Larger Longissimus Muscle Area Research Articles

Effects of growth type on carcass traits of pasture- or feedlot-developed steers.

Carcasses of 342 steers of known genetic backgrounds from four fundamentally different growth types were developed either on pasture or feedlot regimens to study differences in carcass traits. Growth types were large framed-late maturing (LL), intermediate framed-intermediate maturing (II), intermediate framed-early maturing (IE), and small framed-early maturing (SE). Five calves from each growth type were assigned to each regimen in each year of a 9-yr study. Eighteen steers were removed from the study because of accident or illness. Data collected were preslaughter shrunk BW (SBW); hot carcass weight (HCW); chilled carcass weight (CCW); dressing percentage (DRESS); fat thickness at the 12th and 13th-rib interface (FAT); percentage kidney, pelvic, and heart fat (KPH); longissimus muscle area (LMA); marbling score (MARB); quality grade (QG); and yield grade (YG). Differences in carcass traits reflected genetic differences among growth types. The LL steers had heavier BW, HCW, and CCW and larger LMA (P < .05) than steers of other growth types, regardless of development regimen. Among pasture-developed steer carcasses, IE and SE steers had higher (P < .05) MARB and QG than either LL or II steers. Carcasses of large framed-late maturing steers had the lowest (P < .05) MARB and QG of the growth types. Carcasses of the II, IE, and SE steers had a higher (P < .05) numerical value for YG than carcasses of the LL steers. Among the carcasses of the feedlot-developed steers, IE and SE steers had the highest (P < .05) MARB and QG. Carcasses from the IE and SE steers were fatter (P < .05) than those from LL or II steers. Carcasses of the LL steers had the lowest percentage of KPH of growth types developed in the feedlot. No difference was observed in KPH for carcasses of II, IE, and SE steers. The LL steer carcasses had the lowest numerical value for YG of all growth types. These data indicate that variation existed among carcass traits for the four growth types and that carcass traits influenced by fatness were greater and more attainable in the feedlot-developed steers using current methods of evaluation.

Recombinant bovine somatotropin (rbST) administration to creep-fed beef calves increases muscle mass but does not affect satellite cell number or concentration of myosin light chain-1f mRNA.

Our objective in this study was to determine the effect of recombinant bovine somatotropin (rbST) on indices of muscle development in creep-fed beef calves. Crossbred steer calves were assigned to one of two treatment groups: control (sham-injected; n = 12) or rbST-treated (.09 mg x kg(-1) x d(-1); n = 12). Calves were injected every 14 d starting at d 28 of age and were weaned at 205 d of age. Supplemental creep feed was supplied free access to all calves to compensate for an expected increased protein and energy requirement in calves given rbST. Biopsy (d 100) and slaughter (d 206) samples of semitendinosus muscle were evaluated for satellite cell, myofiber nuclei numbers, and myosin light chain (MLC-1f) mRNA quantification. Myofiber nuclei and satellite cell numbers per 100 myofibers and MLC-1f mRNA:rRNA ratios at 100 and 206 d of age were not different (P > .10) between control and rbST-treated calves. Total gain, ADG, quality grade, femur length, percentage kidney, pelvic, and heart fat, dressing percentage, plasma IGF-I, and plasma urea nitrogen concentrations did not differ (P > .10) between control and rbST-treated calves. However, rbST-treated calves had larger longissimus muscle areas (P < .03), less marbling (P < .001), higher carcass conformation scores (P < .04), greater mass of separated muscle (P < .03), more ground meat (P < .01), and heavier carcass weights (P < .05) than control calves. Thus, rbST treatment increased muscle characteristics while nuclei number and MLC-1f mRNA concentrations remained the same, implying that the additional muscle growth was in a normal fashion.

Supplemental chromium picolinate influences nitrogen balance, dry matter digestibility, and carcass traits in growing-finishing pigs.

Four trials were conducted to determine the influence of feeding 200 ppb Cr as chromium picolinate (CrPic) on DM digestibility, N balance, and carcass traits of growing-finishing pigs. A 15% CP corn-soybean meal diet was fed during the grower phase, and a 13% CP corn-soybean meal diet was fed during the finisher phase. In each of three trials, crossbred barrows (six littermate pairs) were used for two N balance periods (end of grower, 61.3 kg; end of finisher, 98.9 kg). After the second balance period, all the barrows were killed and carcass data were collected. Initial and final BW were 23.5 and 104.9 kg, respectively. Growth rate was similar for control and CrPic-fed pigs in all trials. The rate of N absorption was increased by feeding CrPic (P < .05), but N retention was increased only numerically (P = .14). Dry matter digestibility was also increased by feeding CrPic (P < .02). Dressing percentage and backfat thickness at the 10th and last rib did not differ between treatment groups. Longissimus muscle area was larger (P < .05) for pigs fed CrPic. In Trial 4, crossbred barrows (six littermate pairs; initial BW, 82.0 kg) were used in a switch-back design with an extra period. Digestibility of DM (P < .02) and absorption of N (P < .06) were improved with only a numerical increase (P = .22) in N retention. No carryover effect was observed. These findings show that pigs fed 200 ppb Cr from CrPic can have larger longissimus muscle areas and that Cr supplementation improved N absorption and DM digestibility.

Hydrolyzed feather meal as a source of amino acids for finisher pigs

21 gilts and 21 castrated males were used to evaluate the value of hydrolyzed feather meal (FM) as a source of amino acids for finisher pigs, and to determine the possibility of replacing soybean meal (SBM) completely with FM by lysine supplementation. Dietary treatments consisted of five iso-lysinic (planned, 7.3 g kg −1; actual, 8.0–8.8 g kg −1) SBM diets containing 0 to 120 g FM kg −1. Two additional diets containing 90 g FM kg −1 were formulated to be iso-nitrogenous to the SBM diet containing 0 g FM kg −1. For these FM diets, SBM was replaced completely by FM, and one of the two diets was supplemented with L-lysine · HCl to achieve a target level of 7.3 g lysine kg −1. At an average weight of 67.5 ± 3.4 kg, pigs were assigned randomly within sex to seven dietary treatments. Pigs were housed individually, and allowed ad libitum access to feed and water. All pigs were slaughtered at an average weight of 100.4 ± 3.2 kg to assess carcass traits. The rate (linear, P < 0.05; cubic, P = 0.09) and efficiency of weight gain (linear, P = 0.07) decreased as dietary FM increased. However, the response of pigs to the initial increment of FM (30 g kg −1) in weight gain and greater feed intake of pigs fed the diet containing 120 g FM kg −1 seemed to be responsible for overall decreases in these criteria. The rate and efficiency of weight gain in pigs fed other SBM diets containing FM were similar. Although there were no statistically significant trends among pigs fed the SBM diets, the inclusion of 120 g FM kg −1 seemed to result in the inferior carcass quality as indicated by consistently lower values for carcass specific gravity (1.040 vs. 1.045), proportion of carcass lean (48.7 vs. 51.6%) and the rate of lean accretion (236.4 vs. 301.4 g d −1). Pigs fed the two FM diets (with and without lysine supplementation) grew slower than those fed the SBM diet containing 0 ( P < 0.01) or 90 g FM kg −1 ( P = 0.06). Similar results were obtained for the efficiency of weight gain ( P < 0.05) and rate and efficiency of lean accretion ( P < 0.05). There was no effect of lysine supplementation on the rate and efficiency of weight gain. Pigs fed the FM diet supplemented with lysine, however, had less 10th rib backfat ( P = 0.10), larger longissimus muscle area ( P = 0.08), greater proportion of carcass lean ( P < 0.05), and higher rate ( P = 0.08) and efficiency of lean accretion ( P < 0.05) than those fed the FM diet without lysine supplementation. The results indicate that FM up to 90 g kg −1 may be incorporated in the diet without adversely affecting carcass traits of finisher pigs. In addition, although weight gain may be reduced, FM can be used as the only source of protein supplement without decreasing the carcass quality, provided that the diet is supplemented with crystalline lysine to alleviate its deficiency.

Influence of steroid implants and concentrate feeding on performance and carcass composition of cull beef cows.

Sixty nonpregnant, mature beef cows were used to evaluate the influence of steroid implants on performance and carcass composition of beef cows fed a high-concentrate diet. Twelve nonfed cows were slaughtered at 0 d. Remaining cows were stratified by weight and randomly assigned to an implant treatment and feeding period (28 or 56 d). Treatments included 1) no implant (control), 2) a 200-mg trenbolone acetate (TBA) implant, 3) a 200-mg testosterone propionate +20 mg of estradiol benzoate (TEB) implant, or 4) both implants (TBA + TEB). As days on feed increased, hot carcass weight (HCW), carcass soft tissue (CST) weight, adjusted fat thickness (AFT), longissimus muscle area (LMA), percentage of CST, and percentage of CST lipid increased (P < .05) and percentage of CST crude protein and moisture decreased (P < .05). Cows fed for 56 d accumulated (P < .05) more kilograms of lean than cows fed for 28 d, and cows fed for 28 d tended (P = .08) to have more kilograms of lean than nonfed cows. Cows fed for 56 d had (P < .05) higher dressing percentages than nonfed cows or cows fed for 28 d, and nonfed cows had (P < .05) higher dressing percentages than cows fed for 28 d. Implanted cows compared with control cows had (P < .05) heavier final weights, increased gains, improved feed efficiency, heavier hot carcass weights, larger LMA, higher cutability yield grades, compositionally leaner CST (higher percentage of moisture and protein and lower percentage of lipid), and more kilograms of lean. In addition, double-implanted (TBA + TEB) cows had (P < .05) more kilograms of CST than control and TBA-implanted cows. Furthermore, cows implanted with TBA had (P < .05) lower dressing percentages than TEB-implanted cows, less AFT than controls, and fewer kilograms of lipid than cows on the other three treatments. Full feeding of thin beef cows for 28 or 56 d increased carcass weight through an increase in CST lean as well as fat (lipid). The live performance and accretion of lean during realimentation can be enhanced by using anabolic implants.

Effects of hydrolyzed feather meal as a source of extra dietary nitrogen on growth performance and carcass traits of finisher pigs

Two experiments were conducted to investigate the effects of extra dietary nitrogen on the growth performance and carcass traits of crossbred (Landrace × Hampshire × Duroc) finisher pigs. In Experiment 1, 15 pens containing gilts and castrated males (six pigs per pen) averaging 53.7 ± 1.9 kg were randomly assigned to five soybean meal (SBM) diets calculated to contain 4.8–9.8 lysine kg −1 in each of two trials. In Experiment 2, 21 gilts and 21 castrated males averaging 57.1 ± 4.5 kg were randomly assigned within sex to seven diets. Two SBM diets were formulated to contain 7.3 g lysine and 150 g crude protein (CP) kg −1 (Med) or 8.5 g lysine and 167 g CP kg −1 (High). An additional SBM diet containing 6.0 g lysine and 132 g CP kg −1 (Low) was also included as part of dietary treatments. Two hydrolyzed feather meal (FM) diets were formulated to be iso-lysinic (Iso-Lys) to the Med and High SBM diets. Two additional FM diets were formulated to be iso-nitrogenous (Iso-N) to the Med and High SBM diets. Corn and SBM provided 6.0 g lysine or 132 g CP kg −1 to the Iso-Lys and Iso-N diets, respectively, and additional lysine and CP were supplied by FM. A fundamental assumption of the design for Experiment 2 was that providing extra lysine and(or) CP (i.e. above the optimum level) would have no effect on the rate of protein accretion, but it would reduce the rate of fat accretion, thus improving leanness of pigs. Pigs were housed and fed individually in Experiment 2, and allowed ad libitum access to feed and water in both experiments. At the average weights of 101.3 ± 2.0 kg and 108.5 ± 5.5 kg for Experiment 1 and 2, respectively, pigs were slaughtered. In Experiment 1, pigs responded to an increase in dietary lysine up to 7.3 g kg −1 (analyzed to be 8.5 g kg −1), and there seemed to be little or no improvement in the growth performance or carcass traits with further increases. In Experiment 2, weight gain of pigs decreased ( P < 0.05) as dietary lysine and CP levels increased from medium to high, but this depression was not observed in pigs fed the Iso-Lys diets (Iso-Lys vs. Iso-N, P=0.06). Pigs fed the High diets had lower carcass backfat ( P < 0.05), larger longissimus muscle area ( P=0.08) and higher specific gravity ( P < 0.05) and proportion of lean ( P < 0.05) than those fed the Med diets. The improved carcass quality in response to the increased dietary lysine and CP levels from medium to high was independent of the source (SBM or FM) or method of incorporating FM in the diets (Iso-Lys or Iso-N). The results indicate that providing extra dietary nitrogen may be a viable method to enhance leanness of finisher pigs, even though a possible increase in urinary N excretion is a potential environmental concern. In addition, the low quality protein sources for pigs such as FM may be used effectively as a source of extra dietary nitrogen to enhance leanness of finisher pigs.

Influence of dietary background on the response of pigs to the β-adrenergic agonist BRL 476722

The level of protein in the diet both before and during treatment with beta-adrenergic agonist (BAA) was investigated with regard to its effect on growth performance and carcass characteristics of pigs. A total of 76 pigs were divided into two groups and given ad libitum access to diets containing either 12 or 18% crude protein (CP) during growth from 15 to 60 kg. At 60 kg, six pigs from each group were slaughtered and carcass composition was determined. For the test period (growth from 60 to 90 kg) the remainder of the pigs were divided into eight groups of eight pigs each. Half of the pigs from each of the two dietary pretreatment groups were switched to the other diet and half remained on the same diet. Of the four dietary groups, half were fed 0 mg/kg (controls) or 1 mg/kg of BRL 47672. During the test period, all pigs were fed at 90% of their calculated ad libitum DE intake. All pigs were slaughtered at 90 kg and carcass composition was determined. Addition of BRL 47672 to the diet resulted in an overall improvement (P < .05) in daily gain (.72 vs .64 kg) and gain/feed (.28 vs .26); the greatest improvement occurred with pigs fed the 18% CP diet (24 and 14% for daily gain and gain/feed, respectively). Pigs that had received BRL 47672 also had 12% less backfat, 10% less carcass lipid, 16% larger longissimus muscle area, and 5% more carcass protein (P < .05 for each), and the greatest changes occurred in pigs fed the 18% CP diet (-26, -16, +21, and +10%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of supplemental dietary carnitine, betaine, and chromium nicotinate on growth and carcass characteristics in growing-finishing swine (1994)

Sixty-four pigs (initially 75 lb) were used to determine the effects of dietary betaine, carnitine, and chromium nicotinate on growth performance and carcass composition. Pigs were blocked by sex, ancestry, and weight and allotted in a randomized complete block design to each of four dietary treatments. These treatments were a corn-soybean meal-based control diet and control diet plus 50 ppm carnitine, 1,000 ppm betaine, or 200 ppb chromium from chromium nicotinate. Grower diets (75 to 125 lb) were formulated to contain 1.0% lysine and finisher diets (125 to 225 lb) were formulated to contain .8% lysine. All diets were com-soybean meal-based, were fed in meal form, and contained .15% L-Iysine HCl and 2.5% soy oil. When mean weight of pigs in a pen reached 225 lb, one pig per pen was selected at random and slaughtered to obtain carcass measurements. During the grower phase, pigs fed carnitine had greater ADG and feed efficiency (F/G) than pigs fed the control diet. However, during the finishing phase and overall, no differences were observed for ADG, F/G, or ADFI. Pigs fed carnitine had larger longissimus muscle area and greater percentage muscle than pigs fed the control or betaine diets. Also, pigs fed carnitine had lower tenth rib backfat thickness compared to those fed the control diet. Average backfat thickness was lower in the pigs fed camitine or chromium nicotinate than in pigs fed the control diet. These results indicate that additions of dietary carnitine and chromium nicotinate are viable means of increasing carcass leanness in growing-finishing pigs. Further study of the metabolism of carnitine, chromium nicotinate, and betaine is needed to examine possible modes of action in the growing-finishing pig.; Swine Day, Manhattan, KS, November 17, 1994

Effects of exogenous porcine somatotropin on the carcass composition, hormonal and metabolic profiles, lipogenic capacity, and binding of insulin to erythrocyte receptors of fast- versus slow-growing swine

Twenty barrows were designated as fast-growing (FG) and their littermates designated as slow-growing (SG) based on birth, weaning, and 56-d weight. Half of each group received 70 micrograms of porcine somatotropin (pST)/kg BW daily beginning at 40 kg BW. At 60 and 105 kg BW, blood was collected every .5 h for 12 h beginning 1 h before pST injection, fat biopsies were taken for in vitro lipogenic activity, and insulin erythrocytes were isolated for receptor binding. Swine treated with pST had elevated ADG (.95 vs .88 kg/d; P < .1) and reduced days to slaughter (61 vs 67; P < .1). The pST-treated pigs had less average backfat (2.73 vs 3.96 cm; P < .01), larger longissimus muscle areas (32.3 vs 28.2 cm2; P < .05), and a higher percentage of muscle (56.3 vs 50.3%; P < .01) than control pigs. Exogenous pST increased protein (17.4 vs 13.2%; P < .05) and decreased fat (22.9 vs 37.1%; P < .05). The FG pigs had higher ADG (.98 vs .86 kg/d; P < .01) and required fewer days to slaughter (57 vs 71; P < .01) than SG pigs. Administration of pST increased (P < .01) average pST levels (1.7 vs 14.0 ng/mL) in FG and SG pigs at 60 kg BW. At 105 kg BW, pST was higher (P < .01) in pST-FG than in pST-SG swine (46.0 vs 19.3 ng/mL) but was not different between FG and SG control swine (1.9 vs 1.8 ng/mL). Administration of pST increased concentrations of IGF-I (510.0 vs 160.0 ng/mL) and nonesterified fatty acids (182 vs 109 muEq/L, P < .01) in FG and SG swine. Over sample periods and growth rates, pST reduced (P < .05) CO2 production and lipid synthesis (.345 and 1.85 vs .575 and 2.71 mumol of glucose incorporated.g-1.2 h-1). At 60 kg BW, FG swine had less (P < .01) CO2 production and lipid synthesis (.299 and 1.83 vs .921 and 3.61 mumol.g-1.2 h-1) than did SG swine. Exogenous pST increased (P < .05) binding to insulin erythrocyte receptors (7.25 vs 6.34%).

The dietary protein and(or) lysine requirements of barrows and gilts

A cooperative research study involving three experiments and 2,318 pigs was conducted at 12 research stations to evaluate the protein (lysine) requirements of barrows and gilts. The two sexes were penned separately and fed fortified corn-soybean meal diets containing protein levels ranging from 12.0 to 17.2%. Lysine levels in these diets ranged from .52 to .90%. Protein levels in Exp. 1 were 12, 14, and 16%; in Exp. 2, protein levels were 13, 14, 15, and 16%; and in Exp. 3, they were 13.2 15.2, and 17.2%. Fat (5%) was added to one-half of the diets in Exp. 3. Each station that participated contributed a minimum of two replicate pens of pigs per diet-sex combination in a given experiment. Average initial and final weights were 35 and 99 kg in Exp. 1 and 51 and 105 kg in Exp. 2 and 3, respectively. At the end of the test period, pigs were slaughtered and hot carcass weight, 10th rib fat depth, and longissimus muscle area were measured. Percentage of carcass muscle was estimated from these data. Overall, barrows gained weight faster than gilts (P < .01), but gilts required less feed per unit of gain (P < .05) and had less backfat, larger longissimus muscle areas, and a greater percentage of carcass muscle (P < .01) than did barrows. Lean growth rate was similar for barrows and gilts (332 vs 329 g/d). Increasing the dietary protein or lysine level resulted in improved rate and efficiency of gain and increased carcass leanness and lean growth rate in gilts, but the increase was less pronounced or did not occur in barrows, resulting in protein level x sex interactions. Feeding low-protein (12 or 13%) diets decreased performance and carcass leanness to a greater extent in gilts than in barrows. The pooled data from the three experiments indicated that most traits tended to reach a plateau at 13% CP (.60% lysine) in barrows, whereas in gilts, weight gains, feed/gain, carcass muscle, and lean growth rate continued to improve, but at a decreasing rate, with up to 17.2% CP (.90% lysine). The results indicate that gilts require higher concentrations of dietary amino acids to maximize lean growth rate than do barrows.

An embryo transfer study of reciprocal cross differences in growth and carcass traits of Duroc and Landrace pigs.

Reciprocal cross differences have been reported for growth rate and carcass traits in F1 pigs with the Duroc (D) as a parent breed. Such differences are synonymous with maternal effects if effects of sex linkage and genomic imprinting are negligible. In the present study, transfer of embryos (ET) to paternal breed recipients partitioned effects occurring at or before fertilization from postfertilization effects for growth and carcass traits in F1 D-Landrace (L) pigs. Fifteen boars sired 115 F1 litters, 49 produced by ET. Growth rate of 349 barrows and 361 gilts and carcass measurements on 256 barrows and 159 gilts were analyzed assuming mixed linear models with animal and litter as random effects. Contrasts among genotype (D x L, L x D)- treatment (ET, non-ET) means were tested. Reciprocal cross differences were not detected for growth rate or for carcass weight, length, average backfat thickness, estimated carcass lean, or lean per day of age. Reciprocal cross differences for 10th rib backfat thickness (BF) and longissimus muscle area (LMA) were detected only in barrows. The sexual dichotomy for reciprocal cross differences followed expectations for a Y-linked gene(s), consistent with the fact that reciprocal D-L crossbred barrows exhibited a paternal effect, with responses more like the sire breed than the dam breed. Barrows that were non-ET from D sires and L dams had 3.9 cm2 larger LMA and 5.8 mm less BF than barrows from L sires and D dams (P less than .001). Barrows from ET sired by D boars had 3.8 cm2 larger LMA than did barrows from ET sired by L boars (P less than .001), although no difference was detected for BF. Barrows sired by D boars reared in a D postfertilization environment (ET) had 6.2 cm2 greater LMA and 4.1 mm less BF (P less than .05) than barrows sired by L boars gestated and reared by D dams (non-ET). Barrows sired by D boars reared by L dams (non-ET) had 1.5 cm2 greater LMA and 2.3 mm less BF (P greater than .10) than barrows sired by L boars reared by L dams (ET). In conclusion, reciprocal cross differences detected for BF and LMA in barrows were established before or at fertilization and seemed to be Y-linked.

Genetic analyses of growth, real-time ultrasound, carcass, and pork quality traits in Duroc and Landrace pigs: I. Breed effects.

Knowledge of breed effects on carcass and pork quality traits is required to develop commercial crossbreeding programs that emphasize product quality. A 2 x 2 diallel mating system involving Landrace and Duroc pigs was used to estimate individual heterosis, direct breed effects and reciprocal cross differences for post-weaning growth, real-time ultrasound, carcass, and pork quality traits. Data from 5,649 pigs and 960 carcasses representing 65 and 49 sires, respectively, were analyzed assuming animal models. Duroc-sired pigs had 2.1 cm shorter carcasses with 7.3 mm less 10th rib backfat (BF), 4.4 cm2 larger longissimus muscle area (LMA), yielded 2.1 kg more estimated fat standardized lean (FSL), gained 16.5 g more estimated lean per day of age (LDOA), and had 1.0% less water (PWAT) and 1.9% more intramuscular fat (IMF) in the longissimus muscle than did Landrace-sired pigs (P less than .01), adjusted to an off-farm live weight of 111 kg. Reciprocal cross differences were detected for BF, LMA, FSL, LDOA and for subjective marbling, firmness, and muscling scores (P less than .01). Durocsired F1 barrows had 6.3 mm less BF and 5.9 cm2 larger LMA, yielded 3.2 kg more FSL, gained 22.3 g more LDOA, and had less marbling in the longissimus muscle and heavier ham muscling than reciprocal cross barrows. Heterosis estimates (P less than .05) were 27.6 g/d (3.2%) for ADG, -5.8 d (-3.6%) for off-test age, 2.7 cm (3.4%) for carcass length, 1.5 kg (7.2%) for FSL, 14.7 g (5.7%) for LDOA, -.07 (-3.6%) for muscle color, -.5% (-13.2%) for IMF, and .3% (.3%) for PWAT. Breed effects were not detected (P greater than .10) for muscle pH, cooking loss, shear value, and water-holding capacity or for eating quality traits. Reciprocal cross differences suggest an advantage in using the Duroc as a terminal sire, but improved carcass composition and higher intramuscular fat did not seem to affect eating quality traits.

Feed efficiency, carcass characteristics, and sensory quality of lambs, with or without prolific ancestry, fed diets with different protein supplements1

Data were collected on 130 intact male lambs fed diets based on roughages supplemented with fish meal, soybean meal, or corn gluten-blood meal and slaughtered at 43 kg live weight. A nonsupplemented group served as a control. The lambs represented Romanov (R), Finnsheep (F), a new breed developed in Canada (DLS), Coopworth (C), and Suffolk (S), three first crosses of DLS with R, F, and Booroola Merino (B), and their backcrosses to DLS. Supplemented lambs consumed 16 to 22% less (P less than .05) silage than control lambs. Average daily gains of lambs fed fish meal (226 g) and corn gluten-blood meal (217 g) were higher and feed conversion ratio (4.99 and 5.11) lower than that of lambs fed soybean meal (189 g and 5.48) or control (186 g and 5.76) diets (P less than .05). The cost of feed per kilogram of gain or per kilogram of lean produced was similar in the four treatments but was between C $.23 and .65 cheaper in the protein-supplemented groups when the number of days to reach slaughter weight was considered. The effect of diet on carcass traits and meat quality were minimal. Meat of lambs fed the three protein supplements was less juicy than that of control lambs. With a few exceptions, most of the significant differences among genetic groups in growth, carcass, and sensory traits were mainly between prolific (R and F) and meat-type breeds (C, S, and DLS). Gain in weight was highest in S lambs (199 g/d), but F and R first crosses were the youngest at slaughter (196 and 198 d). The F lambs had higher dressing and kidney fat percentages than meat-type breeds. The DLS lambs had the largest longissimus muscle area (14.0 cm2), whereas C had the smallest (10.7 cm2). The B crosses had larger longissimus muscle area than R and F crosses. The R lambs had more lean and less fat in the 12th rib, whereas C lambs had the lowest lean and a high bone percentage. The toughest and the most tender roasts were those of R and B crossbred lambs, respectively. Roasts from F lambs had the most intense lamb flavor.

Performance of Hereford and two-breed rotational crosses of Hereford with Angus and Simmental cattle: II. Carcass traits of steers

Calf carcass traits were evaluated for Simmental (S) x Hereford (H) and Angus (A) x H crosses in two-breed rotations and for straightbred H. Data were grouped into seven dam breed categories: straightbred Hereford (H), F1 S x H cows (SH), S x H cows of low percentage H (SHS), S x H cows of high percentage H (HSH), F1 A x H cows (AH), A x H cows of low percentage H (AHA) and A x H cows of high percentage H (HAH). Straightbred H and crossbred SH, AH, SHS and AHA cows were mated to H bulls, HSH cows were mated to S bulls and HAH cows were mated to A bulls. Calves from the S x H rotation produced heavier carcasses with less fat, lower quality grade, larger longissimus area and increased estimated cutability compared to A x H calves. Some significant intergenerational differences were observed within rotations, particularly within S x H. Calves from HSH cows mated to S bulls produced carcasses with less fat cover, lower quality grade, larger longissimus muscle area and higher estimated cutability compared to calves from SHS dams mated to H bulls. Within both rotations, evaluation of carcass weight per day of age indicated that postweaning ADG was lower for generations for which H was the sire breed. Carcass traits of calves from SHS, HSH, AHA and HAH dam breed groups from the last 3 yr of the study when calves were fed under two different postweaning management systems were evaluated in a separate analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcass grades, rack composition and tenderness of sheep and goats as influenced by market class and breed

Compared to Spanish and Angora goats, sheep had heavier ( P < 0.05) carcass weights, more youthful USDA overall maturity scores, higher flank streaking scores, higher USDA leg conformation scores, larger longissimus muscle areas, and produced loin chops with lower shear force values. Rambouillet sheep had ( P < 0.05) higher scores for USDA skeletal and overall maturity, more feathering and flank streaking, higher USDA leg conformation scores and produced loin chops with lower shear force values than Barbados and Karakul sheep. Karakul sheep (especially the young intact males) had higher adjusted fat thicknesses than the other sheep and goat breeds due to heavy fat deposition near the dock. Racks from young intact males tended to have higher percentages of lean than racks from aged females within most sheep and goat breeds.

Evaluation of Cimaterol for Finishing Swine including a Drug Withdrawal Period

One hundred fifty crossbred pigs (55 kg) were allotted by weight, sex and litter to a randomized complete-block design with five dietary treatments, six blocks per treatment and five pigs per pen with sex equalized across treatments. Corn-soybean meal-based diets (.65% lysine) with 0, .25 and .5 mg/kg cimaterol were fed, on an ad libitum basis, to pigs slaughtered at an average pen weight of 104 kg/pig. Drug withdrawal prior to slaughter was 1, 3 and 5 d for pigs fed cimaterol at .25 mg/kg and 1 d for those fed cimaterol at .5 mg/kg of diet. Dietary cimaterol level influenced (quadratic, P less than .01) average daily gain during the first 42 d on test; however, daily feed intake and feed conversion ratio were not affected (P greater than .1). Pigs fed .25 mg/kg cimaterol with a 1-d drug withdrawal had 6.8, 7.7 and 13.5% less 10th rib fat depth and 11.1, 6.1 and 13.3% less P2 fat depth than those subjected to either a 3- or 5-d drug withdrawal or those fed the 0 mg/kg cimaterol diet (control), respectively. Overall, pigs fed cimaterol had 7.9% larger longissimus muscle area and 2.6% more kilograms of muscle than pigs fed the control diet. Cimaterol fed at .5 mg/kg resulted in higher (P less than .05) Warner-Bratzler shear force values and altered the proportion of saturation in some long-chain fatty acids, although the total saturated:unsaturated fat ratio was not affected. Pigs fed no cimaterol had less thaw loss (P less than .05) than did those fed other treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcass Characteristics of Weanling Calves Grazed at Three Levels of Forage Availability

Twelve heifers and 12 steer calves born in the fall were slaughtered at weaning at an average age of 259 days. Before weaning, calves grazed a bermudagrass-ryegrass-arrowleaf clover sward at three levels of forage availability (FA). Average daily gains (ADG) of cows and calves on the low, medium and high FA paddocks were −.25 and .67, −.02 and .76, and .47 and .97 kg (P<.05), respectively. The low, medium and high FA paddocks supported stocking rates of 6.27, 4.52 and 2.72 cow-calf units/ha (P<.05) and calf weaning weights of 236, 251 and 289 kg (P<.05), respectively. Carcasses of calves that had grazed high FA paddocks were fatter (P<.05) than carcasses of calves that had grazed low FA paddocks (5.08 vs 1.27 mm over the longissimus muscle) and their longissimus muscle areas were more than 18% larger (P<.05). Marbling scores and quality grades of carcasses from calves on high FA paddocks were 33 and 27% higher (P<.05), respectively, than those of calves on low FA paddocks. There were few significant differences in palatability-related traits of loin steaks from carcasses of calves on the three levels of FA. Also, except for juiciness, steaks from 22 grain-fed steers generally received higher (P<.05) taste panel scores and had lower shear force values than did steaks from carcass of any of the three FA groups of calves. Steer carcasses showed higher (P<.05) ADG and weaning weight and larger longissimus muscle areas than did heifer carcasses, whereas heifer carcasses had greater (P<.05) fat thickness over the longissimus muscle, more (P<.05) kidney, pelvic and heart (KPH) fat and a higher (P<.05) yield grade number (lower cutability). There were no differences (P>.05) in other carcass characteristics or in any of the palatability-related traits of loin steaks from steers and heifers.

Characterization of Ram and Ewe Breeds. II. Growth and Carcass Traits2

Rambouillet, Suffolk and Suffolk × Rambouillet rams were mated to Louisiana Native, Hampshire × Native, Rambouillet × Native and Suffolk × Native ewes. When purebred Rambouillet and Suffolk sires were compared to Suffolk × Rambouillet sires, significant differences in favor of purebred-sired lambs were observed for birth weight, feedlot daily gain, lifetime weight per day of age and slaughter weight, but no differences were found for any carcass trait measured. Because of the small sire sample and because the crossbred rams were from a different flock than the Suffolk rams, limited credence should be placed on the slower growth of the crossbred-sired lambs. However, Suffolk-sired lambs were superior to the Rambouillet-sired lambs for most growth and carcass characteristics. Suffolk-sired lambs were significantly heavier at birth, gained more rapidly in the feedlot, had higher lifetime weights per day of age, lower yield grades, less fat thickness over the longissimus muscle, smaller kidney fat weights and heavier weights of retail cuts than lambs from Rambouillet sires. Lambs from Native ewes tended to be smaller at birth, grew more slowly, had smaller longissimus muscle areas and had more kidney fat than lambs from Hampshire × Native, Rambouillet × Native and Suffolk × Native ewes, showing that growth and carcass traits of the Native sheep can be improved by crossing with wool and mutton breeds. Lambs from Suffolk and Hampshire cross ewes excelled those from Rambouillet cross ewes for weaning weight and lifetime weight per day of age. Suffolk and Hampshire cross ewes also produced lambs with larger longissimus muscle areas, less kidney fat and lower yield grades than lambs from Rambouillet cross ewes. In addition, lambs from Hampshire × Native ewes were fatter and lower in cutability than lambs from Suffolk × Native ewes.

Postweaning Performance and Carcass Merit of Purebred and Two-Breed Cross Pigs

The feedlot records of 2,111 purebred and crossbred pigs representing all purebred and all possible two-way crosses of Duroc, Hampshire and Yorkshire were analyzed to evaluate average daily gain on test, age at 100 kg, average backfat probe of gilts, average daily feed consumption and feed conversion. A random sample of 392 barrows was used to evaluate carcass traits. The data were analyzed to determine breed of sire and breed of dam effects, to evaluate differences between reciprocal crosses and to estimate heterosis. Breed of sire and breed of dam effects were significant for many of the traits evaluated. Straightbred Durocs had a higher average daily gain, were fatter and produced carcasses that were firmer and had more marbling than straightbred Hampshires or Yorkshires (P<.05). Yorkshires were the most efficient straightbred while Hampshires had the largest longissimus muscle areas and leanest carcasses of the straightbreds. Significant differences were noted between reciprocal crosses. When Yorkshires were involved in the cross, the pigs were more efficient, consumed less feed per day and produced carcasses that were leaner and had larger longissimus muscle areas when the Yorkshire was used as the dam rather than as the sire (P<.05). Significant and favorable heterosis was found for average daily gain, age at 100 kg, feed efficiency, feed consumption and carcass length when averaged over all crosses. The general lack of heterosis for carcass traits indicates that the carcass merit of crossbred pigs can be approximated by the average of the purebreds involved in the cross.

Heterosis and Management Effects in Carcass Characters of Angus, Hereford and Reciprocal Cross Cattle

Heterosis for carcass characters was estimated from Angus and Hereford crosses. Two data sets were analyzed. Data set I contained records of 1,095 calves placed on feed immediately after weaning. Data set II was made up of records on 210 calves assigned randomly to either immediate feeding or deferred management (wintering, grazing and then feeding). Cattle with Angus sires or dams produced heavier carcasses with higher dressing percentages, conformation scores, marbling scores and final grades, a larger percentage kidney fat and thicker fat cover but lower estimated cutability than cattle with Hereford sires or dams. Steers dressed higher, producing heavier carcasses with higher conformation scores and larger longissimus muscle areas, whereas heifers were fatter and graded higher. Carcasses from deferred cattle were heavier, with higher marbling scores and grades, less kidney fat, larger longissimus muscle areas and higher estimated cutability than carcasses of cattle fed immediately after weaning. Heterosis was observed for carcass weight, longissimus muscle area and measures of fatness in both data sets.