Albertí Lasalle, Pere

Blanco Alibés, Mireia

Casasús Pueyo, Isabel

Joy Torrens, Margalida

Ripoll García, Guillermo

Villalba Mata, Daniel

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Options Méditerranéennes, A no. 116, 2016 – Mountain pastures and livestock farmingfacing uncertainty: environmental, technical and socio economic challenges 157Beef cattle performance, carcass and meatquality traits to discriminate betweenpasture-based and concentrate dietsI. Casasús1, M. Blanco1, M. Joy1, P. Albertí1, G. Ripoll1 and D. Villalba21CITA-Aragón. Avda. Montañana 930, 50059 Zaragoza (Spain)2Universitat de Lleida. Avda. Rovira Roure 191, 25198 Lleida (Spain)Abstract. The aim of this work was to identify general relationships between the fattening diet and weightgains, carcass and meat quality across experiments, using data from bulls (n = 90) and steers (n = 56) ofParda de Montaña and Pirenaica breeds collected in 7 experiments. The different factors considered werediet (1. pasture+supplement; 2. pasture+supplement and indoor finishing for <3 months; 3. concentrates), breedand sex. Dietary energy and protein, forage:concentrate ratio, animal performance (weight gain, dry matterintake, age at slaughter), carcass (weight, conformation and fat scores, fat colour) and meat quality (intra-muscular fat, colour and texture) were registered. The relationships between variables were studied with aPrincipal Component Analysis. Three factors explained 50% of the total variability: Factor 1 (21% of variabil-ity) was associated positively with fat yellowness and colour intensity, and negatively with daily gains duringfattening; Factor 2 (15%) with meat yellowness, lightness and tenderness; and Factor 3 (14%) with meat red-ness and colour intensity. These factors were influenced by diet, sex and/or weight or age at slaughter, butnot by breed. A discriminant analysis classified animals by fattening diet, with total accuracy for concentrate-fed diets (100%), intermediate for pasture+supplement (97%) and lower for cattle finished after grazing(91%), probably because of their intermediate meat and carcass characteristics.Keywords. Attening diets – Cattle performance – Product quality – Discriminant analysis.Utilisation des performances, de la qualité de la carcasse et de la viande pour discriminer entre lesrégimes à base de fourrages ou de concentres dans les des bovins à viandeRésumé. Le but de ce travail était d’identifier des relations générales entre le régime d’engraissement et lesperformances, la qualité de la carcasse et de la viande des bovins, en utilisant données de males entiers (n = 90)et bouvillons (n = 56) de deux races, recueillis dans 7 expériences. On a considéré le régime (1. pâtura -ges+supplément; 2. pâturages+supplément et finition à l’intérieure pendant <3 mois; 3. concentrés), la raceet le sexe. On a enregistré la quantité et qualité des aliments ingérés, les performances, la qualité de la car-casse (conformation, engraissement, couleur du gras) et de la viande (graisse intramusculaire, couleur ettendreté). Les relations entre eux ont été étudiées avec une analyse de composantes principales. Trois fac-teurs expliquaient 50% de la variabilité: Facteur 1 (21%) associée avec l’intensité du couleur jaune de lagraisse, et négativement avec des gains; Facteur 2 (15%) avec le couleur jaune de la viande, sa luminositéet tendreté; et Facteur 3 (14%) avec l’intensité de rouge de la viande. Ils étaient influencés par le régime ali-mentaire, le sexe et/ou le poids ou l’âge à l’abattage, mais pas par la race. Une analyse discriminante aclassé les animaux selon leur régime alimentaire, avec précision totale pour les régimes de concentré(100%), intermédiaire pour le pâturage+supplément (97%) et inférieure pour les bovins finis après pâturage(91%), peut-être parce qu’ils avaient des caractéristiques intermédiaires entre les autres.Mots-clés. Régimes d’engraissement des bovins – Performance – Qualité – Analyse discriminante.I – IntroductionBeef cattle performance and product quality are greatly dependant on the animal type or the feed-ing management. Forage feeding is currently given increasing interest as compared to concentratefattening diets, due both to economic efficiency and consumer demands. These requests are basedon perceptions of animal well-being, environmental sustainability and meat nutritional quality(leaner and with a more healthful fatty acid profile) (Van Elswyk and McNeill, 2014), and have ledto the development of different methods to authenticate meat produced with forage-rich diets(Blanco et al., 2011). The aim of this work was to identify relationships between the fattening dietsof cattle and weight gains, carcass and meat quality.II – Materials and methods1. Animals and dietsThis study was conducted using existing data from seven experiments conducted at the facilitiesof CITA research stations (2003-2010). Performance and carcass and meat quality data were ob-tained from 90 bulls and 56 steers, of Parda de Montaña and Pirenaica beef cattle breeds, raisedduring their fattening period (5-13 months in the different studies) after weaning on several feed-ing strategies. They were classified into three fattening diets: (i) Concentrates: animals receivedad libitum concentrates throughout the fattening phase (n = 62); (ii) Pasture+Supplement: animalsgrazed on pastures (alfalfa pastures or mountain meadows) with supplementation (maize, barleyor concentrates) (n = 62); and (iii) Pasture+Finishing: animals grazed on pastures with supplementsand finished indoors for less than three months, on diets with 40 to 90% concentrates (n = 22).2. MeasurementsThe animals were weighed fortnightly throughout the fattening phase, and daily gains were cal-culated for the whole fattening period (ADG) and for the last 3 months (ADG3). Forage and con-centrate intake was determined or estimated; the forage:concentrate ratio (F:C) was calculated forthe whole fattening period and for the last 3 months. The chemical composition of the different feed-stuffs was determined to estimate the dietary energy and protein intake.The animals were slaughtered in a commercial abattoir when they reached the target age (SA) orweight (SW) for each experiment (Table 1). Carcasses were visually graded for conformation (CONF,SEUROP system transformed into an 18-point scale) and fatness score (FS in a 15-point scale, from1 for 1- to 15 for 5+). Subcutaneous fat colour (CIE lightness: L*fat, redness: a*fat, yellowness: b*fat,Chroma: C*fat and Hue angle: h*fat) was measured at the loin area with a spectrophotometer.The Longissimus thoracis muscle was removed for meat analyses. Meat colour was determinedwith a spectrophotometer after 7 days of air exposure (L*meat, a*meat, b*meat, C*meat, H*meat).For instrumental texture analysis, steaks were aged for 7 days at 4ºC for Warner-Bratzler shearforce determination (maximum stress, STRESS) using an Instron machine. Intramuscular fat con-tent (IMF) was quantified with an XT10 Ankom extractor.Options Méditerranéennes, A no. 116, 2016158Table 1. Mean (± s.d) of slaughter weight (SW), slaughter age (SA), carcass conformation (CONF), fat-ness score (FS) and subcutaneous fat colour, and meat colour, intramuscular fat (IMF) andtoughness (STRESS) (n = 146)Carcass MeatSW, SA, CONF FS L*fat a*fat b*fat L*meat a*meat b*meat IMF, STRESS,kg months % N/cm2483 14.8 9.2 4.4 72.6 2.6 13.5 40.3 13.3 13 1.6 70.4± 47 ± 4 ± 2.3 ± 1.4 ± 4 ± 1.7 ± 3.9 ± 3.4 ± 2.4 ± 2.8 ± 0.8 ± 20.73. Statistical analysesAll the analyses were conducted with SAS (SAS 9.4, Cary, NC, USA). The relationships betweenthe variables of performance (gains), carcass (dressing percentage, conformation, fatness score,subcutaneous fat colour) and meat quality (intramuscular fat content, meat colour and maximumstress) were studied with a Principal Component Analysis (PCA). New groups of variables (factors)that retained as much variance as possible were defined. These factors were analysed with a GLMprocedure, using Diet, Breed and Sex as fixed effects, and SA and SW as covariates. The corre-lations between the factors obtained in the PCA and diet traits (F:C, energy and protein content)were performed using the CORR procedure. A discriminant analysis was performed using the DIS-CRIM procedure, to predict the dietary treatment a given observation belonged to, considering allresponse variables. Cross-validation was run by omitting each observation one at a time, recal-culating the classification function with the rest and classifying the omitted observation.III – Results and discussionThree factors explained 50% of the total variability of the selected variables (Table 2). Factor 1 wasassociated positively with fat colour intensity (C*fat), especially yellowness, and negatively withgains during the fattening phase. It was affected by Diet (Pasture+Supplement had the highest val-ues and Concentrates the lowest) and Sex (higher values in steers than in bulls) but not by Breed.Higher SW led to higher values of Factor 1 (p<0.01). Factor 2 was related with meat yellowness,lightness and toughness. It was influenced by Diet (Pasture+Finishing and Concentrates had highervalues than Pasture+Supplement) and Sex (higher in steers than in bulls) but not by Breed; andanimals with higher SA had lower values of Factor 2 (p<0.001). Factor 3 was related with meatMountain pastures and livestock farming facing uncertainty: environmental,technical and socio economic challenges159Table 2. Contribution of response variables to the main factors in the PCA. Influence of diet, sex, breed,age and liveweight at slaughter on these factorsFactor 1 Factor 2 Factor 3(fat colour and gains) (meat yellowness & toughness) (meat redness)% Variability explained 21% 15% 14%Correlation†with response variablesa*fat 0.65 -0.03 0.01b*fat 0.99 0.08 -0.06C*fat 0.99 0.07 -0.06a*meat 0.14 -0.31 0.94b*meat -0.05 0.80 0.60H*meat -0.14 0.97 -0.15C*meat 0.05 0.34 0.93L* meat -0.33 0.47 0.00ADG -0.65 0.06 -0.09STRESS 0.24 -0.41 -0.08ADG3 -0.58 0.32 0.01EffectsDiet <0.001 <0.001 0.14Sex <0.001 <0.001 0.11Breed 0.36 0.46 0.30SA (covariate) 0.07 <0.001 0.06SW (covariate) 0.01 0.17 0.02†Only variables with correlation >|0.4| (absolute value, in bold) with at least one factor are presented.colour intensity and particularly redness. It was not influenced by any of the fixed effects, but an-imals with higher SA had lower values of Factor 3 (p<0.05). The lack of breed differences agreeswith results of Albertí et al. (2005), who classified them together as “medium meat producers” whencompared with other Spanish beef breeds.Diet composition and quality were correlated with the response variables and therefore with the fac-tors obtained from the PCA. Focusing on forage-based diets, Factor 1 was highly correlated (r>0.60)with the amount and proportion of forage in the diet, the energy and protein content of forage, andnegatively (r<-0.60) with the amount and protein content of concentrate. These relationships indicatethat diets with higher forage content led to more yellow subcutaneous carcass fat and lower gains.The fact that lower performances were achieved despite high forage nutritional quality may be dueto a higher energy expenditure associated to these diets or a suboptimal nutrient synchrony (car-bohydrate and protein fractions), which could be improved with specific supplements or timing sup-plement delivery (Hersom, 2008). Factors 2 and 3 were less related to diet characteristics.The discriminant analysis based on the three factors classified animals into their actual fatteningdiets with a 4.1% error rate (up to 7.7% with cross-validation). The accuracy was 100% for con-centrate-fed diets (all animals correctly classified), intermediate for animals fattened on pasture withsupplements (97%) and lower for cattle finished indoors after grazing (91%) (Fig. 1), probably be-cause the finishing diets of the latter group resulted in carcass and meat traits intermediate betweenthe other two categories, as Blanco et al. (2011) described.Options Méditerranéennes, A no. 116, 2016160Fig. 1. Representation of animals fattened with the different diets in the canonicalspace obtained from the response variables.IV – ConclusionsThe fattening diets influenced cattle gains, fat colour and meat quality attributes. Therefore, thesetraits can be used to discriminate among feeding strategies based on pasture or concentrates, al-though accuracy will depend on the diet type.AcknowledgmentsThe authors gratefully acknowledge the staff of CITA Research Centre for technical support. Researchfunded by Gobierno de Aragón and INIA-ERDF (RZP 2009-05, RZP 2010-02 and RTA 2010-57).ReferencesAlbertí P., Ripoll G., Goyache F., Lahoz F., Olleta J.L., Panea B. and Sañudo C., 2005. Carcass characteri-sation of seven Spanish beef breeds slaughtered at two commercial weights. Meat Science, 71, 514-521.Blanco M., Casasús I., Ripoll G., Sauerwein H. and Joy M., 2011. Grazing lucerne as fattening manage-ment for young bulls: technical and economic performance and diet authentication. Animal, 5, 113-122.Hersom M.J., 2008. Opportunities to enhance performance and efficiency through nutrient synchrony in forage-fed ruminants. Journal of Animal Science, 86, E306-317.Van Elswyk M.E. and McNeill S.H., 2014. Impact of grass/forage feeding versus grain finishing on beef nu-trients and sensory quality: The U.S. experience. Meat Science, 96, 535-540.Mountain pastures and livestock farming facing uncertainty: environmental,technical and socio economic challenges161

Beef cattle performance, carcass and meat quality traits to discriminate between pasture-based and concentrate diets

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Beef cattle performance, carcass and meat quality traits to discriminate between pasture-based and concentrate diets

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