Beef Research News
Brought to you by Kansas State University
College of Veterinary Medicine - Farm Animal Section
January 2007
Contents:
BCS and bST influences on
reproductive function in cows
Corn production estimates impact feeder prices
Influence of early pregnancy diagnosis on fetal
viability
Probability of Male Offspring after Artificial
Insemination
Tritrichomonas infections in beef herds
Nasopharyngeal swabs as diagnostic method for
respiratory infections
BCS and bST influences on
estrous behavior and reproductive function in Brahman-influenced cows
A trial was designed using 99 multiparous
Brahman-influenced cows managed to achieve low (BCS = 4.3) or moderate (BCS
= 6.1) body condition to determine the influence of bovine somatotropin
(bST) on estrous characteristics, reproductive performance, and
concentrations of serum GH and plasma NEFA. Cows within each body
condition category were randomly assigned to be treated or not with bST
at 32 days post partum. Treated cows received bST on days -35, -21, and
-7 before initiation of the breeding season. All cows (regardless of
treatment) received CIDRs on d -7 with removal and administration of
prostaglandin F2 on day 0 (initiation of breeding season).
Radiotelemetry was used to monitor estrous behavior during the first 30
days of the breeding season and blood samples were collected from cows
at dates of each bST treatment and d -28 and 0. A lower percentage of
cows in the low body condition group (64%) were detected in estrus
during the first 30 d of the breeding season relative to cows in the
moderate BC group (82%, p = 0.05). Relative to non-bST treated cows,
more (p < 0.05) cows treated with bST became pregnant during the first 3
d of the breeding season. Low body condition as well as bST reduced
intensity of behavioral estrus in postpartum Brahman-influenced cows.
However, bST increased first service conception during the first 30 d of
breeding and pregnancy rates during the first 3 d of breeding in
postpartum Brahman-influenced cows.
Flores, R., Looper, M.L., Rorie, R.W., Lamb, M.A., Reiter, S.T.,
Hallford, D.M., Kreider, D.L., and Rosenkrans, C.F. (2007) Influence of
body condition and bovine somatotropin on estrous behavior, reproductive
performance, and concentrations of serum somatotropin and plasma fatty
acids in postpartum Brahman-influenced cows. J. Anim Sci. published
online first on January 3, 2007, doi: 10.2527/jas.2006-606.
Corn production estimates
impact feeder prices
USDA lowered its 2006-07 corn yield estimate by 210
million bu. To 10.535 billion bu., still the third-largest crop in
history. Adding to demand was USDA's 50-million-bu. increase in its
export estimate, while maintaining its projected 2.15-billion-bu. demand
figure for ethanol production. With ending stocks dropping 183 million
bu., to 752 million bu., it represents the tightest supply/demand
balance since the 1995-96 marketing year, says University of Nebraska
economist Darrell Mark.
Writing for the Livestock Marketing Information Center (www.lmic.info/),
Mark says volatility in the corn market is playing havoc with cattle
feeding breakevens. A 750-lb. feeder steer placed on feed in Nebraska in
mid-January would have a breakeven selling price of $90.07/cwt in late
June, assuming average feeding performance, using $3.75/bu. for corn and
$85/ton for hay, plus other costs at market rates. This puts total cost
of gain at $74.37/cwt.
"An increase in the corn price to $4/bu. increases the cost of gain to
$76.93/cwt. and the breakeven selling price to $91.10/cwt. Thus, the
25c/bu. corn price increase raises the breakeven selling price for this
yearling steer placement by about $1/cwt.," Mark says.
The result will likely be lower calf prices for cow-calf producers, he
says. Since Sept. 1, 2006, the prices of 500- to 600-lb. and 700- to
800-lb feeder cattle in Nebraska have decreased $17.47/cwt. and
$19.94/cwt, respectively, and Nebraska fed cattle prices have declined
$3/cwt. During this same time, Omaha corn prices rallied $1.41/bu.
"Should corn prices continue their surge higher, look for feeder cattle
prices to continue their downtrend," Mark says. "Regardless, the
uncertainty in the corn market could result in cattle feeders bidding a
'risk premium' into the feeder cattle market (in the form of lower
prices) to gain some additional protection or 'cushion', " Mark says.
-- Livestock Marketing Information Center
Influence of early
pregnancy diagnosis on fetal viability
A controlled, randomized block-design experiment was conducted to
determine the effect of palpation per rectum (for early pregnancy
diagnosis) on embryo/fetal viability in dairy cattle. Pregnant dairy
cows and heifers (n=523) with a viable embryo detected by transrectal
ultrasonography between days 29 and 32 post AI were included. Animals
were randomly allocated into two groups: palpation per rectum (PAL) and
no palpation per rectum (NPAL). The PAL group were palpated using fetal
membrane slip technique once between days 34 and 41 of pregnancy.
Transrectal ultrasound was performed on both groups at days 45 and 60 of
pregnancy to monitor embryo and fetal viability. Embryo or fetal death
was determined by lack of heartbeat or absence of positive signs of
pregnancy in an animal previously diagnosed pregnant. The overall rate
of embryo/fetal death was 14.0% (73/520). Fetal death (4.5%) was lower
than embryonic death (10%, p < 0.001). Overall embryonic/fetal mortality
was higher in adult cows (16.4%) than in heifers (8.8%, p<0.025). Twin
pregnancies (25%) resulted in higher embryo/fetal death loss than
singleton pregnancies (12.9%, p < 0.025). Death loss dis not differ
(p>0.05) between animals that were palpated (14.7%, 38/258) and animals
not palpated (13.4%, 35/262). In this research, palpation per rectum
using fetal membrane slip technique to determine pregnancy status
between days 34 and 41 of gestation did not impact overall embryo/fetal
viability.
Romano, J.E., Thompson, J.A.,
Kraemer, D.C., Westhusin, M.E., Forrest, D.W., and Tomaszweski, M.A.
Early pregnancy diagnosis by palpation per rectum: Influence on
embryo/fetal viability in dairy cattle. Theriogenology 2007; 67(3):
486-493
Probability of Male
Offspring after Artificial Insemination
Data from 642,401 calving records from the Irish national database were
used in an analysis to determine if natural mating affected secondary
sex ratio. Multiple regression generalized estimating equation were used
to determine the logit of the probability of a male calf being born.
Sire of calf was included as a repeated effect. Month of the year at
calving, sex of the previous calf born within dam, breed of service
sire, parity of dam and type of mating (i.e. natural or artificial
insemination ) significantly (p < 0.05) affected the likelihood of a
male calf being born. Male calves were more likely to be born in warmer
months, when the sex of the previous calf to the same dam was male, in
older cows, and when the service sire was a beef breed. Following
adjustment for confounding effects, artificial insemination caused an
increased likelihood of male calf (Odds ratio 1.04 to 10.8, p < 0.01)
when compared to natural service. This equates to a 1% unit increase in
the probability of a male calf being born following artificial
insemination.
Berry, D. and Cromie, A. Artificial insemination increases the
probability of a male calf in dairy and beef cattle. Theriogenology
2007; 67(2): 346-352.
Tritrichomonas
infections in beef herds
Tritrichomonas foetus causes early embryonic death, abortions, and
infertility in beef herds. This disease has been diagnosed in Kansas
herds in the past year. Definitive diagnosis requires culture and
identification of the organism from an animal in the herd. In infected
herds, ranchers may not notice any indications of a problem until the
time of pregnancy examination when an increased number of open cows are
detected. If the breeding season is long (more than 90 days) the astute
rancher may notice an increased number of cows cycling at the end of the
breeding season. The number of cows that calve can be reduced by 20% to
40% and the mean calving date will be later and the calving season will
be spread out longer than in non-infected herds. Proper herd management
techniques are necessary to limit losses due to the disease in future
years.
For further information on
diagnostic techniques and management recommendations, please visit:
http://www.vet.ksu.edu/depts/ClinicalSciences/agpract/articles/Trich_recommendations.pdf
Nasopharyngeal swabs
as diagnostic method for respiratory infections
Research was performed to determine the validity of deep nasopharyngeal
swabs as a diagnostic method in bovine respiratory disease. Thirty-seven
beef calves, approximately four to six months of age, were group housed
in France when a natural outbreak of BRD occurred. Animals were selected
for study using typical BRD identification measures (temperature,
clinical illness scores). Within the group, 20 animals met criteria and
were enrolled in the study. Nasopharyngeal samples were collected from
each animal using sterile equine uterine culture swabs and then each
animal was euthanized and lungs were examined, lavaged and cultured.
Overall, M haemolytica was recovered from 90% of lung samples and 85% of
nasopharyngeal swab samples, and M bovis was recovered from 90% of lung
samples and 70% of nasopharyngeal swab samples. Compared to lung lavage
results, in this study, the positive predictive values for
nasopharyngeal swabs were 100% for M haemolytica and 100% for M bovis.
The negative predictive values for nasopharyngeal swabs were 67% for M
haemolytica and 33% for M bovis. The MIC values for tulathromycin of
isolates recovered from the lung or nasopharyngeal swab samples from the
same calf were equivalent, that is equal or within two-fold dilution for
all pathogens. The DNA fingerprints from each paired nasopharyngeal
swabs and lung lavage isolates were compared for 10 calves for each
pathogen and all samples tested appeared to have the same profile. In
this study, deep nasopharyngeal swab was a quick, simple technique that
accurately predicted the presence and antimicrobial susceptibility of
specific pathogens M haemolytica and M bovis in the lower respiratory
tract.
Godinho, KS., Sarasola, P, Renoult, E., Tilt, N., Keane, S., Windsor,
G.D., Rowan, T.G., and Sunderland, S.J. Use of deep nasopharyngeal swabs
as a predictive diagnostic method for natural respiratory infections in
calves. Vet Rec. 2007; 160:22-25.
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