Decreased glucose tolerance and plasma adiponectin:resistin ratio in a mouse model of post-traumatic stress disorder.

AIMS/HYPOTHESIS: Obesity and type 2 diabetes are among the most serious health pathologies worldwide. Stress has been proposed as a factor contributing to the development of these health risk factors; however, the underlying mechanisms that link stress to obesity and diabetes need to be further clarified. Here, we study in mice how chronic stress affects dietary consumption and how that relationship contributes to obesity and diabetes. METHODS: C57BL/6J mice were subjected to chronic variable stress (CVS) for 15 days and subsequently fed with a standard chow or high-fat diet. Food intake, body weight, respiratory quotient, energy expenditure and spontaneous physical activity were measured with a customised calorimetric system and body composition was measured with nuclear magnetic resonance. A glucose tolerance test was also applied and blood glucose levels were measured with a glucometer. Plasma levels of adiponectin and resistin were measured using Lincoplex kits. RESULTS: Mice under CVS and fed with a high-fat diet showed impaired glucose tolerance associated with low plasma adiponectin:resistin ratios. CONCLUSIONS/INTERPRETATION: This study demonstrates, in a novel mouse model, how post-traumatic stress disorder enhances vulnerability for impaired glucose metabolism in an energy-rich environment and proposes a potential adipokine-based mechanism.

Effects of hydrodynamic pressure processing on the marination and meat quality of turkey breasts.

The effects of hydrodynamic pressure processing (HDP) on marination and meat quality characteristics of turkey breasts were investigated. Breast muscles from 45 turkey hens were removed from the carcasses within 30 min postmortem. From each bird, the breast from one side was treated with HDP and the other side served as a nontreated control. Breasts were then marinated in either 15 or 30% brine (water, salt, and phosphate) based on muscle weight with vacuum tumbling for 30 min or nonmarinated. The control and HDP-treated breasts from each bird received the same marination treatment. Brine uptake, processing yield, and cooking loss were measured as processing characteristics and texture, color, and expressible moisture were measured to document changes in meat quality. Hydrodynamic pressure processing increased (P < 0.001) brine uptake after 10 and 30 min of marination and increased (P < 0.001) processing yield compared with controls. The HDP-induced improvements in these processing characteristics were augmented at 30% brine levels compared with 15% brine. Cooking loss was lower (P < 0.001) in marinated breasts compared with nonmarinated samples. Hydrodynamic pressure processing decreased (P < 0.0001) Warner-Bratzler shear force and significantly influenced texture profile parameters, resulting in reduced hardness but increased cohesiveness and springiness compared with controls at both marination levels. Hydrodynamic pressure processing did not influence color (L*, a*, and b*) or expressible moisture values compared with controls at either marination level. Marinated samples (15 and 30% brine levels) had lower (P < 0.001) Warner-Bratzler shear force values and lower (P < 0.05) hardness, cohesiveness, and chewiness values compared with nonmarinated samples. Data from this study suggest that HDP enhances brine absorption, increases processing yield, and improves texture characteristics in marinated turkey breasts.

Sorting for beef tenderness using high performance liquid chromatography and capillary electrophoresis: A research note.

This study utilized two sampling methods to examine changes in sarcoplasmic proteins during aging of beef and their relation to tenderness. Water-soluble proteins either obtained by manually expressing exudates from the meat (drip) or by an extraction procedure using homogenization and centrifugation (ext) were analyzed for longissimus lumborum muscle using HPLC and capillary electrophoresis (CE) on days 2, 7, 10 and 14 postmortem. A peak that consistently increased with aging was identified using HPLC. Among nine peaks detected in the CE analysis, peak 9 (100kDa) that increased and peak 4 (30kDa) that decreased with aging were correlated (P<0.05) to tenderness as determined by Warner-Bratzler shear force (WBSF). For pooled data of all aging periods, drip sample explained the most variability (49%) in shear force compared to ext sample (25%) using HPLC analyses. At 2 days postmortem, a multiple linear regression model explained 83% of the variation in WBSF using CE-ext or HPLC-drip samples. Sixty percent of the variability in shear force was explained by CE-ext samples for day 7 data. The variability in shear force as explained by either drip or ext sample was less than 51 percent for 10 and 14 days postmortem data. The drip samples were comparable to ext samples in predicting WBSF values for both tough (>46N WBSF on day 2) and tender (<46N WBSF on day 2) strip loins using CE and HPLC procedure. Results suggest that a simple drip sampling may have a potential for use with either HPLC or CE analyses on day 2 postmortem for sorting carcasses into tenderness groups.

Effects of hydrodynamic pressure on the viability of Trichinella spiralis in pork.

Treatment by hydrodynamic pressure is an attractive alternative for meat tenderization and might also have an effect on foodborne pathogens. Numbers of Trichinella spiralis recovered from infected pork were significantly reduced by treatment with the Hydrodyne process, as compared with untreated, infected pork. However, treatment with the hydrodynamic force described in this paper (55 to 60 MPa) did not eliminate the infectivity of this parasite when the larvae from Hydrodyne-treated meat were inoculated into mice.

The callipyge phenomenon: tenderness intervention methods.

Consumers continue to desire leaner meats. Lambs expressing the callipyge gene have been identified as having superior, leaner carcasses compared with normally muscled lambs. However, the longissimus muscle, a major merchandised muscle in lamb, has repeatedly been shown to be significantly less tender in callipyge lamb compared with normally muscled lambs. Preharvest factors, such as genetics, sex, and production/management practices, have thus far shown no promise at alleviating this tenderness problem. But a number of postharvest interventions have been introduced to alleviate it. Included among the strategies are postmortem aging, carcass electrical stimulation, the combination of freezing and thawing before aging, calcium chloride injection, and the Hydrodyne process. These strategies have exhibited various degrees of success. Postharvest strategies to improve callipyge longissimus tenderness are described in this article.

Simultaneous histochemical determination of three fiber types in single sections of ovine, bovine and porcine skeletal muscle.

Classification of muscle fiber types involves tedious comparisons of serial muscle tissue sections. Procedures that would incorporate pertinent histochemical properties into one simplified assay for the successful differentiation and determination of fiber types were evaluated using muscle samples from three different species (ovine, bovine and porcine). For ovine and porcine muscle tissue, the best staining procedure involved initial preincubation of the tissue section at 4.35 (for ovine) and 4.30 (for porcine) followed by incubating for succinate dehydrogenase (SDH) activity, then staining for myofibrillar adenosine triphosphatase (ATPase) activity after an acid preincubation and, finally, counterstaining with hematoxylin. For bovine muscle tissue, the procedure involves first incubating for SDH activity, after which the section is incubated at pH 4.15 and then stained for myofibrillar ATPase activity after an acid preincubation, with a concluding counterstaining using hematoxylin. These procedures permit successful differentiation and identification of three fiber types (beta R, alpha R and alpha W) from a single section of muscle tissue with approximately a 65% saving in time and materials. The results of histochemically typing muscle fibers in a single tissue section stained with these techniques were similar to those obtained with the traditional methods comparing serial sections.

The effect of trenbolone acetate on performance, plasma lipids, and carcass characteristics of growing ram and ewe lambs.

The purpose of the study was to determine the effect of trenbolone acetate (TBA) on performance, plasma lipid metabolites, and carcass characteristics of growing ram and ewe lambs in two separate experiments. Treatments consisted of 1) a control, no implants, and 2) a TBA implant (60 mg of Finaplix; Hoechst-Roussel Agri-Vet). Twelve Rambouillet cross ram lambs (average 19.9 kg BW; Exp. 1) and 18 Suffolk-Hampshire ewe lambs (average 37.2 kg BW; Exp. 2) were given ad libitum access to a 77% forage/23% concentrate diet (15.5% CP and 2.14 Mcal of ME/kg). On d 0, six rams and nine ewes received TBA as an ear implant and six rams and nine ewes were designated as controls. Blood samples were collected via jugular venipuncture on d 0, 28, 56, and 84 and plasma was separated and analyzed for lipid metabolites. Rams (30.5 kg BW) and ewes (50.0 kg BW) were slaughtered after 93 and 91 d, respectively. Average daily gain was not affected by TBA in rams (117 g/d) or ewes (159 g/d). Nutrient intake restricted normal BW gains in the rams. Plasma concentrations of total cholesterol, high-density lipoprotein cholesterol, triglycerides, and nonesterified fatty acids were not affected by TBA in either rams or ewes. Trenbolone acetate had no effect on subcutaneous fat measurements in either rams or ewes. Lamb chops from rams implanted with TBA were less (P < .04) tender (5.58 vs 4.26 kg/1.27-cm core) than lamb chops from control rams. Additional studies examining growth and carcass composition are needed in ruminants implanted with anabolic steroids and fed high-forage diets.

Influence of rapeseed meal, whole rapeseed, and soybean meal on fatty acid composition and cholesterol content of muscle and adipose tissue from ram lambs.

Twenty-four Suffolk x Hampshire ram lambs (average 46 kg) were assigned to one of three diets containing rapeseed meal (RM), soybean meal (SBM), or whole rapeseed-soybean meal (RSSBM) as the protein source. Diets contained 75% roughage, 14% CP and 2.0 Mcal of ME/kg and lambs were allowed ad libitum access to diets for 35 d. Lipid composition of the longissimus, semimembranosus, and triceps brachii muscles and their corresponding s.c. adipose tissue was determined by gas-liquid chromatography (GLC). The total lipid content in either muscle or subcutaneous fat was not different (P greater than .01) by diet. In lean tissue, palmitic and palmitoleic acids were higher and stearic acid was lower (P less than .01) in rams fed RM than in rams fed RSSBM or SBM, regardless of anatomical location. In the s.c. adipose tissue, the amounts of myristoleic, pentadecylic, and palmitoleic acids were lower and the amount of stearic acid was higher (P less than .01) in rams fed RSSM than in those fed RM or SBM, regardless of anatomical location. The semimembranosus and triceps brachii muscles from all treatments contained 12 to 19% more polyunsaturated fatty acids (PUFA) than the longissimus muscle. The cholesterol content of the three muscles was highest in SBM-fed lambs, lowest in RM-fed lambs, and intermediate in RSSBM-fed lambs. These results demonstrate that dietary treatments of the types used in the present study elicit changes in fatty acid composition of both adipose and muscle tissue without affecting the quantity of total lipid.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of slaughter weight and carcass electrical stimulation on the quality and palatability of beef from young purebred bulls.

Seventy-eight purebred Angus and Brahman bulls (10 to 18 mo at slaughter) were used to determine the effects of slaughter weight (60, 80, 90 or 100% of the average mature-cow weight for the respective breed) and carcass electrical stimulation (500 V, 20 2-s impulses on the right side) on carcass and meat characteristics. Angus bulls grazed summer forage (millet) after weaning, while Brahman bulls were fed to stimulate gains achieved on forage by Angus bulls. Bulls were then placed in the feedlot for finishing to their designated slaughter weight (293, 381, 412 and 463 kg for Angus and 316, 420, 463 and 516 kg for Brahman). Coarse dark band formation and lean color problems normally associated with bullock carcasses were either eliminated or reduced by stimulation. Increasing slaughter weight from 60 to 90% was associated with an increase in panel tenderness scores for loin steaks. However, increasing slaughter weight from 90 to 100% little change was detected. On the other hand, shear values for loin steaks decreased with increasing slaughter weight. Stimulation increased the tenderness of loin steaks as determined by both panel scores and shear values, and of bottom round steaks (shear-force values). The data from this study suggest that meat from the bulls slaughtered at lighter weights was generally tough, but was improved when bulls were fed to heavier, yet acceptable weights. This research encourages implementation of electrical stimulation on carcasses from young bulls to improve quality-indicating factors.

Influence of dietary palm oil supplementation on serum lipid metabolites, carcass characteristics, and lipid composition of carcass tissues of growing ram and ewe lambs.

The objective of this research was to determine the influence of dietary palm oil supplementation on carcass characteristics and lipid composition of tissues from growing lambs. Twenty-eight Suffolk x Hampshire lambs were weaned at 60 d of age (average 36 kg BW) and assigned to a 2 x 2 factorial arrangement consisting of diet (control [NPO] or 10.6% added dietary palm oil [PO]) and sex (ram vs ewe). The NPO diet (77% forage and 23% concentrate) contained 11.2% CP and 2.66 Mcal of ME/kg. Palm oil replaced molasses in the PO diet. Lambs were individually given ad libitum access to feed for 60 d to a final BW average of 50.1 kg. Lipid composition of the longissimus muscle and corresponding subcutaneous (s.c.) adipose tissue was determined by gas-liquid chromatography (GLC). Lambs fed PO were fatter (P less than .01) than lambs fed NPO (.77 vs .56 cm, s.c. fat). Diet had no effect on cholesterol content of lean tissue; however, feeding PO increased the saturated fatty acids of lean tissue. The s.c. fat from lambs fed PO had less (P less than .01) cholesterol (64.79 vs 89.67 mg/100 g) and more saturated fatty acids than that from lambs fed NPO. Ewes were fatter (P less than .01) than rams, yet they had less cholesterol content in the s.c. adipose tissue (68.71 vs 85.74 mg/100 g). High amounts of dietary palm oil fed to growing lambs caused changes in fatty acid deposition and cholesterol metabolism and may be a useful investigative tool to study lipid metabolism in growing ruminants.(ABSTRACT TRUNCATED AT 250 WORDS)

The hydrodyne: a new process to improve beef tenderness.

The organoleptic trait most affecting consumer acceptance of beef is tenderness. The Hydrodyne process uses a small amount of explosive to generate a shock wave in water. The shock wave passes through (in fractions of a millisecond) objects in the water that are an acoustic match with water. Four beef muscles (longissimus, semimembranosus, biceps femoris, and semitendinosus) exposed to either 50, 75, or 100 g of explosives were significantly tenderized compared with controls. As much as a 72% reduction in shear force was observed for the longissimus muscle using 100 g of explosives. Reductions in shear force with magnitudes of 30 to 59% improvements were observed for the other three muscle types. Results suggest that tenderizing beef with the Hydrodyne process presents a potentially novel opportunity in the way the meat industry can tenderize meat.

The effect of roasted soybeans in the diet of feedlot steers and Synovex-S ear implants on carcass characteristics and estimated composition.

Beef steer carcasses from three 2 x 2 factorial feeding experiments (Exp. 1, 20 carcasses; Exp. 2 and 3, 19 carcasses each) were evaluated to study the influence of supplementing with roasted soybeans (RSB; 127 degrees C for 10 min) vs soybean meal (SBM) and implanting with the estrogenic growth promoter Synovex-S (SYN, 20 mg estradiol benzoate and 200 mg progesterone) on carcass merit, composition of dissected 9-10-11th rib section, estimated edible carcass composition, and cooking characteristics of strip loin steaks. In all experiments, steers were fed diets consisting of 15% corn silage, 15% orchardgrass silage, and 70% corn-based concentrate. There were no treatment interactions found in this study. Final BW averaged 480.4, 498.5, and 500.7 kg for Exp. 1, 2, and 3, respectively, and hot carcass weights averaged 288.4, 296.4, and 309.1 kg. Across experiments, hot carcass weight was 8.3 kg less (P < .03) for RSB steers than for SBM steers. Fat weight (P < .01) and percentage of fat (P < .01) were less and percentage of bone (P < .04) was greater in the 9-10-11th rib section of RSB steers than of SBM steers. Estimated percentage of fat (P < .02) was less and percentage of bone (P < .04) was greater in edible carcass of RSB steers than in that of SBM steers. Total 9-10-11th rib section weight tended to be less for RSB steers (P < .08) than for SBM steers. Carcass merit measurements were not affected (P > .10) by supplement, but numerically the percentage of kidney, pelvic, and heart fat was 11% greater for RSB steers than for SBM steers in Exp. 2 and 3. Final BW and carcass weight were 38.7 and 22.6 kg greater (P < .01), respectively, for SYN-implanted steers than for steers not implanted. Longissimus muscle area was greater (P < .01), percentage of kidney, pelvic, and heart fat (P < .02) was less, USDA quality grade tended to be less (P < .09), and shear force of strip loin was greater (P < .01) for SYN-implanted steers than for steers not implanted. The 9-10-11th rib section and estimated carcass compositions were not different (P > .10) between SYN-implanted steers and steers not implanted but reflected a somewhat leaner carcass. The authors conclude from this study that in feedlot steers, either implanted or not implanted, there is no benefit from supplementing with RSB in place of SBM, and that the use of RSB in place of SBM in feedlot diets may reduce the amount of edible carcass.

Influence of level of dietary protein or energy on effects of ractopamine in finishing swine.

The effect of ractopamine, a beta-adrenergic agonist, on growth, nutrient utilization, and carcass composition was studied in pigs fed either 18% CP, 12% CP, or 18% CP restricted (RES = 67% of ad libitum) diets. The 18 and 12% CP diets provided 3.52 and 3.68 Mcal of DE/kg, respectively. All pigs were fed a low-protein (12% CP) diet during pretreatment growth from 15 to 60 kg. Ractopamine at 20 or 30 ppm (30 ppm for RES pigs) in the diet was fed from 60 kg live BW until slaughter at 105 kg (9 pigs/treatment). No ractopamine treatment effect (P greater than .05) was observed for either daily gain or gain/feed, although gain/feed was improved by 8% in both of the ad libitum groups. Ractopamine treatment resulted (P less than .01) in an overall reduction of carcass lipid by 8%, an increase of carcass protein by 5%, and a 21% improvement in the efficiency of protein utilization; the greatest changes occurred in the pigs fed the 12% CP diet (-17%, +11%, and +32%, respectively). The ad libitum daily feed intake was 15% less for pigs fed the 12% CP diet than for those fed the 18% CP diet (P less than .01), and there was a 10% reduction in intake of both diets with the addition of ractopamine (P less than .05). Both carcass lipid and protein deposition seemed to be closely related to energy intake (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of sex and exogenous porcine somatotropin on longissimus muscle fiber characteristics of growing pigs.

Thirty-seven pigs with an initial live weight of 60 kg were used to investigate the effects of daily exogenous porcine somatotropin (pST) administration at two dose levels (0 and 100 micrograms.kg-1.d-1) for a 31-d period on muscle fiber characteristics and meat tenderness of boars, gilts and barrows. Excipient boars and gilts had more alpha W and fewer alpha R fibers than did those receiving pST. The percentage of muscle fiber type for barrows was not affected by pST treatment. The administration of pST resulted in an increase in muscle fiber size for all three fiber types in all three sexes, but these changes were of greater magnitude in barrows (31.8%) and gilts (27.8%) than in boars (9.3%). Somatotropin negated the intrinsic sex effect differences in fiber area of the pigs. There was no difference in tenderness among excipient boars, barrows and gilts; however, with the inclusion of pST, shear force decreased in boars and gilts and increased in barrows. A high proportion of the pST-treated pigs contained giant fibers in the longissimus muscle. Furthermore, a small proportion of the pST-treated pigs exhibited pale, soft, exudative muscle. Whether the giant fiber anomalies occurred through increased muscle activity or from fibers undergoing degenerative changes was not determined.

Response of low and high protein select lines of pigs to the feeding of the beta-adrenergic agonist ractopamine (phenethanolamine).

The effect of ractopamine, a phenethanolamine beta-adrenergic agonist, on growth, nutrient utilization and carcass composition was studied in two lines of pigs that were fed high (24%) or low (12%) protein diets. Of the two lines of pigs that had been selected for seven generations for rapid lean growth when fed either the higher (HS line) or low (LS line) protein diet, the HS line tended to exhibit a leaner carcass when fed either diet. Ractopamine, at 20 ppm in the diet, was fed from 60 kg live body weight until slaughter at 90 kg. When compared with their respective line-diet control group, the greatest response to ractopamine treatment was observed in the LS-12 group; at 90 kg, that group had 31% less carcass lipid (P less than .05) and 17% more carcass protein (P less than .05). Considering the change that took place only between 60 and 90 kg live body weight, this translated into 57% less lipid and 59% more protein deposited in the carcasses with ractopamine treatment. This group also was 73% more efficient (P less than .05) in converting dietary protein to carcass protein but 39% less efficient (P less than .05) in energy utilization. Response to ractopamine treatment was least by the LS-24 group, followed by the HS-12 and HS-24 groups. A line x diet x treatment interaction (P less than .05) was noted for whole-carcass lipid, backfat, longissimus muscle area and efficiency of protein utilization.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid composition of muscle and adipose tissue from crossbred ram, wether and cryptorchid lambs.

Lambs from rams (R), cryptorchids (C) and wethers (W) were examined to compare with the dietary guidelines for humans on fat and cholesterol intake. Twenty-four lambs were assigned to treatments as R, C or W at weaning (60 d). Each lamb had ad libitum access to a 77:23% forage:concentrate diet containing 11.7% crude protein and 1.84 Mcal ME/kg. The experiment was terminated when the lambs reached 50 kg body weight. Lipid composition of the longissimus muscle (LM) and s.c. adipose tissue was determined by gas-liquid chromatography. Rams has less (P less than .01) s.c. fat (cm) and i.m. lipid (%) (.26 cm; 3.*%) than W (.56 cm; 4.9%). Total polyunsaturated fatty acids were greater (P less than .01) in the LM of R (7.06%) than in LM of W (5.21%). Rams had higher percentages of C18:2, C18:3, C20:4 and C18:1 in their LM than W did. On the basis of a 100-g serving of LM, R had 1.73, C had 2.15 and W had 2.21 g saturated fatty acids. There were no (P less than .01) differences among sex types for cholesterol content of LM, which averaged 66.6 mg/100 g wet tissue. The only major difference of the s.c. fat lipid composition was in saturated fatty acids. Wethers had higher (P less than .01) saturated fatty acids (51.4%) than C 46.8%) and R (43.3%). Based on the lipid composition of these three types of lambs, the LM muscle from young R lambs approached dietary fat guidelines for humans more closely than did that from castrates.

Effects of high-forage diets with added palm oil on performance, plasma lipids, and carcass characteristics of ram and ewe lambs.

The objectives of this study were to determine the effects of high-forage diets with and without added dietary palm oil (high in palmitic acid) fed at equalized ME intakes on performance, plasma lipids, and carcass characteristics of growing ram and ewe lambs. Thirty-one Hampshire or Suffolk lambs (35.7 kg BW) were used in a 2 x 2 factorial arrangement of the following treatments: 1) rams, no palm oil (R-NPO); 2) ewes, no palm oil (E-NPO); 3) rams, 10.7% dietary palm oil (R-PO); and 4) ewes, 10.7% dietary palm oil (E-PO). Both diets consisted of 77% forage and 23% concentrate. Diet DM contained 15.0% CP and 2.14 Mcal of ME/kg (NPO) or 2.62 Mcal of ME/kg (PO). Lambs were fed individually specified amounts of diet based on BW to equalize ME intake (.20 Mcal of ME/kg of BW.75) for both dietary treatments. Lambs were weighed and feed intakes were adjusted weekly. Lambs were bled by jugular venipuncture on d 28, 56, and 84 and were slaughtered after they had been fed the diets for 90 d. Lambs fed PO had greater (P < .01) ADG and efficiency (ADG/ME intake) than lambs fed NPO. Plasma concentrations of cholesterol, high-density lipoprotein cholesterol, triglycerides, and nonesterified fatty acids were increased (P < .01) by feeding PO. Lambs fed PO were fatter than lambs fed NPO, as evidenced by greater subcutaneous fat thickness and kidney and pelvic fat. Ewes had greater (P < .01) subcutaneous fat than did rams.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth and tissue accretion of lambs fed concentrate in drylot, grazed on alfalfa or ryegrass at weaning, or after backgrounding on ryegrass.

Weaned Targhee x Hampshire lambs (average BW 27.6 kg) were used to determine the effects of concentrate feeding, forage grazing, or finishing on concentrate after grazing upon growth and carcass tissue accretion. Lambs were assigned randomly and balanced by weight and sex to five replicated treatments (12 lambs/treatment): all-concentrate in drylot (DL); rotational grazing alfalfa (ALF); rotational grazing ryegrass (RG); RG for 62 d, then DL (RGDL); RG for 62 d, then ALF (RGALF). Lambs were slaughtered when fat thickness over the ribeye was estimated at 3.8 to 5.6 mm. Lamb growth and carcass measurements included ADG, accretion of bone, lean, and fat in the carcass, and final BW. Lambs on DL had the highest (P = .001) ADG, whereas lambs on RG treatments tended to have the lowest ADG and heaviest final BW. Compared with DL lambs, ALF lambs had lower (P < .05) ADG but comparable final BW. Lambs that grazed RG had more (P = .001) carcass lean weight than lambs fed in DL, but carcass lean weight of lambs grazed on ALF did not differ (P > .05) from that of lambs on the DL or RG treatment. Carcass fat was less (P = .001) for ALF lambs than for the DL, RGDL, or RGALF treatment group. Daily accretion of bone, lean, and fat was highest (P = .001) for DL. Daily accretion of lean and fat for the RG group was less (P = .001) than for the ALF group but did not differ (P > .05) from that of RGALF lambs. Lean:fat ratio in weight gain for DL lambs was less (P < .01) than ratios for the ALF and RG groups, which were similar to those for RGDL and RGALF lambs. When slaughtered at the same level of fat over the ribeye, DL-fed lambs had higher ADG and fewer days on test than grazed lambs. However, lambs finished or backgrounded on forage had high lean:fat tissue gain and a higher percentage of lean in their carcasses than DL-fed lambs.

Lipid composition of carcass tissue from transgenic pigs expressing a bovine growth hormone gene.

Fatty acid profiles and cholesterol content of whole-carcass ground tissue were compared from 26 transgenic (T) pigs expressing a bovine growth hormone gene (bGH) to 26 sibling control (C) pigs. All pigs were fed a common diet and were slaughtered at five different live weights: 14, 28, 48, 68, and 92 kg. The left side of each intact carcass was ground and tissue samples were analyzed for lipid composition and cholesterol content. At 14-kg body weight, carcasses from bGH-T pigs contained 38% less fat, 44% less saturated fatty acids (SFA), 48% less monounsaturated fatty acids (MUFA), and 38% less polyunsaturated fatty acids (PUFA) than C pigs. At 28 kg, bGH-T pigs had 38% less total carcass fat, 42% less SFA, 46% less MUFA, and 24% less PUFA than C pigs. At 48-kg body weight, bGH-T pigs contained 48% less carcass fat, 55% less SFA, 59% less MUFA, and 22% less PUFA than C pigs. At 68 kg, bGH-T pigs had 78% less carcass fat, 78% less SFA, 79% less MUFA, and 53% less PUFA than C pigs. At 92 kg, carcasses from bGH-T pigs contained 85% less carcass fat, 85% less SFA, 91% less MUFA, and 66% less PUFA than those from C pigs. Cholesterol content was not different between bGH-T pigs and C pigs at any of the carcass weights. The trend was for cholesterol content to decrease from the 14- to 92-kg weight group. These results suggest a dilution effect of carcass fat and fatty acids in carcass tissue from bGH-T pigs with increasing live weight.

Effects of restricted feeding on growth performance and carcass composition of lambs.

Fifty-eight crossbred lambs (26 kg BW) with moderate growth potential were used in a completely randomized design experiment to determine the effects of restricted feeding of all-concentrate diets on performance and carcass composition. Feeding levels studied were 100, 85, and 70% of ad libitum intake. Diets that were restricted-fed were formulated to have increased nutrient concentrations to provide equal daily intakes of protein, vitamins, and minerals among DM intake levels. Lambs were fed to a final weight that would yield carcasses of equal weight (24 kg). Average daily gain was reduced linearly (P < .02) and days on feed were increased linearly (P < .02) because of restricted feeding. Feed efficiency, however, was not affected by intake level. The quantity of separable lean tissue within carcass sides was increased (P < .05) with restricted feeding. Total separable fat within the side was reduced (P < .05) in an amount equal to the increase in lean tissue accretion. Chemical analysis of the carcass side showed a decrease (P < .05) in fat percentage and a corresponding increase (P < .05) in water percentage because of restricted feeding. Daily accretion rates of lean and bone tissue were not affected by restricted feeding; however, fat accretion was decreased linearly with decreasing feeding levels. Separable lean tissue within the primal cuts was generally increased with decreasing intakes, which led to a corresponding decrease in separable fat. Restricted feeding strategies can lead to the production of leaner carcasses. Reductions in fat content occur in the subcutaneous, seam, and mesenteric depot sites, but intramuscular fat content of consumable product also is reduced.