Hereford Bulls Research Articles

Fatty acid profiles of intramuscular, intermuscular, external and internal fat in Polish Holstein-Friesian × Hereford bulls and steers fed grass silage-based diets supplemented with concentrates

This paper determined the impact of gender and feeding intensity on the profile of fatty acids in different types of fat deposits. The studies were conducted with 20 young bulls and 20 steers, which were Polish Holstein-Friesian and Hereford crossbreds fattened intensively – grass silage ad libitum and concentrate covered 50% of the net energy requirement in fattened cattle or semi-intensively – concentrate covered 30% of the net energy. The fatty acid profile in intramuscular, intermuscular, external and internal fat was determined. The content of intramuscular fat was lower (P < 0.001) in the longissimus muscle in the bulls (1.74%) than in the steers (3.71%). In fat of steers, the proportion of monounsaturated fatty acids was higher whereas in fat of bulls, the content of polyunsaturated fatty acids was higher. Generally the impact of the location of fat depots on the profile of fatty acids was statistically significant (P < 0.001) but there was no effect of feeding intensity.

The influence of crossbreeding on collagen solubility and tenderness of Infraspinatus and Semimembranosus muscles of semi-intensively reared young bulls.

The aim of the present study was to investigate the effects of crossbreeding on collagen content and solubility, shear force (WBSF) and the eating quality of Infraspinatus (INF) and Semimembranosus (SM) muscles of young bulls and the relationships between collagen content and solubility, shear force and the eating quality of beef. The experimental material comprised muscles of crossbred young bulls (about 600 days old) of Polish Holstein-Friesian (PHF) × Limousine (LM) (n = 10), PHF × Charolaise (CH) (n = 9), PHF × Hereford (HER) (n = 9) breeds. The crossbreeding influenced WBSF, aroma and taste, total, water-soluble, acid-soluble, total soluble and insoluble collagen content, as well as the acid-soluble, total soluble and insoluble collagen proportions. WBSF was significantly negatively correlated with sensorial tenderness and water-soluble collagen content. The eating quality of beef obtained from different crossbreds was similar; however, the meat from PHF × LM and PHF × HER bulls had lower WBSF values than PHF × CH bulls. © 2016 Japanese Society of Animal Science.

Effect of easy calving beef sires on the birth weight and growth of dairy beef cattle

The impact of using high genetic merit beef bulls in a dairy beef supply chain was compared to using unrecorded beef bulls. Dairy cows were inseminated with Ezicalve Hereford semen (high genetic merit for calving ease and growth), followed by natural mating with Ezicalve and unrecorded Hereford bulls. The resulting 186 progeny were monitored from birth to 2 years old. Ezicalve sired calves required no calving assistance and averaged 4 kg lighter at birth than those from unrecorded sires (P

Time budgets of finishing bulls housed in an uninsulated barn or at pasture

This study aimed at comparing the behaviour of finishing bulls raised in an uninsulated barn (UB) and at pasture (PAS). In experiment 1, dairy bulls were housed in an uninsulated barn (two groups of five bulls, 32 m2/pen) or at pasture (groups of four and five bulls, 5000 m2/paddock). In experiment 2, Hereford bulls were housed in an uninsulated barn (three groups of four or five bulls, 32 m2/pen) or at pasture (three groups of five bulls, 5000 m2/paddock). There were no differences in drinking, social licking, butting, other social behaviour, self-licking or idling between the UB and PAS bulls. The UB bulls spent more time in lying, ruminating, oral explorative and manipulative behaviour and rubbing and less time foraging and walking than the PAS bulls. The UB bulls performed more social licking and oral manipulation of objects and less mounting than the PAS bulls. These differences resulted most probably from the different feeding regimes and different space allowances.

Production, carcass characteristics and valuable cuts of beef breed bulls and heifers in Finnish beef cattle population

The objective of the present study was to determine growth and carcass traits of beef breed bulls and heifers in the Finnish beef cattle population. The data collected from Finnish slaughterhouses included observations of 6323 and 2385 Hereford (bulls and heifers, respectively), 4421 and 1794 Charolais, 4335 and 1951 Limousin, 4068 and 1692 Aberdeen Angus, 2151 and 774 Simmental, 344 and 147 Blonde d’Aquitaine animals. For estimating valuable cuttings, a separate dataset including in total 1112 bulls and 260 heifers was also collected. Significant breed differences were observed in growth performance, carcass traits and retail product yield. The later maturing, Continental beef breeds seem to reach higher carcass gains, produce less fat and have more valuable cuts than the earlier maturing British beef breeds. The later maturing beef breeds tend to have carcass traits that suit well in the Finnish beef production system.

Sustainable crossbreeding systems of beef cattle in the era of climate change

Beef cattle are unique, because they not only suffer from climate change, but they also contribute to climate change through the emission of greenhouse gases (GHG). Mitigation and adaptation strategies are therefore needed. An effective way to reduce the carbon footprint from beef cattle would be to reduce the numbers and increase the production per animal, thereby improving their productivity. Sustainable crossbreeding systems can be an effective way to reduce GHG, as it has been shown to increase production. There are a wide range of different cattle breeds in South Africa which can be optimally utilized for effective and sustainable crossbreeding. This paper reports on the effects of crossbreeding on the kilogram calf weaned per Large Stock Unit (kgC/LSU) for 29 genotypes. These genotypes were formed by crossing Afrikaner (A) cows with Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S) bulls and by back-crossing the F1 cows to the sire lines. A LSU is the equivalent of an ox of 450 kg with a daily weight gain of 500 g on grass pastures with a mean digestible energy (DE) content of 55% and a requirement of 75 MJ metabolizable energy (ME). Crossbreeding with A as dam line increased the kgC/LSU on average by 8 kg (+6%) - with the CA cross producing the most kgC/LSU (+8%) above that of the AA. The BA dam in crosses with C, H and S, increased kgC/LSU on average by 26 kg (+18%) above that of the AA dam, with the H x BA cross, producing the most kgC/LSU (+21%). The BA, CA, HA and SA F1 dam lines, back-crossed to the sire line breeds, increased kgC/LSU on average by 30 kg (21%), 21 kg (15%), 19kg (13%) and 26 kg (18%) above the that of the AA, respectively. The big differences between breeds in kgC/LSU provide the opportunity to facilitate effective crossbreeding that can be useful in the era of climate change. From this study it is clear that cow productivity can be increased by up to 21% through properly designed, sustainable crossbreeding systems, thereby reducing the carbon footprint of beef production.Keywords: Carbon footprint, cow productivity, kilogram calf, production systems

Age peculiarities of simmenthal breed and its cross-breeds with hereford and charolais

Biochemical blood test analysis results of cross-breed bull-calves, obtained from crossing Simmenthal cows with both Hereford and Charolais bulls, are provided in the article. Data on both protein and lipid content metabolism indices in various age periods in bull-calves blood are also provided. It has been discovered that urea content in blood of new-born bull-calves exceeded its content in one-year-old bull-calves by 65.4-80.1%, and glucose content - by 66,6-112,7% (P ≤ 0,001). As compared to new-born bull-calves content nonesterified fatty acids in blood of a day-old bull-calves increased by 17,7-39,0%, and in a month-old bull-calves - by 32,3-48,8% (P ≤ 0,01-0,05).

Concentrations of Toxic and Nutritional Essential Elements in Meat from Different Beef Breeds Reared under Intensive Production Systems

Concentrations of major nutritional and trace elements (Ca, P, Mg, Na, K, Fe, Zn, Cu, Mn, Se, Co, Cr, Ni, Sr, and Ba), as well as toxic heavy metals (Cd and Pb), were analyzed in the longissimus muscle of Charolais, Hereford, and Simmental bulls. The elements were determined using inductively coupled plasma optical emission spectrometry. The study showed that the breeds differed in the concentrations of K, Mg, Zn, Cu, Fe, and Mn in meat. Meat from Charolais bulls had a significantly higher K (P < 0.01) content and significantly lower Cu, Zn (P < 0.001), and Mn (P < 0.05) contents compared to Hereford and Simmental meats. Meat from Charolais bulls also had a significantly lower Fe (P < 0.05) content in comparison with Hereford meat and a significantly lower Mg (P < 0.05) content compared to Simmental meat. Moreover, meat from Hereford bulls was characterized by a significantly higher Fe (P < 0.05) content and a lower Mg (P < 0.01) content than that from Simmental bulls. The Se and Fe contents in meat from bulls of breeds used in this study were lower than those previously reported. No breed differences were found in Pb and Cd contents. However, the Pb concentration in meat was higher than the recommended standards. In meat from bulls of all breeds, significantly strong positive correlations were observed between the contents of Pb and Ni, Cd and Ni, K and P, as well as Mg and P. Correlations between other elements within each of the breeds separately were also found.

Milk production traits of beef cows as affected by horn fly count and sire breed type1

Horn fly infestations negatively impact economic traits of beef cattle. Our objective was to determine the impact of horn flies on beef cattle milk yield and quality. Cows (n = 53) were derived from Brangus dams and sired by Bonsmara (n = 7), Brangus (n = 13), Charolais (n = 8), Gelbvieh (n = 5), Hereford (n = 12), and Romosinuano (n = 8) bulls. Horn fly counts and estimates of milk yield and quality were recorded monthly from May through October on individual cows. Data for milk yield and quality and horn fly count were analyzed by mixed model least squares using a linear model including sire breed, cow in sire breed, month, and month × sire breed. Effects of horn fly count on milk yield and quality were estimated by analysis of covariance using log horn fly count and log horn fly count × sire breed. Horn fly counts varied by month (P < 0.0001), with lowest population recorded in May (99 flies) and peaked in August (520 flies). Bonsmara and Gelbvieh sired cows had greater (P < 0.05) milk yield compared to Hereford sired cows (8.75 and 8.62 vs. 6.02 kg/d, respectively). Milk yield from Charolais, Romosinuano, and Brangus sired cows was intermediate (7.28, 7.00, and 7.06 kg/d, respectively). Regression of milk yield on fly count differed (P < 0.05) among sire breeds. Milk yield was reduced (P < 0.05) by 0.99 and 0.64 kg/d per unit increase in log horn fly count in Gelbvieh and Bonsmara sired cows. Regression coefficient for milk yield on log horn fly count was reduced (P < 0.01) in Gelbvieh sired cows when compared with Brangus, Charolais, Hereford, and Romosinuano sired cows, and coefficients for Bonsmara sired cows were reduced (P < 0.05) in comparison to Brangus sired cows. Increases in log fly count were associated with decreases (P < 0.05) in milk fat, solids-not-fat, and milk urea nitrogen. Milk yield was reduced (P < 0.05) by increased fly numbers depending on month of lactation and interaction with log horn fly count. In May, June, and July milk yield was reduced 0.72, 0.68, and 0.71 kg/d per unit increase in log horn fly count. Our results indicate that horn fly infestations reduce milk yield and quality of spring-calving beef cows depending on sire breed and month of lactation. Development of sustainable beef production systems may include selecting breed types whose milk yield and quality is less influenced by horn flies, allowing for better expression of genetic potential for milk yield in nutritionally challenging environments.

Transcriptional background of beef marbling — Novel genes implicated in intramuscular fat deposition

The purpose of this study was to identify novel marbling-related genes by comparison of the global gene expression in semitendinosus muscle of 15-month-old Limousin (LIM), Holstein-Friesian (HF) and Hereford (HER) bulls. Muscle of LIM was lean with low intramuscular fat (IMF) content (0.53%) unlike the marbled muscles of HER and HF characterized by higher amounts of IMF (1.10 and 0.81%, respectively). The comparison of muscle transcriptional profile between marbled and lean beef revealed significant differences in expression of 144 genes, presumably involved in consecutive stages of adipose tissue development, such as preadipocyte proliferation and differentiation, adipocyte maturation, lipid filling and lipid metabolism leading to increased IMF deposition and marbling development. Correlation coefficients and regression analysis for nine of them (gadd45a, pias3, ccrn4l, diras3, pou5f1, hoxa9, atp2a2 and pim1) validated by real-time qPCR confirmed their moderate-high correlation with IMF% and explained up to 70.5% of the total variability in IMF deposition in the bulls.

The effect of silage plant species, concentrate proportion and sugar beet pulp supplementation on the performance of growing and finishing crossbred bulls

A 2 × 2 × 2 factorial design was used to study the effects on animal performance of (1) the silage plant species, (2) the proportion of concentrate, and (3) the inclusion of molassed sugar beet pulp (SBP) in a barley-based concentrate. A feeding experiment was conducted using 32 crossbred bulls (Aberdeen Angus × Nordic Red dams sired by Hereford bulls) and lasting 359 days. The experimental silages were harvested from either pure timothy grass (Phleum pratense) or mixed timothy grass and red clover (Trifolium pratense) stands. The bulls were offered silage ad libitum. The two concentrate proportions were 330 and 660 g/kg diet DM. The concentrate used was either rolled barley or a mixture of rolled barley (700 g/kg DM) and SBP (300 g/kg DM). Concentrate proportion and silage plant species had no effect on total intake of the bulls (7.66 kg DM/day, on average) but SBP supplementation increased intake by 5% (P &lt; 0.05). The dietary treatments had no effect on liveweight gain (1120 g/day) or carcass gain (705 g/day) of the bulls. The average carcass weight of the bulls was 405 kg. SBP supplementation increased carcass weight by 3% (P &lt; 0.05) but it was not influenced by concentrate proportion or silage plant species. The dietary treatments had no effect (P &gt; 0.05) on the dressing proportion or carcass conformation of the bulls. The carcass fat score was 13% higher in the bulls fed with pure grass silage compared with bulls fed the grass–red clover silage (P &lt; 0.05), while the concentrate proportion and SBP supplementation had no effect on fat score.

Hepatic transcriptome profiling identifies differences in expression of genes associated with changes in metabolism and postnatal growth between Hereford and Holstein‐Friesian bulls

This study examined liver transcriptomic profiles of cattle distinctly different in meat and milk production capacity. It was performed on bulls of two different genetic backgrounds: Herefords (H), a meat breed, and Holstein-Friesians (HF), a dairy breed. Using bovine long oligo-microarrays and qPCR, we identified 128 genes that are differentially expressed between the two breeds. In H bulls, we observed up-regulation of genes involved in fatty acid biosynthesis and lipid metabolism (CD36, CAT, HSD3B1, FABP1, ACAA1) and involved in insulin signaling (INSR, INSIG2, NR4A1) and down-regulation of genes involved in somatotropic axis signaling (IGF1, GHR, IGFBP3) as compared to HF. Transcriptome profiling of these two breeds allowed us to pinpoint the transcriptional differences between Holstein and Hereford bulls at hepatic level associated with changes in metabolism and postnatal growth.

Within- and across-breed imputation of high-density genotypes in dairy and beef cattle from medium- and low-density genotypes.

The objective of this study was to evaluate, using three different genotype density panels, the accuracy of imputation from lower- to higher-density genotypes in dairy and beef cattle. High-density genotypes consisting of 777,962 single-nucleotide polymorphisms (SNP) were available on 3122 animals comprised of 269, 196, 710, 234, 719, 730 and 264 Angus, Belgian Blue, Charolais, Hereford, Holstein-Friesian, Limousin and Simmental bulls, respectively. Three different genotype densities were generated: low density (LD; 6501 autosomal SNPs), medium density (50K; 47,770 autosomal SNPs) and high density (HD; 735,151 autosomal SNPs). Imputation from lower- to higher-density genotype platforms was undertaken within and across breeds exploiting population-wide linkage disequilibrium. The mean allele concordance rate per breed from LD to HD when undertaken using a single breed or multiple breed reference population varied from 0.956 to 0.974 and from 0.947 to 0.967, respectively. The mean allele concordance rate per breed from 50K to HD when undertaken using a single breed or multiple breed reference population varied from 0.987 to 0.994 and from 0.987 to 0.993, respectively. The accuracy of imputation was generally greater when the reference population was solely comprised of the breed to be imputed compared to when the reference population comprised of multiple breeds, although the impact was less when imputing from 50K to HD compared to imputing from LD.

Evaluation of Selected Parameters of Quality and Nutritive Value of Meat of Fattened Bulls Fed Diet with Distillers Dried Grains with Solubles (DDGS) from Wheat or Maize as a Source of Protein

The objective of this study was to evaluate the quality and nutritive value of meat of bulls receiving wheat or maize DDGS (distillers dried grains with solubles) as a source of protein in a feed ration. The Hereford bulls were fed maize silage, hay and concentrates. The factor differentiating the feeding of experimental groups was the composition of concentrates. All concentrates contained cereal meals, rapeseed cake, and additionally - depending on the group: soybean meal (group CC), wheat DDGS (group EC-1), and maize DDGS (group EC-2).The feed ration was found not to affect the chemical composition of Longissimus thoracis muscle. All feeding groups were characterised by a similar total content of SFA, MUFA and PUFA. The EC-2 group was characterised by a significantly higher content of C18:1 n-7 acid as compared to the two other groups and of CLA when compared to EC-1 group. L. thoracis muscle of animals from CC group was characterised by the highest content of C14:1, C 16:1 n-9, C 17:1 and C20:1 n-9 acids, with the differences being statistically significant when compared to EC-2 group. In group EC-2 analyses demonstrated a statistically higher n-6/n-3 PUFA ratio, in respect of the other groups. Muscle of the animals from EC-2 group, compared to that of CC group, was characterised by a significantly higher content of α-tocopherol. Out of the analysed quality parameters of meat, only pH value in group EC-1 was higher than in EC-2 group.

Relationship between feed intake, feeding behaviors, performance, and ultrasound carcass measurements in growing purebred Angus and Hereford bulls1

The objectives of this study were to examine the growth, DMI, and feeding behaviors of Angus and Hereford bulls; identify the relationships between feeding behaviors and variation in DMI and residual feed intake (RFI); and determine the value of feeding behaviors in predicting DMI. Individual DMI was measured in Angus bulls (n=189; initial BW=427±3.4 kg) and Hereford bulls (n=146; initial BW=411±4.1 kg) fed a grower ration for 71 d in 2009, 78 d in 2010, and 74 d in 2011 using a GrowSafe intake monitoring system. Feeding frequency (FF, meals/d), head down duration (HDD, s/d), head down duration per meal (HDDM, HDD/FF, s/meal), average meal size [AMS, kg/(meal·d)], and feeding rate (FR, g/s) were also measured or calculated using behavior data collected by the GrowSafe system. Ultrasound measures of 12th-rib fat thickness (UFT), longissimus muscle area (ULMA), and intramuscular fat (IMF) were determined during the midtest-weight event of every trial. The data from 3 yr were pooled to generate mean differences between the breeds. Residual feed intake was calculated using a linear regression of DMI on ADG and midtest BW0.75 (MMWT). Animals were classified into 3 RFI groups based on their RFI score as Low (>0.5 SD below the mean), Average (±0.5 SD from the mean), or High RFI (>0.5 SD above the mean). Angus bulls in the Low RFI group consumed 17% (P<0.0001) less DM than the bulls in the High RFI group, while in the Hereford bulls there was a 14% (P<0.0001) difference in DMI between Low and High RFI groups. Significant phenotypic correlations were observed between RFI and DMI (0.83, 0.77), G:F (-0.65, -0.51), HDD (0.41, 0.59), HDDM (0.40, 0.53), AMS (0.52, 0.36), and FR (-0.31, -0.51) in Angus and Hereford bulls, respectively. The HDD, HDDM, and FR were significantly correlated with DMI. The feeding behavior traits, HDD, HDDM, and FR when added to the RFI base model, explained 18, 17, and 13%, respectively, of the variation in DMI not explained by ADG and MMWT in Angus bulls. Similarly, in Hereford bulls, HDD, HDDM, and FR explained 35, 26, and 24%, respectively, of the variation in DMI not explained by ADG and MMWT. These data suggest that feeding behaviors are related to DMI of growing Angus and Hereford bulls.

Effects of pain mitigation and method of castration on behavior and feedlot performance in cull beef bulls

The objectives of this study were to evaluate the effects of castration method (banding vs. surgical) and use of analgesia on behavior and feedlot performance in cull bulls. Angus, Hereford, and Angus-crossbred bulls (n = 20; initial BW = 384 ± 59.3 kg; 336 ± 20.1 d old) were housed in feedlot pens equipped with the ability to measure individual daily feed intake. A balanced randomized block design using a 2 × 2 factorial arrangement of treatments was used. A multimodal analgesia (MMA) protocol was used and consisted of sutcutaneous ketamine stun containing butorphanol (0.01 mg/kg BW), xylazine (0.02 mg/kg BW), ketamine (0.04 mg/kg BW), and a local 2% lidocaine hydrochloride anesthetic block of the spermatic cords (10 mL/cord) and scrotum (10 mL) on d 0. Flunixin meglumine (1.2 mg/kg) was administered intravenously on d 0, 1, 2, and 3 to MMA cattle. Cattle were stratified to treatments based on breed, BW, age, and a temperament score. Treatments included 1) band castration without analgesia (BND), 2) band castration with analgesia (BND-MMA), 3) surgical castration without analgesia (SURG), and 4) surgical castration with analgesia (SURG-MMA). All castrations were performed on d 0. Chute exit velocity (EV) and time in chute (TIC) were collected on d -9, 0, 1, 2, and 13. Willingness-to-enter-chute (WTE) score, rectal temperature (TEMP), heart rate (HR), and respiration (RESP) were collected on d 0, 1, 2, 3, and 13. Cattle were weighed on d -9 and 13 while feeding behaviors were collected continuously for 57 d precastration and 28 d postcastration. There was a tendency (P < 0.09) for ADG to be greater in cattle receiving analgesia. Both SURG treatments exhibited elevated TEMP on d 1 (P < 0.001) and 2 (P < 0.05) compared to BND treatments. Postcastration DMI was greater (P = 0.02) in MMA treatments compared with nonmedicated treatments throughout the trial. Meal duration was greater (P < 0.05) in BND than SURG castrates during the first week postcastration. Results suggest that pain mitigation reduces the impact of castration on ADG and DMI.

Suplementação de touros com sabões cálcicos de ácidos graxos poli-insaturados e qualidade seminal pré e pós-congelação

The objective of this experiment was to evaluate semen quality of bulls supplemented with calcium soaps of fatty acids polyunsaturated. Twenty Angus, Brangus, Hereford and Braford bulls were randomly allocated into two groups, each with ten animals. Each group received a diet consisting of forage, commercial ration, mineral supplements and supplement. Two supplements types were evaluated: functional supplement, with fatty acids polyunsaturated (PUFA) incorporation or energy supplement, with cassava meal (Manihot esculenta, Crantz) incorporation. During trial period the semen quality was evaluated using routine test (volume, concentration, mass motility, individual motility, sperm morphology) and complementary test: (hypo-osmotic test, giemsa/tripan-azul coloration and thermotolerance test). The semen of group bulls supplemented with commercial calcium soaps of PUFA (Megalac-E®) showed greater sperm motility (83.3% vs. 75.3%), percentage of sperm with intact acrosome (94.8% vs. 91.8%) and percentage of sperm with intact plasma membrane (98.0% vs. 96.6%) when compared with semen of group bulls supplemented with cassava (P&lt;0.05). The supplement type did not affect semen volume, sperm concentration and testosterone concentration in blood (P&gt;0.05). There were interactions between treatment and collection period for percentage of normal sperm and percentage of spermatozoa with hypo-osmotic positive test (P&lt;0.05). The type of supplement did not affect sperm motility, the hypo-osmotic test and fast thermotolerance test after thawing (P&gt;0.05). PUFA calcium soaps supplementation increased percentage of spermatozoa with plasma membrane integrity (51.5 vs. 42.2%) and spermatozoa intact acrosome (48.0% vs. 39.2%) after thawing.

Identification of predicted genes expressed differentially in pituitary gland tissue of young growing bulls revealed by cDNA-AFLP technique

Differentially expressed transcript derived fragments (TDFs) of bovine pituitary gland tissue at different developmental ages of Limousine and Hereford bulls were identified by cDNA-AFLP technique. Study revealed comparatively higher differentially expressed transcripts in 6-month Limousine bulls and 12-month Hereford bulls. The BLASTn/p analysis identified 3 and 21 predicted genes which gave significant e-values for Limousine and Hereford respectively, in assembled Bos taurus genome. The identified predicted genes expressed in bovine pituitary gland showed their mapped positions on bovine chromosomes: BTA2, 3, 5, 8, 9, 11, 12, 15&amp;ndash;23, 26, and 28, respectively. Results based on TDF annotation identified 10 sequences that have BLAST hits to known annotated bovine genes and 14 sequences to unannotated contig regions in the latest gene Ensembl database Btau_4.0. Two breed specific predicted target genes were validated by qRT-PCR. Within and between breeds, qRT-PCR results revealed highly significant differences in the expression levels of bovine euchromatic histone-lysine N-methyltransferase 1 (EHMT1) and NCK adaptor protein 2 (NCK2) predicted genes. Obtained results conclude that cDNA-AFLP is a reliable technique for studying within breed age dependent gene expression patterns.

Effects of concentrate level and rapeseed meal supplementation on performance, carcass characteristics, meat quality and valuable cuts of Hereford and Charolais bulls offered grass silage-barley-based rations

The objectives of this experiment with Hereford (Hf) and Charolais (Ch) bulls offered grass silage-based diets were to determine the effects on performance, carcass traits and meat quality of the proportion of concentrate in the diet, and the inclusion of rapeseed meal (RSM) in the barley-based concentrate. The two concentrate proportions were 200 and 500 g kg-1 dry matter, fed without or with RSM. The Ch bulls tended to achieve higher gain, produced less fat, had a higher percentage of meat from high-priced joints and had a lower degree of marbling in their meat compared to the Hf bulls. Dry matter and energy intakes, growth performance and carcass conformation improved with increasing concentrate level. Intake parameters and conformation improved more with the Ch bulls than with the Hf bulls as a consequence of increased concentrate allowance. RSM had only limited effects on the performance, carcass traits or meat quality.

Production, carcass and meat quality traits of Hereford, Charolais and Hereford×Charolais bulls offered grass silage-grain-based rations and slaughtered at high carcass weights

The objective of the experiment was to study performance and meat quality aspects of pure-bred Hereford (Hf) and Charolais (Ch) bulls and Hf×Ch cross-bred bulls offered grass silage-grain-based rations and raised to heavy carcass weights (CWs). The average slaughter age for all breeds was 565 days and the mean CWs for Hf, Hf×Ch and Ch bulls were 414, 476 and 507 kg, respectively. The Ch bulls tended to achieve higher weight gains, produce less fat and had a higher percentage of valuable cuts in comparison with Hf bulls. Breed group had no significant effects on the beef flavour of Musculus longissimus lumborum, but tenderness and juiciness were better in the meat of Hf bulls than that of Ch bulls. The cross-bred Hf×Ch bulls produced heavier and better conformed carcasses compared to pure Hf bulls which indicate that this type of cross-breeding can enhance beef production under the conditions studied.