Effects of percentage Brahman and Angus breeding, age-season of feeding and slaughter end point on meat palatability and muscle characteristics.

Abstract

Steers (n = 125) of known percentage Angus (A) and Brahman (B) breeding (A = 31, 3/4A:1/4B = 32, 1/2A:1/2B = 31, 1/4A:3/4B = 31) were slaughtered after being fed as calves during the cool period of the year or fed as yearlings during the warm period of the year. Steers were slaughtered at equivalent outside fat thickness as monitored visually and with real-time ultrasound. Warner-Bratzler shear (WBS) force increased and sensory panel tenderness decreased as percentage Brahman increased. Loin muscle characteristics indicated that differences in tenderness between breed groups were not attributed to cold shortening effects or differences in amount or integrity of connective tissue. Fragmentation values suggested that breed group tenderness differences probably resulted from differences in the muscle fiber component. A 10-d postmortem aging study revealed a differential breed group response to postmortem aging, suggesting that breed groups differed in amount and(or) activity of naturally occurring proteolytic enzymes in muscle tissue.

Brahman and Brahman crossbred cattle grown on pasture and in feedlots in subtropical and temperate Australia. 2. Meat quality and palatability

“…Crossbreds with 50 and 75% B. indicus content did not differ significantly for objective and sensory meat quality traits, except for Continental crosses for SFST. Consistent findings were reported by Johnson et al (1990) and Pringle et al (1997) who found no significant difference in SF and sensory panel evaluation between Brahman · Angus steers with 50 and 75% Brahman content, feedlot finished in Florida in separate experiments. Wythes et al (1989) reported no effect of genotype on SFLT, cooking loss or ultimate pH in 25-70% B. indicus content steers.…”

“…for ICST, it would appear connective tissue toughness has limited market importance when Brahmans and Brahman crossbreds are slaughtered by 24 months of age. Other studies have also failed to find significant breed differences in collagen content and solubility (Johnson et al 1990;Whipple et al 1990). The myofibrillar component of muscle is believed to be the major contributor to tenderness variation (Johnson et al 1990;Whipple et al 1990;Shackelford et al 1995;Harper 1999).…”

“…Other studies have also failed to find significant breed differences in collagen content and solubility (Johnson et al 1990;Whipple et al 1990). The myofibrillar component of muscle is believed to be the major contributor to tenderness variation (Johnson et al 1990;Whipple et al 1990;Shackelford et al 1995;Harper 1999). Post-mortem rates of glycolysis and subsequent pH decline have been shown to be slower in B. indicus muscle relative to B. taurus, leading to increased shortening of the myofibrillar proteins (Wheeler et al 1990;Shackelford et al 1991).…”

“…However, there was only a difference of 1.2 units for the tropically adapted straightbreds, whereas crossbreds in our experiment differed by 5.0 units. A study by Johnson et al (1990) reported higher sensory panel ratings for loin steaks from calves finished in the cool season relative to their contemporaries finished in the warm season. This effect was attributed to a higher percentage of heat-soluble collagen in animals finished in the cool season resulting in more connective tissue break down during cooking.…”

“…While there have been many studies comparing cattle with varying proportions of B. indicus genes to Bos taurus animals in temperate environments, there are few studies comparing B. indicus with B. indicus · B. taurus crosses in tropical and subtropical environments. The majority of experiments conducted in subtropical environments have been in the USA and vary in the breadth of the breed combinations used and findings of the effect of B. indicus content on meat quality (Peacock et al 1982;Wythes et al 1989;Johnson et al 1990;DeRouen et al 1992;Pringle et al 1997;Bidner et al 2002). The debate on genotype · environment interactions on meat quality remains controversial.…”