Belgian Blue Research Articles

Malic acid supplementation in growing/finishing feedlot bull calves: Influence of chemical form on blood acid–base balance and productive performance

The aim of the present study was to evaluate the effects of two chemical forms of malate (malic acid and a commercial malate salt) on acid–base balance and productive performance in cattle maintained in a commercial feedlot system, taking into account the entire productive cycle (i.e., the growing and finishing periods). Thirty-eight Belgian Blue bull calves were utilized for a 148-day feedlot study. Animals were allotted randomly to one of three experimental groups: (1) control group (C, no supplementation, n = 10), (2) dl-malic acid supplementation (MA, n = 14; 4 g/kg DM basis) and (3), supplementation with a commercial salt of dl-malic acid (MS, n = 14; 4 g/kg DM basis). Blood pH, pCO 2, HCO 3 −, base excess (BE) and serum l-lactate were determined. Productive data were also evaluated as complementary information for understanding internal changes associated with supplementation. Although no differences (P>0.1) were found in performance parameters, results were numerically better for supplemented animals than for controls. The efficiency of the organic acid supplementation varies depending on its chemical form and on productive stage: while similar results were observed using the salt form or the free acid in the growing period, better results were obtained with the acid form in the finishing period. Looking at blood parameters, the malate salt seems to be more effective than the acid form due to the fact that the latter tended to decrease blood bases (although the possibility that the malate salt may cause blood alkalinization due to decreased pCO 2 needs to be further explored). Finally, the effect of supplementation on blood l-lactate was shown (P<0.05) from the first week of the study: controls showed higher values than supplemented animals. In the growing period, differences were observed between C and MA steers, and between C and MS in the finishing period. In our opinion, there is a clear need for research evaluating the effects of organic acids on ruminant health in vivo.

Comparison of sperm quality of Belgian Blue and Holstein Friesian bulls

Few data are currently available on sperm quality of Belgian Blue (BB) bulls. The present study compared sperm quality of BB to Holstein Friesian (HF) bulls of several age categories, by means of a classical semen evaluation. Volume and concentration, and consequently total sperm output depended largely on age. Gross, total, and progressive motility, % live and % normal spermatozoa were significantly lower in the BB breed. Primary sperm abnormalities, such as nuclear vacuoles, midpiece defects and cytoplasmic droplets which were noticed most frequently, occurred far more in the BB breed. Hence, disturbances in spermiogenesis are deemed to be the cause of the poorer BB sperm quality. Since these sperm abnormalities occur significantly more in the BB breed than in the HF breed, it seems as if the BB breed is genetically predisposed to a higher susceptibility to environmental stresses which are known to interfere with normal spermiogenesis. The small scrota typical of the inbred BB breed might in part be responsible for this, and therefore selection for larger scrota in the BB breed is advisable.

Monitoring of the genetic health of cattle in the Czech Republic

A screening was carried out for CVM, BLAD, DUMPS, bovine citrullinaemia, glycogen storage disease V, and Robertsonian translocations in the cattle population of the Czech Republic. In 406 Holstein sires and 146 Czech Pied (Czech Simmental) sires entering the AI programme in the Czech Republic from 2003&amp;ndash;2005, no heterozygous sire for DUMPS, bovine citrullinaemia and BLAD was found. The heterozygote was not found also in the beef sires of Charolais, Limousine, Beef Simmental, Blonde d&amp;rsquo;Aquitaine, Belgian Blue, Aberdeen-Angus, and Hereford breeds. In 111 elite Holstein females, 21 (18.9%) were heterozygotes for CVM, and were dominant homozygotes for BLAD, DUMPS and bovine citrullinaemia. In the myophosphorylase gene responsible for the glycogen storage disease V, in the Charolais (n = 30), Czech Pied (n = 53), and Belgian Blue, Limousine, Blonde d&amp;rsquo;Aquitaine, Aberdeen Angus, and Beef Simmental sires analysed, the heterozygote was not found. Robertsonian translocations were examined in 767 Holstein sires, 1 010 Czech Pied (Simmental) sires, 142 beef sires, and 48&amp;nbsp;dams. Of these, 10 sires of Czech Pied breed, 5 beef sires, and 13 females were found to be positive. The monitoring of BLAD, CVM, and Robertsonian translocations is recommended.

Comparison of composition and quality traits of meat from young finishing bulls from Belgian Blue, Limousin and Aberdeen Angus breeds

Thirty-six young finishing bulls from three breeds (Belgian Blue, Limousin and Aberdeen Angus) were fattened over five months with finishing diets based either on sugar-beet pulp or on cereals. Nutritional quality traits of meat – fat content and fatty acid composition with emphasis on the n − 6 and n − 3 polyunsaturated fatty acids – along with some organoleptic quality traits were measured. The Belgian Blue bulls had the lowest intramuscular fat content associated with lower saturated and monounsaturated fatty acid contents. The polyunsaturated fatty acid content did not differ to a large extent between the breeds, the Aberdeen Angus bulls showing slightly higher values. Relative to energy intake, the overall contribution of meat to the n − 3 fatty acid recommended intake was small, whatever the breed. By contrast, the contribution of meat to daily fat intake was of greater importance, especially for the Aberdeen Angus bulls. The quality traits of meat varied also according to the breed: compared to the Aberdeen Angus, the Belgian Blue bull meat had the stablest colour, the highest drip and the lowest cooking losses. The meat of Limousin bulls had intermediate characteristics for all the parameters.

Growth- and breed-related changes of marbling characteristics in cattle1

The objective of this study was to investigate the growth- and breed-related changes of marbling characteristics in cattle. Four cattle breeds with different growth impetus and muscularity were reared and slaughtered under experimental conditions. German Angus, as a typical beef cattle; Galloway, as a smaller, environmentally resistant beef cattle; Holstein-Friesian, as a dairy-type cattle; and double-muscled Belgian Blue, as an extreme type for muscle growth, were used. These 4 breeds were expected to have differences in muscle development and i.m. fat deposition. Between 5 and 15 bulls of each breed were slaughtered at 2, 4, 6, 12, or 24 mo of age. Marbling characteristics were determined and classified in LM and semitendinosus muscle by computerized image analysis. Among breeds, differences appeared in the quantity, structure, and distribution of the marbling flecks in both muscles. The deposition of fat in the double-muscled Belgian Blue bulls remained substantially inferior to that of the other breeds, up to the age of 24 mo. Marbling in German Angus bulls particularly showed larger (P < 0.05) marbling fleck areas. Galloway cattle had the greatest (P < 0.05) number and the most regular (P < 0.05) distribution of the marbling flecks in young animals. Furthermore, for marbling characteristics in Holstein-Friesian animals, a great number and slightly finer structure were observed compared with the other breeds investigated. Postnatal growth-related changes of marbling in LM were characterized by as much as a 40-fold increase in the number of marbling flecks from 2 to 24 mo of age but also by up to a 4-fold enlargement in the area of the marbling flecks. The structure of marbling flecks was determined by 2 development trends. On the one hand, the marbling flecks became larger (P < 0.05), and the structure became coarser, which was reflected by an increasing (P < 0.01) proportion of long marbling flecks as well as an increasing (P < 0.01) maximum skeleton line length. On the other hand, continually new small, round marbling flecks appeared. This caused a decrease (P < 0.01) in the proportion of the 3 largest marbling fleck areas. The distribution of the marbling flecks became more regular (P < 0.05) with increasing proportion and number of marbling flecks. The results suggest that hyperplasia of adipocytes plays an important role in marbling during growth of muscle in cattle.

Effect of various levels of imbalance between energy and nitrogen release in the rumen on microbial protein synthesis and nitrogen metabolism in growing double-muscled Belgian Blue bulls fed a corn silage-based diet1

Seven double-muscled Belgian Blue bulls (initial BW: 341 +/- 21 kg) with cannulas in the rumen and proximal duodenum were used in an incomplete replicated Latin square. The study examined the effect of imbalance between energy and N in the rumen on microbial protein synthesis and N metabolism by giving the same diet according to 3 different feeding patterns. The feed ingredients of the diet were separated into 2 groups supplying the same amount of fermentable OM (FOM) but characterized by different levels of ruminally degradable N (RDN). The first group primarily provided energy for the ruminal microbes (12.5 g of RDN/kg of FOM), whereas the second provided greater N (33.3 g of RDN/kg of FOM). These 2 groups were fed to the bulls in different combinations with the aim of creating 3 levels of imbalance (0, 20, and 40 g/ kg of DM) between energy and N supplies in the rumen. Imbalance was measured by the variation of the degradable protein balance (OEB value in the Dutch system) of the diet between the 2 meals each a day. Diurnal variations in ruminal NH3-N concentrations and plasma urea concentrations were greatly influenced by the feeding patterns of the diet. Introduction of imbalance affected neither microbial N flow at the duodenum (P = 0.97) nor efficiency of growth (P = 0.54). The feeding patterns of the diet had no negative impact on NDF degradation in the rumen (P = 0.33). Nitrogen retention was not affected by imbalance (P = 0.74) and reached 49.7, 52.0, and 51.3 g/d, respectively for 0, 20, and 40 g of OEB/kg of DM imbalance. It seems that introduction of an imbalance between energy and N supplies for the ruminal microbes by altering the feeding pattern of the same diet does not negatively influence the microbial activity in the rumen nor N retention of the animal. Nitrogen recycling in the rumen plays a major role in regulating the amount of ruminally available N and allows a continuous synchronization of N and energy-yielding substrates for the microorganisms in the rumen. Therefore, imbalance between dietary energy and N created over a 24-h interval was not detrimental to rumen microbial growth for the animal as long as the level of imbalance did not exceed 40 g of OEB/kg of DM. Thus, these feeding patterns of the diet can be used under practical feeding conditions with minimal impact on the performance of ruminant animals for meat production.

Less intensified grazing management with growing fattening bulls

Animal performance, composition and quality of meat from Belgian Blue bulls either fattened indoors (FI) or finished indoors after a previous grazing period were studied during six years. During the grazing period, three intensification managements were tested on a permanent pasture conducted as set stocking. The intensification levels were either high (HN: 140 kg N·ha −1 with 6 bulls·ha −1 ) or moderate with a 33% reduction of nitrogen fertilisation but with the same stocking rate (MN: 93 kg N·ha −1 , 6 bulls·ha −1 ) or low with no nitrogen fertiliser but with a reduced stocking rate (ON, 4 bulls·ha −1 ). The levels of intensification did not affect sward characteristics and chemical composition of the grass. The apparent nitrogen efficiency per ha was larger in the ON plot than in the HN and MN plots (26 vs. 14%). The average daily gain of bulls during the grazing season was similar in the three groups at 1.0 kg·d −1 . The bulls from the FI group were characterised by average daily gains significantly higher than the bulls which were previously grazed and then finished indoors (1.5 vs. 1.2 kg·d −1 ; P < 0.01). The slaughter weight, the carcass composition, the dressing percentage and most of the meat quality parameters were similar between the treatment groups. The inclusion of a grazing period in the fattening system produced a meat which was darker (lower L*, P < 0.01), more red (higher a*, P < 0.05) and had a higher content of linolenic acid (C18:3 n-3) than that of the animals fattened indoors.

Performance, slaughter characteristics and meat quality of young bulls from Belgian Blue, Limousin and Aberdeen Angus breeds fattened with a sugar-beet pulp or a cereal-based diet

AbstractThirty-six young fattening bulls from three breeds (Belgian Blue, Limousin and Aberdeen Angus) were fattened over 5 months with fattening diets based either on sugar-beet pulp or on cereals. Fattening performance as well as carcass and meat characteristics were measured. There were few relevant effects of the diets on the parameters. The breeds also showed similar fattening features. However, the BB had higher killing-out proportion and their carcasses presented better scores in terms of conformation and fattening. The meat quality of the breeds differed, especially in terms of luminosity, redness and cooking losses. There were also significant influences of breed on the chemical composition of meat; fat content was lowest in Belgian Blue and highest in Aberdeen Angus. Such specificities could help to allocate breeds in appropriate niches in Belgium.

Voluntary food intake, live-weight gain, carcass quality and food conversion in contrasting genotypes of weaned suckler-bred bulls finished intensively on a cereal-based diet

AbstractA bull beef finishing experiment was conducted with the objective of comparing physical performance of constrasting genotypes of suckler-bred bull beef animals finished intensively on a cereal-based diet at approximately 12 to 13 months of age. Nine bulls per genotype were drawn from weaned, bull calves born to one of two dam types (Belgian Blue×Holstein/Friesian (BB) or Simmental×Holstein/Friesian (SIM)) and which had been sired by one of two contrasting sire types (Aberdeen Angus (AA) or Charolais (CH)). Bull calves were weaned at approximately 8 months of age and the finishing experiment ran from approximately 9 months of age until slaughter at 12 to 13 months of age. Cereal-based concentrate diets were offered to all bulls on an ad libitum basis throughout the experimental finishing period. Dry matter intake (DMI), live-weight gain (LWG), food conversion ratio (FCR), and carcass slaughter characteristics were quantified.Average daily LWG was 2·07, 2·11, 2·34 and 2·65 kg/day, average FCR was 5·14, 5·06, 4·70 and 4·12 kg DMI per kg LWG and average age at slaughter was 387, 381, 374 and 366 days for the AA/BB, AA/SIM, CH/BB and CH/SIM bulls respectively. These figures showed that CH sired bulls grew faster ( P&lt;0·001), finished at an earlier age ( P&lt;0·01) and had better food conversion ratios ( P&lt;0·01) than AA sired bulls. CH sired bulls also produced heavier carcasses (P&lt;0·001) with better conformation ( P&lt;0·001) than AA sired bulls. Average cold carcass weights (CCW) at slaughter were 309, 318, 348 and 365 kg and average conformation scores (15-point scale) at slaughter were 9·28, 10·28, 12·39 and 12·75 for the AA/BB, AA/SIM, CH/BB and CH/SIM bulls respectively. Finished bulls from SIM dams had higher LWGs (P&lt;0·01) and produced heavier carcasses (P&lt;0·05) than bulls from BB dams. No statistically significant differences in fat score (15-point scale) were seen between any of the breed combinations with fat scores of 7·50, 7·25, 6·75 and 6·75 for the AA/BB, AA/SIM, CH/BB and CH/SIM bulls respectively. No significant differences in average daily food intake were observed between breed combinations in the experiment with average daily DMI being 10·6, 10·6, 11·0 and 10·9 kg/day for AA/BB, AA/SIM, CH/BB and CH/SIM bulls respectively.Overall, there was little evidence to suggest that the rate of bull LWG declined to bring about any meaningful reduction in productivity as average bull live weight increased from approximately 9 months of age until slaughter at 12 to 13 months of age. When finished on a nutrient-rich, cereal-based concentrate diet, excellent animal performance and commercially acceptable carcasses can be produced from the UK suckler herd using genetically superior sires of either traditional UK or continental beef cattle breeds. Results from this study indicate that CH sired bulls out-performed AA sired bulls, especially when produced from SIM cows.

Variance components for birth and carcass traits of crossbred cattle

During a 4-year period (1994–97) of the Australian ‘Southern Crossbreeding Project’, mature Hereford cows (n = 637) were mated to 97 sires from 7 breeds (Jersey, Wagyu, Angus, Hereford, South Devon, Limousin and Belgian Blue), resulting in 1334 calves. Heifers were slaughtered at around 16 months and steers at 23 months. The objective of the study was to quantify between- and within-breed genetic variation for numerous production and quality traits in a southern-Australian production system. Calf survival, birth weight and carcass production traits (carcass weight, fat depth, loin eye area, intramuscular fat) were obtained from these cattle. The carcass traits were loge-transformed because of a scale effect on the variance. Data were analysed using multi-variate animal models containing fixed effects of sex with random effects of management group, sire breed and animal. In addition, birth month and age of dam were included as fixed effects for birth weight. Covariances between survival and other traits could not be estimated from the multi-variate model so they were estimated from a series of bi-variate models. On average, management group and sire breed accounted for similar proportions of variance. Heritability ranged from 0.14 (survival), 0.17 (intramuscular fat), 0.28 (loin eye area), 0.29 (P8 fat depth), 0.31 (birth weight) to 0.50 (carcass weight). In general, environmental (management and residual) correlations between meat (carcass weight and loin eye area) and fat traits (fat depth and intramuscular fat) were positive, but the genetic correlations (both between and within breed) were negative. Management and genetic (co)variation has been quantified and can facilitate production of calves with carcasses suitable for specific market requirements.

9 CAN ONE PREDICT THE RESISTANCE OF BULL SPERM TO CRYOPRESERVATION BY ANALYZING MOTILITY PARAMETERS BEFORE FREEZING?

Batches of straws often need to be thrown away after freezing due to a too-few-number of motile or progressive sperm cells (spz), whereas the quality of the fresh sperm was considered as acceptable. Our objective was to evaluate whether variables related to velocity or linearity for fresh spz could help to predict the resistance to freezing and allow the discard of poor-quality batches before freezing. Motility traits of 20 ejaculates from 20 Belgian Blue bulls collected at an AI center were evaluated for motile spz both before and after freezing using Computer-Assisted Sperm Analysis (CASA, Spermvision; Minit�b, Tiefenbach, Germany). Only six traits of motility showed a normal distribution in the population of motile spz and were kept for further analysis together with the proportion of motile (%mot) and progressive (%prog) spz: velocity on the curved line (VCL), velocity on the straight line (VSL), velocity on the average path (VAP), linearity (LIN = VSL/VCL), beat cross frequency (BCF), and average orientation change of the head (AOC). Significant variation between bulls was observed both before and after freezing for all of the analyzed traits (ANOVA2; P &amp;lt; 0.001). Moreover, freezing significantly altered the motility measures (ANOVA2; P &amp;lt; 0.001). For each variable, a significant correlation was observed between the values (mean or percentage) obtained for each bull before and after freezing (Pearson coefficient: R = 0.43 to 0.72; P &amp;lt; 0.05). However, the impact of freezing on the quality of motility differed between bulls, with low impact for some bulls and major impact for others. Three motility traits measured before freezing were highly correlated with %mot or %prog after freezing: VAP, VSL, and %prog (R = 0.75 to 0.82; P &amp;lt; 0.001). When we evaluated the prediction of rejection or acceptance of a batch of straws after freezing (based on a threshold of 15% progressive spz) by using motility measures recorded before freezing, five traits allowed us to discriminate low-quality batches: %mot, %prog, VAP, VSL, and LIN. Applying to fresh sperm a threshold of 92 �m s-1 for VAP or 84 �m s-1 for VSL allowed us to predict, respectively, 6 and 7 out of the 9 batches that would be rejected after freezing, without discarding batches of acceptable quality. Moreover, using the %mot or %prog before freezing caused us to discard only 3 and 4 batches, respectively. Combining different traits did not add to the precision. In conclusion, analysis of velocity traits for fresh sperm seems more efficient than analysis of %mot or %prog to discard batches that will be of poor quality after freezing. Such analysis could prevent useless work and expense related to straw filling and freezing. However, the definition of thresholds needs further analysis with a larger number of batches of semen and will vary from one AI center to another, depending, for example, on the breed characteristics, the number of spz per straw, the CASA system, or the freezing procedure. This work was supported by the programme FIRST Objective 3 of the European Commission and the Ministery of the R�gion wallonne de Belgique.

Breeding soundness and libido examination of Belgian Blue and Holstein Friesian artificial insemination bulls in Belgium and The Netherlands

Data on breeding soundness and libido evaluations in Belgian Blue (BB) bulls are scarce. The present study compared results of breeding soundness and libido evaluations of young BB bulls to young Holstein Friesian (HF) bulls prior to acceptance into an AI program. Breed differences for breeding soundness exist between BB and HF bulls, as 93.7% of the young BB bulls failed the breeding soundness examination (BSE) compared to 59.3% of the HF bulls ( P = 0.0005). Within the BB breed, differences were present between bulls of different ages, and bull selection for better fertility with increasing age apparently influenced the results. The number of reasons for which bulls failed the test differed between the age groups in the BB breed, whereas a tendency for more failure reasons in the BB breed was noticed in the breed comparison. The most important reasons for failure were sperm morphology and scrotal circumference (SC), but far more BB bulls failed for these traits compared to the HF breed (82.8% versus 56.0% and 43.8% versus 17.6% in the BB and the HF breed for sperm morphology ( P = 0.0005) and SC ( P < 0.0001), respectively). The high proportion of BB bulls with a substandard SC and poor sperm morphology might suggest an increased prevalence of testicular hypoplasia or degeneration within this breed. Concerning libido, the reaction time did not differ either between breeds or between age groups within the BB breed, whereas mounting enthusiasm, although not different between the two breeds, did decline with increasing age, probably due to the greater mating experience of the older bulls. All in all, libido did not seem to be different between the breeds.

Myostatin: a modulator of skeletal-muscle stem cells.

Myostatin, or GDF-8 (growth and differentiation factor-8), was first identified through sequence identity with members of the BMP (bone morphogenetic protein)/TGF-beta (transforming growth factor-beta) superfamily. The skeletal-muscle-specific expression pattern of myostatin suggested a role in muscle development. Mice with a targeted deletion of the myostatin gene exhibit a hypermuscular phenotype. In addition, inactivating mutations in the myostatin gene have been identified in 'double muscled' cattle breeds, such as the Belgian Blue and Piedmontese, as well as in a hypermuscular child. These findings define myostatin as a negative regulator of skeletal-muscle development. Myostatin binds with high affinity to the receptor serine threonine kinase ActRIIB (activin type IIB receptor), which initiates signalling through a smad2/3-dependent pathway. In an effort to validate myostatin as a therapeutic target in a post-embryonic setting, a neutralizing antibody was developed by screening for inhibition of myostatin binding to ActRIIB. Administration of this antimyostatin antibody to adult mice resulted in a significant increase in both muscle mass and functional strength. Importantly, similar results were obtained in a murine model of muscular dystrophy, the mdx mouse. Unlike the myostatin-deficient animals, which exhibit both muscle hypertrophy and hyperplasia, the antibody-treated mice demonstrate increased musculature through a hypertrophic mechanism. These results validate myostatin inhibition as a therapeutic approach to muscle wasting diseases such as muscular dystrophy, sarcopenic frailty of the elderly and amylotrophic lateral sclerosis.

Myostatin: a modulator of skeletal-muscle stem cells

Myostatin, or GDF-8 (growth and differentiation factor-8), was first identified through sequence identity with members of the BMP (bone morphogenetic protein)/TGF-beta (transforming growth factor-beta) superfamily. The skeletal-muscle-specific expression pattern of myostatin suggested a role in muscle development. Mice with a targeted deletion of the myostatin gene exhibit a hypermuscular phenotype. In addition, inactivating mutations in the myostatin gene have been identified in 'double muscled' cattle breeds, such as the Belgian Blue and Piedmontese, as well as in a hypermuscular child. These findings define myostatin as a negative regulator of skeletal-muscle development. Myostatin binds with high affinity to the receptor serine threonine kinase ActRIIB (activin type IIB receptor), which initiates signalling through a smad2/3-dependent pathway. In an effort to validate myostatin as a therapeutic target in a post-embryonic setting, a neutralizing antibody was developed by screening for inhibition of myostatin binding to ActRIIB. Administration of this antimyostatin antibody to adult mice resulted in a significant increase in both muscle mass and functional strength. Importantly, similar results were obtained in a murine model of muscular dystrophy, the mdx mouse. Unlike the myostatin-deficient animals, which exhibit both muscle hypertrophy and hyperplasia, the antibody-treated mice demonstrate increased musculature through a hypertrophic mechanism. These results validate myostatin inhibition as a therapeutic approach to muscle wasting diseases such as muscular dystrophy, sarcopenic frailty of the elderly and amylotrophic lateral sclerosis.

Myostatin auto‐regulates its expression by feedback loop through Smad7 dependent mechanism

Myostatin, a secreted growth factor, is a member of the TGF-beta superfamily and an inhibitor of myogenesis. Previously, we have shown that myostatin gene expression is regulated at the level of transcription and that myostatin is a downstream target gene of MyoD. Here we show that myostatin gene expression is auto-regulated by a negative feedback mechanism. Northern blot analysis indicated that there are relatively higher levels of myostatin mRNA in the biceps femoris muscle of cattle that express a non- functional myostatin allele (Belgian Blue) as compared to normal cattle. In contrast, addition of exogenous myostatin decreases endogenous myostatin mRNA. Consistent with this result, wild type myostatin protein is able to repress myostatin promoter activity via Activin type IIb receptor (ActRIIB) and ALK5 (P < 0.001). However, non-functional myostatin (Piedmontese) failed to repress the myostatin promoter suggesting that myostatin auto-regulates its promoter by negative feedback inhibition. Auto-regulation by myostatin appears to be signaled through Smad7, since the expression of the inhibitory Smad7 is induced by myostatin and the over-expression of Smad7 in turn inhibits the myostatin promoter activity (P < 0.001). In contrast down regulation of Smad7 by siRNA results in increased myostatin mRNA indicating that Smad7 is a negative regulator of myostatin gene expression. Consistent with these results, a decrease in Smad7 mRNA and concomitant increase in myostatin expression is seen in myotubes that express non functional myostatin. In addition, interference with myostatin signaling prevents the induction of Smad7 promoter activity by myostatin. Based on these results, we propose that myostatin auto-regulates its gene expression through a Smad7 dependent mechanism in myogenic cells.

Carcass dissection and commercial meat yield in Piemontese and Belgian Blue double-muscled young bulls

To study the differences in meat yield in hypertrophied cattle, a commercial dissection trial was carried out on 48 carcasses obtained from 24 Piemontese (P: 12 reared with a restricted feeding, P-R, and 12 fed ad libitum, P-L), and 24 Belgian Blue (B: 12 reared with a restricted feeding, BB-R, and 12 fed ad libitum, BB-L) young bulls. The animals were reared under the same environmental condition and slaughtered at the same age and fattening degree. During commercial dissection, the weights of the retail cuts were recorded. Three fore-quarter meat cuts were heavier in P than in BB, while nine meat cuts (two from fore-quarter and seven from hind-quarter), hind-quarter meat and prime quality meat were heavier in BB than in P. Fat weight was higher in BB than in P, whereas meat production as a percentage of carcass side weight was higher in P than in BB. Only one hind-quarter meat cut was heavier in the ad libitum (L) than in the restricted (R) group, whereas meat yield was higher in R than in L. In comparing the meat yield in carcass sides of P-R, P-L, BB-R and BB-L fed young bulls, four meat cuts (one from fore-quarter and three from hind-quarter), hind-quarter, prime quality and 3rd quality meat were heavier in BB-L ( P ≤ 0.05), while one shoulder cut and fore-quarter were heavier in P-R group.

Genetic Relationships Between Male and Female Reproductive Traits in Beef Cattle

AbstractReproductive traits were measured for 234 bulls and 1184 heifers from matings of three dam breeds (Angus, Hereford, and MARC III) with six sire breeds (Angus, Hereford, Brahman, Boran, Tuli, and Belgian Blue) from the Germ Plasm Evaluation (GPE) Program at Roman L. Hruska US Meat Animal Research Center. Male traits were yearling scrotal circumference (YSC), height (YH), and yearling BW; age at puberty (API; production of 50 million sperm with ≥10% progressive motility); age, scrotal circumference, average testis length, and testicular volume when 500 million sperm were produced with ≥50% progressive motility (AP3, SC3, L3 and V3, respectively); and 15-mo BW (15W) and height (15H). Traits of females were age at puberty (AP, first estrus) and pregnancy rate (PR) at 18 mo. The objective was to determine whether indirect selection on male traits would be effective for improving female fertility traits. Selection of males on AP1, AP3, SC3, L3, V3, YH, 15W, and 15H may be useful for improving PR because of genetic correlations and low heritability for PR. Although no male trait was found to be effective for improving AP in females through indirect selection, YSC and SC3 were the most favorable. If heritability were as large as estimated in this study for AP (0.52), direct rather than indirect selection would seem to be more effective for AP in heifers, although the difficulty of measuring AP in heifers also would need to be considered. Male reproductive traits, such as scrotal circumference and also YH and 15H, however, are easier and less expensive to measure than female reproductive traits, and greater selection intensity can be applied to these male traits.

Effect of dietary structure on animal performance and lesions in the ruminal wall and feet of Belgian Blue double-muscled bulls

AbstractThe influence of the physical structure level in the diet on animal performance was investigated in 52 Belgian Blue doublemuscled bulls starting from a live weight of 348 kg until slaughter at about 645 kg. Four diets with different concentrate/maize silage ratios were offered ad libitum. The structural value (SV), developed in Belgium as a measure of physical structure in the diet for dairy cows, amounted to respectively 0.63 (HSV; high SV), 0.54 (MSV; moderate SV), 0.43 (LSV; low SV) and 0.34 (VLSV; very low SV) per kg dry matter.Growth rate, food intake and food conversion were all linearly affected by the decreasing SV of the diet. Among carcass parameters only the SEUROP conformation score showed a significant effect of the SV, with the MSV group having the highest score and VLSV the lowest. No important influence of the SV on the histological damage of the ruminal papillae or on the foot lesions was found.Based on the lower growth rate and food intake of the LSV group versus the HSV group, a SV of the diet between 0.54 and 0.43 is considered as an absolute minimum for Belgian Blue double-muscled bulls.

Proteomic analysis of bovine skeletal muscle hypertrophy

Myostatin plays a major role in muscle growth and development and animals with disruption of this gene display marked increases in muscle mass. Little is known about muscle physiological adaptations in relation to this muscle hypertrophy. To provide a more comprehensive view, we analyzed bovine muscles from control, heterozygote and homozygote young Belgian blue bulls for myostatin deletion, which results in a normal level of inactive myostatin. Heterozygote and homozygote animals were characterized by a higher proportion of fast-twitch glycolytic fibers in Semitendinosus muscle. Differential proteomic analysis of this muscle was performed using two-dimensional gel electrophoresis followed by mass spectrometry. Thirteen proteins, corresponding to 28 protein spots, were significantly altered in response to the myostatin deletion. The observed changes in protein expression are consistent with an increased fast muscle phenotype, suggesting that myostatin negatively controls mainly fast-twitch glycolytic fiber number. Finally, we demonstrated that differential mRNA splicing of fast troponin T is altered by the loss of myostatin function. The structure of mutually exclusive exon 16 appears predominantly expressed in muscles from heterozygote and homozygote animals. This suggests a role for exon 16 of fast troponin T in the physiological adaptation of the fast muscle phenotype.

Effect of ruminal degradable nitrogen deficit on nitrogen metabolism in growing double-muscled Belgian Blue bulls fed maize silage based diet

As concerns for environmental damage instigated by agricultural processes increase, there is a greater need to develop more ecologically acceptable methods of producing agricultural products. Therefore, in beef production we have to minimise N excretion and maximise N retained. Urea recycling provides a mechanism by which N may be salvaged into bacterial matter that may be digested by the animal to supply amino acids for production purposes. According to Huntington and Archibeque (2000), the amount of recycled urea-N can be influenced by the ruminal ammonia concentration, the OM digestibility and the plasma concentration of urea. The objective of the present study was to examine the effect of different levels of ruminal degradable N (RDN) on nutrient digestion and N metabolism in double-muscled Belgian Blue (dm-BB) bulls fed maize silage based diet.