Effects of feeding system and slaughter age on the growth and carcass characteristics of tropical-breed steers1

Abstract

This study aimed to compare the growth performances and carcass characteristics of tropical-breed steers reared in 2 contrasted feeding systems (indoor vs. pasture) and slaughtered at different ages (early vs. late). A total of 309 Creole steers (growing at an initial BW of 173 ± 3 kg and an initial age of 252 ± 4 d) were used over a continuous 12-yr study. Indoor steers were housed in a cattle shed, fed fresh-cut grass plus concentrate, and slaughtered at 14.5 or 17.1 ± 0.1 mo of age. Pasture steers were pasture grazed without supplemental feed, and slaughtered at 17.6 and 21.2 ± 0.1 mo of age. Indoor-fed steers had a greater ADG (786 vs. 517 ± 29 g•d(-1); P < 0.0001) and more carcass fat (164 vs. 145 ± 4.5 g•kg(-1); P = 0.001) than pasture-fed steers. Late-slaughtered steers had decreased ADG (630 vs. 673 ± 27 g•d(-1); P = 0.001) but greater dressing percentages (hot dressing percentage = 55.7 vs. 54.7 ± 0.34%; chilled dressing percentage = 54.5 vs. 53.4 ± 0.34%; P < 0.0001) than early-slaughtered steers. The interaction between feeding system and slaughter age was significant for carcass tissue composition. Whole-carcass muscle content was greater in late-slaughtered steers than early-slaughtered steers, especially in pasture-fed steers (720 vs. 698 ± 6.0 g•kg(-1); P < 0.0001), but less so in indoor-fed steers (707 vs. 700 ± 5.9 g•kg(-1); P = 0.046). Furthermore, increasing slaughter age had no effect on carcass fat in indoor-fed steers (162 vs. 166 ± 4.8 g•kg(-1); P = 0.342), but decreased carcass fat in pasture-fed steers (150 vs. 140 ± 5.0 g•kg(-1); P = 0.014). The results showed that slaughter age and feeding system are 2 major factors that independently affect most of the growth and carcass traits of tropical-breed steers but jointly influence tissue deposition. Our study found that in tropical-breed steers that are grazing, late slaughtering grazing steers increased carcass muscle content without extra fat, thus yielding a carcass quality better suited to consumer choices.

Influence of trough versus pasture feeding on average daily gain and carcass characteristics in ruminants: A meta-analysis

“…In trough-fed animals, which are usually diet supplemented, the greater amount of energy intake induced a linear response with more fat accretion whereas in pasture-fed animals, daily energy intake may provide enough energy to cover potential requirements, as previously suggested (Carrasco et al, 2009;data included). This finding is also consistent with decreased fat deposition and increased muscle percentages observed in grazing animals (Carrasco et al, 2009;Blanco et al, 2010;Agastin et al, 2013). This finding is also consistent with decreased fat deposition and increased muscle percentages observed in grazing animals (Carrasco et al, 2009;Blanco et al, 2010;Agastin et al, 2013).…”

“…Trough-fed animals were fatter and had less muscle and bone than pasture-fed animals in proportion, in line with Agastin et al (2013;data not included). Trough-fed animals were fatter and had less muscle and bone than pasture-fed animals in proportion, in line with Agastin et al (2013;data not included).…”

Genetic, management, and nutritional factors affecting intramuscular fat deposition in beef cattle — A review

“…Pethick et al [ 69 ] suggested that a prolonged feeding period gives the cattle time to obtain high IMF levels because time is needed for muscle to reach maturity, followed by time for the muscle to fill up with IMF. However, feed efficiency decreases as animals age due to a decrease in the rate of muscle growth [ 70 ]. Thus, animals with low genetic potential for QG are not recommended for a long fattening stage, which would result in low feed efficiency.…”

Performance and carcass characteristics of cattle fed lipid sources in the diet

“…Nowadays, except for some market niches, carcasses should have a greater proportion of muscle and minimum amount of fat. Fat content should be just enough to prevent dehydration and darkening under refrigeration and to ensure meat juiciness and taste (Luchiari Filho 2000;Agastin et al 2013). Adequate carcass yield and fat thickness (FT) should be achieved taking economic aspects into consideration.…”