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Intensive dairy and beef cattle farming contribute significantly to the emissions of greenhouse gases from Belgian agriculture. Two main breeds dominate the Belgian cattle livestock; Holstein-Friesian (HF) dairy cattle and double-muscled Belgian Blue (DMBB) beef cattle. The aim of our study was to quantify and compare methane emissions of both breeds under conditions of equal diet composition, environment and physiological stage (using heifers of the same age). The methanogen and bacterial communities were thoroughly investigated using metabarcoding to correlate taxonomic compositions with breed and methane emission levels. HF heifers had significantly higher absolute enteric methane emissions as compared to DMBB heifers. Methane production was positively correlated to the dry matter intake (DMI). Due to the significantly higher DMI and energy intake of HF heifers, methane yield per DMI was not significantly different between breeds. Furthermore, no significant differences were observed between the gross feed efficiency (GFE) of both breeds, but the DMBB heifers demonstrated significantly lower CH4:CO2 ratios (mole-to-mole ratio), suggesting a more efficient fermentation by the rumen microbial ecosystem. Although both breeds accommodated a common core of taxonomic groups, the bacterial communities also showed a breed specific composition due to differential abundance of specific species belonging to the main taxonomic groups and the presence of a few species of minor taxonomic groups that were significantly associated with one of both breeds. In contrast to the bacterial communities, the methanogen community was consistent and stable between breeds and at different sampling times. Our results suggest that breed related factors influence the bacterial community composition, while the variation in methane emission levels can be attributed mainly to the feed intake of the animals.

The objective of this study was to verify the feasibility of a joint genetic evaluation system for calving ease trait of Belgian Blue (BBB) and Holstein (HOL) Walloon cattle based on data of purebred and crossbred animals. Variance components and derived genetic parameters for purebred BBB and HOL animals were estimated by using single-breed linear animal models. This analysis showed clear genetic differences between breeds. Estimates of direct and maternal heritabilities (±standard error) were 0.34 (±0.02) and 0.09 (±0.01) for BBB, respectively, but only 0.09 (±0.01) and 0.04 (±0.01) for HOL, respectively. Moreover, a significant negative genetic correlation between direct and maternal effects was obtained in both breeds: −0.46 (±0.04) for BBB and −0.29 (±0.11) for HOL. Variance components and derived genetic parameters for purebred BBB and HOL and crossbred BBB × HOL cattle were then estimated by using two multi-breed linear animal models: a multi-breed model based on a random regression test-day model (Model MBV), and a multi-breed model based on the random regression multi-breed model (Model MBSM). Both multi-breed models use different functions of breed proportions as random regressions, thereby enabling modelling different additive effects according to animal's breed composition. The main difference between these models is the way in which relationships between breeds are accounted for in the genetic (co)variance structure. Genetic parameters differed between single-breed and multi-breed analysis, but are similar to the literature. For BBB, estimates of direct and maternal heritabilities (±SE) were 0.45 (±0.07) and 0.08 (±0.01) by using Model MBV, and 0.45 (±0.08) and 0.09 (±0.02) for Model MBSM, respectively. For HOL, these estimates were 0.18 (±0.04) and 0.05 (±0.01) using Model MBV, and 0.16 (±0.04) and 0.05 (±0.01) for Model MBSM, respectively. Reliability gains (up to 25%) indicated that the use of crossbred data in the multi-breed models had a positive influence on the estimation of genetic merit of purebred animals. A slight re-ranking of purebred sires and maternal grandsires was observed between single-breed and multi-breed models. Moreover, both multi-breed models can be considered as quasi-equivalent models because they performed almost equally well with respect to MSE and correlations, for purebred and crossbred animals.

Double-muscled cattle differ in body composition in comparison with non-double-muscled cattle, which may result in a different mineral content. Therefore, the concentrations of calcium (Ca) and phosphorus (P) in the empty body weight (EBW) of double-muscled Belgian Blue (DMBB) cattle, and the consequence for their requirements were investigated. Forty-nine animals were sacrificed: 8 neonatal calves, 17 growing-finishing bulls with diverging EBW and 24 cows with diverging EBW and body condition. Mean EBW±SE averaged 47±2 kg, 472±32 kg and 625±25 kg, respectively. Concentrations of ash, Ca and P per kg EBW averaged 48, 11 and 7 g, 37, 11 and 7 g, 40, 11 and 7 g/kg for calves, bulls and cows, respectively. Finishing cows (n = 5 out of 24) showed a tendency for lower concentrations of ash and Ca per kg EBW than finishing bulls (n = 5). Concentrations of P per kg EBW were lower in finishing cows than in breeding cows (n = 7), due to a dilution effect as a consequence of a higher fat content in the EBW. Calcium and P contents in the EBW of bulls were very accurately predicted by a linear function (all P 〈 0.001; all R2 〉 0.9) based on BW, but estimates were less accurate in cows, even when BCS and age were used as independent variables. The dietary requirements were calculated using regression equations based on the compositional data and recent information on metabolic losses and absorption coefficients from the literature. From a BW of about 400 kg onwards the accretion of P in growing DMBB bulls is higher than generally assumed. Furthermore, due to a lower feed intake capacity of DMBB cattle compared with non-double-muscled cattle, dietary P concentrations need to be higher than for other breeds. Daily Ca and P requirements for foetal growth are similar to those of non-double-muscled cows.

Two experiments were conducted to determine the effect of an energy restriction (80% (ER) vs. 100% (CON) of total energy requirements; 140 d: P1) followed by a re-alimentation (ad libitum intake; 70 d; P2) on feed intake, body weight (BW) change, and feed efficiency in double-muscled Belgian Blue cows. Regression analysis based on feed intake and BW change during P1 was used to deduce energy requirements for maintenance by setting BW change to zero. The diet consisted of maize silage and 0.5 kg mineral–vitamin premix in experiment 1, where dietary crude protein (CP) concentration was constant (105 g/kg dry matter (DM)) during the whole experiment. A similar diet was fed during the restriction period in experiment 2 with 97 g CP/kg DM. Extra soybean meal and urea were fed to all cows during the re-alimentation period of experiment 2, resulting in 198 g CP/kg DM. Both experiments showed that BW loss of ER cows during P1 was not compensated during P2, so that BW gain of ER cows during the entire experiment remained lower compared to CON cows (Po0.05). Similar results were obtained for feed intake. Feed conversion ratio was not different between treatments during P2, but it tended to be worse for ER cows vs. CON cows for the entire experiment (Po0.10). Extra dietary crude protein during P2 in experiment 2 did not modify the effect of treatment on animal performance compared to experiment 1. Therefore, feeding double-muscled Belgian Blue cows below their energy requirements for maintenance, and growth in case of first and second-calf cows should be strongly discouraged. Metabolisable and net energy requirements for maintenance were estimated at 0.586 MJ and 0.338 MJ/ kg BW 0.75 , respectively.

A palatable concentrate may stimulate intake and ease weaning stress. This study investigated the effect of the incorporation of spelt in the concentrate on calf performance (Experiment 1) and the palatability (Experiment 2). Sixty-six newborn Belgian Blue double-muscled female calves were involved in Experiment 1 to investigate the effect of incorporating 30% spelt grain in the concentrate (S+) as a replacement for 15% barley and 15% wheat (S−) during a 143-day rearing period. Calves received reconstituted milk at 10% of their birth weight. They were weaned when concentrate intake achieved 0.75 kg/day. Grass hay was fed ad lib. After the rearing period all calves were adapted during 2 weeks to the same diet, fed to appetite, and consisting of maize silage and concentrate without spelt. Performances were investigated during 4 weeks. Spelt reduced the in vitro organic matter digestibility and the net energy content of the concentrate from 91.5% and 7.4 MJ/kg to 88.1% and 7.0 MJ/kg, respectively. It stimulated concentrate intake initially, so that calves were weaned after 58 days compared to 67 days for calves fed S− concentrate (P=0.012). A higher amount of dry matter (P=0.056) was required per kg live-weight gain for S+ concentrate, but energy efficiency was similar for both treatments (P=0.415). Daily live-weight gain for the entire rearing period was not affected (P=0.970) and averaged 0.77 kg. Daily live-weight gain and feed intake were lower for the S+ treatment during the transition period (P

The objective of this study was to assess the potential of video image analysis (VIA) in predicting various wholesale carcass cuts in cattle. Video image analysis and meat cut weights were available from two different sources: an experimental (n = 346) and a commercial dataset (n = 281). The cattle used were crossbred steers (predominant breeds were Belgian Blue, Angus, Friesian, Charolais, Holstein, Limousin, and Simmental) in the experimental dataset, and crossbred heifers (predominant breeds were Limousin, Belgian Blue, Charolais, and Simmental) in the commercial dataset. In both datasets, the meat cuts were grouped into four groups based on retail value: Low Value Cuts (LVC), Medium Value Cuts (MVC), High Value Cuts (HVC), and Very High Value Cuts (VHVC); total meat weight was calculated as the sum of the individual meat cut weights. In addition, total bone weight and total fat weight were available in the experimental dataset. In both datasets, a calibration and a validation sub-dataset were created for each of the carcass cut groups. Multiple regression analyses were applied to each calibration dataset to predict the cuts from using three different sets of models based on the predictors: 1) carcass weight only, 2) carcass weight plus EUROP carcass classification, and 3) carcass weight plus VIA parameters. The accuracy of predicting yields of cuts was superior to prediction of cut yields as a proportion of the carcass weight. Across both the experimental and the commercial datasets, the proportion of variation of wholesale cut yields in the validation dataset explained (R2) ranged from 0.33 (total fat weight in the experimental dataset) to 0.91 (total meat weight in the experimental dataset) using carcass weight as the sole predictor. The R2 increased to between 0.65 (LVC in the commercial dataset) and 0.97 (total meat weight in the experimental dataset) when carcass weight plus VIA variables were used as predictors. In the analyses of both the experimental and the commercial data, models that included the VIA variables had the lowest root mean square error of prediction across traits. Mean bias and correlations between the residuals and predicted values were generally not different from zero. Results from this study show that wholesale cuts in steers and heifers can be accurately predicted using multiple regression models incorporating carcass weight and VIA variables. The carcass images routinely stored provide a powerful tool for use in a beef breeding program to select for more valuable carcasses.

This study investigated the effects of free malic acid and a commercial malate salt on serum metabolic parameters in finishing-stage Belgian Blue bull calves maintained in a commercial feedlot. Serum levels of glucose, non-esterified fatty acids (NEFA), β-Hydroxibutirate (BHBT) urea nitrogen (SUN), creatinine, total protein (TSP), L-lactate, aspartate aminotransferase (AST) and gamma glutamyl transferase (GGT) were monitored over 86 days in 38 animals randomly allotted to three groups: MA (supplementation of feed with 4-g DL-malic acid per kg on a dry mass (DM) basis; 14 animals), MS (supplementation of feed with 4 g of a commercial disodium/calcium DL-malic acid salt per kg DM; 14 animals), and C (controls with no malate supplement; 10 animals). All the parameters considered except SUN lay within the physiological ranges for intensively reared beef, possibly due to the high crude protein (CP) content of the diet and the forage fiber source (barley straw). However, animals fed either form of malate had lower serum L-lactate and creatinine levels than those that did not receive this supplement, and their NEFA levels fell over time instead of rising. The only parameters differing between the free acid and salt groups were SUN and BHBT, which for unknown reasons, were higher in group MA than in either controls or group MS. That SUN was higher in group MA than in group C is attributed to its favoring CP-degrading ruminal flora. That BHBT was higher in group MA than in groups MS and C could be due to that the acid form can promote butyrate synthesis in rumen.

Genetic merit for growth rate, expressed as expected progeny difference for carcass weight (EPD CWT ), is available for dairy and beef sires used in Ireland. The once predominantly Friesian (FR) dairy herd has experienced significant introgression of Holstein (HO) genes over the past two decades, and cross-breeding of dairy cows, not required to produce herd replacements, with beef bulls is common. The objective of this study was to compare growth rate, feed intake, live animal measurements and slaughter traits of progeny of Holstein–Friesian dairy cows and bulls of two contrasting maturity beef breeds namely Aberdeen Angus (AA) and Belgian Blue (BB), each selected for either high (H) or low (L) estimated genetic merit for carcass weight. Two dairy strains (FR and HO) were also included giving six genetic groups in total. A total of 170 male progeny from spring-calving cows were artificially reared indoors and subsequently managed together at pasture until the end of their second grazing season when they were assigned to one of two mean slaughter weights (i) 560 kg (Light) or (ii) 620 kg (Heavy). Daily feed intake was recorded during the first winter and during finishing. Body measurements were recorded four times during the animals' life, and linear scoring was carried out at 9 months of age and again at slaughter. Carcasses were graded for conformation and fatness (15 point scale). Slaughter and carcass weights per day of age for AAH, AAL, BBH, BBL, FR and HO were 782, 719, 795, 793, 804 and 783 (SE 12.9) g, and 415, 372, 438, 436, 413 and 401 (SE 5.8) g, respectively. Corresponding values for carcass weight, kill-out proportion, carcass conformation class (15 point scale) and carcass fat class (15 point scale) were 314, 283, 334, 333, 317 and 305 (SE 4.7) kg, 526, 518, 553, 550, 519 and 511 (SE 2.9) g/kg, 6.2, 5.4, 8.0, 7.9, 5.3 and 3.7 (SE 0.26), and 9.8, 9.3, 7.4, 7.2, 9.3 and 8.2 (SE 0.26). There were significant interactions between estimated genetic merit for carcass weight and beef breed with the differences between H and L mainly expressed for AA only. Feed intake differences between H and L animals were negligible and largely attributable to the differences in live weight. Following scaling for live weight, beef breeds of high estimated genetic merit for carcass weight had lower skeletal measurements, indicating greater compactness, with the effect more pronounced in AA. It is concluded that using beef sires of estimated high genetic merit for carcass weight on dairy cows increases growth rate and carcass weight of the progeny but the effect may not be similar for all breeds.

The objectives of this study were to compare the progeny of 1) late-maturing beef with dairy breeds and 2) Charolais (CH), Limousin (LM), Simmental (SM) and Belgian Blue (BB) sires bred to beef suckler dams, for feed intake, blood hormones and metabolites, live animal measurements, carcass traits and carcass value in bull and steer production systems. The bull system included 50 late-maturing beef breeds and 22 Holsteins (HO) slaughtered at approximately 15 months of age, whereas the steer system consisted of 56 late-maturing beef breeds and 23 British Friesians (FR) slaughtered at approximately 24 months of age. Beef breeds were suckled until approximately 8 months of age, while dairy breeds were artificially reared until weaning at approximately 3 months of age. All animals were finished on an ad libitum concentrate diet. Mean live weight, live weight gain, carcass gain and feed efficiency were greater (P 0.05). The improvement obtained for beef over dairy breeds in live weight gain was 12%, while the improvements in carcass gain and meat produced was 24% and 33%, respectively. This demonstrates that the importance of carcass data contributing to breed comparison studies cannot be over-emphasised.

In Ireland, a new beef genetic index has been developed. Growth rate is expressed as expected progeny difference for carcass weight (EPDCWT) and is estimated on an across-breed basis. Cross-breeding of dairy cows with both Aberdeen Angus and Belgian Blue beef sires is widely practised. The objective of this study was to compare blood metabolites, slaughter traits and carcass composition of progeny from Holstein–Friesian dairy cows and Aberdeen Angus (AA), Belgian Blue (BB), Friesian (FR) and Holstein (HO) sires. The AA and BB sires were selected, within breed, to be of either high (H) or low (L) estimated genetic merit for carcass weight. A total of 170 male progeny from spring-calving cows and 42 sires (10 AA, 13 BB, 7 FR and 12 HO) were artificially reared indoors and managed together until the end of their second grazing season when they were assigned to either a Light (560 kg) or Heavy (620 kg) slaughter weight. Blood metabolite concentrations were measured six times throughout life and feed intake was recorded during the first and second winter. Carcass measurements and selected non-carcass components were recorded after slaughter and the right side of each carcass was dissected into lean, fat and bone. Differences in blood metabolite concentrations amongst genetic groups were negligible although there were some effects of the prevailing level of nutrition. M. longissimus area scaled for carcass weight was 0.220, 0.221, 0.260, 0.255, 0.212 and 0.208 (SE 0.004) cm2/kg for AAH, AAL, BBH, BBL, FR and HO, respectively. Carcass measurements scaled for carcass weight were greater for L, AA, HO and the dairy strains than for H, BB, FR and the beef breeds, respectively. There was no effect of estimated genetic merit for carcass weight on carcass composition. Statistically significant interactions between genetic merit and beef breed existed for some traits with the genetic merit effect largely evident for AA only. BB and the beef breeds had more lean, less fat and more high value lean in the carcass than AA and the dairy strains, respectively. It is concluded that genetic group had little effect on blood metabolite concentrations but there were some feeding level effects. Estimated genetic merit for carcass weight affected carcass weight, m. longissimus area and carcass measurements scaled for carcass weight but the effects were confined to AA. There were large effects of beef breed and dairy strain on carcass composition.

Live weight is an important trait in cattle farming. Weighing is not always feasible and therefore live weight is often estimated from easily accessible data. In this study, data on live weight, age and gender, and four body measurements, withers height (WH), heart girth (HG) and width of the shoulders (SW) and hind quarters (BcW) of double-muscled Belgian Blue beef (DM-BBB) farm animals were used to develop multivariable non-linear and linear regression models that predict live weight from these easily accessible data. The relationship between the logarithm of the live weight and the logarithm of time is adequately described by a general logistic function. The age period from 100 to 600 days of age is contained in the linear part of the logistic function. This region is of particular economic interest because it contains the yearling age and slaughter age that are important in DM-BBB breeding and management. Adding one of the body traits in the linear models that contain age and gender as fixed effects decreases the coefficient of variation. A model with withers height and shoulder width has the lowest coefficient of variation, with no further significant improvement when adding either heart girth or width of the hind quarters.

Pure bred Holstein–Friesian (FR) and beef breed × FR male calves are used for beef production in Ireland. Beef breeds used for crossbreeding on FR cows include Aberdeen Angus (AA) and Belgian Blue (BB) which represent extremes in terms of maturity. The objective of this study was to compare spring-born steers of FR, AA and BB breed types, offered two feeding levels in their second winter, and subsequently finished on pasture or on a high concentrate diet indoors. Seventy-two steers (24 per breed type) were managed together to the end of their second grazing season. They were then blocked on weight within breed type and assigned to a 3 (FR, AA and BB breed types) × 2 (winter feeding levels) × 2 (finishing systems) factorial experiment. The two winter feeding levels were grass silage ad libitum plus mean daily concentrate levels of 0.91 (L) or 4.0 (H) kg dry matter for 113 days. The two finishing systems were pasture or concentrates ad libitum for a mean period of 94 days. Mean slaughter and carcass weights for FR, AA and BB were 634, 644 and 642 (s.e. 8.1), and 313, 326 and 340 (s.e. 4.7) kg, respectively. Other than bone proportion which was lower for AA, there were few differences in ribs joint composition or in m. longissimus chemical composition between FR and AA. BB had less fat and more muscle in the ribs joint, and more moisture and protein, and less lipid in m. longissimus than both FR and AA. Compared with L, the H winter feeding level increased slaughter weight and carcass weight by 24 and 15 kg, respectively. Indoor finished animals were 63 kg live weight and 39 kg carcass weight heavier than those finished at pasture. They also had more fat and less muscle and bone in the ribs joint and more lipid and less moisture in m. longissimus. It is concluded that except for BB finished at pasture all carcasses were commercially acceptable. Despite the excellent finishing performance on concentrates, this system is not profitable at current concentrate and beef prices.

The accuracy of the Rice pelvimeter for measuring pelvic area of double muscled Belgian Blue (BB) cattle was investigated bycomparing measurements in the live animal with these obtained from the same animal after slaughter. Pelvic measurements from 466 BB-cows aged 2–10 years old and of an excellent carcass qualification (S and E in the SEUROP classification) were measured with the pelvimeter approximately 12 h prior to, and by graded ruler within 2 h after, slaughter. The mean difference of measurements between living and dead cattle were −0.2 cm for pelvic width (95% limits of agreement −2.5–2.1 cm), and 1.2 cm for pelvic height (95% limits of agreement −1.8–4.1 cm). The correlation coefficient between all pelvic measurements was between 0.46 and 0.59 (pb0.001). The age of the animals influenced only pelvic height whilst carcass weight influenced all the components of the pelvic area. There was a significant correlation between the pelvimetric measurements of the birth canal in living cattle obtained using a Rice pelvimeter compared to actual measurements obtained from the carcass. The Rice pelvimeter is a suitable tool for assessing accurate pelvic skeletal conformation and to select animals in this breed with a larger birth canal and hence less dystocia problems.

This study evaluated the influence of diet grain mix on the serum acid–base balance and productive performance of calves maintained on high-grain diets in a commercial feedlot system, monitoring progress over the entire 140-day productive cycle (i.e. both the growing and finishing periods). Thirty 14-week-old Belgian Blue bull calves were randomly allotted in equal numbers to one of three experimental groups defined by whether the cereal grain in their diet was predominantly corn (group C), predominantly barley (group B), or predominantly a mixture of corn and barley in approximately equal proportions (group CB). Blood pH, p CO 2 , HCO 3 − , base excess and serum l -lactate were determined, as were several productive performance variables. The three groups differed significantly with respect to their weights at the end of the growing period (CB > C > B), but not in final weight; group B gained significantly more weight and had a lower daily intake than either group C or group CB during the finishing period. At no time during the study period was altered ruminal function suggested by either clinical signs or blood parameters, possibly because of the relatively high crude protein (CP) contents of the feeds and the use of barley straw as forage. Nevertheless, HCO 3 − and base excess were significantly higher in group C than in the other groups during the growing period, suggesting that supplementation of a high-CP corn-based diet with bicarbonate could lead to alkalotic blood base values (group C was the only group to receive bicarbonate supplement in this study). Also, in group CB HCO 3 − and base excess were generally lower than in the other groups during both the growing and finishing periods, much of the time exhibiting a falling trend compatible with the use of blood bases to counteract overproduction of ruminal acids; this behaviour, which may have been due to the lower dietary fibre content of the CB diet, does not support claims that diets with equal proportions of rapidly and slowly digested starch sources are more beneficial than those including only one of these starch source types. Serum l -lactate levels were almost invariably higher in group B than in group C, with group CB in between, in both the growing and the finishing periods; and a significant time × group interaction during the growing period suggests that the time course of serum l -lactate was determined mainly by the influence of diet on microbial growth rates in the rumen. Negative correlation between blood pH and p CO 2 around the switch between growing and finishing regimens suggests that diet may possibly modulate the influence of breed on p CO 2 , but further is required to examine this hypothesis.

Cross-breeding of dairy cows with beef bulls is common in Ireland with the Aberdeen Angus and Belgian Blue beef breeds both widely used. These breeds differ in maturity and consequently in their suitability for production systems differing in intensity and slaughter age. The objective of this study was to compare spring-born Holstein–Friesian (FR), Aberdeen Angus × Holstein–Friesian (AA) and Belgian Blue × Holstein–Friesian (BB) steers slaughtered off pasture at the end of their second grazing season or slaughtered at the end of the second winter following indoor finishing. Fifty-four (18 per breed type) steers were managed together to 16 months of age. They were then blocked on weight within breed type and assigned to a 3 (breed types) × 2 (finishing strategies) factorial experiment. The two finishing strategies were (i) concentrate supplementation (mean 3.65 kg/day) at pasture for 105 days to slaughter, and (ii) pasture only for 105 days followed by indoor finishing on grass silage plus concentrates for 141 days to slaughter. Mean slaughter and carcass weights per day of age for FR, AA and BB were 852, 802 and 834 (S.E. 13.1) g, and 427, 412 and 452 (S.E. 7.3) g, respectively. Corresponding kill-out proportions, carcass conformation and carcass fat classes were 501, 514 and 542 (S.E. 2.4) g/kg, 1.90, 2.15 and 2.89 (S.E. 0.073), and 3.09, 3.27 and 2.59 (S.E. 0.122), respectively. The response to concentrates at pasture was 101 g live weight and 83 g carcass weight per kg dry matter. It is concluded that there were few differences between FR and AA in carcass growth and composition but BB had heavier carcasses of better conformation with higher proportions of lean meat and high-value lean joints than both FR and AA. Acceptable live weight and carcass weight gains were obtained on pasture plus concentrates but BB and FR carcasses were not acceptably finished off pasture. Both FR and AA produced acceptable carcasses following indoor finishing and BB carcasses, while below the target fat class, were acceptably finished based on internal fat and dissected carcass fat proportions.

Belgian Blue (BB) beef cattle is particularly prone to selenium (Se) deficiency due to the poor Se content of soil and roughages on rearing farms and the higher requirements of this hypermuscled breed. The goal of this trial was to compare the effects of different forms and concentrations of Se supplementation on Se status, health and performance in 60 pregnant Se-deficient BB cows. Cows were allocated to 3 experimental groups receiving selenized-yeast at 0.5 ppm Se on total ration (Y–Se 0.5), Na–selenite at 0.5 ppm Se on total ration (Na–Se 0.5) and Na–selenite at 0.1 ppm Se on total ration (Na–Se 0.1), respectively. Cows were supplemented from 2 months before calving until 2 months after calving. Data on performance, health and Se status of the dams and their calves were analyzed using a linear model, least squares means and logistic regression. At the end of the study, plasmatic Se (pSe) was significantly higher (P 0.1). At the same dosage, Y–Se conferred better Se status in both dams and their calves than did Na–Se. Requirement of 0.1 ppm Se seems to be insufficient in BB to optimise health and performance. Regarding health status and ADG in calves, Y–Se seems also to result in better performance.