Belgian Blue Research Articles

Breed differences and genetic parameters for melting point, marbling score and fatty acid composition of lot‐fed cattle

SummaryFatty acid composition, marbling score and melting point data collected between 1994 and 1996 were analysed. The data were from the adipose tissue of 764 Angus, Belgian Blue, Hereford, Jersey, Limousin, South Devon and Wagyu crossbred cattle slaughtered after lot‐feeding at 500 days of age. The aim was to investigate sire‐breed differences and to estimate heritability and genetic and phenotypic correlations. Significant breed differences were found: Jersey crosses had the highest marbling score and Belgian Blue crosses had the lowest. Limousin crosses had the highest melting point and Jersey crosses the lowest. South Devon crosses had the highest proportion of stearate and Jersey crosses the lowest. Desaturation indices in C16 and C18 fatty acids were highest in Jersey crosses and lowest in Limousin and South Devon crosses. In contrast, there were no breed differences in the proportions of palmitate, oleate, total saturated, total mono‐unsaturated fatty acids and elongation index. Heritability estimates of individual fatty acids and their summations, melting point and marbling were low to moderately low (0.05–0.27). Strong genetic correlations of melting point and desaturation index in C16 fatty acids (‐0.93), melting point and stearate (0.62), marbling and stearate (‐0.71) and marbling and desaturation index in C18 fatty acids (0.62) were observed. Phenotypic correlation were generally low. The results imply that fatty acids in the adipose tissue of lot‐fed cattle have a moderately low heritability, hence genetic progress might be slow.

Feed restriction in young bulls alters the onset of puberty in relationship with plasma insulin-like growth factor-I (IGF-I) and IGF-binding proteins☆

The objectives of this study were to evaluate the effect of feed restriction and re-alimentation on the onset of puberty and IGF status in peripubertal male calves and to compare the radioimmunoassay (RIA) and western ligand blotting (WLB) methods for bovine IGFBP-2. Twelve prepubertal 290 d-old Belgian Blue bulls (mean weight: ± 290 kg) were randomly assigned in three groups: a control group (NG; n = 4) receiving a classic fattening diet to induce “normal” growth (1.48 kg/d), a feed restricted group (RG; n = 4) to obtain reduced growth (0.50 kg/d) and, a severely restricted group (SG; n = 4) to nearly stop growth (0.08 kg/d). The feed restriction period was maintained over a period of 114 d. After the period of differential feeding, all animals received the control feed regime over a period of 100 d. Blood samples were collected at fortnightly intervals. Circulating IGF-I was measured by RIA whereas plasma IGFBPs was evaluated by WLB; IGFBP-2 was additionally quantified by RIA procedure. At the beginning of the trial, IGF-I levels were low (<100 ng/ml) and similar in the three groups in accordance with prepubertal status. In the NG group, a progressive rise in IGF-I was observed from Day 42 to Day 142 whereas in the RG and SG groups, IGF-I levels did not change until the experimental restriction period ended. The delay of the rise in plasma IGF-I was longer for the SG group, IGF-I remained low until 2 wk after the end of the period of restricted feeding. Surprisingly, although differences were detected for IGF-I levels between the three groups, the IGFBP-2 and -3 data, evaluated by WLB could only discriminate between NG and SG group and not between NG and RG. However, by using a RIA method, an IGFBP-2 decrease was observed in the NG group coincident with increasing IGF-I levels. For both RG and SG groups, IGFBP-2 levels remained high throughout the feed restriction period whereas plasma IGFBP-2 levels declined upon feeding in both groups. During this feed restriction period, IGFBP-2 was significantly lower in NG than in RG or SG groups. Moreover, SG group animals had higher levels in plasma IGFBP-2 than RG animals. In conclusion, puberty is characterized by developmental changes in plasma IGF-I and IGFBPs that were altered by feed restriction. Moreover, RIA evaluation of plasma IGFBP-2 is able to better reflect group differences than WLB.

Evaluation of urinary creatinine excretion to estimate in vivo body composition of Belgian Blue double-muscled bulls

Urinary creatinine excretion (UCE) and chemical body composition of 18 Belgian Blue double-muscled bulls were determined. Partly due to the large fasted live weight (fLW) range (308-710 kg), kg water and protein in the empty body were quite accurately predicted (adjR 2 = 0.94 and 0.97) by UCE. The precision of the prediction of kg empty body fat was less good (adjR 2 = 0.77). However, the empty body composition of the bulls varied only slightly and linearly with increa- sing live weight so that the fLW was the best parameter to estimate empty body water and protein with an adjR 2 value of 0.99 for both. The empty body fat was estimated from fLW with an adjR 2 = 0.75. The equations predicting relative body composition from UCE had much smaller adjR 2 values, varying from 0.53 for % empty body water to 0.30 for % empty body protein. However, the coeffi- cients of variation were much smaller. The prediction of the relative composition based on UCE was always somewhat better than based on fLW, but the improvement was not enough to justify the work involved in determining UCE. Conclusively, due to the small compositional changes, UCE did not significantly improve the estimation of the body composition from fLW. From the compari- son of the results with other studies, it can be concluded that the double-muscled bulls have an extre- mely high urinary creatinine concentration, which cannot entirely be explained by their increased protein content.

Determination of the methionine requirement of growing double-muscled Belgian blue bulls with a three-step method.

The three-step technique was used to determine the requirements of total amino acids (TAA) and the first-limiting amino acid (AA) in growing double-muscled Belgian Blue bulls (BBb). In Exp. 1, three double-muscled BBb weighing initially 306 +/- 28 kg received a basal diet consisting of 30% meadow hay and 70% concentrate that was poor in digestible protein but had adequate NE because of continuous infusion of dextrose into the duodenum. The intestinal apparent digestibility of essential AA (EAA) was defined according to their duodenal and ileal flows. It averaged 72% but varied between 60% for Met and 79% for Arg. In Exp. 2, five double-muscled BBb (334 +/- 22 kg) received the same diet supplemented with duodenal infusions of dextrose and four doses of Na-caseinate (28, 56, 84, and 112% of intestinal digestible dietary AA) in a 4 x 4 Latin square design with one additional animal. Nitrogen retention for the basal diet alone and the four increasing supplements of Na-caseinate reached 49, 61, 70, 80, and 86 g/d, respectively. Nitrogen utilization improved from 34.3% without Na-caseinate supplementation to a maximum of 40.6%, with the third dose supplying 788 g/d of apparently digestible AA. Based on patterns of plasma concentrations, Met, Phe, and Arg were probably the limiting AA when animals optimized N utilization. In Exp. 3, six double-muscled BBb (315 +/- 25 kg) fed the basal diet received duodenal infusions of dextrose and AA, equivalent to the third dose in Exp. 2, except for digestible Met (9.3, 14.4, 18.4, 22.4, 26.4, and 30.4 g/d) in a 6 x 6 Latin square design. The Met requirement was close to 26.4 g/d on the basis of N retention.

Quantitative trait loci affecting growth and carcass composition of cattle segregating alternate forms of myostatin.

The effects of the bovine myostatin gene on chromosome 2 on birth and carcass traits have been previously assessed. The objective of this study was to identify additional quantitative trait loci (QTL) for economically important traits in two families segregating an inactive copy of myostatin. Two half-sib families were developed from Belgian Blue x MARC III (n = 246) and Piedmontese x Angus (n = 209) sires. Traits analyzed were birth (kg) and yearling weight (kg); hot carcass weight (kg); fat depth (cm); marbling score; longissimus muscle area (cm2); estimated kidney, pelvic, and heart fat (%); USDA yield grade; retail product yield (%); fat yield (%); and wholesale rib-fat yield (%). Meat tenderness was measured as Warner-Bratzler shear force at 3 and 14 d postmortem. The effect of myostatin on these traits was removed by using phase information obtained from the previous study with six microsatellite markers flanking the locus. Selective genotyping was done on 92 animals from both families to identify genomic regions potentially associated with retail product yield and fat depth, using a total of 150 informative markers in each family. Regions in which selective genotyping indicated the presence of QTL were evaluated further by genotyping the entire population and additional markers. For the family with Belgian Blue inheritance (n = 246), a significant QTL for birth and yearling weight was identified on chromosome 6. Suggestive QTL were identified for longissimus muscle area and hot carcass weight on chromosome 6 and for marbling on chromosomes 17 and 27. For the family with Piedmontese inheritance (n = 209), suggestive QTL on chromosome 5 were identified for fat depth, retail product yield, and USDA yield grade and on chromosome 29 for Warner-Bratzler shear force at 3 and 14 d postmortem. Interactions suggesting the presence of QTL were observed between myostatin and chromosome 5 for Warner-Bratzler shear force at 14 d postmortem and between myostatin and chromosome 14 for fat depth. Thus, in families segregating an inactive copy of myostatin in cattle, other loci influencing quantitative traits can be detected. These results are the initial effort to identify and characterize QTL affecting carcass and growth traits in families segregating myostatin.

Growth- and breed-related changes of muscle fiber characteristics in cattle.

The objective of this study was to investigate the growth- and breed-related changes of muscle fiber characteristics in cattle and their importance to meat quality. Four cattle breeds with different growth impetus and muscularity were reared and slaughtered under experimental conditions. German Angus as a beef type, Galloway as a hardy type, Holstein Friesian as a dairy type, and double-muscled Belgian Blue as an extreme type for muscle growth were used. Between 5 and 17 bulls of each breed were slaughtered at 0, 2, 4, 6, 12, 18, and 24 mo of age. Muscle fiber traits were determined and classified by computerized image analysis, and several measures of meat quality were also determined, including shear force value, meat color, and i.m. fat content. The postnatal growth of semitendinosus muscle in cattle was characterized by a nearly 10-fold increase of muscle fiber area from birth to 24 mo of age. In the first few months after birth, a transformation of type IIA fibers into IIB fibers was found, whereas type I fibers were nearly unaffected by age. The apparent total muscle fiber number of semitendinosus muscle did not increase during postnatal life. These results confirm that the fiber number is determined in embryonic development. Throughout the study, the double-muscled Belgian Blue (BBDM) bulls had almost twice the fiber number of the other breeds, emphasizing a more extensive hyperplasia of muscle fibers during embryonic development in BBDM compared with the other three breeds. The apparent number of type I fibers was, however, not affected by breed, which suggests that the additional fibers found in BBDM postnatally were type IIB and IIA fibers. We did not find significant differences in muscle fiber total number, muscle fiber type frequencies, or meat quality characteristics among breeds, with the exception of BBDM. Having pooled the four breeds, paler meat was related to a higher frequency of type IIB fibers, a lower area of type IIA and type I fiber, and a higher total muscle fiber number. These findings based on data of double muscling give us some hints for biological causes for the variation of meat quality. Further investigation, in particular within each breed, is necessary to identify the superior fiber traits for bovine meat production.

Different modes of food restriction and compensatory growth in double-muscled Belgian Blue bulls: animal performance, carcass and meat characteristics

AbstractFifty double-muscled Belgian Blue bulls were divided into five groups. The first group (control, CG) was given, on an ad libitum basis, a fattening diet based on sugar-beet pulp. In G2 and G3, fattening was interrupted 103 and 187 days, respectively after the beginning of the experiment, by approximately a 2-month period of food restriction during which the animals received a maintenance ration. The last two groups, namely G4 and G5, received for about 4 months a limited amount of the restriction diet to support growth of 0·5 and 0 kg/day, respectively, before being fattened as CG. The average daily gain was 1·48 kg/day in CG v. 1·33, 1·30, 1·43 and 1·61 kg/day during the period of ad libitum feeding in G2, G3, G4 and G5. Higher nitrogen (N) balance during compensatory growth in G2, G4 and G5 (78·8, 81·0 and 74·6 v. 53·3 g N per day in CG, P &lt; 0·001) resulted mainly from a higher efficiency of N retention. In G3, however, compensatory growth was characterized by lower N digestibility and efficiency of N retention. Muscle proportion in the carcass was higher in G3 while fat plus connective tissue proportion was lower (P &lt; 0·05). Muscle pH values in CG were lower than in the other groups (P &lt; 0·01) but ether extract values were higher. The intramuscular fat of G2 and G3 was characterized by higher proportions of polyunsaturated fatty acids.

Effect of Preslaughter Bull Handling on Ante Mortem Muscle Glycogen and Post Mortem pH and Glycogen Level (short communication)

Abstract. Forty three bulls (13 Holstein, 12 crosses Holstein x Belgium Blue, 9 Slovak Pied and 9 crosses Slovak Pinzgauer x Piemontese) were taken in this experiment. Thirteen were stressed by mixing overnight before slaughter. Muscle values were analysed for glycogen ante mortem (M. semitendinosus), glycogen and pH post mortem (1 h, 3 h, 48 h) from logissimus dorsi. The ante mortem and post mortem (1 h, 3 h) muscle glycogen concentration was depleted (P &lt; 0.01) in all stressed bulls. Differences (P &lt; 0.01) were found also in pH (48 h). Significant correlations (P &lt; 0.01) between ante mortem and post mortem (1 h, 3 h) muscle glycogen respectivelly and ultimate pH supported the possibility to measure of stress and to predict carcass ultimate pH of bulls.

Growth factors controlling muscle development

The enlarged muscles of certain breeds of cattle, such as the Belgian Blue, have been shown to result from a marked increase in the number of normal sized muscle fibers. Originally insulin-like growth factors (IGFs) were implicated in this myofiber hyperplasia, as IGFs have been shown to stimulate myoblast proliferation as well as maintain fiber differentiation. Recently it has been reported that mice lacking a myostatin gene, a member of the TGFβ superfamily, have enhanced skeletal mass resulting from increased muscle fiber number and size. Mutations in this gene have been found in double-muscled cattle, indicating that myostatin is an inhibitor of muscle growth. Myostatin is expressed early in gestation and then maintained to adulthood in certain muscles. Myostatin expression in bovine muscle is highest during gestation when muscle fibers are forming and some of the myogenic regulatory factors have elevated expression over the same period as myostatin. Molecular expression of the IGF axis does not differ between Belgian Blue and normal muscled cattle, and IGF-II mRNA is increased throughout formation of secondary fibers in both breeds. However, myostatin and MyoD expression in muscle differ between normal and hypertrophied muscle cattle breeds. This evidence strongly suggests that lack of myostatin is associated with an increase in fiber number which then results in a marked increase in potential muscle mass in double-muscled cattle.

The use of double-muscled cattle breeds in terminal crosses: Meat quality

The purpose of this study was to assess the quality of meat from 84 calves born from British (50% Hereford and 50% Red Angus) and Continental (50% Simmental and 50% Maine Anjou) dams inseminated with semen from normal (Charolais) or double-muscled (Piedmontese, Belgian Blue) sires. Lean composition of Belgian Blue and Piedmontese sired cattle had less intramuscular fat and more protein than Charolais sired cattle (P &lt; 0.01 to 0.05). Breed of sire, origin of dam or calf sex had no effect on longissimus ultimate pH, thawing and cooking losses, shear forces, tenderness and overall flavour. However, meat from male progeny displayed higher drip loss (P &lt; 0.05) and meat colour of male calves born from British dams was slightly more saturated than that of male calves born from Continental dams (P &lt; 0.02). There were no other single effects of parental traits on meat quality. Significant interactions on total and soluble collagen content involving parental traits together with the single sex effect of the progeny (P &lt; 0.05) did not induce textural differences, but meat from male progeny and that from Continental dams crossed with Belgian Blue sires was more juicy (P &lt; 0.05). The use of DM bulls in terminal crosses resulted in increased lean yield and less marbling of the meat of the progeny but did not exert any other important effect on meat quality. Key words: Beef, double-muscling, meat quality

The use of double-muscled cattle breeds in terminal crosses: Animal performance and blood metabolites

Eighty-nine calves born of dams from British (50% Hereford and 50% Red Angus) and Continental (50% Simmental and 50% Maine Anjou) breeds crossed with Charolais (CH), Belgian Blue (BB) and Piedmontese (PM) sires were used to evaluate the productivity of using double-muscled cattle in terminal crosses. Breed of sire did not exert a significant effect on any parameter measured before weaning. Calving difficulty was related to breed of dam, being higher in British than in Continental dams (P &lt; 0.05) and tended to be higher for male than for female calves (P &lt; 0.10). Average daily gains to weaning and weight corrected at 200 d were higher for male than for female calves (P &lt; 0.05), and for calves from Continental dams than for those from British dams (P &lt; 0.05). Average daily gain during backgrounding was higher for CH than for PM-sired calves (P &lt; 0.05). Also, ADG in feedlot (backgrounding + fattening) was higher for male than for female calves (P &lt; 0.05). Slaughter weight and dressing percentage were higher in calves from Continental dams than in those from British dams (P &lt; 0.05). At similar backfat thickness, slaughter weight was higher in male than in female calves (P &lt; 0.05). Total plasma cholesterol, HDL cholesterol and triglycerides were higher in PM sired cattle than in those sired by CH (P &lt; 0.01 to 0.10). Similarly, cattle from British dams presented higher values of plasma cholesterol, HDL cholesterol and LDL cholesterol than cattle from Continental dams (P &lt; 0.01 to 0.05). Insulin and IGF-I values increased with age (P &lt; 0.01). Plasma insulin concentrations during fattening were higher for PM than for BB or CH sired cattle (P &lt; 0.05), for cattle from Continental than from British dams (P &lt; 0.01) and for males than for females (P &lt; 0.01). During fattening, IGF-I values were higher in male than in female cattle (P &lt; 0.01). The use of double-muscled sires in terminal crosses resulted in little effect on performance of the progeny. Key words: Double-muscled, terminal crosses, Belgian Blue, Piedmontese

Some maternal factors associated with dystocia in Belgian Blue cattle

Abstract Measurements of conformation and pelvic characteristics of pedigree Belgian Blue cows were compared in cattle from 11 herds. In seven herds comprising 56 cows caesarean sections were routinely used to deliver pedigree calves and in four herds comprising 52 cows they were given the opportunity to calve naturally per vaginum. Cows in the seven herds were approximately 10 months younger than those in the other herds. External pelvic measurements were linear distances between the tuber coxae, between the tuber coxarum and the tuber ischium, between the tuber ischii, the vertical distance between the underside of the tail and the tuber ischii, and heights of the tuber coxae and tuber ischii from the floor. Internal pelvic measurements were the vertical distance between the ventral body of the sacrum and the pubic symphysis and the horizontal distance between the wings of the ileum at the widest point of the pelvic inlet, both made with a Rice pelvimeter. Condition scores were assessed for all cows. There were correlations (P &lt; 0·001) between internal pelvic height and width, external measurements, and age. For cattle that calved unassisted, pelvic height (P &lt; 0·05) and area (P &lt; 0·05) were significantly larger than those delivered by elective caesarean section. From internal pelvic measurements of 74 cows, those which always delivered live calves had a larger pelvic area (P &lt; 0·01) than cows that delivered a dead foetus following any parturition.

Phase-feeding to optimize performance and quality of Belgian Blue double-muscled bulls

Abstract To optimize performance and carcass quality of Belgian Blue double-muscled bulls four phased feeding regimens were evaluated. All diets were offered ad libitum and consisted of 650 g concentrates and 350 g maize silage per kg dry matter (DM). Total period was divided into three phases (ca. 360 to 460, 460 to 570 and 570 to 680 kg). All four groups received the same maize silage but the different energy and protein densities were applied using different concentrates. During the three phases, the negative control (NC) group constantly received a diet with a low protein and a moderate energy density; the second group (DP) received with each phase diets with decreasing protein density while the energy density remained moderate; the third group (IE) received diets with increasing energy density at a constantly high protein density and the last group (DPIE) received diets which decreased in protein and increased in energy density. The NC group grew significantly slower during the first interval (1·37 v. 1·62 kg/day for the other groups), resulting in a significantly longer total finishing period. During the third period IE had the slowest growth. The NC group needed 21 and 20 days more than the DP and DPIE groups, respectively, to reach the same slaughter weight. The NC group had the lowest DM intake during the first interval, the IE group during the third interval. No significant differences (P &gt; 0·05) were found for food conversion, when expressed as DM or NEF (net energy for fattening). IE had the worst protein conversion while NC had the best, with the two other groups being intermediate. The only important significant difference concerning carcass quality was the improved dressing proportion of the IE and DP groups. Although significant, differences in the fat content of the m. longissimus thoracis are of minor importance. These results proved that for Belgian Blue double-muscled bulls, protein density of the diet can be decreased with increasing live weight, while energy should be increased to give optimal performance.

A missense mutation in the bovine MGF gene is associated with the roan phenotype in Belgian Blue and Shorthorn cattle.

The Roan locus is responsible for the coat coloration of Belgian Blue and Shorthorn cattle. The solid-colored and white animals are homozygotes, and the roan animals, with intermingled colored and white hairs, are heterozygous. The roan phenotype was mapped to cattle Chromosome (Chr) 5 with microsatellites, and a candidate gene was proposed (Charlier et al. Mamm Genome 7, 138, 1996). PCR primers to the exons of this candidate gene, the steel locus or mast cell growth factor (MGF) were designed. Solid-colored and white animals were sequenced. A missense mutation at 654 bp (amino acid 193, Ala --> Asp) was detected in these two groups. A PCR-RFLP was designed to this single base pair change, and 143 animals in total (Belgian Blue, Shorthorn, and various other breeds) were screened. In addition, the Canadian Beef Cattle Reference Herd (http://skyway. usask.ca/ approximately schmutz) was used to verify Mendelian inheritance of this marker with the phenotypic inheritance of roan. Our data suggest that this mutation in the bovine MGF gene is responsible for the roan phenotype.

Myostatin, a transforming growth factor-beta superfamily member, is expressed in heart muscle and is upregulated in cardiomyocytes after infarct.

Myostatin is a secreted growth and differentiating factor (GDF-8) that belongs to the transforming growth factor-beta (TGF-beta) superfamily. Targeted disruption of the myostatin gene in mice and a mutation in the third exon of the myostatin gene in double-muscled Belgian Blue cattle breed result in skeletal muscle hyperplasia. Hence, myostatin has been shown to be involved in the regulation of skeletal muscle mass in both mice and cattle. Previous published reports utilizing Northern hybridization had shown that myostatin expression was seen exclusively in skeletal muscle. A significantly lower level of myostatin mRNA was also reported in adipose tissue. Using a sensitive reverse transcription-polymerase chain reaction (RT-PCR) technique and Western blotting with anti-myostatin antibodies, we show that myostatin mRNA and protein are not restricted to skeletal muscle. We also show that myostatin expression is detected in the muscle of both fetal and adult hearts. Sequence analysis reveals that the Belgian Blue heart myostatin cDNA sequence contains an 11 nucleotide deletion in the third exon that causes a frameshift that eliminates virtually all of the mature, active region of the protein. Anti-myostatin immunostaining on heart sections also demonstrates that myostatin protein is localized in Purkinje fibers and cardiomyocytes in heart tissue. Furthermore, following myocardial infarction, myostatin expression is upregulated in the cardiomyocytes surrounding the infarct area. Given that myostatin is expressed in fetal and adult hearts and that myostatin expression is upregulated in cardiomyocytes after the infarction, myostatin could play an important role in cardiac development and physiology.

Spirometric Variables Recorded after Lobeline Administration in Healthy Friesian and Belgian White and Blue Calves: Normal Values and Effects of Somatic Growth

The purposes of the present study were: (1) to develop original equations to predict spirometric variables (SV) in healthy Friesian and Belgian White and Blue (BWB) calves < 1 year of age; and (2) to determine the effects of somatic growth on SV. Sixty-seven Friesian and 500 BWB calves were investigated. For each calf, the following SV were calculated: (1) the average minute volume derived using all the ventilatory cycles recorded during the 15 s of maximal ventilatory changes induced by lobeline administration (0.25 mg/kg, i.v.) (15-s LMV); (2) the maximal tidal volume, the maximal peak expiratory flow and the maximal peak inspiratory flow recorded from single breaths after lobeline administration (MVTL, MPEFLand MPIFL, respectively); (3) the ventilatory reserve (VRL= 15-s LMV – VEr; VEr= minute volume at rest). Mass specific (s) values were also calculated. All SV changed linearly with somatic growth in both Friesian and BWB calves. Since the rise in SV was more related to body weight than the age of calves, equations for reference values of SV always had body weight as the only independent variable. In the youngest calves,sSV were lower in the BWB breed. In the oldest calves (i.e. 1 year of age),sMPEFLandsMPIFLremained small in BWB calves whereassMVTL,s15-s LMV andsVRLwere almost equal in both breeds. These results could be related to the lower resistance to respiratory disorders in BWB calves < 1 year of age than in Friesian calves < 1 year of age.

Empty body chemical composition estimated from non-carcass parts in Belgian Blue double-muscled bulls

AbstractProperties of the non-carcass parts in combination with empty body and half carcass weight (EBW and CCW; kg) were used to generate equations for predicting empty body chemical composition. Therefore, chemical composition of the non-carcass parts and weight of the depot fatty tissues were determined on 18 Belgian Blue double-muscled fattening bulls. Very high coefficients of determination (R2) were found between the empty body composition and on the one hand the non-carcass parts composition and on the other hand the weight of the fatty tissues. Fat in the empty body was most difficult to predict. The very high coefficients of determination are partly caused by the large variation in slaughter weight (309 to 723 kg). Therefore equations to estimate proportional composition of the empty body are discussed. Although R2 values are strongly reduced, residual standard deviations remain very low and the precision of prediction is good. The proportion of protein is most difficult to predict, as it shows a very small variation. Estimations based on composition of the non-carcass parts are mostly a little more precise than the estimates based on weight of the fatty tissues but as the latter are much easier to determine, these equations will be more appropriate for practical use. Similarly the little improvement of the estimation based on EBW instead of CCW, cannot account for the extra costs and time to determine EBW. The results of the homogenizations have proven that there is very little variation in composition, despite the large range in slaughter weight. As the Belgian Blue double-muscled animals are very deviant from other breeds, the equations found in this study can only be applied for this breed type.

In vivo estimation of body composition in Belgian Blue double-muscled bulls from urea space and fasted live weight

Urea is non-toxic, not foreign to the body and it shows an even and rapid distribution throughout the total body water without any physiological effect or toxic manifestation. For these reasons and for its easy and accurate measurement, urea is an ideal tracer to estimate body composition in vivo. Total body water volume (urea space) can be estimated by dividing the total amount of urea infused by the increase in plasma urea concentration between prior to infusion and 12, 18 or 24 min after mean infusion time (Preston and Kock, 1973). In this experiment the urea infusion technique was evaluated to estimate body composition of Belgian Blue double-muscled bulls.

Estimation of chemical carcass composition from 8th rib characteristics with Belgian blue double-muscled bulls

Characteristics from the 8th rib cut: chemical composition, tissue composition after dissection, specific gravity (SG) and m. longissimus thoracis (LT) composition, collected on 17 Belgian Blue double-muscled fattening bulls were used to generate equations for predicting chemical carcass composition. Carcass composition was best predicted from chemical analysis of the 8th rib cut and the empty body weight (EBW) of the bull. Carcass chemical fat content (CCF, kg) was predicted from the 8th rib cut fat content (ether extract, 8RF, kg) by the following regression: CCF=1.94+27.37 8RF ( R 2=0.957, RSD =9.89%). A higher coefficient was found for carcass water (CCW, kg) predicted from 8RF and EBW: CCW=−2.26+0.28 EBW-34.28 8RF ( R 2=0.997, RSD=1.48%). No parameter was found to improve the prediction of CCP from EBW solely: CCP=−0.86+0.08 EBW ( R 2 =0.992, RSD=2.61%). Prediction equations based solely on LT composition had low R 2 values of between 0.38 and 0.67, whereas no significant equations were found using SG. However, equations based on EBW had R 2 values between 0.78 and 0.99. Chemical components of the 8th rib cut in combination with EBW are most useful in predicting the chemical composition of the carcass of Belgian-Blue double-muscled bulls.

Effect of supplementation with methionine during fattening of Belgian Blue cull cows of three different ages on animal performance, carcass composition and meat quality

By contrast to bulls, fattening cull cows deposite large amounts of fat in the carcass. Furthermore, the live weight gain are low. Methionine (M) is a limiting amino acid for muscle growth in Belgian blue cattle (Hornick et al., 1997). Supplementation with M in fattening diets for cattle could therefore improve weight gain or feed conversion ratio. An experiment was thus conducted in Belgian Blue cull cows in order to assess the effects of M in fattening diet on characteristics of tissue deposition.Twenty four Belgian Blue females from double muscled type -8 heifers (H), 8 cows with 2 calving (C2) and 8 cows with 4 calving (C4)- were used. In each group, 4 animals received a control fattening diet (M0) based on maize silage complemented with cereals, sugar beet pulp and protein from vegetable origin (10.3 MJ ME and 160 g/ kg CP per kg DM), while 4 other received similar diet but with 3.5 g of rumen protected methionine (M1).