Muscle Tenderness, Other Carcass Traits and the Effect of Crossbreeding on these Traits in Beef Cattle

Abstract

Cundiff (1985) states: "It is estimated that today about 70 percent of the calves marketed from beef cattle breeds in the United States are crossbred and that between 50 and 60 percent of the cows are crossbred. This represents a ma jor shift to crossbreeding fro m straightbreeding which prevailed into the late 1 9~ in response to research demonstrating favorable effects of heterosis (e.g. see review by Cundiff, 1970." Research results have continued to affinn this trend of increased crossbreeding. For in stance, re earch ha s shown that a th ree-b reed crossbreeding program can increase productio n in terms of pounds of calf weaned per cow exposed to breeding by 23 percent (Cundiff et aI., 1974). Cundiff (1 984) provided further information on the productivity of FI cows. Clearly, this trend of increased marketing of finished crossbred cattle would not have continued if crossbreeding resulted in obvious detriments to the tenderness of the cooked meat or to other important carcass traits. However, objective information on the effect of crossbreeding on tenderness and other carcass traits was needed to asses the immediate and long-term ramifica tions of suppying meat from crossbred cattle to con sumers. If sexing of bull semen becomes possible, it will be important to know if steers and heifers are different with regard to carcass traits. Also of interest is the extent of the differences, if any, among different cooked muscles. Therefore the objectives of this study were to: 1) measure differences of tenderness among muscles, 2) assess the dif ferences between steer and heifers for various carcass characteristics, and 3) to estimate the effect that crossbreeding has o n carcass traits (Slanger et al., 1985). ExperiDlent~Procedure Carcass information was accumulated for eight years (197 1 through 1978) on approximately 475 steer and 125 heifer carcasses representing eight breeds and 62 combina tions of these eight breeds. All tbese cattle were raised, finished and slaughtered at North Dakota State University. The eight breeds were Angus. Hereford, Shorthorn, Charolais , Brown Swiss, Simmental, Galloway and Red Angus. The data were from straightbred, two-, three-and four-way crossbred cattle. However, straightbreds. F I' S Sfanger and Danielson are associate professors and Marchello is professor, Department of Animal and Range Sciences.

Efeitos de Raça e Heterose na Composição Física da Carcaça e na Qualidade da Carne de Novilhos da Primeira Geração de Cruzamento entre Charolês e Nelore

“…Em seus trabalhos, Slanger et al (1985) e Urick et al (1989) comentam que as características relacionadas à deposição de gordura na carcaça são as que apresentam maiores valores de heterose. Usando animais Bos taurus, Gregory et al (1994) estimaram a heterose retida na terceira geração (F 3 ) de populações compostas, concluindo que esta só foi significativa para porcentagem de gordura na carcaça, salientando a grande variabilidade que esta característica apresenta nas diferentes raças.…”

“…Heterose alta para marmoreio da carne foi verificada por Marshall et al (1987), ao analisarem os efeitos genéticos sobre o desenvolvimento e as características de carcaça dos novilhos Aberdeen Tabela 3 -Valores médios para composição física da carcaça de novilhos com relação à composição racial Angus e Pardo Suíço, observando que o efeito do vigor híbrido individual para marmoreio atingiu um nível de heterose de 24,9%. O alto valor da heterose observado para uma característica que reflete o acúmulo de gordura corporal também é relatado por Slanger et al (1985) e Urick et al (1989). Na Tabela 5, são apresentados os resultados referentes às características sensoriais da carne e à força necessária para cortar as fibras da carne.…”

International perspective: characterisation of United States Department of Agriculture and Meat Standards Australia systems for assessing beef quality

“…shear force values and those of other muscles in the beef carcass have been reported to be: (i) 0.20-0.32 (Joseph and Connolly 1979) based on sensory panel tenderness ratings, and (ii) 0.40 (Slanger et al 1985) and 0.26-0.43 (Shackelford et al 1995) based on shear force values. (4) Researchers at the US Meat Animal Research Center (Clay Center, NE, USA) originally reported (Shackelford et al 1995) that: (i) shear force values did not accurately reflect differences among muscles in overall tenderness, and (ii) shear force value of the LD was not highly related to the shear force values of other muscles in the carcass.…”

Composição física da carcaça e qualidade da carne de novilhos de gerações avançadas do cruzamento alternado entre as raças Charolês e Nelore, terminados em confinamento

“…A heterose retida foi de 9,39 e -11,36%, respectivamente, para maciez da carne avaliada pelo painel e para força de cisalhamento. Slanger et al (1985), utilizando oito raças Bos taurus e suas combinações, verificaram que o incremento do nível de heterozigose aumentou a maciez da carne. DeRouen et al (1992) acreditam que, apesar de o efeito heterótico da raça Brahman ser positivo para maciez da carne, sua inclusão em cruzamentos pode diminuir a maciez da carne, devido ao seu forte efeito genético aditivo.…”