The objectives of this study were to develop ultrasound-derived prediction equations in young bulls before slaughter to estimate carcass traits and beef sensory parameters and to determine the optimum moment pre-slaughter to estimate the sensory quality of beef from young bulls. Ultrasound images were measured in twenty live young bulls at 50, 25 and 1 days prior to slaughter. Intramuscular fat content, longissimus lumborum muscle area, carcass fatness, texture and sensory analysis were measured by a trained panel after slaughter. Partial least square methodology was used to find the relationship between the ultrasound measurements and the dependent variables, such as carcass traits, Warner-Bratzler shear force and the sensory profile. Additionally, a stepwise procedure was used to select the most informative ultrasound variables in the prediction equations for carcass and beef sensory traits. The results indicate that ultrasound testing in the feedlot offers promising potential. Early ultrasound scan measurements were useful during fattening to predict intramuscular fat content (R2 = 0.619, RMSE = 0.44%, 50 days prior to slaughter), while ultrasound scans taken close to slaughter were useful to predict kidney fat content (R2 = 0.717, RMSE = 0.96%, 1 day prior to slaughter). However, the prediction of sensory beef attributes was only useful for fatty flavor (R2 = 0.556, RMSE = 0.47%) at 1 day pre-slaughter. Thus, the prediction of fat parameters using ultrasound measurements could constitute a valuable tool in the process of selecting beef quality traits in young bulls before slaughter.

The objective of the current paper was to compare those parameters used in the European Union and United States beef grading system, in typical carcasses of each market (Spain in the case of Europe), and their influence in the economic value of beef. To achieve these objectives, twenty Spanish intact bulls of the Pirenaica breed (Southern Europe) were slaughtered at 351 days of age and 330 kg of carcass weight on average. These carcasses could be considered the typical Spanish yearling bull. Twenty US beef steers carcasses were randomly selected at Tyson Fresh Meats, Joslin (Illlinois) which have been designated as "Angus influenced". Spaniard bulls produced carcasses with superior conformation scores, higher carcass yield, and greater longissimus dorsi area; the US carcasses, were heavier because they were significantly older than the Pirenaica bulls carcasses, (18 vs 12 months), although both type of carcasses had the same maturity grade (A). Beside, US carcasses were fatter because they showed higher marbling grades, thinker dorsal fat and a higher proportion of pelvic, kidney and hearth fat. The Spaniard beef had a higher economic value than the US beef with regard to pricing based on the European beef carcass grading system (21% higher per kilogram basis and 11% higher per carcass basis). However, the Spaniard beef had a lower value than the US beef when using the USDA beef grading system (27% higher per kilogram basis and 35% higher per carcass basis). These results show that each beef market values different characteristics when pricing beef and a highly valuated product in a market not necessary have to be highly evaluated in other market.

Because of the health-promoting effects of conjugated linoleic acid (CLA) isomers in humans, there is growing interest in increasing the content of C18:1 t11 in the rumen in order to enhance the final CLA level in ruminant milk and meat products. Modifying ruminal microflora populations has been viewed as a means to increase their C18:1 t11 content. Therefore, the objective of this experiment was to identify whether chitosan, a natural antimicrobial agent, could be used to modify the biohydrogenation intermediates of two fat sources. The study used a Rusitec unit consisting of eight vessels, and the diets were grass hay and a concentrate mixture (10:90) formulated using either sunflower or rapeseed meal as a fatty acid (FA) source. The incubation experiment consisted of a 6-day adaptation followed by a 5-day chitosan dosing period (750 mg/d), sampling for FA profile and pH determination on the last 3 days. Chitosan interfered in FA biohydrogenation, decreasing total C18:0 (48.7 g/100 g FA versus 23.2 g/100 g FA; P < 0.01) and increasing total C18:1 (5.4 g/100 g FA versus 25.8 g/100 g FA; P < 0.05), C18:1 t11 (4.5 g/100 g FA versus 19.6 g/100 g FA; P < 0.05), total CLA (0.17 g/100 g FA versus 0.37 g/100 g FA; P < 0.05), t9t11 CLA (0.10 g/100 g FA versus 0.21 g/100 g FA; P < 0.05), and the C18:1 t11/C18:0 ratio (0.09 g/100g FA versus 0.89 g/100 g FA; P < 0.05). Compared to sunflower meal, when rapeseed meal was incubated as the fat source in the concentrate mixture, only total C16:0 was decreased (22.9 g/100 g FA versus 20.6 g/100 g FA; P < 0.05). Chitosan supplementation increased proportions of C18:1 c9, C18:1 c11, and t10c12 CLA only when rapeseed meal was used as the fat source in the concentrate mixture. Chitosan was very effective at inhibiting biohydrogenation in vitro by increasing C18:1 t11 and total CLA proportions and lowering the proportion of saturated FA, regardless of the FA source. However, chitosan increased other biohydrogenation intermediates to a greater extent with rapeseed meal as the dietary fat source. (C) 2010 Elsevier B.V. All rights reserved.

The effect of slaughter weight and breed on the composition of intramuscular fat (IMF) of seven Spanish cattle breeds was studied. Lipid classes and fatty acids were evaluated in young bulls of seven local Spanish cattle breeds, Asturiana, Avileña, Morucha, Parda Alpina, Pirenaica, Retinta and Rubia Gallega, slaughtered at a live weight of 320 kg (veal type) and 550 kg (yearling bull type). Higher slaughter weight and early maturating breeds produced higher IMF content in the longissimus muscle (P < 0.001), which was linked to a reduction in phospholipids, monoglycerides, diglycerides, cholesterol and free-fatty acids content, but an increase in triacylglycerols. Besides, heavier animals displayed a higher percentage of saturated and monounsaturated fatty acids (MUFA), but a lower polyunsaturated fatty acids (PUFA) percentage (P < 0.001). The increase in triglycerides (TG), saturated fatty acids (SFA) and MUFA illustrates the increasing importance of lipid storage as fattening proceeds and the acquisition of ruminal functionality. The feeding system based on cereals had a strong influence on the fatty acid profile, giving the studied beef a relatively high PUFA/SFA and n-6/n-3 ratios.

Sixty young bulls of the Pirenaica breed, representative of the beef production and marketing system in northern Spain, were used. The carcass grading and weight, pH at 24h post-mortem, and objective colour measurements (CIE L(∗)a(∗)b(∗)) were recorded on the Latissimus dorsi, Rectus abdominis and Longissimus dorsi in order to find indicators and predictors of beef colour stability (Longissimus dorsi metmyoglobin percentage on ageing for 3, 7 and 14days) by means of early post-mortem measurements on the carcass. Neither the conformation nor the degree of fattening, under the current EU beef carcass classification system, displayed any statistically significant relationship with colour stability of beef aged 3, 7 and 14days. However, there was a relationship between the instrumental colour measured on the carcass and the colour stability of the beef. This relationship allowed prediction of colour stability (Longissimus dorsi MMb percentage) after 3, 7 and 14days of ageing and 48h blooming using colour coordinates measured on the carcass.

Forty beef carcasses were classified for conformation and fatness. Besides, carcass weight, fat thickness (FT), carcass dimension, marbling by computer image analysis and ultrasound readings was recorded to complement grading. For predicting intramuscular fat (IMF) content, FT, number of intramuscular flecks and conformation increased R(2)-value from 0.19 to 0.64 compared to conformation alone. For visual marbling, ultrasound readings and thoracic depth (TD) increased the R(2)-value from 0.24 to 0.57 compared to fatness score (FS). The best variables for predicting weight of fabricated subprimals were carcass weight or compactness which is a function of carcass weight (R(2) between 0.94 and 0.63). Fatness score was poorer than FT for predicting yield of subprimals cuts from round (R(2)=0.16 vs. 0.50) and ultrasound readings for less valuable subprimals (R(2)=0.31 vs. 0.39). These results showed that other variables could be used in combination with carcass fatness or conformation to achieve a more accurate estimation of fat and carcass yield.

In a population of 268 yearling bulls, those carcasses graded as U-, U0 or U+ for beef carcass conformation (n = 240) and those graded as 2-, 20 or 2+ for beef carcass fatness (n = 213) were selected to study the efficiency of carcass weight, carcass dimensions and instrumental colour of latissimus dorsi, rectus abdominis and subcutaneous fat, to discriminate among these carcass grades, in a population of high-muscled and very lean carcasses from young bulls. The increase in conformation grade meant an increase in carcass weight and perimeter of the leg. Classifiers use attributes characterizing muscular development and carcass profiles from a general impression of the whole carcass. There were no significant differences for carcass weight or carcass dimensions, among the carcasses classified according to the three fat classes. The a* and b* coordinate values for the latissimus dorsi muscle were observed to decrease significantly as the carcass conformation score increased (P < 0.05). However, muscle and subcutaneous fat of fatter carcasses showed higher a*, b* colour coordinates and chroma (C*) values than leaner carcasses. The CIE (Commission International de l'Éclairage) L*, a* and b* colour coordinate measurements taken on the carcasses 45 min post mortem varied significantly from the readings taken after hanging for 24 h (P < 0,001). The higher a* and b* values on the carcasses chilled for 24 h could be caused by oxygenation of both subcutaneous fat, and latissimus dorsi and rectus abdominis muscles in the time elapsing after slaughter and after carcass exposition to circulating air in the cooler for 24 h. Lightness of the latissimus dorsi muscle underwent a decrease, compared with an increase in the rectus abdominis muscle. Hardening of the subcutaneous fat during cold storage may exert an influence on the decrease in lightness observed. These differences in carcass colour during chilling storage would suggest that the relationship between carcass colour and conformation grades was higher shortly after slaughter. Both L* colour coordinate of fat colour (P < 0.01) and a*, b* and C* colour coordinates of latissimus dorsi muscle (P < 0.05) were related to conformation classification. Colour was more efficient to differentiate conformation than fat cover classes. Sixty-two percent of carcasses were correctly classified for conformation by colour differences but only 37% of carcasses were correctly classified for fatness by colour.

ABSTRACT Color of sirloin in 60 intact young bulls of the Pirenaica breed was studied with a view to grading the meat quality of the beef. The correlation between visual evaluation of color with the use of reference standards and instrumental color measurements were analyzed. Use of reference standards in the visual evaluation of beef color yielded visual assessment results in an objective, reproducible and closely correlated with the instrumental values. Overall, classification of the muscle samples was the same using both the visual and instrumental methods in 83% of cases. The results showed that objective systems for evaluating meat color can be developed from either visual evaluation using reference standards or instrumental measurements. PRACTICAL APPLICATIONS Reference standards produced visual appraisals of beef color that were closely correlated to the color coordinates L*a*b*, and these instrumental measurements could be useful (to give support to) color assessors. Both visual assessment aided by reference standards and instrumental measurements are appropriate and objective systems for meat color evaluation. They may prove to be useful for meat packing plants that sell carcasses piecemeal.

Sixty young bulls of Pirenaica breed that were representative of the beef production and marketing systems in Northern Spain were studied. The following parameters were determined with the aim of predicting beef texture characteristics of the longissimus dorsi based on the objective measurements taken on the carcass at the early post-mortem period: colour measurement (CIE L(∗)a(∗)b(∗)) readings were taken on the latissimus dorsi (LTD), rectus abdominis (RA), and longissimus dorsi (LD) muscles. In this study, it was observed that more information on beef tenderness is obtained with colour measurements taken on the carcass LTD and RA, and LD at 24h post-mortem. However, the regression analysis showed that beef TI from Pireanica young bulls can be predicted quite accurately by C(∗) measured on the RA muscle just 45min after slaughter.

Sixty Pirenaica yearling intact bulls were raised and slaughtered at 519±50kg live weight and 371±18 days of age. Fatty acid composition of intramuscular lipids in longissimus dorsi muscle and subcutaneous fat were determined by capillary gas chromatography. Carcass conformation and fatness, carcass weight, ether extractable intramuscular fat percentage, marbling, dorsal fat thickness, and ultrasonic parameters were recorded to study the relationship between these traits and fatty acid profile. Lipids of subcutaneous adipose tissue had higher monounsaturated fatty acids (MUFA) percentage (49% vs. 33%) but lower saturated fatty acids (SFA) (51% vs. 46%) and polyunsaturated fatty acids (PUFA) (16% vs. 5%) percentages than intramuscular fat depots (p<0.001). Fatter carcasses had higher MUFA percentage and lower PUFA percentage (p<0.01) in intramuscular fat. Carcass weight and conformation would contribute to explain the fatty acid profile of subcutaneous fat (p<0.05). Ultrasound readings reflected the effect of fatness on fat composition.

The colour of the foal meat aged 4 days was study to determine the oxygenation effect on the colour coordinates CIE L-10*, a(10)*, b(10)*, C*, h(ab)* and on the myoglobin content. The foal meat was from animals reared in two livestock production systems of 16-months and 24-months of age. The livestock production system and the moment of the colour measurement showed differences in every colour coordinate except to L-10* where it was not found differences due to the oxygenation of the samples.