Beef Breed Differences: Preliminary Results from the U.S. Meat Animal Research Center

Livestock Update, September 2002

Scott Greiner, Extension Animal Scientist, Beef, VA Tech

Over the past 25 years, considerable research has been conducted to characterize and compare the major beef breeds in the U.S. The most comprehensive studies have been conducted at the U.S. Meat Animal Research Center in Clay Center, NE. Since 1970, over 30 breeds have been evaluated in a common environment and management system for characterization of economically important traits. Many of the largest and most widely used breeds in the U.S. were characterized 25-30 years ago at Clay Center. Since that time, considerable changes have been made to these breed populations as the result of selection. Therefore, research has been initiated at the U.S. MARC to evaluate relative changes that have occurred among the prominent U.S. beef breeds since they were initially evaluated in the 1970's, and to provide a current evaluation for these breeds. The following tables present preliminary results from Cycle VII of the Germplasm Evaluation Program at the U.S. MARC.

Procedures for the evaluation of the breeds were similar to that utilized in previous GPE cycles. For the current breed characterization, sires from the seven largest U.S. beef breeds (based on number of registrations) were mated to mature Angus, Hereford and composite MARC III cows (1/4 Angus, _ Hereford, _ Pinzgauer, _ Red Poll). Approximately one-half of the sires sampled from each breed were among the top 50 in number of calf registrations in their respective breed, and about one-half were young unproven sires of each breed. Calves were born in the spring of 1999 and 2000. Following a postweaning adjustment period, steers were fed a high energy diet and slaughtered (average of 239 days on feed). Steers were slaughtered serially in 5 groups spanning 43 days. Steers were harvested in a commercial facility, and individual carcass measurements taken after a 36-hour chill.

Sire breed effects for preweaning traits for calves born in 1999 and 2000 are shown below. Lighter birth weights and a higher percentage of unassisted births were reported for Angus and Red Angus compared to Hereford and the Continental breeds (Simmental, Gelbvieh, Limousin, Charolais). The three British breeds (Hereford, Angus, Red Angus) were similar for 200-day weaning weight. Limousin sired calves were lighter at weaning than all other breed groups. 200-day weaning weights for Gelbvieh topcrosses were similar to those of the British breeds. Simmental topcrosses were heavier at weaning that all other breed groups. Charolais sired calves were heavier at weaning than Limousin, Hereford, and Red Angus.

Sire Breed Means for Preweaning Traits^a

Sire breed of calf	Gestation length, d	Unassisted calvings, %	Birth weight, lb.	Survival to wean., %	200-d wean. wt., lb.
Hereford	284	95.6	90.4	96.2	524
Angus	282	99.6	84.0	96.7	533
Red Angus	282	99.1	84.5	96.7	526
Simmental	285	97.7	92.2	96.7	553
Gelbvieh	284	97.8	88.7	97.1	534
Limousin	286	97.6	89.5	96.9	519
Charolais	283	92.8	93.7	97.1	540
LSDb	1.5	3.4	3.1	3.8	14
asource: Cundiff et al., 2001, Germplasm Evaluation Program Progress Report No. 21 bBreed differences that exceed the LSD are significant (P < .05)

Postweaning growth and carcass traits for the sire breed groups are presented for the 1999-born calf crop only. Postweaning average daily gains were similar among all breed groups. The British breeds were similar in slaughter weight adjusted to 448 days of age. Limousin topcrosses were generally lighter than other sire breed groups at slaughter. Differences between the breed groups in slaughter weight are also reflected in carcass weight. Among the British breeds, Angus and Red Angus sires were superior to Hereford in marbling score and percent Choice. Angus and Red Angus also had higher marbling scores than the Continental breeds. The Continental breeds were similar for marbling score. Continental breed topcrosses had less 12th-rib fat than British topcrosses. Additionally, Continental breed topcrosses had larger ribeye areas that British topcrosses except for Angus. Angus-sired calves had greater ribeye area than Red Angus and Hereford-sired calves, and were not different from the Continental breeds. Collectively, the British breeds produced progeny which were 88.8% Choice or higher, and 22.3% Yield Grades 1 & 2. The Continental breed sires produced progeny with carcasses that were 60.9% Choice or higher, and 57.0% Yield Grades 1 & 2 (data not shown).

Sire Breed Means for Postweaning and Carcass Traits (adjusted to constant age of 448 days)^a

Sire breed of calf	Post-wean.ADG, lb./d	Slaughter wt., lb.	Carcass weight, lb.	Marb. score, %	USDA Choice, %	Yield Grade	Fat Th., in.	REA, sq. in.
Hereford	3.46	1363	832	538	79.1	3.35	.55	12.74
Angus	3.40	1375	846	577	93.6	3.32	.58	13.48
Red Angus	3.40	1362	839	589	96.0	3.76	.60	12.21
Simmental	3.47	1390	854	536	61.2	2.95	.42	13.71
Gelbvieh	3.33	1348	826	514	63.0	2.80	.39	13.43
Limousin	3.30	1308	815	507	44.8	2.63	.41	14.02
Charolais	3.43	1370	843	517	75.7	2.77	.43	14.01
LSDb	.18	55	33	35	22.5	.41	.11	.75
asource: Cundiff et al., 2001, Germplasm Evaluation Program Progress Report No. 21 bBreed differences that exceed the LSD are significant (P < .05)

Preliminary results from these breed comparisons indicate that differences between British and Continental breeds are not as great for unassisted calving percentage, weaning weight, postweaning gain, and slaughter weight compared to when the same breeds were evaluated in the 1970šs. British breeds have emphasized selection for growth rate, whereas Continental breeds have emphasized improvement in birth weight and calving ease. Consequently, smaller differences exist between British and Continental breeds for growth rate and calving ease as compared to 25 years ago. However, significant differences exist between British and Continental breeds for marbling and percentage retail product (yield grade). These differences in carcass composition exist despite the increases in growth rate and corresponding carcass weight that have been characterized in the British breeds.

These results confirm that no single breed excels in all economically important traits. A well-designed crossbreeding system that captures the advantages of heterosis and utilizes these breed differences in a complimentary fashion is the most effective genetic resource for an efficient beef production system.

For the full report on Cycle VII of the GPE study visit http://sol.marc.usda.gov/.

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