidence is emerging which suggests that Mo, a
well-known Cu antagonist, is directly impacting reproductive
processes independent of Cu. This symposium presentation
will focus on the impacts of P, Cu, and Se on reproduction in
cattle with emphasis on important antagonists (S and Mo) and
new technologies influencing supplementation management.
Key words: Minerals, Cattle, Phosphorus,
Selenium, Copper
doi: 10.2527/ssasas2015-120
in the functioning of the complex and multifaceted immune
system. However, there is still much to be learned about
determining the mineral status of herds (and hence when
supplementation will be beneficial), requirements for different
genetic and environmental conditions, understanding the
bioavailability of these nutrients from feedstuffs and forages,
quantifying the bioavailability of different supplemental
sources of these nutrients, and identifying the impact of
dietary antagonists on these nutrients.
Key words: beef cattle, minerals, vitamins
doi: 10.2527/ssasas2015-121
121 Impact of mineral and vitamin status on beef
cattle immune function and health.
E. B. Kegley*1, J. J. Ball2, P. Beck3
1
122 Assessing the influence of vitamin and
mineral nutrition on carcass characteristics
and meat quality.
Department of Animal Science, Division of
Agriculture, University of Arkansas, Fayetteville,
AR, 2Department of Animal Science, University of
Arkansas Division of Agriculture, Fayetteville, AR,
3
University of Arkansas, Hope, AR
T. E. Lawrence*
West Texas A&M University, Canyon, TX
The impact of vitamin and mineral nutrition on beef carcass
quality has received variable attention in the peer reviewed
literature. Most work on the topic appears with reference to
fat soluble vitamins. Serum vitamin A appears to be weakly
correlated to marbling score; high concentrations of vitamin A
may inhibit adipogenic differentiation. A diet rich in vitamin A
will also impact fat color; an orange/yellow fat color dominates
during b carotene deposition in fat stores. Supplemental
vitamin D appears to increase endogenous calcium levels and
thus improve tenderness via enhanced activity of µ-calpain.
Enhanced dietary vitamin D may also improve retail color
stability. A plethora of research indicates that supplemental
vitamin E scavenges free radicals thus reducing peroxidation
of polyunsaturated fatty acids leading to longer retail color
life. Vitamin K levels appear to be variable between breeds
and muscles but supplemental K does not appear to be in the
literature in reference to beef quality.
Vitamin C injected intravenously immediately antemortem (or postmortem via vascular infusion) has illustrated variable effects on retail color life. Moreover, supplemental C has
received mixed results (increased marbling score, subcutaneous fat deposition, vitamin E, calcium, and iron; decreased
L*) for cattle on a high sulfur diet. Supplemental B does not
appear to be in the literature in reference to beef quality and
should not be needed with proper rumen function.
Minimal peer-reviewed literature has investigated the
association of mineral status in-life and subsequent beef
quality. Supplemental calcium antemortem does not appear to
affect tenderness or maturity however supplemental calcium
postmortem activates the calpain enzyme system and improves
myofibrillar tenderness. Supplemental phosphorus antemortem
does not appear to affect tenderness or maturity. Supplemental
potassium as a pre-slaughter electrolyte may positively
influence carcass yield. Excess sulfur may depress LM area,
marbling, subcutaneous fat, yield grade, and hot carcass weight.
The importance of optimal mineral and vitamin nutrition on
improving immune function and health has been recognized
in the preceding decades. In the southeast, beef cattle are
raised on forages that may be limiting in these nutrients,
especially some trace minerals (particularly Cu, Zn, and Se),
for optimizing health. Dietary mineral concentrations often
considered adequate for maximum growth, reproductive
performance, or optimal immune function have been found
to be insufficient at times of physiological stresses (weaning,
transport, comingling, etc.). Clinical deficiencies of these
nutrients produce classic symptoms that are common to several
nutrient deficiencies (slow growth and unthrifty appearance),
however subclinical deficiencies are more widespread and
more difficult to detect; yet may result in broader economic
losses. The impacts of these deficiencies on beef cattle health
may not be apparent until the herd has been stressed in some
way or calves have been weaned and potentially transported out
of the region. Health problems that are caused or exacerbated
by mineral and/or vitamin deficiencies include: bovine
respiratory disease, footrot, retained placenta, metritis, and
mastitis. Research indicates that trace minerals (including Zn,
Cu, Se, Cr, and Co), and vitamins or vitamin precursors, such
as vitamin E and carotenoids, impact immunocompetence.
Many micronutrients have antioxidant properties through
being components of enzymes and proteins that benefit
animal health. In dairy cattle, high levels of supplemental
Zn are generally associated with reduced somatic cell counts
and improved foot health, possibly reflecting the importance
of Zn in maintaining effective epithelial barriers. Neutrophils
isolated from ruminants deficient in Cu or Se have reduced
ability to kill ingested bacteria in vitro. Supplemental vitamin
E, in its role as an intracellular antioxidant has been shown
to decrease morbidity in stressed calves. There is more
understanding of the biological role that these nutrients play
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