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Effect of Selection for Residual Feed Intake on Postpartum
Performance of Brahman Cows
•
Effects of of Tilmicosin alone or in
combination with Mannheimia haemolytica toxoid administered at
initial feedlot processing on morbidity and mortality of high-risk
calves
•
Corn oil or corn grain supplementation to steers grazing endophyte-free tall fescue: I. Effects on in vivo digestibility,
performance and carcass quality
•
Effects of commingling beef calves
from different sources and weaning protocols during a 42-day
receiving period on performance and bovine respiratory disease
•
Animal performance and economic comparison of novel and toxic endophyte tall fescues to cool-season annuals
• Impact of age and
source verification of calves on value received via video auctions
Effect of Selection for Residual Feed
Intake on Postpartum Performance of Brahman Cows
Loyd et al., Texas A&M University
With the rising cost of feedstuffs, reducing feed expenses is
important for livestock producers. Residual feed intake is a measure
of feed efficiency developed to identify animals which may require
less feed to achieve the same performance as their cohorts. This
study investigated the postpartum performance of Brahman first-calf
heifers (n=16) and multiparous cows (n=38) which had been evaluated
postweaning for residual feed intake.
Females were weighed and evaluated for body condition score at 28-day intervals for three months prior to the expected start of the 2008 calving season. Females were weighed and evaluated for body condition score 24 hours and 21 days after calving. Serum samples were collected weekly beginning 21 days after calving for progesterone analysis to determine corpus luteum formation and functionality. After calving, females were exposed to vasectomized bulls fitted with chin-ball markers and were visually observed at least once per day to detect estrus.
Eight and 10 days following observed estrus, cows were examined
using real- time ultrasonography to determine the presence of a
corpus luteum. Females were assigned to a residual feed intake group based on the sign of their residual feed intake values, where a negative residual feed intake = efficient and a positive residual feed intake = inefficient.
- Parity had a significant effect on all parameters evaluated;
therefore, cows and heifers were analyzed separately.
- Prepartum and postpartum body weight and body condition score
did not differ by residual feed intake group for either cows or
heifers.
- Efficient cows exhibited estrus sooner (42 ± 4.1 vs. 55 ± 3.7
days), developed a corpus luteum sooner (40 ± 4.1 vs. 53 ± 3.7 days)
and exhibited estrus in conjunction with corpus luteum formation
sooner (42 ± 4.1 vs. 54 ± 3.9 days) than inefficient cows.
- No difference was detected between efficient and inefficient heifers for estrus, corpus luteum formation or estrus with corpus luteum formation.
These data suggest that selection for efficient cattle using residual feed intake as a selection tool may result in a shorter postpartum interval in multiparous Brahman cows.
Effects of Tilmicosin Alone or in
Combination With Mannheimia Haemolytica Toxoid Administered at
Initial Feedlot Processing on Morbidity and Mortality of High-Risk
Calves
Bryant et al., Colorado
A total of 3,996 high-risk steer calves were used to compare
effects of metaphylactic treatment with Tilmicosin (Micotil®) alone
or in combination with an adjuvanted Mannheimia haemolytica toxoid (Presponse®SQ)
on health parameters and economic returns in a commercial feedlot
setting.
- Steers receiving Micotil®-Presponse®SQ at processing had 17%
fewer first-time treatments for BRD than calves in the Micotil®
group and a 19% lower relapse rate.
- The Micotil®-Presponse®SQ calves had 22% less mortality than
calves in the Micotil® group.
- Calves receiving Micotil®-Presponse®SQ had $1.37 and $13.14
lower therapy and mortality costs, respectively, than calves in
the Micotil® group.
In total, combined processing, therapy, railer (culls) and
mortality costs for Micotil®-Presponse®SQ calves were $14.77 lower
than for Micotil® calves.
Corn Oil or Corn Grain Supplementation
to Steers Grazing Endophyte-Free Tall Fescue: I. Effects on In Vivo
Digestibility, Performance and Carcass Quality
Pavan and Duckett, Clemson University
Twenty-eight Angus (637 pounds) steers were used to evaluate the
effect of isocaloric supplementation of two different energy sources
to steers rotationally grazing tall fescue pastures for 197 days in
comparison to positive and negative controls. Steers were
supplemented with either corn grain (0.52% body weight on a dry
matter basis) or soybean hulls plus corn oil (0.45% body weight on a
dry matter basis + 0.10% body weight on an as-fed basis). Negative,
pasture only, and positive, high-concentrate, control diets (85%
concentrate:15% roughage on dry matter basis) were also included in
the study. Steers on corn, soybean hulls plus corn oil and
pasture-only treatments were managed together under a rotational
grazing system, whereas high-concentrate control diet steers were
fed a high-concentrate diet for the final 113 days.
- Energy supplementation decreased forage dry matter intake (%
of BW) with respect to pasture only, but not total dry matter
intake.
- There were no differences among grazing treatments on
apparent total dry matter digestibility.
- Overall, average daily gain was greater in supplemented,
regardless of type, than in nonsupplemented grazing treatments.
- During the final 113 days, average daily gain was greater in
high-concentrate control diet steers than in the grazing
treatments.
- Overall supplement conversion did not differ between
supplement types and was less than high-concentrate control
diets.
- Carcass traits did not differ between energy sources.
Dressing percentage and hot carcass weight were greater in
supplemented cattle than in pasture-only steers.
- Fat thickness and kidney, pelvic and heart fat percentage
for pasture-only steers were less than for soybean hulls plus
corn oil but did not differ from corn supplemented steers.
- Marbling score, rib eye area and quality grade did not
differ between grazing treatments.
- Hot carcass weight for high-concentrate control diet steers
was heavier than for pastured cattle. Quality and yield grades
of high-concentrate control diet steer carcasses were also
greater than for carcasses from pastured steers.
Energy supplementation, regardless of source, to grazing steers
increased average daily gain, dressing percentage and carcass weight
compared with pasture-only steers; however, supplemented steers had
less average daily gain, efficiency, dressing percentage and carcass
weight compared with high- concentrate finished steers.
Effects of Commingling Beef Calves
From Different Sources and Weaning Protocols During a 42-Day
Receiving Period on Performance and Bovine Respiratory Disease
Step et al., Oklahoma State University
The study objective was to determine health and performance of
ranch calves from different preconditioning strategies during a
42-day receiving period when commingled with calves of unknown
health histories from multiple sources. Steer calves from a single
source ranch (RANCH) were weaned and immediately shipped to a
feedlot (WEAN, initial body weight = 545 pounds); weaned on the
ranch for 45 days before shipping but did not receive any
vaccinations (WEAN45, initial body weight = 509 pounds); or weaned,
vaccinated with modified live viral vaccine and held on the ranch
for 45 days before shipping (WEANVAC45, initial body weight = 604
pounds). Multiple-source steers were purchased through auction
markets (MARKET, initial body weight = 525 pounds), and upon
receiving, a portion of ranch-origin steers from each weaning group
was commingled with a portion of MARKET cattle.
- Ranch-origin calves tended to have greater average daily
gain than commingled or auction market purchased calves,
although average daily gain was not affected by weaning
management.
- Across the 42-day receiving period, dry matter intake was
not affected by cattle origin. However, auction market purchased
calves, WEAN45 and WEANVAC45 calves consumed more dry matter
than WEAN calves.
- Gain efficiency was not affected by treatment.
- Ranch-origin calves were less likely to be treated for
bovine respiratory disease than auction market purchased calves;
commingled calves were intermediate.
- Calves that were retained on the ranch after weaning (WEAN45
and WEANVAC45) were also less likely to be treated than auction
market purchased calves or WEAN calves.
- As expected, differences in morbidity related to differences
in health costs. Calves of WEAN45 and WEANVAC45 had less health
costs than auction market purchased calves and WEAN calves.
Calves from a single source that are retained on the ranch for 45
days after weaning exhibit less morbidity and lower health costs
during the receiving period at the feedyard than when cattle are
commingled or trucked to the feedyard immediately after weaning.
Animal Performance and Economic
Comparison of Novel and Toxic Endophyte Tall Fescues to Cool-Season
Annuals
Beck et al., University of Arkansas
Increased costs of annual establishment of small grain pasture
associated with fuel, machinery and labor are eroding the
profitability of stocker cattle enterprises. Interest has therefore
increased in development of cool-season perennial grasses that are
persistent and high quality. This study occurred on 53 acres
(divided into thirty 0.81-acre paddocks) located at the University
of Arkansas Division of Agriculture Livestock and Forestry Branch
Station, near Batesville. Two tall fescue cultivars infected with
novel endophytes, Jesup and HiMag, were established in September
2002. Jesup and HiMag were compared with endemic endophyte Kentucky
31 tall fescue; wheat and cereal rye planted in September 2003, 2004
and 2005; and annual ryegrass planted in September 2004 and 2005.
Each year, 3 steers (1.5 steers/acre) were placed on each pasture
for fall and winter grazing, and 5 steers (2.0 steers/acre) were
placed on each pasture for spring grazing.
- Body weight gain per acre of steers grazing novel endophyte
tall fescue was greater than those grazing Kentucky 31 tall
fescue and cereal rye during 2003 to 2004; whereas, in 2004 to
2005, body weight gain per acre for steers grazing novel
endophyte tall fescue and annual ryegrass did not differ and was
greater than that of cereal rye, which was greater than that of
Kentucky 31 tall fescue.
- During 2005 to 2006, body weight gain per acre was greater
for steers grazing annual ryegrass than those grazing novel
endophyte tall fescue and cereal rye, which did not differ.
- Body weight gain per acre was least for steers grazing
Kentucky 31 tall fescue.
- Average net return of novel endophyte tall fescue was
greater than Kentucky 31 tall fescue, but profitability of novel
endophyte tall fescue did not consistently differ from
cool-season annuals. Across the three-year study, novel
endophyte tall fescue produced net returns per acre of $88; this
level of profitability would require four years for a new
planting of novel endophyte tall fescue to break even.
Novel endophyte tall fescues offer potential benefits related to
decreased risk of stand establishment of annual forage crops, longer
growing season and acceptable animal performance.
Impact of Age and Source Verification
of Calves on Value Received Via Video Auctions
Kellom et al., Montana State University
The objective of this project was to determine if a premium was
being paid for source- and age-verified feeder calves via video
auction. Data on 68,665 Montana calves marketed during June and July
of 2007 were provided by Superior Livestock Video. Average sale
weight of all calves was 584 lb, and average sale price was $1.17/lb
with an average lot size of 116 calves. Thirty- one percent of all
calves sold were age and source verified, 60% were steers, 15% were
weaned from their dam and 88% were vaccinated prior to shipment (VAC
34 or VAC 35 protocols). When calculated for a 600-lb calf, the
premium received for source and age verification was $12.83. Other
premiums received for this weight of calf were ($/head): vaccinated,
$14.81; weaned, $17.64; steers, $52.43 more than heifers. The
authors concluded when calves were source and age verified, weaned
and/or followed a vaccination protocol, additional dollars were
received when marked via a video auction.
Tom R. Troxel
Professor and Associate Department Head - Animal Science
The information given herein is for educational purposes only.
Reference to commercial products or trade names is made with the
understanding that no discrimination is intended and no endorsement
by the Arkansas Cooperative Extension Service is implied.
Printed by the University of Arkansas Cooperative Extension
Service Printing Services.
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