Slaughter End Points Research Articles

Effects of percentage Brahman and Angus breeding, age-season of feeding and slaughter end point on feedlot performance and carcass characteristics.

Steers (n = 165) of known percentage Brahman (B) and Angus (A) breeding were used to study effects of breed group (A, 3/4A:1/4B, 1/2A:1/2B, 1/4A:3/4B), age-season of feeding (calves fed during the cool season vs yearlings fed during the warm season) and slaughter end point (less than .90, 1.0 to 1.15, 1.27 to 1.40, greater than or equal to 1.5 cm of adjusted fat over the ribeye) on feedlot performance and carcass characteristics. The 1/2B and 3/4B steers had heavier (P less than .05) initial and final feedlot weights than the A and 1/4B steers and higher (P less than .05) unshrunk ADG than the A steers did. Breed types did not differ for feed efficiency. Yearling steers fed in the warm season had higher (P less than .05) unshrunk ADG than calves fed in the cool season, but ADG calculated on an empty-rumen basis did not differ between the two age-seasons of feeding. Calves fed in the cool season were more efficient (P less than .05) than yearlings fed in the warm season when efficiency was expressed on an empty-rumen basis; however, on a live weight basis there was no difference in feed efficiency. No breed group by age-season of feeding interactions on performance were detected. Slaughter end point did not significantly affect feed efficiency on an empty-rumen basis. The 1/2B and 3/4B steers had smaller ribeye areas (REA) per 100 kg hot carcass and lower marbling scores than the 1/4B and A steers. Yearlings fed in the warm season produced heavier carcasses (P less than .05) than calves fed in the cool season. As s.c. fat thickness at slaughter increased, hot carcass weight and numerical yield grade increased, whereas REA per 100 kg of hot carcass decreased. Marbling also increased as fatness increased up to about 1.5 cm subcutaneous fat.

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

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.

Sire Breed Effects in Matings with Angus Cows: II. Carcass Characteristics of Steer Progeny3

Carcass data from 190 steers sired by Angus (A), Charolais (C) and Holstein (F) bulls bred to Angus cows, were analyzed by least-squares procedures to estimate effects of sire breed and postweaning management on carcass weight, composition and quality of steers fed a high forage diet. Data were adjusted separately to a common live weight or slaughter age. Using either method of adjustment, CA steers had larger carcass weights per day of age, rib eye areas (REA) and REA/100 kg carcass weight and lower yield grades than FA and AA steers. At the same live weight, AA steers were older and scored higher in marbling than CA and FA steers. The CA steers also had lower marbling scores, lower carcass grades, more desirable yield grades and poorer tenderness scores than FA steers. At the same slaughter age, CA steers had heavier carcasses than both FA and AA steers. The AA steers had less kidney and pelvic fat, thicker backfat and less desirable yield grades than the larger CA and FA steers. The FA steers were more tender (P<.05) than CA steers. No significant differences in marbling or carcass grade existed at a constant slaughter age. Postweaning management had no effect on carcass characteristics. Because these three breed types differed in rate of maturity, neither a common slaughter age nor a common slaughter weight was necessarily most appropriate as a slaughter end point. Comparison of regressions of carcass characteristics on age and live weight indicate that each type has its own optimum end points for yield and quality.

Bovine metacarpal and metatarsal dimensions: Comparison of aberdeen—Angus and charolais steers slaughtered at three percentages of mature cow weight

Fifty-six Aberdeen—Angus (Angus) and 56 Charolais steers were used in a 2 (diet energy levels) × 4 (slaughter weights) × 2 (breeds) factorial experiment. Live slaughter weight groups within each breed were initial, 86 (light), 100 (middle) or 114% (heavy) of average mature cow weight (Angus dams, 467 kg; Charolais dams, 612 kg). Therefore, Angus were slaughtered at 408, 476 or 544 kg and Charolais at 526, 612 or 699 kg. Live, carcass and metacarpal and metatarsal traits were obtained. There were no important effects of diet (2.72 vs. 2.96 Meal metabolizable energy/kg of dry matter). Breed affected ( P < 0.01) live body measurements in each slaughter weight group except in initial groups. Within initial groups, breed affected ( P < 0.01) live fore- and rear-cannon lengths and wither height. Mean limb-bone weight, expressed as a percentage of live weight, was greater for Charolais than for Angus in each weight group. Bone length increases ceased within Angus between initial- and light-weight slaughter endpoints, but ceased in Charolais between light and heavy groups. Bone area and circumference increased through most weight increments for both breeds, confirming that appositional bone growth continues after length increases cease. Bone specific gravity was maximized in the middle-weight Angus, but increased ( P < 0.01) between middle and heavy Charolais. Generally, these results indicate that bone growth subsides earlier and ossification is more advanced in Angus than in Charolais if both breeds are slaughtered at the same percentages of mature weight.

Collagen Solubility of A-Maturity Bovine Longissimus Muscle as affected by Nutritional Regimen

Fifty large-type crossbred steers were assigned in groups of five to one of ten nutritional regimens to measure the effects of diet on collagen characteristics. Initially, steers in a control group were slaughtered at about 280 d of age and weighing 300 kg. Steers in the nine remaining treatment groups were fed either roughage ad libitum, concentrate ad libitum or concentrate at a maintenance (CM) level. Animal slaughter endpoint (SEP) weights were about 400 kg (SEP-2), 500 kg (SEP-3) and 600 kg (SEP-4). Feeding times ranged from 0 to 560 d. Dietary regimen had small and inconsistent effects on total collagen and measures of collagen solubility. At SEP-4, the percentages of salt-soluble and salt- plus acid-soluble collagen were higher (P<.05) in steaks from the roughage group than in steaks from the concentrate and CM groups. Because of small palatability differences among nutritional regimens, data were stratified into tender (n = 16) and less tender (n = 15) groups based on overall tenderness. The tender group tended to have less total collagen (P<.10) and more salt-soluble collagen (P<.14) than did the less tender group. Steers slaughtered while in the A-maturity age range tolerated wide ranges in feeding regimen with little affect on tenderness, amounts of total collagen or collagen solubility.

Sire Breed Effects on Economic Efficiency of a Terminal-Cross Beef Production System

Economic efficiency was evaluated for a terminal-cross production system in which Hereford and Angus cows were bred to Hereford, Angus, Jersey, South Devon, Limousin, Charolais and Simmental bulls. Consideration was given to level of calving difficulty, preweaning survival, growth rate, feed efficiency, carcass composition and quality grade. Sire breeds were compared for retail product cost, profit per calf and profit per cow at age- (217 days on feed), weight- (5 30 kg slaughter weight) and grade-constant (5% longissimus fat) slaughter end points separately by age-of-cow subclass. Limousin, Charolais and Simmental crosses were generally favored for all cow ages, slaughter end points and evaluation criteria. South Devon and Hereford-Angus reciprocal crosses tended to have similar merit and to rank intermediate between the straightbred Hereford and Angus and the favored Limousin, Charolais and Simmental crosses. Jersey crosses ranked low in all comparisons. Alterations of grain/forage and choice/good price ratios had minimal effect on the interpretation of results. The apparent ability of cattle which have increased growth rate, feed efficiency and carcass merit to offset large differences in cost per calf weaned suggested that calves out of the large, growthy breeds should warrant a premium in the market place.