Carcass characteristics, chemical composition and fatty acid profile of the Longissimus muscle of bulls finished in pasture systems

ABSTRACT : This experiment was carried out to evaluate the carcass characteristics, chemical composition and fatty acid profile of the Longissimus muscle (LM) of three cattle genetic groups (Puruna, PUR, 11; 1/2 Puruna vs. 1/2 British, PUB, 6 and 1/2 Charolais vs. 1/2 Caracu, CHC, 10) finished in pasture systems. The field work took place at the Lapa Research Farm of the Agronomic Institute of Parana, in the city of Lapa, south Brazil. The animals were fed during the winter with corn silage, cottonseed meal, cracked corn, urea, limestone and mineral salts as sources of protein, as well as an energy supplement, in pasture systems of Brachiaria decumbens Stapf. The animal groups were slaughtered at 20 months of age, at 501 [+ or -] 22.6 kg live weight. CHC bulls had higher (p<0.05) final weight than PUR and PUB bulls. Hot carcass weight was similar (p>0.10) between PUR and PUB. Hot carcass dressing percentage was higher (p<0.05) for PUB bulls than for PUR and CHC bulls. On the other hand, hot carcass dressing percentage was similar (p>0.05) between PUR and CHC bulls. Fat thickness was similar (p>0.10) among all genetic groups. However, the Longissimus area of CHC bulls was greater (p<0.05) than in PUR and PUB genetic groups. The genetic groups did not affect (p>0.10) the marbling of Longissimus. There was no observed difference (p>0.10) in moisture, ash, crude protein and total cholesterol contents among the three genetic groups. On the other hand, the total lipid percentage was higher (p<0.05) for the PUB genetic group in comparison with PUR and CHC. CLA percentage was highest for PUR animals. However, total CLA amounts were not altered by the different genetic groups. (Key Words : Beef, British, Caracu, Chemical Composition, Longissimus Muscle)

INTRODUCTION

Brazil has the largest commercial cattle herd of the world, and has potential to become the greatest producer of cattle meat for export; there are 159 million heads of cattle, able to produce 8.2 million tons/year of carcasses (Anualpec, 2007), which makes the control of meat quality extremely important to maintain a long-term market.

Beef is considered one of the factors that may lead to the development of human cardiovascular diseases, obesity, hypertension and cancer, especially due to the presence of saturated fat and cholesterol. Low presence of fat contents (less than 3% relative to muscle: Moreira et al., 2003; Padre et al., 2006 and 2007) and low cholesterol contents (less than 50 mg/100 g in the muscle) have been observed in beef chemical analyses, ranging from one-third to one-half of the daily recommended cholesterol intake (Greghi et al., 2003; Padre et al., 2006 and 2007).

Cattle breed is one of the most important factors for fat deposition and composition, which needs to be understood because of its genetic transmission. However, the detailed mechanisms of this variation, and whether or how they can be manipulated are not clearly known (Martin Nieto, 2004). British cattle are well known for their highly marbled meat, while the Nellore breed contains less fat and more connective tissue (Silva et al., 2002; Moreira et al., 2003).

In the warm regions of the Brazil, adapted breeds of cattle are primarily limited to the Bos indicus indicus (Zebu) cattle, bred from Brazilian Nellore.

The Caracu is a tropically adopted, criollo beef breed native to Brazil. Few studies have investigated the meat characteristics of Caracu, focusing instead more on reproductive and carcass performance (Perotto et al., 2000 and 2001). Marbling and fatty acid composition of Caracu cattle, especially as compared to other purebreds and crossbreds, remain little studied. Like most animal production traits, meat quality is influenced by both genetic and environmental factors (Martin Nieto, 2004; Webb, 2006). The latter includes management but mainly feeding, explaining why the majority of studies attempting to achieve meat quality that better correspond to current human nutrition guidelines have dealt with animal feeding (Webb, 2006).

Genetic variability consists of differences between species, breeds or lines; differences due to the crossing of breeds; and differences between animals within breeds. The latter source of variation is estimated by heritability and genetic correlations. Breed effects may be influenced by the segregation of major genes, one of which is the double-muscled gene in cattle. It is sometimes difficult to assess the real contribution of genetics to differences in meat quality. Breed comparisons are often confounded by other effects, like fat level, live weight, age at slaughter and production system (Webb, 2006).

The State of Parana, located in south Brazil, features a milder climate as compared to the Center-West, North and Northeast regions of Brazil. Thus, research has been undertaken in this region since the 1980s regarding the crossbreeding of Zebu and European breeds, aiming to increase production and quality of offspring beef (Perotto et al., 2000 and 2001; Padre et al., 2007). After several stages of crossbreeding, a bloodline was defined as the best-adapted to the region. In the beginning, crossbreeding between Nellore specimens with Charolais, Angus, Caracu and Canchin breeds was undertaken, which resulted in the creation of a breed denominated Puruna.