Slaughter Weight Groups Research Articles

Meat production traits of a new sheep breed called Bafra in Turkey 1. Fattening, slaughter, and carcass characteristics of lambs

Fattening performance, slaughter, and carcass traits of Bafra ram lambs slaughtered at different weights were evaluated. A total of 40 lambs were fattened and 24 of them were slaughtered at four slaughter weights of 30, 35, 40, and 45 kg. The lambs showed decreasing fattening performance with increasing live weight. Dressing percentages and carcass compactness indices, as well as fat depots and back fat depth, were increased with greater slaughter weights. The proportions of individual cuts varied with slaughter weight; leg (P < 0.05), foreleg (P < 0.001), and loin (P < 0.05) percentages decreased while neck (P < 0.05) percentage increased. The percentages of carcass bone dropped (P < 0.05), but fat percentages rose (P < 0.001) as slaughter weight increased. The effect of slaughter weight on the lean/fat ratio was significant (P < 0.001), but the effect on the lean/bone ratio was non-significant. It was observed that the leg had the highest lean percentages, while the greatest fat ratio was ascertained in the breast + flank and back in all slaughter weight groups.

Effect of genotype, sex and slaughter weight on veal Longissimus muscle area measured by ultrasound and planimeter

The aim of this research was to determine effect of genotype (Holstein, Simmental and their crossbreeds), sex and slaughter weight groups (SW1=150-160kg and SW2=190-200kg) on veal Longissimus muscle area (LMA). Between the12th and the13th rib, two ultrasound LMA (ULMA) images were taken from each animal and carcass LMA (CLMA) traced on transparent foil was measured by planimeter. For both measures, Simmental calves had larger LMA than Holstein (P<0.001) and crossbreeds (P<0.05). Male and female calves did not differ significantly in ULMA and CLMA. Calves of SW2 group had larger LMA (P<0.0001) than SW1 group. High correlation coefficient between ULMA and CLMA was determined in this research. Veal LMA was significantly affected by genotype and slaughter weight. According to high correlation coefficients, ultrasound can be useful in estimating carcass traits of cattle at early age.

Backfat Characteristics of Barrows and Gilts Fed on Tuna Oil Supplemented Diets during the Growing-finishing Periods

This study was conducted to evaluate the effect of supplementing tuna oil to diets of growing-finishing pigs (barrows and gilts) on backfat characteristics when slaughtered at different weights. Four hundred and eighty crossbred (Large White×Landrace× Duroc) pigs averaging 30 kg were allotted to 12 treatment combinations (40 pigs/treatment combination) in a completely randomized design with a 2×2×3 factorial arrangement of treatments. The treatments were: dietary tuna oil supplementation (0 and 2%); sex (barrows and gilts); and slaughter weight (90, 100 and 110 kg). As pigs reached their slaughter weight, they were randomly selected (8 pigs/treatment combination; 96 pigs in total) and slaughtered. Backfat colour, hardness and fatty acid profile were assessed. There was significant (p<0.05) differences in colour (L* and a* values) among treatments. Backfat of control group was harder than those on the tuna oil (p<0.001) and also that of barrows was harder than of gilts (p<0.05). In addition, the thiobarbituric acid reactive substances (TBARS) values of fat from tuna oil group stored for 3 days was higher (p<0.001) than that of the control group. The TBARS values of gilts tended to be higher than that of barrows and it increased with increasing slaughter weight in the tuna oil group. The cholesterol and triglyceride levels were not affected by diet and sex but the triglyceride level increased with increasing slaughter weight (p<0.01). The tuna oil group had higher polyunsaturated fatty acid (PUFA) content, ratio of PUFA: saturated fatty acid (SFA) and total n-3 fatty acids but lower monounsaturated fatty acids content and n-6:n-3 fatty acids than those of the control group (p<0.01). Gilts had higher PUFA and n-6 fatty acids in backfat than barrows (p<0.05). The backfat from both 90 and 100 kg slaughter weight groups had a lower ratio of n6:n3 fatty acid than that of the 110 kg slaughter weight group (p<0.05). However this was more pronounced in tuna oil group. The PUFA: SFA was also increased while the n-6:n-3 ratio tended to reach the recommended levels for healthy eating in human beings of <5. However, due to oxidative susceptibility, barrows should not be slaughtered at more than 100 kg for the meat to be acceptable to

Paramètres de découpe et de mensurations des carcasses d’agneaux Martinik élevés en conditions intensives

L’ovin Martinik est sélectionné pour ses capacités d’adaptation et sa productivité. Les filières lui reprochent une faible conformation de carcasse, alors même que ces carcasses ont été peu décrites. Au cours de deux essais d’engraissement intensif, des abattages ont été réalisés et des découpes et des mensurations linéaires ont été relevées. Ces variables ont été analysées et la détermination des équations d’allométrie a été réalisée. La base de données (n = 43 agneaux) a été codifiée pour les niveaux d’alimentation et la classe de poids d’abattage (PA : 28, 32 et 36 kg). Les poids moyens de carcasse froide (CF) ont varié (P &lt; 0,05) de 11,7 à 15,6 kg. Les rendements de carcasse ont été en moyenne de 59 p. 100 (P &gt; 0,05). Les poids des différents morceaux ont augmenté significativement (P &lt; 0,01) avec la gamme de CF. Les proportions d’épaule et de gigot ont représenté respectivement 18 et 34 p. 100 de la CF. Les différentes longueurs mesurées sur la carcasse et la largeur de bassin ont augmenté (P &lt; 0,05) avec la CF (près de 9 p. 100 de différence entre les poids extrêmes). Les index de compacité de carcasse (0,32) et de gigot (0,45) n’ont pas varié selon le PA, alors que les index pondéraux ont été différents. Les coefficients d’allométrie de l’épaule (0,915) et du gigot (0,891) ont été du même ordre de grandeur que ceux de la littérature. Ces premières descriptions des carcasses de l’ovin Martinik pourraient être proposées à la filière afin de poursuivre le travail et mieux baser les choix de race et de systèmes.

Effects of weight at slaughter and sex on the carcass characteristics of Florida suckling kids

The effect of slaughter weight and sex on some carcass traits of suckling kids of the Florida breed was evaluated. A total of 60 kids (30 male and 30 female), fed exclusively on milk replacers, were slaughtered at 7–8 kg (group 1), 10–11 kg (group 2) or 14–15 kg (group 3) of liveweight (mean weights of 7.6 kg, 10.8 kg and 14.4 kg, respectively). Higher slaughter weights decreased the percentage of subproducts (blood, skin, head, feet) and internal organs (lungs + traquea, heart, liver, spleen, thymus) but significantly increased the percentage of intestine and fat depots (omental fat and mesenteric fat). Higher slaughter weights also increased carcass measures ( L 40.5 vs 49.1; F 22.5 vs 25.9; G 10.4 vs 14.2; Wr 10.1 vs 13.9; Wth 8.0 vs 10.5; Th 16.5 vs 199; B 32.3 vs 42.4; PT 41.5 vs 50.8), compactness carcass index (96.6 vs 152.3) and compactness leg index (27.5 vs 44.1). Sex only significantly affected the percentages of feet, internal organs, omental fat, measure L, carcass compactness index and hind limb compactness index. The meat colour and fat colour were mainly scored as pale and white respectively in the carcasses of the lightest animals, whereas heavier kids were scored as pink and cream. Slaughter weight also influenced significantly the carcass fatness (score 1 in lightest kids and 2 or 3 in heavier ones). There were no significant ( p > 0.05) differences between slaughter weight group and sex in dressing percentages. Percentages corresponding to the long leg, back and neck (30–33%, 18–19% and 8–10%, respectively) decreased when the slaughter weight increased, whereas the ribs (23–25%) and the flank (10–11%) increased slightly. The carcasses comprised 57–58% muscle, 22–25% bone, 5–6% subcutaneous fat and 9–12% intermuscular fat. The percentage muscle stayed the same with increasing slaughter weight, whereas the bone decreased and the fat increased. The carcasses of the heavier females contained less lean and more fat than the males. The bone percentage was significantly ( p < 0.05) lower in the females and the carcass fat percentage was significantly ( p < 0.05) higher than in the males.

Efeitos do grupo genético, sexo e peso ao abate sobre as propriedades físico-químicas da carne de cordeiros em crescimento

O objetivo desse trabalho foi avaliar a evolução do pH post mortem, cor, perda de peso por cozimento e força de cisalhamento dos músculos Longissimus dorsi (LD) e Semimembranosus (SM) de 49 cordeiros provenientes de cruzamentos entre as raças Bergamácia com Santa Inês (BgxSI) e Ile de France com Santa Inês (IFxSI), machos inteiros e fêmeas, distribuídos nos grupos pesos ao abate de 15, 25, 35 e 45kg. Os grupos genéticos apresentaram diferenças (P<0,05) sobre o pH dos músculos LD e SM, sendo que BgxSI apresentou média de pH mais elevada, do que IFxSI. O fator sexo não afetou a cor, entretanto o grupo genético influenciou (P<0,001) o valor L* e o valor a*; o valor L* de 35,25 e 32,89, para IFxSI e BgxSI, respectivamente; e o valor a* de 16,09 e 14,64, para BgxSI e IFxSI, respectivamente. A perda de peso por cozimento não foi influenciada pelos fatores grupos genéticos, sexos e grupos de peso. A maciez no músculo SM não foi afetada pelos fatores estudados. Entretanto no LD, os grupos de peso afetaram a maciez (P<0,05). Os grupos de 15 e 25kg apresentaram força de cisalhamento mais elevada (13,57 e 10,98kgf, respectivamente), do que os cordeiros de 35 e 45kg (8,56 e 7,97kgf, respectivamente).

Influência do sexo e faixas de peso ao abate nas características físico-químicas da carne de capivara

The aim of this work was to evaluate the effects of the factors sex and different slaughter weight groups (30-40, 40-50, 50-60kg) in the pH decline, ultimate pH, colour, water holding capacity (WHC), cooking loss (CL) and shear force (SF) of capybara (Hydrochaeris hydrochaeris) meat. Samples were constituted of longissimus dorsi (LD) muscle of 28 capybaras (16 males and 12 females) from the same farm. There were no effect of the factors sex and slaughter weight groups on the pH values at 2h (6.29), 5h (6.29), 8h (6.25) and 24h (6.01) post mortem; on colour values (CIE LAB System) for brightness (34.28), redness (10.74) and yellowness (1.74); WHC (0.47), CL (32.27%) and SF (5.20kgf/g). Comparing to livestock species, capybara meat had a high ultimate pH value, low values of brightness and high values of redness, looking like bovine and ovine meats (red meats); WHC and CL inside limits considered normal; and SF considered soft.

Part 1. Growth, carcass and meat quality parameters of male goats: effects of genotype and liveweight at slaughter

Male kids (110) from six goat genotypes, i.e. Boer×Angora (BA), Boer×Feral (BF), Boer×Saanen (BS), Feral×Feral (FF), Saanen×Angora (SA) and Saanen×Feral (SF) and two slaughter weight groups, i.e. Capretto and Chevon (liveweight at slaughter 14–22 and 30–35 kg, respectively) were compared for growth, carcass and meat quality characteristics. Due to their better growth rate, kids from BS and SF genotypes reached the required liveweight for slaughter earlier than kids from other genotypes used in the study. Chevon kids had a significantly ( P<0.05) lower average daily gain (119 g per day) compared to Capretto kids (171 g per day). SA, SF and FF kids deposited more internal fat in comparison to kids from other genotypes. The dressing percentage of kids ranged from 51 to 54%, with significant differences between genotypes. BS and SF kids had longer carcasses, while BF kids had larger eye muscle area compared to other genotypes. Goat carcasses had a thin subcutaneous fat cover (1.6–2.2 mm). Genotype had a significant ( P<0.05) influence on cooking loss, pigment concentration and muscle colour parameters (CIE L ∗, a ∗ and b ∗ values). As denoted by the higher L ∗ and fibre optic probe values and lower subjective muscle score, the longissimus muscle colour was lighter for BS kids than other genotypes. Cooked meat from the BF kids had lower shear force values and better sensory scores compared to other genotypes. A significant ( P<0.05) decrease in muscle tenderness was observed from Capretto to Chevon carcasses, whereas cooked meat from these two slaughter weight groups was equally accepted ( P>0.05) by the panellists.

Part 2. Carcass composition and fatty acid profiles of adipose tissue of male goats: effects of genotype and liveweight at slaughter

The dissected carcass composition and fatty acid profiles of intermuscular fat from 110 male goat kids from six genotypes i.e. Boer×Angora (BA), Boer×Feral (BF), Boer×Saanen (BS), Feral×Feral (FF), Saanen×Angora (SA) and Saanen×Feral (SF) and two slaughter weight groups i.e. Capretto and Chevon (liveweight at slaughter 14–22 and 30–35 kg, respectively) were compared. Carcass tissue distribution for various genotypes was: muscle (63–66%), fat (10–13%) and bone (21–24%). Genotype significantly ( P<0.05) influenced the carcass composition; BA and FF carcasses had significantly higher muscle to bone ratio, while carcasses from BS kids were leaner compared to other genotypes. However, the two slaughter weight groups did not differ significantly ( P>0.05) in terms of carcass composition, when compared at the same carcass weight. In the present study, significant ( P<0.01) correlations were observed between percentage of muscle, fat and bone in most of the primal cuts and that in the carcass side. The main saturated fatty acids (SFAs) identified were palmitic (16:0) and stearic acid (18:0), while oleic acid (18:1, ω9) was the main unsaturated fatty acid (UFA) in the intermuscular fat from goat kids. There were significant ( P<0.05) differences between genotypes in the proportions of individual fatty acids. Adipose tissue from BS kids had significantly higher UFAs (mainly oleic acid) and thus had a significantly lower melting point compared to other genotypes. There were significantly higher proportions of palmitic acid (35%) in the adipose tissue from Capretto kids compared to that from Chevon kids (22%). The concentration of UFAs increased in the adipose tissue from Capretto to Chevon carcasses.

Growth, carcass characteristics and androgen concentrations of gonad-altered ram lambs

The study was designed to determine the effect of multiple types of gonadal alteration on circulating androgen concentrations, the rate of body weight gain, and carcass characteristics, when lambs were slaughtered at approximately 41 kg versus 49 kg of shorn-shrunk body weight. Seventy-four lambs, 2 months old were placed in the experiment and continued until lambs reached the planned body weight in each group. Ram lambs were assigned at random across the two slaughter weight groups to be treated in six groups as follows: Group I, intact rams; Group II, rams to be castrated unilaterally; Group III, rams to be castrated unilaterally plus removal of the tail of the epididymis of the remaining testis; Group IV, bilateral short scrotum rams to simulate cryptorchidism; Group V, unilateral short scrotum rams, and the other testis removed; Group VI, rams bilaterally castrated (wethers); plus Group VII, ewe lambs. Compensatory hypertrophy of the scrotal testis occurred in the groups with unilateral castration, and the short scrotum ram testes were smaller. Circulating plasma testosterone and androstenedione concentrations were not markedly affected by any gonadal treatment, except that they remained at baseline levels in the bilaterally castrated rams, comparable to the ewes. Daily weight gain was less in these latter two groups ( P<0.05), but was not different from the other groups. At both slaughter weights, wethers and ewes had less lean, more fat, less bone, and a lower yield of trimmed or untrimmed retail cuts ( P<0.05). They also recorded a higher carcass quality grade. These studies indicate that all gonadal alterations which maintain androgen secretion produce beneficial effects, similar to intact rams on growth and most carcass characteristics. Slaughtering younger animals at lower weights produced leaner carcasses.

Influence of sex and slaughter weight on carcass and meat quality in light and medium weight lambs produced in intensive systems

Effects of slaughter weight and sex on carcass characteristics and lamb meat quality of Manchega Spanish breed were analysed. Forty-five lambs were divided into two slaughter weight groups: light (LW=21.7±0.16 kg; n=24) and medium (MW=27.8±0.16 kg; n=21). Dressing proportion and conformation were significantly different between groups and sex. There were also differences between light and medium group in fatness but not between males and females. Water holding capacity decreased with increasing slaughter weight ( p<0.05) and was lower in females than in males ( p<0.001). The increase in weight was associated with a decrease in L* ( p<0.01), while a* showed an increase which failed to reach statistical significance. Slaughter weight and sex affected neither pH and its decrease post-slaughter nor meat toughness. ©

Fattening heifers to heavy weights to enhance marbling: Efficiency of gain

Feedlot performance and carcass composition were measured in two studies to evaluate the use of common Canadian breeds and nutrition programs for production of highly marbled beef for the Japanese market. Weaned heifer calves (n = 221, initial weight 265 kg) of Angus, Hereford, and Hereford × Angus (HA) breeding were slaughtered at 500, 590, and 680 kg in exp. 1. In exp. 2, yearling heifers (n = 216, initial weight 395 kg, same breeds as exp. 1 but including Holstein) were slaughtered at 590 and 680 kg. Cattle were randomly assigned to either a high plane of nutrition (HP) until slaughter or a moderate plane of nutrition to 500 kg (exp. 1) or 550 kg (exp. 2), followed by a high plane to slaughter (MHP). Mean days on feed, percent carcass fat, and percent intramuscular fat in longissimus muscle were 347 d, 38.6%, and 8.50% in exp. 1, and 281 d, 37.5%, and 7.87%, respectively, in exp. 2. In exp. 1, Herefords produced the most economical gains but the fattest carcasses (P &lt; 0.05). In exp. 2, Holsteins had the most economical liveweight and lean carcass weight gains (P &lt; 0.05). The cost of a percentage increase in intramuscular fat was lowest for Angus in exp. 1 (P = 0.05), similar for the breeds in exp. 2 (P = 0.29), and not affected by slaughter weight group. HP cattle gained liveweight, carcass, lean carcass, and intramuscular fat more economically than did MHP cattle (P ≤ 0.0002). The rate of deposition of intramuscular fat did not appear to increase with maturity. Feeding cattle to extreme slaughter weights using conventional feedlot diets produced extremely fat carcasses but did not produce highly marbled beef. Key words: Beef cattle, carcass, growth, intramuscular fat, marbling

Evaluation of Australian merino and U.S. sheep breeds for growth and carcass traits.

One hundred twenty 4-mo-old wether lambs born to Targhee ewes and sired by six rams each from Merino (Finewool, FM and Strongwool, SM), Rambouillet (Dubois, DR and Texas, TR), and Targhee (T) breeds were randomly assigned to predetermined slaughter weight groups of 43, 48, 52, and 57 kg and evaluated for growth and carcass traits. Overall mean ADG and feed conversion rate (FC, kilograms of feed/kilogram of gain) were .28 and 6.4 kg, respectively; T grew the fastest (.31 kg) and FM grew the slowest (.23 kg). Targhee and SM had the best FC (6.2), whereas FM (6.8) had the poorest FC (P < .05). Overall mean backfat thickness (BT) and carcass fat (CF) were 4.8 mm and 25.6%, respectively. Targhee had the lowest (24%) and FM the highest (27.8%) CF percentage (P < .05). Differences (P < .05) were observed for BT and CF among slaughter weight groups; overall means for both traits gradually increased from the 43- to the 57-kg groups. Separate analysis of the 43- and the 48-kg groups indicated nonsignificant breed differences for feed traits, whereas significant differences still existed for CF. It was concluded that Merino strains grew more slowly, were less efficient in postweaning growth, and had higher carcass fat content than U.S. breeds at a constant slaughter weight; SM were more comparable to U.S. breeds than were FM. Merino-cross lambs should be slaughtered at lighter BW to avoid excessive carcass fat.

Retail acceptability of lamb as influenced by gender and slaughter weight

A retail survey was conducted to determine the retail acceptability of lamb rib chops from animals differing in gender and slaughter weight. A random array of 12 packages of untrimmed chops, with equal weight, representative of three genders (rams, ewes, and wethers) and four slaughter weight groups (40·5–49·5; 50·0–58·6; 58·9–67·7, and 68·2–76·8 kg live) were presented to 2002 consumers as they passed through 31 supermarkets in two cities. Respondents demonstrated an obvious aversion to fatness, and over 50% of the respondents indicated chops from all genders and slaughter weight groups were unacceptable, with the exception of chops from ram lambs up to 58·6 kg in liveweight at the time of slaughter. Therefore the population of lambs currently being produced and marketed are too fat to be acceptable to the vast majority of Canadian consumers.

Prediction of carcass characteristics by real-time ultrasound in barrows and gilts slaughtered at three weights.

The carcass characteristics of 27 market barrows and 27 market gilts were evaluated at various times (n = 8) with real-time ultrasound (Aloka 210 DX) from approximately 20 kg until slaughter at three end points. The pigs were randomly assigned to slaughter weight groups of 91, 104.5, and 118 kg at weaning time. Correlations were determined over slaughter weight group and sex, and the accuracies of ultrasound measurements were also evaluated. The regressions of ultrasound 10th-rib fat and ultrasound longissimus muscle area on live weight were also developed. Correlations between actual and ultrasound-measured last-rib fat, 10th-rib fat, and longissimus muscle area were high (r = .91, .63, and .53, respectively; P less than .01). The accuracy of ultrasound longissimus muscle area prediction was lower for 118-kg pigs than for the two lighter groups, whereas the accuracy for prediction of last-rib fat was lower for 91-kg pigs than for the two heavier groups, as indicated by higher absolute differences (P less than .05). Last-rib fat and longissimus muscle area tended to be overestimated and 10th-rib fat tended to be underestimated by real-time ultrasound. Prediction of last-rib fat by ultrasound was more accurate for gilts than for barrows, as indicated by a lower absolute difference (P less than .05).

Studies on the Criollo goat of Northern Mexico: Part 1 — The effects of body weight on body components and carcass development

Male Criollo castrate goats were reared on natural rangeland and also given some concentrate supplementation. They were slaughtered in groups of ten at 8, 12, 16 and 24 kg live weight. At slaughter the weights of body components were recorded and also carcass measurements and joint weights on the chilled left half of each carcass, which was then completely dissected into lean, fat and bone tissues. With increasing slaughter weight the proportion of internal body components minus gut contents, increased relative to the external components. In some of the goats from the higher slaughter weight groups the gut contents formed up to 26% of the total live weight. The dressing percentage based on empty body weight did not show an appreciable increase with increasing slaughter weight. The lean proportion in the carcass rose from 56% of the carcass weight in the 8 kg group to about 68% in the 24 kg group. The proportion of fat in the carcasses did not show any increase with increasing slaughter weight. The results indicate that, in terms of yield of lean meat and also edible offal, it is better not to slaughter castrate male Criollo goats before 24 kg live weight.

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.

A single backfat measurement taken by optical probe as a predictor of lean body content of the pig carcass

Abstract Carcass data obtained from 528 pigs which comprised gilts, barrows, and entires reared to slaughter at 40, 80, and 100 kg liveweight at 1 location and to 100 kg liveweight at another centre, were analysed to determine the value of a single backfat measurement as a predictor of the lean body content of the carcass. This measurement was taken on the slaughterline with an optical probe 4 cm lateral to the centre of the vertebral column immediately posterior to the last rib. At slaughter weights of 40 and 80 kg, sex of the carcass did not influence either the slope or elevation of regression lines relating the backfat measurement and percentage lean body content. At the heavier slaughter weight, corresponding regression equations established for entires differed in slope and elevation from those for gilts and barrows and there were no differences between these 2 latter types. Separate regression equations established for the 40, 80, and 100 kg slaughter weight groups ignoring sex and location, had re...

Effect of breed, slaughter weight and sex on histological properties of ovine muscle.

Thirty-three wether and ewe lambs of two breed groups- Suffolk ram x Suffolk-Rambouillet ewe (Su x R) and Suffolk ram x Finnish Landrace-Southdown ewe (Su x F x So)-and two slaughter weight groups (32 and 41 kg) were studied. Carcass studies, including histological examinations of muscle fiber types, sarcomere lengths and fat cell, were made. The longissimus (LD) muscle at the 13th rib and a sample of the semimembranosus (SM) from the upper proximal location were used. Fibers in both muscles were classified as beta R, alpha R or alpha W. Su x F x So lambs had more alpha W fibers and fewer alphaR fibers in both muscles. Breed type appeared to cause a physiological shift from alpha R to alpha W fiber types. Furthermore, beta R fibers were larger in the SM of the Su x F x So lambs than in that of the Su x R lambs. beta Red fibers in the LD, and all three types fibers in the SM, increased in size with increased weight. Wethers had fewer alpha R fibers in the SM, while ewe lambs had larger alpha R and alpha W fibers in the SM. The more phasic LD muscle had fewer beta R fibers, more alpha W fibers and smaller alpha R and alpha W fibers than the more tonic SM. Su x F x So lambs were fatter, as indicated by larger fat cells in both muscles. In addition, as slaughter weight increased, there was a concurrent increase in fat cell diameters in both muscles. Fat cells were larger in the LD than in the SM. Sarcomere lengths were not affected by breed, slaughter weight or sex. However, sarcomeres were longer in the SM than in the LD. Fat cell size and beta Red cells size for the LD were positively correlated with carcass fat indices, while shear values were negatively correlated with fat cell diameters. There was also a positive relationship between sarcomere length and fat cell size in the SM.

Effect of Breed and Slaughter Weight on Physical, Chemical and Organoleptic Properties of Lamb Carcasses

Physical, chemical and organoleptic properties of 33 lambs (wethers and ewes) representing two breed groups – (1) ½ Suffolk, ¼ Finnish Landrace and ¼ Southdown (Su × F × So), and (2) ¾ Suffolk and ¼ Rambouillet (Su × R) – and two slaughter weight groups – 32 and 41 kg – were compared. After slaughter, carcasses were chilled at 3 C for 48 hr, graded and evaluated. Carcass moisture, protein, ether extract and ash were analyzed on the right side minus small samples taken for histological studies. The rib and center leg roast from the left side were cooked and evaluated for palatability. Carcasses from Su × R lambs were heavier (P<.01) per day of age and contained a higher percentage leg (P<.01), moisture (P<.01) and protein (P<.05). Su × F × So lambs had higher (P<.01) dressing percentages and their carcasses were fatter (P<.01), as indicated by higher quality grades, width behind the shoulder and higher percentage ether extract. Also, their longissimus muscles were more tender (P<. 10) by shear test. As slaughter weight increased, there was a concurrent increase within each breed group in dressing percentage (P<.01), quality grade (P<.05) and yield grade (P<.01). Percentage kidney fat, ether extract and drip loss for rib roasts also increased (P<.01). Carcasses from the 32-kg group showed a higher (P<.01) percentage of leg moisture, protein and rib roast evaporative loss. This study reveals distinct differences in chemical, physical and organoleptic properties between lambs from different genetic backgrounds (breeds) and slaughter weights.