Lower Intramuscular Fat Content Research Articles

Lipid composition of the intramuscular fat of beef from Spanish cattle breeds stored under modified atmosphere

The lipid composition of intramuscular fat from 30 young bulls of 5 Spanish cattle breeds (Asturiana de los Valles, Morucha, Parda Alpina, Pirenaica and Retinta) was studied. Steaks from each shortloin were packaged in 60% O 2, 30% CO 2 and 10% N 2 and aged for 0, 5, 10 and 15 days. Lipid classes obtained by thin layer chromatography and total fatty acids obtained by gas chromatography were evaluated. Meat from Asturiana de los Valles had high PL and C contents, and low TG contents that reflected its low intramuscular percentage content. This breed showed high FFA content that likely originated from lipolysis of PL. The main breed effect was due to the low intramuscular fat content observed in the Asturiana de los Valles. After 5 days, FFA decreased because they were probably transformed into other compounds. The Morucha breed may have a genetic predisposition for depositing MUFA, and the high MUFA and C14:0 values observed in the Morucha breed were likely due to its high intramuscular fat percentage. Regarding fatty acid composition, no “days of storage” effect was observed for any of the studied fatty acids, except for C18:3ω6 that increased during the first 5 days of storage in Asturiana de los Valles. Concerning the fatty acid composition, Asturiana de los Valles had the highest PUFA/SFA ratio, while Parda Alpina and Morucha possessed low ω6/ω3 ratios but high C22:6ω3 contents. Finally, the presence of C22:6ω3 and 15-CH 3-C16:0 may be related to higher intramuscular fat contents.

Post-weaning growth of cattle in northern New South Wales. 3. Carry-over effects on finishing, carcass characteristics and intramuscular fat

The effects of prior growth on subsequent growth and body composition of cattle potentially affect the profitability of growing cattle to meet specifications based on weight and fatness. The effects of different growth rates and patterns of growth between weaning (about 230 kg) and entry to finishing (average 400 kg) on growth rate, carcass characteristics and intramuscular fat content of steers finished on pasture and in a feedlot on a predominantly grain ration to 2 liveweights (520 kg, Korean and >600 kg, Japanese) are reported here. Over a period of 4 years (1994–1997), 1095 Bos taurus steers of 4 breeds (Angus, Hereford, Murray Grey and Shorthorn), were allocated to 1 of 3 grow-out pathways from weaning until entry into finishing. The pathways were based on introduced pasture (P1), with different animal growth rates induced by strategic supplementation with a pelleted concentrate feed (P2), or a forage crop (P3) (Ayres et al. 2001; Dicker et al. 2001). In general, the mean growth rate of steers from the different growth pathways during finishing was inversely related to mean growth rate during grow-out. However, where the difference in liveweight at the end of grow-out was greater than 15 kg, increased growth rate during finishing was insufficient to permit complete catch up of liveweight by the end of finishing. There was no further compensation beyond 520 kg liveweight. Steers with better nutrition during grow-out tended to have more intramuscular fat at Japanese market weights, but lower retail meat yield. Steers finished on pasture had less fat thickness and intramuscular fat content than those finished on the grain based ration. Compared with P3 steers, there was a tendency for steers from pathways P1 and P2 to have lower intramuscular fat content in their M. longissimus at Japanesese market weights.

Genetic parameters for lean meat yield, meat quality, reproduction and feed efficiency traits for Australian pigs: 3. Genetic parameters for reproduction traits and genetic correlations with production, carcase and meat quality traits

Genetic parameters were obtained using REML procedures applied to a multiple trait animal model for number born alive (NBA), litter birth weight (LBW), average piglet weight at birth (ABW) recorded in the first, second and third parity (NBA 1,2,3, LBW 1,2,3, ABW 1,2,3) and 21-day litter weight (LW21 1) for 6050 Large White and Landrace sows. Heritability estimates ranged from 0.06 to 0.22 for these reproductive traits, with lowest estimates for NBA 1,2,3 and LW21 1. Reproductive performance in the first parity should be regarded as a different trait than reproductive performance in later parities (range of genetic correlations (rg): 0.52–0.78, ±0.16–0.30). NBA 1,2,3 was unfavourably related with LBW 1, ABW 1,2,3 and LW21 1. In addition, NBA 1,2,3 was negatively correlated with growth rate traits, feed intake and weight of the back leg and ham (BLW, LMW) (rg range: −0.45 to −0.01, ±0.13–0.15). In contrast, genetic correlations were favourable between LBW 1,2,3, ABW 1,2,3 and growth rate, BLW and LMW (rg values: 0.08–0.55, ±0.12–0.25). NBA 1,2,3 and ABW 1,2,3 were not genetically related with backfat measurements, while a low backfat was associated with a high LBW 1,2,3 (rg: −0.54 to −0.08, ±0.09–0.36). Genetic correlations between reproduction traits and meat quality traits were inconsistent between traits and parities. A lower intramuscular fat content was associated with a higher LBW 1,2,3 and ABW 1,2,3 (rg: −0.37 to −0.12, ±0.12–0.18). In summary, genetic correlations between reproduction traits and performance traits were only unfavourable between litter size and growth rate and feed intake. Genetic correlations between litter birth weight and average piglet weight at birth indicate that selection for leanness will also improve litter weight traits.

Effect of type of housing on veal calf growth performance, behaviour and meat quality

A study compared the traditional housing of veal calves in individual crates (IC) with group pen housing (GP). Thirty-four pure Holstein male calves (67.6±4.9 kg LW) imported from Poland were used, of which 16 were kept tethered in IC while the remaining animals were housed in six pens of three calves each. The growth trial lasted 142 days during which the calves were fed only a milk replacer diet. Calves health, average daily gain (ADG) and feed efficiency (FE) were similar between types of housing throughout the trial. However, GP calves had higher ADG (1387 vs. 1317 g/day; P<0.05) and better FE (1.83 vs. 1.94; P<0.05) than IC calves in the last 72 days of the trial. Behavioural measurements were taken at the 10th week of the study. The GP calves were allowed to adopt more comfortable resting postures and displayed increased social behaviour than the IC calves. Haemoglobin in samples taken at the end of the growing cycle was higher in GP than in IC calves (10.9 vs. 7.7 g/100 ml; P<0.01). At slaughter, the dressing percentage was unaffected by the housing system, but GP calves showed a better carcass conformation than IC calves. Meat quality evaluation was carried out on the Longissimus thoracis muscle. The meat of GP calves had lower intramuscular fat content (3.92 vs. 6.85% DM; P<0.01) and showed a better tenderness and flavour than that of the IC calves. Consistent with the haemoglobin data, the calves reared in group pens produced carcasses and meat with a darker colour than calves in individual crates.

Proximate, amino acid and mineral composition of ostrich meat

The proximate composition, amino acid composition and mineral composition of three different muscles from the legs of seven ostriches were determined. Results indicated that components analyzed remained relatively constant between different muscles. Ostrich meat is characterized by an extremely low intramuscular fat content. Values for water, protein, ash, amino acid and mineral contents are in agreement with values obtained for beef and chicken.

Histological, Biophysical, Physical and Chemical Characteristics of Different Ostrich Muscles

Some characteristics generally related to meat quality were evaluated in several muscles from the leg of the ostrich. Ostrich meat is characterised by a relatively high pHf and low intramuscular fat content. Although standard slaughtering procedures of ostriches at present comprise the removal of legs within 30 minpost mortemfrom the carcass, relatively long sarcomere lengths and the absence of a linear relationship (P>0·05) between sarcomere length and Warner–Bratzler shear measurements (WBS) show that no cold shortening occurs in the different muscles. The means obtained for theIliotibialis lateralisare representative of the mean of all the individual muscles combined regarding the characteristics muscle fibre diameter, WBS and pigment content. The overall mean for sarcomere length, pHf and collagen content of all the individual muscles combined can be deduced from determination of these characteristics in theFemorotibialis medius.

Histological, Biophysical, Physical and Chemical Characteristics of Different Ostrich Muscles

Some characteristics generally related to meat quality were evaluated in several muscles from the leg of the ostrich. Ostrich meat is characterised by a relatively high pH f and low intramuscular fat content. Although standard slaughtering procedures of ostriches at present comprise the removal of legs within 30 min post mortem from the carcass, relatively long sarcomere lengths and the absence of a linear relationship (P > 0.05) between sarcomere length and Warner-Bratzler shear measurements (WBS) show that no cold shortening occurs in the different muscles. The means obtained for the Iliotibialis lateralis are representative of the mean of all the individual muscles combined regarding the characteristics muscle fibre diameter, WBS and pigment content. The overall mean for sarcomere length, pH f and collagen content of all the individual muscles combined can be deduced from determination of these characteristics in the Femorotibialis medius.

Effect on Carcass Traits of Selection for Increased Lean Tissue Growth Rate in Swine on Low or High Dietary Protein Levels

Pigs were selected for lean tissue growth rate (LTGR) in two lines, fed low (LP line) or high (HP line) protein levels. This investigation comprised 92 and 95 pigs, respectively, from generation 3 of the two lines, tested on low, medium and high protein diets between 25 and 105 kg body weight. HP compared to LP line pigs had higher ham percentage (P=0.02), thinner backfat (P=0.003) and lower intramuscular fat content (P = 0.01). A positive correlated response (P=0.02) in osteochondrosis score of femur (OCDf) was found in the HP line. There were unfavourable correlations (P<0.05) between OCDf and performance in the LP line. There were numerically negative correlations between length of the small intestines (LSI) and feed conversion ratio in both lines, and a numerically positive correlation between LSI and daily weight gain in the HP line. There were no interactions between selection lines and test diets. The present results indicate that selection for LTGR ought to be performed on a high protein feeding r...

Muscle histochemical and biochemical properties in relation to meat quality during selection for increased lean tissue growth rate in pigs1

The relationship between the histochemical and biochemical properties of muscle and the quality of meat during selection to improving the lean tissue growth rate was studied. Pigs (n = 82) from Generations 2 and 4 were randomly sampled in a selection experiment in which the genotype x protein interaction was studied. Comparisons were made of longissimus muscle (LM) and quadriceps femoris (QF) from Generations 2 and 4, and biceps femoris (BF) in the fourth generation from pigs fed a low- or high-protein diet. A higher total growth rate, lean tissue growth rate, and lean percentage were found in pigs fed the high-protein diet than in pigs fed the low-protein diet. Pigs fed the high-protein diet had a higher glycolytic capacity in all muscles than pigs fed the low-protein diet. When the meat quality traits were compared, pigs fed the high-protein diet had a lower intramuscular fat content, higher shear force value, higher protein extractability, lower light reflectance, and somewhat higher water-holding capacity. With selection, pigs became fatter on both diets. In Generation 4, glycolytic and oxidative capacity was somewhat higher in muscle tissue than in Generation 2. Muscle metabolic profile and meat quality traits differed among muscles (LM, BF, QF) but no pronounced differences were found between generations. No marked changes were observed in Type I, IIA, or IIB fibers, either between diets or between generations. The Type IIC fibers could only be identified in Generation 4.