An experiment with 30 Hereford growing bulls was designed to study the effects of (1) forage type and (2) inclusion of rapeseed meal (RSM) in the barley-based concentrate. The three forage types were grass silage (GS), whole crop barley silage harvested at the milk stage (BSM) or at the dough stage (BSD). The concentrate used was rolled barley alone or barley plus RSM. Mean total dry matter (DM) intakes for the GS, BSM and BSD bulls were 9.04, 8.74 and 9.46 kg/day, and carcass gains were 883, 770 and 867 g/day, respectively. Both DM intake and carcass gain were significantly higher in the BSD bulls compared with the BSM bulls. Mean carcass weights of the GS, BSM and BSD bulls were 395, 369 and 392 kg, respectively, and tended to be lower in the BSM bulls. Forage type and RSM had no effects on the carcass conformation or fat score. Rapeseed meal supplementation increased total DM intake (+10%, P<0.01), carcass gain (+14%, P<0.001) and carcass weight (+8%, P<0.01) of the bulls. Overall, GS could be totally replaced by whole crop barley silage in the diet of growing bulls when the concentrate constitutes 0.4 of the diet, but whole crop barley silage should be harvested at the dough stage instead of the milk stage.

Marbling is an economically important factor in many beef carcass grading schemes. This study aimed to evaluate marbling traits of longissimus thoracis muscle (LT) with different methods: USDA marbling score, intramuscular fat (IMF) content by image analysis of X-ray computed tomography (CT) scans and by conventional analytical method. Bulls (n=46) were slaughtered at an average weight of 536 kg and an average age of 646 days. Mean values of EUROP fat scores varied from 2− to 2+, whereas mean values of EUROP conformation grade from O0 to R0. Average growth rate of bulls was 955 g/day. Average chemical fat content of LT varied from 2.2% to 3.1% across conformation classes, and from 2.3% to 5.0% across fat classes. Intramuscular fat content in the 12th rib and in LT on CT-scans closely correlated with chemical fat content (r=0.81 and 0.85, respectively). The highest frequency of USDA marbling score was ‘small’ (55.2%), followed by ‘slight’ (25.5%), ‘modest’ (17%) and ‘moderate’ (2.1%). Computed tomography scans of LT can be used for the evaluation of marbling in Hungarian Simmental cattle. Bulls with higher growth rate had lower marbling level in LT (r=−0.4 to −0.5). EUROP conformation and fat scores have no relationship with marbling traits in this specific cattle population.

The aim of this study was to analyse cow reproductive performance on 37 Irish suckler beef farms and determine how reproductive efficiency influences farm profitability. The main reproductive factors associated with gross output value per livestock unit (GO/LU) were average age at first calving (r=−0.19, P<0.01) and number of months with a calving (r=−0.15, P<0.05). A 1 month increase in average age at first calving was shown to reduce GO/LU by €14 across suckler farms. Average age at first calving was positively correlated with calving interval (r=0.21, P<0.001) and the number of months with a calving (r=0.18, P<0.01). Number of months with a calving was also positively correlated with calf mortality (r=0.21, P<0.01). However, these relationships between reproductive variables had no statistically significant impact on farm financial performance. It is therefore concluded that additional analysis at animal level is required to determine key reproductive indicators contributing to farm profitability.

This study aimed to examine the effects of replacing rolled barley (high in starch) with citrus pulp (high in digestible fibre) in a supplement on intake and performance of young growing cattle offered grass silage ad libitum for 101 days. Weaned, early- and late-maturing breed, male suckled beef calves (n=120) were blocked by sire breed, gender and weight and from within block randomly assigned to one of two concentrate supplements based mainly on rolled barley (BAR) or citrus pulp (CIT) and formulated to have similar concentrations of true protein digestible in the small intestine. On day 87, blood samples were taken before and 2 h after feeding, and rumen fluid samples were collected 2 h post-feeding. Supplement type did not affect (P>0.05) grass silage intake, live weight gain, final live weight, ultrasonically assessed body composition or measurements of skeletal size. Rumen pH (6.64 v. 6.79), ammonia (51 v. 81 mg/l) and acetate-to-propionate ratio (2.7 v. 3.2) were lower (P<0.001) for CIT than BAR. In conclusion, citrus pulp can replace barley in concentrate supplements for growing cattle without negatively affecting performance.

Accurately quantifying a consumer’s willingness to pay (WTP) for beef of different eating qualities is intrinsically linked to the development of eating-quality-based meat grading systems, and therefore the delivery of consistent, quality beef to the consumer. Following Australian MSA (Meat Standards Australia) testing protocols, over 19 000 consumers from Northern Ireland, Poland, Ireland, France and Australia were asked to detail their willingness to pay for beef from one of four categories that best described the sample; unsatisfactory, good-every-day, better-than-every-day or premium quality. These figures were subsequently converted to a proportion relative to the good-every-day category (P-WTP) to allow comparison between different currencies and time periods. Consumers also answered a short demographic questionnaire. Consumer P-WTP was found to be remarkably consistent between different demographic groups. After quality grade, by far the greatest influence on P-WTP was country of origin. This difference was unable to be explained by the other demographic factors examined in this study, such as occupation, gender, frequency of consumption and the importance of beef in the diet. Therefore, we can conclude that the P-WTP for beef is highly transferrable between different consumer groups, but not countries.

The aim of this 3 year study was to compare two suckler cow genotypes, namely Limousin×Holstein (LH) (sourced from the dairy herd) and Stabiliser (ST) (a composite breed), in terms performance at calving. Both dam genotypes were bred to a ST sire and calved in spring/early summer. There was no significant effect of dam genotype on concentrations of casein, lactose, protein or urea nitrogen in the colostrum. Colostrum from LH cows had a significantly higher fat concentration compared with ST cows (P<0.05). Dam genotype had no effect on incidence of calving difficulty, cow temperament or mothering ability score. There was a significant difference in milk supply scores between the two breeds of cows when the 3 years of data were combined (P=0.002), with a higher percentage of LH cows having a plentiful supply of milk compared with ST cows and conversely a higher percentage of ST having limited milk compared with LH cows. However this was not a consistent effect over the 3 years. This study demonstrated that both dam breeds exhibit high maternal attributes at calving. However further work is required to investigate if LH cows have a more plentiful milk supply since this has potential to influence growth rate of progeny.

This study aimed to compare the quality of beef from suckler bulls raised on a high-energy concentrate ration and slaughtered at different carcass weights (CW)/ages. In total, 42 spring-born, Charolais and Limousin-sired, weaned suckler bulls were provided with a finishing diet of ad libitum concentrates and grass silage until they reached target CW of 340, 380 and 420 kg. Intramuscular fat (IMF) content tended (P<0.06) to be higher for 420 kg CW than for 380 and 340 kg CW. Sensory tenderness was lower (P<0.001) for 420 kg CW than for 380 and 340 kg CW. Juiciness was higher (P<0.05) for 420 kg CW than for 380 kg CW. Flavour liking was higher (P<0.05) for 420 and 380 kg CW (which did not differ) than for 340 kg CW. Overall, an increase in CW resulted in a slight increase in IMF content which could be responsible for the increase in juiciness and flavour liking of the beef. An increase in CW led to a decrease in the tenderness of the beef even though the overall liking of the beef was not affected.

The major histocompatibility complex region has been implicated in explaining some of the variation observed in adaptability and tick susceptibility of cattle. The bovine leukocyte antigen region of 192 cattle representing indigenous, composite and exotic breeds used in commercial beef production in Namibia and South Africa was investigated using four microsatellite markers. Ticks counted under the tail were taken as an indicator of tick susceptibility. Tick scores of all but one population was low (11 to 20 ticks), with only the South African Bonsmara population having an average score of 31 to 40 ticks per animal. The observed variation based on four microsatellite markers ranged from 5.5 alleles in Namibian Afrikaner to 7.7 alleles in South African Nguni and Bonsmara cattle. Unbiased heterozygosity values ranged from 0.66 (Namibian Afrikaner) to 0.76 (South African Bonsmara). Structure analyses grouped the five populations into three indistinct clusters with limited genetic variation between the populations.

The most popular beef breed in South Africa is the Bonsmara, a locally developed composite breed adapted to sub-tropical conditions. The establishment of a genomic reference population is currently ongoing for the application of genomic selection. To date, 583 Bonsmara cattle (388 bulls and 195 cows) have been genotyped with the GeneSeek® Genomic Profiler Bovine HD™ Chip (GGP-HD) 80 K chip, and the population structure of the reference population was studied. The average minor allele frequency for the Bonsmara was 0.280 across 56 248 autosomal single-nucleotide polymorphisms (SNPs), whereas the observed and expected heterozygosity values were 0.361 and 0.365, respectively. After pruning the data set for SNPs in linkage disequilibrium, 19 119 SNPs were retained, averaging 659 SNPs per autosomal chromosome. This generated an average SNP density of 1 SNP per 90 kb. Structure analysis revealed a non-homogenous population with a high level of genetic admixture, which may negatively influence genomic breeding value prediction accuracy. Genotyping of a further 990 Bonsmara cattle are pending, using the GeneSeek® GGP-HD 150 K chip. As more animals will be added to the reference population, the profile of the reference population are expected to change in such a way to ensure improved genomic estimated breeding value accuracies.

The most important factors known to influence the eating quality of beef are well established and include both pre- and post-slaughter events with many of the determinants interacting with each other. A substantial programme of work has been conducted by the Agri-Food and Biosciences Institute in Northern Ireland aimed at quantifying those factors of most importance to the local beef industry. Post-slaughter effects such as carcase chilling and electrical stimulation, ageing, carcase hanging and cooking method have been shown to have a significant impact on eating quality when compared with pre-slaughter activities such as animal handling and lairage time in the Northern Ireland studies. However, the effect of animal breed, particularly the use of dairy breed animals, was shown to significantly improve eating quality. Many of these factors were found to interact with each other.

Activity of brown and beige adipocytes could contribute to breed differences in fat deposition. Therefore, we compared the abundance of markers for adipocyte types in steers from three cattle breeds differing in fat deposition (Japanese Black, Holstein, Charolais). Markers for white (leptin (LEP)), beige (transmembrane protein 26 (TMEM26), uncoupling protein 1 (UCP1)), and brown adipocytes (Zic family member 1 (ZIC1), UCP1) were analysed by quantitative reverse transcription PCR in subcutaneous fat (SCF), intramuscular fat (IMF), intermuscular fat (IRMF), perirenal fat (PF) and visceral fat (VF). LEP messenger RNA (mRNA) was less abundant in VF compared with other depots (P<0.05). TMEM26 was weakly but evenly expressed in all depots in all animals, whereas UCP1 mRNA showed higher individual variation in some depots. ZIC1 was not detectable in VF and PF but abundant in SCF, IMF and even more abundant in IRMF (P<0.05). No significant breed differences were detected. Using antibodies against UCP1, TMEM26 and ZIC1, we demonstrated that fat depots of 26-month-old cattle still comprise different adipocyte types. However, our results did not support the hypothesis that higher energy expenditure associated with higher abundance or activity of beige or brown adipocytes contributed to differences in fat deposition.

This study aimed to evaluate levels of beef cow fertility using calving interval (CI; measured in days) as a measure, and investigate the effects of breed, season, year and progeny gender on CI. The CI data included 273 764 records collected between 1997 and 2012 and included the seven most common breeds (and their crosses) in Northern Ireland (Charolais, Limousin, Belgian Blue, Simmental, Blonde d’Aquitaine, Aberdeen Angus and Hereford), accounting for 94.1% of beef dams recorded. Mean CI for all cows was 395 days, 30 days longer than the optimum 365 days. Charolais and Belgian Blue dams had the longest CI (P<0.05). Cows older than 144 months had a longer CI (P<0.05) compared with cows younger than 144 months. Charolais sires had a shorter subsequent CI of 392 days (P<0.05) compared with the other breeds. Cows calving in June had the shortest subsequent CI (376 days; P<0.05), whereas cows calving in November had the longest subsequent CI (410 days). Progeny gender did not significantly affect CI. This study establishes the level of beef cow fertility using CI as a measure in Northern Ireland is sub optimal and there are opportunities for improvement. Factors identified as influencing CI included dam breed, sire breed and month of parturition. This knowledge can be used to direct breeding programmes and inform knowledge transfer protocol to improve sustainability of beef production.

Genomic imprinting is a term applied to an epigenetic phenomenon where alleles are fully or partially inactivated depending on their parental origin. The relevance of this kind of parent-of-origin effects (POEs) for agriculturally important traits is widely known. A model (imprinting model) with a transmitting ability (TA) as sire and a TA as dam has been proposed that provides an estimate of the imprinting variance, whether the allelic inactivation is maternal, paternal, full or partial. Although the model can be used in a reduced version, large data sets still prevent the imprinting variance from being estimated. To further reduce the size of the equation system, we developed a parsimonious imprinting model with genetic effects for male ancestors only, as the TA as dam is replaced by her father’s TA. This parsimonious model was applied to 1 366 160 Simmental fattening bulls with slaughter data available on killing out percentage, net BW gain, EUROP class and fat score in a linear and generalised linear version. The pedigrees contained up to 2 637 761 ancestors. Proportion of the total genetic variance attributed to POEs ranged between 8.6% and 17.0%. On average, the maternal gamete accounted for the greater proportion of the imprinting variance. An equivalent version of the parsimonious model facilitated the estimation of POEs with reliabilities ranging between zero and 0.97.