Effect of dietary thiamin supplementation on milk production by dairy cows
Effect of Dietary Thiamin Supplementation on Milk Production by Dairy Cows R. D. Shaver and M. A. Bal ABSTRACT
fiber carbohydrate, PEM = polioencephalomalacia, TH
= thiamin supplemented diet, TLC = theoretical length
We conducted three experiments to determine the
effects of dietary thiamin supplementation on milk pro-duction by dairy cows. In trial 1, 28 Holstein cows were
INTRODUCTION
blocked by parity and assigned randomly to either pla-cebo or thiamin top-dress for the 8-wk experiment to
Most of the study of thiamin for ruminants has been
provide a supplemental thiamin intake of 0 or 150 mg/d
in relation to a clinical central nervous system condition
per cow. Within each of these groups, cows were further
observed in beef cattle called polioencephalomalacia
assigned randomly to two total mixed rations (TMR)
(PEM). Cattle with clinical signs of PEM, which include
for 4 wk, with the TMR treatments then reversed for
circling behavior, rigid stance, and convulsions, re-
a second 4-wk experimental period. Milk yield was 2.7
spond dramatically to large intravenous doses of thia-
kg/d higher for thiamin-supplemented cows. Yields of
min (3, 6). Incidence of PEM appears to be related to
milk fat and protein were increased 0.13 and 0.10 kg/
ruminal destruction of thiamin by thiaminase enzymes
d, respectively, by dietary thiamin supplementation. In
produced by ruminal bacteria (3, 6). Cattle fed high
trial 2, 20 multiparous Holstein cows were used in a
concentrate or feedlot diets are most susceptible to
crossover design with 4-wk periods. Placebo or thiamin
PEM, but it has also been observed in grazing animals
premixes were added to TMR to provide an approximate
daily supplemental thiamin intake of 0 or 300 mg/cow.
In lactating dairy cows, we are unaware of any re-
Milk and protein yields tended to be 0.7 and 0.04 kg/d
ports of PEM or performance response to dietary thia-
higher, respectively, for thiamin-supplemented cows.
min supplementation. Without extensive ruminal thia-
In trial 3, 16 multiparous Holstein cows were used in
min destruction, a thiamin deficiency in lactating dairy
a replicated 4 × 4 Latin square with 21-d periods. Pla-
cows seems unlikely, since Erdman (7) estimated a
cebo or thiamin premixes were added to TMR to provide
fivefold higher small intestinal flow of thiamin (ruminal
an approximate daily supplemental thiamin intake of
escape + production) relative to requirements extrapo-
0 or 300 mg/cow. Dry matter intake tended to be 0.8
lated with data from lactating sows. Some practical
kg/d lower for thiamin-supplemented cows. Milk fat
feeding guides recommend dietary thiamin supplemen-
percentage tended to be 0.18 percentage units lower and
tation when high levels of corn gluten feed are used in
fat yield was 0.08 kg/d lower for thiamin-supplemented
cows. Thiamin supplementation tended to increase
The main objective of our first trial was to evaluate
milk and component production when dietary concen-
intake and milk production by dairy cows being fed a
trations of neutral and acid detergent fiber were lower
corn byproduct-based diet (CBP) versus a corn-soybean
and nonfiber carbohydrate was higher than recom-
meal-based diet (CS). Because a corn byproduct-based
on corn gluten feed was under evaluation in trial 1, a
(Key words: thiamin, milk production, intake)
secondary objective was to evaluate the effect of dietarythiamin supplementation on lactation performance. Abbreviation key: C = control diet, CBP = corn by-
Based on the results of trial 1, our objective in trials 2
product diet, CS = corn-soybean meal diet, NFC = non-
and 3 was to further evaluate the effect of dietary thia-min supplementation on intake and milk production bydairy cows. Corn silage was the main forage used intrial 2, because it was available after a forage feeding
trial conducted by our laboratory. Alfalfa silage was the
Accepted April 20, 2000. Corresponding author: R. D. Shaver; e-mail: rdshaver@facstaff.
sole forage used in trial 3, because our main objective
was to evaluate the effect of processing alfalfa silage
on intake, digestion, and milk production by dairy cows.
(Arthur H. Thomas, Philadelphia, PA). Samples were
Although there is no proposed relationship between
analyzed for DM, OM, and CP (1), NDF using α-amylase
these factors, dietary thiamin supplementation was in-
(Sigma no. A3306; Sigma Chemical Co., St. Louis, MO)
cluded in the factorial design used in trial 3 to gain
and sodium sulfite (15), and ADF (8). Nonfiber carbohy-
more data on its effects. Only effects related to dietary
drate (NFC) content was calculated as the difference
thiamin supplementation are presented and discussed
between 100 and the sum of (NDF + CP + ash + fat)
with NDF, CP, and ash determined analytically andfat with NRC (11) tabular values. MATERIALS AND METHODS
Cows were milked twice daily and production was
recorded at each milking during the preliminary and
experimental periods. Milk samples taken from a.m.
Twenty-eight Holstein cows (16 multiparous and 12
and p.m. milkings on d 20 and 21 and d 27 and 28 of each
primiparous) averaging 142 DIM (SD = 41) and 605 kg
period were analyzed for fat, CP, and urea-nitrogen by
of BW (SD = 82) at trial initiation were blocked by parity
infrared analysis (Ag Source Milk Analysis Laboratory,
and assigned randomly to either placebo or thiamin
Menomonie, WI). Milk composition was calculated as
top-dress for the 8-wk experiment. Within each of these
an average of a.m. and p.m. samples with the proportion
groups, cows were further assigned randomly to TMR
of daily milk production at that milking as a
containing either CS or CBP for 4 wk with the TMR
treatments then reversed for a second 4-wk experimen-
Data from wk 3 and 4 and wk 7 and 8 of the experi-
tal period. Before the start of the experiment, all cows
ment were analyzed as a split-plot design using the
were fed diet CS during a 2-wk preliminary period.
general linear models procedure of SAS (13). Milk pro-
Cows were housed and fed individually in tie stalls.
duction data from the second week of the preliminary
The top-dress—composed of either wheat middlings or
period were used as a covariate. The model included
a thiamin mononitrate—wheat middlings mixture was
covariate, parity (primiparous vs. multiparous cows),
fed at the rate of 57 g/d per cow to individual cows once
diet (CS vs. CBP), top-dress (C vs. TH), cow, and two-
daily to provide a supplemental thiamin intake of 0 (C)
way interaction terms. Cow effects were used as the
or 150 (TH) mg/d per cow.
error term for testing top-dress effects and residual
The ingredient composition of CS and CBP diets is
error was used to test diet and top-dress by diet inter-
presented in Table 1. Both diets contained 55% alfalfa
silage and 45% concentrate (DM basis). Corn byproductwas included in the CBP diet as replacement for two-
thirds of the ground, shelled corn found in the CS diet. The dried, pelleted corn byproduct (Koch Feed Prod-
Twenty multiparous Holstein cows averaging 195
ucts, Wichita, KS) was composed of wet corn gluten
DIM (SD = 33) and 657 kg of BW (SD = 52) at trial
feed and starch sludge, starch, and syrup. Starch sludge
initiation were used in a crossover design with 4-wk
is composed of the settlings from starch cookers used
periods. Wheat middlings or thiamin mononitrate-
in the production of corn syrup. The higher CP content
wheat middlings mixture were added to TMR to provide
of corn byproduct than shelled corn allowed for elimina-
an approximate daily supplemental thiamin intake of
tion of soybean meal from the CBP diet and dictated
that diet CS also be formulated for 20% CP (DM basis).
Dietary ingredient composition is presented in Table
Diets were formulated to meet or exceed NRC (11) re-
1. Diets contained 50% forage (two-thirds corn silage
quirements for minerals and vitamins and were fed as
and one-third alfalfa silage) and 50% concentrate (DM
TMR once daily. All cows were injected with bST (Posi-
basis). Placebo or thiamin supplements were added to
lac, Monsanto Company, St. Louis, MO) every 14 d
respective TMR at 0.5% of DM. Diets were formulated
for 17.5% CP (DM basis) and to meet or exceed NRC (11)
Dry matter content of alfalfa silage was determined
requirements for minerals and vitamins. Diets were fed
weekly with a 60°C forced-air oven to adjust as-fed
as TMR once daily. All cows were injected with Posilac
ratios of diet ingredients. The amounts of TMR offered
every 14 d starting on d 1 of the experiment.
and refused were recorded daily during the experimen-
Dry matter content of corn silage and alfalfa silage
tal period. The alfalfa silage and concentrate mixtures
was determined weekly with 60°C forced-air oven for
were sampled on d 15 and 22 of each period and each
adjustment of as-fed ratios of dietary ingredients. Cows
was composited by period for nutrient analysis. Com-
were housed and fed individually in tie stalls. The
posite feed samples were dried for 48 h in a 60°C forced-
amounts of TMR offered and refused were recorded
air oven and ground to pass a 1-mm Wiley mill screen
daily. The corn silage, alfalfa silage, and concentrate
Journal of Dairy Science Vol. 83, No. 10, 2000
Table 1. Diet ingredient and nutrient composition for trials 1, 2, and 3.
1CS = Corn-soybean meal diet. 2CBP = Corn byproduct diet. 3C = Control diet. 4TH = Thiamin-supplemented diet. 5Trial 1: Contained 22.8% CP, 36.8% NDF, and 28.4% ADF (DM basis). Trial 2: Contained 25.2% CP,
36.7% NDF, and 32.9% ADF (DM basis). Trial 3: Contained 20.3% CP, 44.1% NDF, and 32.8% ADF (DMbasis).
6Contained 35.6% DM and 7.3% CP, 40.6% NDF, and 23.9% ADF (DM basis). 7Contained 88% DM and 21.4% CP, 25.6% NDF, 13.6% ADF, and 3.4% ether extract (DM basis). 8SoyPlus, West Central Cooperative, Ralston, IA. 9Trace-mineralized salt: NaCl, 92.5 to 95.5%; not less than 0.55% Zn, 0.55% Mn, 0.35% Fe, 0.14% Cu,
10Vitamin supplement was added to provide vitamins A, D, and E at the rate of 150,000, 50,000, and 500
11Trial 1: Wheat middlings or thiamin mononitrate-wheat middlings mixture top-dressed at the rate of
57 g/d per cow to individual cows once daily to provide 0 or 150 mg of thiamin/d per cow. Trials 2 and 3:Wheat middlings or thiamin mononitrate-wheat middlings mixture added to TMR to provide an approximatedaily thiamin intake of 0 or 300 mg/cow.
12NFC = Nonfiber carbohydrate = 100 − (NDF + CP + ether extract + ash).
mixture were sampled on d 15 and 22 of each period and
design using the general linear models procedure of
each was composited by period for nutrient analysis.
Composite feed samples were dried for 48 h in a 60°Cforced-air oven and ground to pass a 1-mm Wiley mill
screen (Arthur H. Thomas, Philadelphia, PA). Sampleswere analyzed for DM, OM, CP, NDF, and ADF, and
Sixteen multiparous Holstein cows (eight ruminally
NFC was calculated as described for trial 1.
cannulated and eight intact) averaging 120 DIM (SD =
Cows were milked twice daily, and production was
36) and 600 kg of BW (SD = 39) at trial initiation were
recorded at each milking. Milk samples taken from a.m.
used in a replicated 4 × 4 Latin square design with 21-
and p.m. milkings on d 20 and 21 and d 27 and 28 of each
d periods, 14 d for dietary adaptation. Thiamin supple-
period were analyzed for fat, CP, and urea-nitrogen by
mentation and alfalfa silage processing were main ef-
infrared analysis (Ag Source Milk Analysis Laboratory,
fects in the 2 × 2 factorial arrangement of treatments.
Wheat middlings or thiamin mononitrate-wheat mid-
Dry matter intake and milk production data from wk
dlings mixture were added to TMR to provide an ap-
3 and 4 and wk 7 and 8 were analyzed as a crossover
proximate daily supplemental thiamin intake of 0 or
Journal of Dairy Science Vol. 83, No. 10, 2000
300 mg/cow. Alfalfa silage was either harvested at 0.95
bags were washed in a commercial washing machine
cm theoretical length of cut (TLC) without rolling or
with cold water for two cycles of 12 min each (4). Bags
1.90 cm TLC with a 1-mm roll clearance with an experi-
and residue were then dried at 60°C for 48 h to deter-
mental pull-type chopper fitted with an on-board
Data from wk 3 of each period were analyzed as a
Dietary ingredient composition is presented in Table
replicated Latin square using the general linear models
1. Diets contained 60% alfalfa silage and 40% concen-
procedure of SAS (13). Ruminal pH data were analyzed
trate (DM basis). Placebo or thiamin supplements were
using PROC MIXED of SAS (10) for repeated measures.
added to respective TMR at 0.5% of DM. Diets wereformulated for 18.5% CP (DM basis) and to meet or
RESULTS AND DISCUSSION
exceed NRC (11) requirements for minerals and vita-mins. Diets were fed as TMR once daily. All cows were
Dietary nutrient composition and DMI and milk pro-
injected with Posilac every 10 d starting on d 1 of the ex-
duction data from the three experiments are presented
Dry matter content of alfalfa silage was determined
weekly with a 60°C forced-air oven for adjustment of
as-fed ratios of diet ingredients. Cows were housed and
Diets contained 19.4 to 20.7% CP, which exceeds NRC
fed individually in tie stalls. The amounts of feed offered
(11) guidelines. This was related to the high CP content
and refused were recorded daily. The alfalfa silage
of the alfalfa silage and its dietary inclusion rate and
treatments and concentrate mixtures were sampled on
the higher CP content of corn byproduct and its dietary
d 15 of each period for nutrient analysis. Feed samples
substitution rate for ground, shelled corn. Although not
were dried for 48 h in a 60°C forced-air oven and ground
measured, high ruminal degradability of dietary CP
to pass a 1-mm Wiley mill screen (Arthur H. Thomas,
was likely because high CP degradability has been re-
Philadelphia, PA). Samples were analyzed for DM, OM,
ported for alfalfa silage, solvent-extracted soybean
CP, NDF, and ADF, and NFC was calculated as de-
meal, and corn gluten feed (14). The concentration of
dietary NDF (27.4% of DM on average) was above the
Cows were milked twice daily and production was
NRC (11) minimum recommended allowance. However,
recorded at each milking. Milk samples taken from a.m.
the concentration of NDF in diet CS was slightly below
and p.m. milkings on d 17, 18, and 19 of each period
the NRC (11) minimum recommended allowance, and
were analyzed for fat, CP, and urea-nitrogen by infrared
diet CS contained 5.6 percentage units less NDF than
analysis (Ag Source Milk Analysis Laboratory, Meno-
diet CBP. This was related to the higher NDF content of
corn byproduct and its substitution rate for corn grain.
Ruminal fluid from the eight ruminally cannulated
Concentration of dietary NFC (41.5% of DM on average)
cows was sampled immediately before feeding and at
was slightly above the optimum concentration of 40%
4, 8, and 12 h postfeeding on d 19 and 20 of each period.
(DM basis) suggested by Nocek and Russell (12), but
Samples were taken from five different locations in the
diet CS contained 6.5 percentage units more NFC than
rumen via the cannula using a custom-made metal filter
probe and pH was determined (Twin pH meter Model
Milk yield was 2.7 kg/d (P = 0.01) higher for cows fed
B-213, Spectrum Technologies, Inc., Plainfield, IL).
TH. Milk fat and protein percentages were unaffected
The 48-h ruminal in situ DM degradation of the al-
by dietary thiamin supplementation, but yields of fat
falfa silage treatments was determined in ruminally
and protein were increased 0.13 and 0.10 kg/d (P =
cannulated cows on d 19 of each period. In situ bags
0.01), respectively, for TH. Grigat and Mathison (9)
(25 × 35 cm, 52-µ pore size) were made of Dacron polyes-
reported that dietary thiamin supplementation in-
ter cloth (R102 Marvelaire White, N. Erlanger, Blum-
creased average daily gain in feedlot steers fed all-con-
gardt and Co., Inc., New York). The alfalfa silage treat-
centrate diets. Positive effects of dietary thiamin sup-
ments were incubated with triplicate bags per cow and
plementation on milk and component yields were evi-
matching incubation alfalfa silage with diet alfalfa si-
dent on both CS and CBP diets, and no thiamin
lage by cow and period. Twenty-five grams of DM was
supplementation × diet interaction was observed. This
weighed into each bag (30 mg/cm2 sample size to surface
suggests that effects of dietary thiamin supplementa-
area ratio) and incubated without drying or grinding
tion observed in this trial were unrelated to the use of
at 2 h postfeeding. In situ bags were placed in a nylon
corn byproduct vs. corn grain plus soybean meal. This
laundry bag and positioned in the ventral rumen. Dupli-
finding contradicts Berger et al. (2) who recommended
cate blank bags were incubated in each laundry bag to
dietary thiamin supplementation only when feeding
correct for influx of DM into the sample bags. In situ
Journal of Dairy Science Vol. 83, No. 10, 2000
Table 2. Effect of dietary thiamin supplementation on DMI, milk production, and milk composition by dairy cows in trials 1, 2, and 3.
1Means are covariate-adjusted least square means. 2C = Control diet. 3TH = Thiamin-supplemented diet. 4NS = Not significant (P > 0.15).
was unaffected by dietary thiamin supplementationand there were no treatment × sampling time interac-
The concentrations of dietary NDF and ADF were
tions; pH averaged 6.49 for C versus 6.52 for TH and
below the NRC (11) minimum recommended allowance.
6.26 for C versus 6.27 for TH at 4 h and 8 h postfeeding,
The concentration of dietary NFC (46.7% of DM) was
respectively (data not presented in table). In situ DM
well above the optimum concentration of 40% (DM ba-
degradation of alfalfa silage was also unaffected by di-
sis) suggested by Nocek and Russell (12). Dietary CP
etary thiamin supplementation, averaging 68.8% and
concentration (17.0% of DM) was lower than for trial 1
69.0% for C and TH, respectively (data not presented
(20.1% of DM on average). Although not measured in
either trial, lower ruminal degradability of dietary CPfor this trial versus trial 1 was likely because of the useof corn silage and expeller-extracted soybean meal (14). CONCLUSIONS
Milk and protein yields tended to be 0.7 (P = 0.15)
Supplementing dietary thiamin at the rate of 150 to
and 0.04 kg/d (P = 0.09) higher, respectively, for cows
300 mg/d per cow increased or tended to increase milk
fed TH. Dietary thiamin supplementation did not affect
and component production in trials 1 and 2, respec-
tively. In trial 1, increased milk, fat, and protein yieldsin response to dietary thiamin supplementation were
observed in cows fed TMR containing either corn-by-
Dietary concentrations of NDF (32.3% vs. 24.3 to
product or corn-soybean meal-based concentrates. Dif-
30.2% of DM) and ADF (22.2% vs. 15.6 to 18.3% of DM)
ferences in response to dietary thiamin supplementa-
were higher and NFC (36.0% vs. 38.3 to 46.7% of DM)
tion between trials cannot be clearly explained, but
was lower for this trial than for trials 1 and 2. Also,
diets fed in trials 1 and 2 contained lower concentra-
dietary NDF from forage was higher for this trial than
tions of NDF from forage and total NDF and higher
for trials 1 and 2 (26.5% vs. 19.7 to 20.2% of DM). The
concentrations of NFC than the diet fed in trial 3. Also,
concentration of CP in the diet for this trial (18.7% of
the CP concentration of diets fed in trial 1 greatly ex-
DM) was intermediate between diets for trials 1 (20.1%
ceeded NRC (11) guidelines and of diets fed in trials 2
of DM on average) and 2 (17.0% of DM).
and 3. These differences in dietary nutrient concentra-
Intakes of DM tended to be 0.8 kg/d lower (P = 0.15)
tions between trials may have influenced ruminal thia-
for cows fed TH. Milk fat percentage tended to be 0.18
minase production by rumen bacteria and hence the
percentage units lower (P = 0.06) and fat yield was 0.08
observed response to dietary thiamin supplementation
kg/d lower (P = 0.05) for cows fed TH. Dietary thiamin
(3, 6). Another possible explanation for the observed
supplementation did not affect milk yield or protein in
variation in response to dietary thiamin supplementa-
this trial. No interactions of thiamin supplementation
tion between trials could be the presence or nonpres-
by alfalfa silage processing were observed.
ence of an antithiamin factor produced by Fusarium
Ruminal fluid was sampled as part of our evaluation
molds (5). However, we collected no thiaminase or myco-
of alfalfa silage processing effects on digestion. Thus,
toxin data in these trials to support or refute either
ruminal data were also collected regarding the effects
explanation. It is unlikely that response differences
of dietary thiamin supplementation. Ruminal fluid pH
among trials were related to problems with thiamin
Journal of Dairy Science Vol. 83, No. 10, 2000
stability, because the expected loss of potency is only
2 Berger, L. L., J. C. Weigel, and S. C. Bidner. 1986. Corn gluten
feed for beef cattle. Pages 4–5 in Corn Gluten Feed-The Future
5% over 8- to 12-wk of storage after mixing in a premix
of Feeding. Illinois Corn Growers Assoc. Bloomington, IL.
and negligible over 24 h after mixing in TMR (M. B.
3 Brent, B. E., and E. E. Bartley. 1984. Thiamin and niacin in the
Coelho, BASF Corp., Mount Olive, NJ, personal commu-
4 Cherney, D.J.R., J. A. Patterson, and R. P. Lemenager. 1990.
nication). The trend for reduced DMI and milk fat in
Influence of in situ bag rinsing technique on determination of dry
response to dietary thiamin supplementation noted in
matter disappearance. J. Dairy Sci. 73:391–397.
5 DiNicola, N. L. 1995. Evidence for an unidentified autoclave-labile
trial 3 was unexpected, and we offer no explanation
anti-thiamin factor produced by Fusarium proliferatum cultures
for this observation. Results of these trials suggest a
associated with spiking mortality syndrome. Ph.D. Thesis, Univ.
possible role for thiamin supplementation when dietary
6 Edwin, E. E., and R. Jackman. 1982. Ruminant thiamine require-
concentrations of NDF and ADF are lower and NFC is
ment in perspective. Vet. Res. Comm. 5:237–250.
higher than recommended. More research with lactat-
7 Erdman, R. A. 1992. Vitamins. Pages 297–308 in Large Dairy
Herd Management. H. H. Van Horn and C. J. Wilcox, ed. Am.
ing dairy cows on the response to dietary thiamin sup-
plementation and on nutritional factors affecting this
8 Goering, H. K., and P. J. Van Soest. 1970. Forage Fiber Analyses.
(Apparatus, Reagents, Procedures, and Some Applications). Agric. Handbook No. 379. ARS-USDA, Washington, DC.
9 Grigat, G. A., and G. W. Mathison. 1982. Thiamin supplementa-
tion of an all-concentrate diet for feedlot steers. Can. J. Anim. ACKNOWLEDGMENTS
10 Littell, R. C., G. A. Milliken, W. W. Stroup, and R. D. Wolfinger.
Appreciation is extended to Sandra Trower and Rob-
1996. SAS System for Mixed Models. SAS Inst., Inc., Cary, NC.
11 National Research Council. 1989. Nutrient Requirements of Dairy
ert Elderbrook at the University of Wisconsin Arlington
Cattle. 6th rev. ed. Natl. Acad. Sci., Washington, DC.
and Madison Dairy Cattle Centers, respectively, for the
12 Nocek, J. E., and J. B. Russell. 1988. Protein and energy as an
care and feeding of the cows. The technical assistance
integrated system. Relationship of ruminal protein and carbohy-drate availability to microbial synthesis and milk production. J.
in the laboratory of Sandra Bertics and Erin Miller is
13 SAS User’s Guide: Statistics. Release 6.03 Edition. 1988. SAS
14 Satter, L. D. 1986. Protein supply from undegraded dietary pro-
REFERENCES
15 Van Soest, P. J., J. B. Robertson, and B. A. Lewis. 1991. Methods
of dietary fiber, neutral detergent fiber, and nonstarch polysac-
1 Association of Official Analytical Chemists. 1990. Official Methods
charides in relation to animal nutrition. J. Dairy Sci. 74:3583–
of Analysis. Vol. I. 15th ed. AOAC, Arlington, VA.
Journal of Dairy Science Vol. 83, No. 10, 2000
Inactivation of Picornaviruses using EcoQuest Radiant Catalytic Ionization Introduction The viral family Picornaviridae , which includes Hepatitis A virus, is characterized as including viruses which are non-enveloped with single stranded positive sensed RNA genomes known to be very resistant to physical and chemical means of inactivation (1). Hepatitis A virus (HAV) is known t
Colon cancer in Chile before and after the start of the flourfortification program with folic acidSandra Hirsch, Hugo Sanchez, Cecilia Albala, Marı´a Pı´a de la Maza,Gladys Barrera, Laura Leiva and Daniel BunoutBackground Folate depletion is associated with anratio: 2.6, confidence interval: 99% 2.93–2.58) andincreased risk of colorectal carcinogenesis. A temporalin the 65–79 years