effect of age at weaning and post-weaning management on performance and carcass characteristics of...

Effect of Age at Weaning and Effect of Age at Weaning and Post-Weaning Management on Post-Weaning Management on

Performance and Carcass Performance and Carcass Characteristics of Angus and Characteristics of Angus and

Charolais-Angus SteersCharolais-Angus Steers

John F. GrimesJohn F. Grimes

County Extension Educator, ANRCounty Extension Educator, ANR

OSU Extension – Highland Co.OSU Extension – Highland Co.

HISTORY AT SOUTHERN ARSHISTORY AT SOUTHERN ARS

Early weaning work began in the mid-1980’s.Early weaning work began in the mid-1980’s.

Most recent study began with purchase of bred Most recent study began with purchase of bred heifers in 1998.heifers in 1998.

Replacement females came from one additional Replacement females came from one additional female purchase and retained heifer calves.female purchase and retained heifer calves.

First four calf crops were sired by Angus bulls.First four calf crops were sired by Angus bulls.

Last two calf crops were sired by Charolais bulls.Last two calf crops were sired by Charolais bulls.

INVESTIGATORSINVESTIGATORS

John F. Grimes, OSU Extension-Highland Co.John F. Grimes, OSU Extension-Highland Co.

Francis L. Fluharty, OSU Dept. of Animal Francis L. Fluharty, OSU Dept. of Animal Sciences, WoosterSciences, Wooster

Thomas B. Turner, OSU Dept. of Animal Thomas B. Turner, OSU Dept. of Animal Sciences, ColumbusSciences, Columbus

Henry N. Zerby, OSU Dept. of Animal Sciences, Henry N. Zerby, OSU Dept. of Animal Sciences, ColumbusColumbus

Gary D. Lowe, OSU Dept. of Animal Sciences, Gary D. Lowe, OSU Dept. of Animal Sciences, WoosterWooster

STUDY OBJECTIVESTUDY OBJECTIVE

To examine the effects of different calf To examine the effects of different calf management systems on live animal management systems on live animal performance and carcass merit.performance and carcass merit.

Days on Feed Determines MarblingDays on Feed Determines Marbling

Smith (1995) predicted that cattle needed Smith (1995) predicted that cattle needed to be on feed 167 to 236 days, and be 835 to be on feed 167 to 236 days, and be 835 to 945 pounds before lipogenesis begins, to 945 pounds before lipogenesis begins, but the cattle were 265 d. of age when but the cattle were 265 d. of age when they started in the feedlot, which meant they started in the feedlot, which meant that they had to be 14 to 16 months old that they had to be 14 to 16 months old before they were predicted to begin before they were predicted to begin marbling.marbling.


HOWEVER, Myers et al. (1999) weaned HOWEVER, Myers et al. (1999) weaned steers at 117 days of age, and fed them a steers at 117 days of age, and fed them a high-concentrate diet for 268 days before high-concentrate diet for 268 days before they were slaughtered at 394 days of age they were slaughtered at 394 days of age (13 months of age). The cattle graded (13 months of age). The cattle graded 89% low choice or higher, with 56% in the 89% low choice or higher, with 56% in the upper 2/3 of the choice grade or higher.upper 2/3 of the choice grade or higher.


Fluharty (2000) weaned steers at 103 Fluharty (2000) weaned steers at 103 days of age, and fed them a high-days of age, and fed them a high-concentrate diet for 282 days before they concentrate diet for 282 days before they were slaughtered at 385 days of age (13 were slaughtered at 385 days of age (13 months of age). The cattle graded 85% months of age). The cattle graded 85% low choice or higher, with 60% in the low choice or higher, with 60% in the upper 2/3 of the choice grade or higher.upper 2/3 of the choice grade or higher.


Research has shown that cattle can grade Research has shown that cattle can grade choice anywhere from 13 to 26 months of choice anywhere from 13 to 26 months of age. Diet, management, and genetics age. Diet, management, and genetics determine whether an animal will grade determine whether an animal will grade choice within this age range. Many of the choice within this age range. Many of the papers that have reported that cattle papers that have reported that cattle needed to be a certain age to grade needed to be a certain age to grade choice already started with yearlings.choice already started with yearlings.


In fact, many animals that do not grade In fact, many animals that do not grade choice at an advanced age probably choice at an advanced age probably would have graded choice at a younger would have graded choice at a younger age under management and diet age under management and diet strategies that used a high concentrate strategies that used a high concentrate diet earlier in life.diet earlier in life.

University of Illinois research shows that University of Illinois research shows that yearlings need 1/4 inch more backfat to yearlings need 1/4 inch more backfat to achieve the same marbling score as achieve the same marbling score as early weaned calves harvested at the early weaned calves harvested at the same marbling end point.same marbling end point.

USDA Quality GradesUSDA Quality Grades

Slight = USDA SelectSlight = USDA Select

Small = USDA Low ChoiceSmall = USDA Low Choice

Modest = USDA Avg. ChoiceModest = USDA Avg. Choice

Moderate = USDA High ChoiceModerate = USDA High Choice

Sl. Abundant = USDA Low PrimeSl. Abundant = USDA Low Prime

Mod. Abundant = USDA Avg. Mod. Abundant = USDA Avg. Prime Prime

TREATMENTSTREATMENTS

1.1. Early weanEarly wean (EW) (EW) at approximately 100 at approximately 100 days, fast-track feeding, harvest at 12-13 days, fast-track feeding, harvest at 12-13 months of age.months of age.

2.2. Normal weanNormal wean (NW) (NW) at approximately at approximately 200 days, fast-track feeding, harvest at 200 days, fast-track feeding, harvest at 15-16 months of age.15-16 months of age.

3.3. Normal wean at approximately 200 days, Normal wean at approximately 200 days, stockerstocker (YR) (YR) to 800-900 lbs., finish and to 800-900 lbs., finish and harvest at 18-19 months of age.harvest at 18-19 months of age.

MATERIALS AND METHODSMATERIALS AND METHODS

Calving season of approx. 90 days in early Calving season of approx. 90 days in early Feb. to early May.Feb. to early May.

2001 & 2002 calf crops were sired by 2001 & 2002 calf crops were sired by Angus bulls.Angus bulls.

2003 & 2004 calf crops were sired by 2003 & 2004 calf crops were sired by Charolais bulls.Charolais bulls.

No calves received creep feed while No calves received creep feed while nursing their dams.nursing their dams.


Once the entire calf crop was born, the Once the entire calf crop was born, the “average” birth date was established.“average” birth date was established.Steer calves were alternately assigned Steer calves were alternately assigned into the three treatment groups based on into the three treatment groups based on chronological birth order.chronological birth order.Once placed into their treatment groups, Once placed into their treatment groups, calves were alternately assigned to calves were alternately assigned to replication groups based on chronological replication groups based on chronological birth order.birth order.


All calves were fed a high-gain diet during All calves were fed a high-gain diet during the finishing phase.the finishing phase.Harvest time for the steers was Harvest time for the steers was determined by a combination of visual determined by a combination of visual appraisal and monitoring the weight and appraisal and monitoring the weight and average daily gain for each steer.average daily gain for each steer.All steers were processed at The OSU All steers were processed at The OSU Animal Science Dept.’s Meat Laboratory in Animal Science Dept.’s Meat Laboratory in Columbus.Columbus.

2001-2002 RESULTS2001-2002 RESULTS

Harvest weight increased as age at feedlot Harvest weight increased as age at feedlot entry increased: EW: 1143 lbs., NW: 1164 entry increased: EW: 1143 lbs., NW: 1164 lbs., and YR: 1216 lbs. (P<.01)lbs., and YR: 1216 lbs. (P<.01)Dressing % decreased as age at feedlot Dressing % decreased as age at feedlot entry increased: EW: 63.6%, NW: 62.8%, entry increased: EW: 63.6%, NW: 62.8%, and YR: 60.9% (P<.01)and YR: 60.9% (P<.01)Backfat decreased as age at feedlot entry Backfat decreased as age at feedlot entry increased: EW: .70”, NW: .59”, and increased: EW: .70”, NW: .59”, and YR: .52” (P<.01)YR: .52” (P<.01)


The percentage of carcasses grading USDA The percentage of carcasses grading USDA Average or High Choice was higher for EW Average or High Choice was higher for EW (75.9%) and NW (75.9%) than YR (45%). (75.9%) and NW (75.9%) than YR (45%). (P<.05)(P<.05)The percentage of carcasses grading USDA The percentage of carcasses grading USDA Prime was higher for EW (15.8%) and NW Prime was higher for EW (15.8%) and NW (8.3%) than YR (0%).(8.3%) than YR (0%).Yield Grades tended to be numerically higher Yield Grades tended to be numerically higher with the EW cattle than the other 2 groups.with the EW cattle than the other 2 groups.No clear trends in tenderness emerged in this No clear trends in tenderness emerged in this study. study.


Age at harvest: EW - 387 days, NW – 408 Age at harvest: EW - 387 days, NW – 408 days, YR – 535 daysdays, YR – 535 days

Feed conversion (lbs. feed per lb. gain): Feed conversion (lbs. feed per lb. gain): EW – 5.1, NW – 5.7, YR – 6.4 EW – 5.1, NW – 5.7, YR – 6.4


Harvest weight increased as age at feedlot Harvest weight increased as age at feedlot entry increased: EW: 1163 lbs., NW: 1179 entry increased: EW: 1163 lbs., NW: 1179 lbs., and YR: 1280 lbs. (P<.01)lbs., and YR: 1280 lbs. (P<.01)Dressing % decreased as age at feedlot Dressing % decreased as age at feedlot entry increased: EW: 63.4%, NW: 62.8%, entry increased: EW: 63.4%, NW: 62.8%, and YR: 61.3% (P<.01)and YR: 61.3% (P<.01)Backfat decreased as age at feedlot entry Backfat decreased as age at feedlot entry increased: EW: .54”, NW: .45”, and increased: EW: .54”, NW: .45”, and YR: .39” (P<.01)YR: .39” (P<.01)


The percentage of carcasses grading USDA The percentage of carcasses grading USDA Average or High Choice trended higher for EW Average or High Choice trended higher for EW (49.2%) and NW (40.3%) than YR (38.1%). (49.2%) and NW (40.3%) than YR (38.1%).

The percentage of carcasses grading USDA The percentage of carcasses grading USDA Prime was higher for EW (4.2%) than NW (0%) Prime was higher for EW (4.2%) than NW (0%) and YR (0%).and YR (0%).

Yield Grades were numerically higher with the Yield Grades were numerically higher with the EW (3.2) than the NW (3.1) or YR (3.0) cattle. EW (3.2) than the NW (3.1) or YR (3.0) cattle. (P(P<.05)<.05)


Age at harvest: EW - 394 days, NW – 419 Age at harvest: EW - 394 days, NW – 419 days, YR – 559 daysdays, YR – 559 days

Feed conversion (lbs. feed per lb. gain): Feed conversion (lbs. feed per lb. gain): EW – 5.3, NW – 5.4, YR – 6.6 EW – 5.3, NW – 5.4, YR – 6.6

SIRE DIFFERENCESSIRE DIFFERENCES

Charolais-sired calves had less backfat at Charolais-sired calves had less backfat at harvest: EW: - .16 in., NW: - .15 in., harvest: EW: - .16 in., NW: - .15 in., YR: -.13 in.YR: -.13 in.Charolais-sired calves had more rib eye Charolais-sired calves had more rib eye area at harvest: EW: 1.0 in., NW: .6 in., area at harvest: EW: 1.0 in., NW: .6 in., YR: 1.0 in.YR: 1.0 in.Charolais-sired calves had numerically Charolais-sired calves had numerically lower Yield Grades: EW: - .7, NW: -.5, lower Yield Grades: EW: - .7, NW: -.5, YR: -.6YR: -.6

SIRE DIFFERENCESSIRE DIFFERENCES

Angus-sired calves had higher Quality Angus-sired calves had higher Quality Grades (% Avg. Choice and higher): Grades (% Avg. Choice and higher): EW: +26.7%, NW: +35.6%, YR: +6.9% EW: +26.7%, NW: +35.6%, YR: +6.9%

Both sire groups had similar feed Both sire groups had similar feed conversion rates across treatment groupsconversion rates across treatment groups