Beef Sires Research Articles

Evaluation of estimated genetic merit for carcass weight in beef cattle: Live weights, feed intake, body measurements, skeletal and muscular scores, and carcass characteristics

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.

Evaluation of estimated genetic merit for carcass weight in beef cattle: Blood metabolites, carcass measurements, carcass composition and selected non-carcass components

In Ireland, a new beef genetic index has been developed. Growth rate is expressed as expected progeny difference for carcass weight (EPD CWT) 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) cm 2/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 animal measurements, carcass composition and plasma hormone and metabolite concentrations in male progeny of sires differing in genetic merit for beef production

In genetic improvement programmes for beef cattle, the effect of selecting for a given trait or index on other economically important traits, or their predictors, must be quantified to ensure no deleterious consequential effects go unnoticed. The objective was to compare live animal measurements, carcass composition and plasma hormone and metabolite concentrations of male progeny of sires selected on an economic index in Ireland. This beef carcass index (BCI) is expressed in euros and based on weaning weight, feed intake, carcass weight and carcass conformation and fat scores. The index is used to aid in the genetic comparison of animals for the expected profitability of their progeny at slaughter. A total of 107 progeny from beef sires of high (n = 11) or low (n = 11) genetic merit for the BCI were compared in either a bull (slaughtered at 16 months of age) or steer (slaughtered at 24 months of age) production system, following purchase after weaning (8 months of age) from commercial beef herds. Data were analysed as a 2 × 2 factorial design (two levels of genetic merit by two production systems). Progeny of high BCI sires had heavier carcasses, greater (P < 0.01) muscularity scores after weaning, greater (P < 0.05) skeletal scores and scanned muscle depth pre-slaughter, higher (P < 0.05) plasma insulin concentrations and greater (P < 0.01) animal value (obtained by multiplying carcass weight by carcass value, which was based on the weight of meat in each cut by its commercial value) than progeny of low BCI sires. Regression of progeny performance on sire genetic merit was also undertaken across the entire data set. In steers, the effect of BCI on carcass meat proportion, calculated carcass value (c/kg) and animal value was positive (P < 0.01), while a negative association was observed for scanned fat depth pre-slaughter and carcass fat proportion (P < 0.01), but there was no effect in bulls. The effect of sire expected progeny difference (EPD) for carcass weight followed the same trends as BCI. Muscularity scores, carcass meat proportion and calculated carcass value increased, whereas scanned fat depth, carcass fat and bone proportions decreased with increasing sire EPD for conformation score. The opposite association was observed for sire EPD for fat score. Results from this study show that selection using the BCI had positive effects on live animal muscularity, carcass meat proportion, proportions of high-value cuts and carcass value in steer progeny, which are desirable traits in beef production.

Intake, growth and carcass traits in male progeny of sires differing in genetic merit for beef production

Validation of economic indexes under a controlled experimental environment, can aid in their acceptance and use as breeding tools to increase herd profitability. The objective of this study was to compare intake, growth and carcass traits in bull and steer progeny of high and low ranking sires, for genetic merit in an economic index. The Beef Carcass Index (BCI; expressed in euro (€) and based on weaning weight, feed intake, carcass weight, carcass conformation and fat scores) was generated by the Irish Cattle Breeding Federation as a tool to compare animals on genetic merit for the expected profitability of their progeny at slaughter. A total of 107 male suckler herd progeny, from 22 late-maturing ‘continental’ beef sires of high (n = 11) or low (n = 11) BCI were compared under either a bull or steer production system, and slaughtered at approximately 16 and 24 months of age, respectively. All progeny were purchased after weaning at approximately 6 to 8 months of age. Dry matter (DM) intake and live-weight gain in steer progeny offered grazed grass or grass silage alone, did not differ between the two genetic groups. Similarly, DM intake and feed efficiency did not differ between genetic groups during an ad libitum concentrate-finishing period on either production system. Carcasses of progeny of high BCI sires were 14 kg heavier (P < 0.05) than those of low BCI sires. In a series of regression analyses, increasing sire BCI resulted in increases in carcass weight (P < 0.01) and carcass conformation (P = 0.051) scores, and decreases in carcass fat (P < 0.001) scores, but had no effect on weaning weight or DM intake of the progeny. Each unit increase in sire expected progeny difference led to an increase in progeny weaning weight, DM intake, carcass weight, carcass conformation score and carcass fat score of 1.0 (s.e. = 0.53) kg, 1.1 (s.e. = 0.32) kg, 1.3 (s.e. = 0.31) kg, 0.9 (s.e. = 0.32; scale 1 to 15) and 1.0 (s.e. = 0.25; scale 1 to 15), respectively, none of which differed from the theoretical expectation of unity. The expected difference in profitability at slaughter between progeny of the high and low BCI sires was €42, whereas the observed phenotypic profit differential of the progeny was €53 in favour of the high BCI sires. Results from this study indicate that the BCI is a useful tool in the selection of genetically superior sires, and that actual progeny performance under the conditions of this study is within expectations for both bull and steer beef production systems.

Mixed-breed twin production by contralateral direct-transfer of male embryos to beef cow recipients bred to GnRH-based, fixed-time AI

Two experiments were conducted to develop protocols for the use of fixed-time artificial insemination and embryo transfer (TAI and TET, respectively) to increase beef cattle productivity. Suckled beef cows were given GnRH (100 µg im) on Day − 10, and PGF (25 mg im) on Day − 3, with TAI on Day 0 (66 h later), and assigned to either embryo recipient (ER) or no embryo (NR) treatments on Days 6 or 7. Semen from Gelbvieh (GB) beef sires was used for TAI; sexed-male in vivo developed Holstein embryos (HO) were placed nonsurgically (TET) into the uterine horn contralateral to the corpus luteum. In Experiment 1, ovarian status of cows ( n = 111; 69 ± 11 d postpartum; mean ± SD on Day 0) in Groups I and II was presynchronized with a single PGF treatment on Day − 24; Groups II and III received GnRH concurrent with TAI, and ER ( n = 78) were selected from all groups on Days 6 or 7. Neither presynchronization nor GnRH affected rates of recipient selection, Day 45 pregnancy (43.2, 43.2, and 54.0% for Groups I, II and III, respectively), or calving (40.5, 37.8, and 43.2%). However, treatment with GnRH increased HO-birth rate (8.0, 14.0 and 24.0%; P < 0.05). In Experiment 2, cows ( n = 99, 113 ± 10 d postpartum) were assigned on Day 7 to NR and ER, with and without hCG (2500 IU im), following a TAI protocol (as per Group III in Experiment 1). Treatment with hCG increased reproductive rate (1.16 vs 1.44 calves/calving; P < 0.05), but had no significant effect on rates of Day 45 pregnancy (45.3 vs 41.3%), calving (31.2 vs 37.0%) or HO-births (20.0 vs 26.0%). In summary, GnRH-based synchronization rates were 71.2% (based on circulating progesterone concentrations that were < 1.0 ng/mL on Day 0 and ≥ 1.0 ng/mL on Day 7); TET did not affect GB-birth rate, but more calves were produced by ER than NR cows (1.43 vs 1.02 calves/calving; P < 0.01); and weaned calf production was 53% greater for twin- than singleton-suckled cows (392 ± 25 vs 256 ± 11 kg/dam; mean ± SEM, P < 0.05). Therefore, GnRH-based TAI and TET protocols for mixed-breed twin production increased beef cow productivity.

Joint disorder; a contributory cause to reproductive failure in beef bulls?

The lame sire, unsound for breeding, can cause substantial economic loss due to reduced pregnancies in the beef-producing herd.To test the hypothesis that joint disorder is a possible cause of infertility in beef sires, right and left hind limb bones from 34 beef sires were examined postmortem to identify lesions in the femorotibial, femoropatellar (stifle), tarsocrural, talocalcaneus, and proximal intertarsal (tarsal) joints. The bulls were slaughtered during or after the breeding season due to poor fertility results. Aliquots of the cauda epididymal contents taken postmortem from 26 bulls were used for sperm morphology evaluation. As a control, hind limbs (but no semen samples) from 11 beef bulls with good fertility results were included.Almost all infertile bulls (30/34) had lesions in at least one joint. Twenty-eight bulls (28/30, 93%) had lesions in the stifle joint, and 24 (24/28, 86%) of these were bilateral. Fourteen bulls (14/30, 47%) had lesions in the tarsal joint, and 10 (10/14, 71%) of these were bilateral. Four bulls (4/34, 12%) had no lesions, three bulls (3/34, 9%) had mild osteoarthritis (OA), 5 (5/34, 15%) moderate OA, 17 (17/34, 50%) severe OA and 5 (5/34, 15%) deformed OA. Almost all OA lesions (97%) were characterized as lesions secondary to osteochondrosis dissecans. All the bulls with satisfactory sperm morphology (n = 12/34) had joint lesions, with mostly severe or deformed bilateral lesions (83%). Consequently, the most likely cause of infertility in these 12 bulls was joint disease. Almost all control bulls (10/11) had OA lesions, but most of them were graded as mild (55%) or moderate (36%). None of the control bulls had severe lesions or deformed OA.We suggest that joint lesions should be taken into consideration as a contributory cause of reproductive failure in beef sires without symptoms of lameness.

Evaluation of Production Systems for Progeny of Beef Sires with Higher Marbling Expected Progeny Differences

ABSTRACT Two experiments evaluated higher-marbling, expected progeny difference (EPD) Angus sires on progeny growth, carcass traits, and meat composition. In trial 1, 40 progeny of sires with either high or low EPD for marbling were evaluated for feedlot performance, disposition score, carcass traits, palatability, and fat composition. Half of the cattle in each marbling group were harvested at an estimated 1.0 cm s.c. fat, and the remainder were harvested at an estimated 1.5 cm s.c. fat. In trial 2, 20 steers from high-marbling EPD sires were assigned to 1 of 4 treatments prior to entering a feedlot: 1) weaned at 170 d of age and backgrounded for 40 d; 2) weaned at 170 d of age; 3) weaned at 212 d of age and backgrounded for 40 d; or 4) weaned at 212 d of age. All steers were harvested at an estimated 1.25 cm s.c. fat. In trial 1, marbling score was significantly different for sire group. Percentage USDA choice carcasses and YG were different for sire and harvest groups (P

Selection for Profit in Cattle: II. Economic Weights for Dairy and Beef Sires in Crossbreeding Systems

The relative economic importance (economic weights) of 18 traits was determined for Holstein and Charolais sires used in a dairy production system applying cross-breeding with beef sires and in a cow-calf pasture cross-breeding system with integrated fattening of surplus animals. A bioeconomic model containing a profit function was used for the calculations in both systems. Discounted expressions for direct and maternal components of the traits during an investment period of 25 yr were calculated using the gene-flow technique. The relative economic weights for some traits or trait components of the dairy sires differed substantially between the purebred and crossbred dairy systems. There were also meaningful differences among the relative economic weights of traits for beef sires, depending on whether these bulls were used for terminal crossing with F1 females in the cow-calf pasture system (back-crossing), for crossing in dairy herds producing slaughter animals, or for crossing in dairy herds producing F1 females for the cow-calf pasture system. We therefore recommend construction of specific sets of subindices for dairy and beef sires to allow users to rank the bulls according to expected merit of their progeny in specific production systems.

In vivo body measures and growth of Holstein Friesian and double muscled Marchigiana or Belgian Blue crosses

The beef meat production must be improved in order to reduce the imports. To increase the muscle development and therefore to improve the valuable cuts, the crossbreed between dairy cows and beef sire can be utilized. A double muscled Marchigiana calf called Cicoria, found in a farm of the Ancona province, allowed to suppose in this breed the same strategy followed in other meat breeds (as Piemontese or Belgian Blue) that are utilized to obtain crosses with dairy cows. In this work the performance of crossbreeds between double muscled Marchigiana sire and Holstein cows are tested.Twelve Holstein Friesian were utilized; six of them were inseminated with Belgian Blue sires (BB) namely Derobe, Amiral and Eldorado, while the other six ones with the semen of a Marchigiana (M) sire (Osso), homozygous for the mutation at the myostatin gene, that causes the muscular hypertrophy in this breed. In this trial were therefore utilized twelve animals, six of which from the cross with the Marchigiana sire (three males and three females) and six from the cross with the Belgian Blue sire (two males and four females). To evaluate the growth of the calves the weight was monthly recorded with an electronic scale, together with body measures. To improve the accuracy, the measures were taken two times. On all the traits a GLM was performed according to a model concerning with the factors: genotype, sex, repetition and interactions. Only for the weight the linear regression on age was tested separately for the two genotypes and sexes. All the statistical analysis were performed by software SAS.The GLM analysis showed that differences between the two genotypes in almost all the traits are not significant. The main exceptions was width of thorax from 7 to 13 months of age where the significance level ranged from 0.05 (7 months) to 0.006 (13 months) with measures always bigger in BB (34.4, 37.9, 40.6, 42.3, 43.8, 44.5, 46.8) than in M (32.1, 34.6, 36.4, 41.0, 40.3, 41.3, 42.8). An other trait (width of shoulders) showed a significant interactions (P from 0.03 to 0.01) genotype * sex in the growth period 9-13 months. As a matter of fact in this trait a constant superiority of BB was observed in the males (41.8, 43.5, 46.3, 47.5, vs 38.5, 39.0, 40.3, 43.3), on the contrary in the females the shoulders were larger in M (39.0, 40.5, 43.0, 44.3 vs 37.3, 40.5, 41.5, 42.5). Also the regression parameters in the different genotypes and sexes were quite similar; the intercept (birth weight) ranged from 31.6 (M, F) to37.1 (BB, M) and the b coefficient (daily gain) ranged from 1.33 (BB, M) to 1.08 (BB, F).Finally, it’s necessary to take into consideration that M crosses were obtained by just one sire not genetically tested, while the BB crosses were obtained by sires qualified for the artificial insemination and with a high genetic index. Also if has to be taken into account the size of the experimental sample, it’s possible to conclude that the utilization of double muscled Marchigiana sire on dairy cows can allow the same performances obtained by the more used BB sires.

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.

Differences among beef sire breeds and relationships between terrain use and performance when daughters graze foothill rangelands as cows

A study was conducted on foothill rangeland to determine if breed of sire affected grazing distribution patterns and to evaluate relationships between individual grazing patterns and performance of beef cows. Angus (AN), Charolais (CH), Piedmontese (PI), and Salers (SA) sires were mated to dams with Hereford and Tarentaise breeding to produce cows observed during the summers of 1998–2001. Locations of individual cows were recorded two to three times per week during 1.5–2.5-h periods in the morning by observers on horseback. Terrain use was analyzed using a mixed statistical model that included breed of sire, dam terrain use category as fixed effects and cow as a random effect. Piedmontese-sired cows were observed farther ( P < 0.05) horizontally from water and showed a tendency toward higher ( P = 0.09) pasture ratios (PR) of terrain use than AN-sired cows. Cows from dams that used steeper slopes and areas farther from water grazed farther ( P < 0.05) vertically from water, tended to be observed farther ( P = 0.09) horizontally from water, and had a PR greater ( P < 0.05) than cows from dams that used gentle terrain near water. Relationships between terrain use and animal performance were evaluated each year using residual correlations from a model that included sire breed, dam breed, cow age, and pasture. In 1998 and 2001, cows that were heavier ( P < 0.05) and in 1998 taller ( P < 0.05) traveled farther horizontally from water than did lighter cows. Relationships between cow weight or hip height and horizontal distance to water were not observed during other years. No other relationships between terrain use and cow performance were found ( P > 0.05). Terrain use was not correlated ( P > 0.05) to calving date, actual weaning weight, or age-adjusted weaning weight. Pregnant cows used steeper ( P < 0.05) slopes in 2001, but no differences were detected in the other 3 years ( P > 0.05). Cows sired by bulls from breeds developed in mountainous terrain appeared to use rugged extensive pastures more uniformly than cows sired by bulls from breeds developed in gentler terrain. As observed in an earlier study, terrain use of cows grazing foothill rangeland was not consistently related to their weight, hip height, body condition, reproductive performance, or calf weight.

Selecting AI Beef Sires for Maximum Profit

Beef producers face a complex decision-making process when selecting from among AI sires that range widely in price and expected progeny difference (EPD) for various traits. Although individual producers vary in specific production goals, their goal in genetic improvement is generally motivated by potential profit. Because of the complexity of the sire selection decision and with semen prices as great as $100 per vial, economically optimal choices are not always clearly evident. To assist the producer in this decision, AI service sires were ranked according to their net present value (NPV). The analysis considered multiple genetic traits and examined the impact of various production goals and management situations faced by producers. Spring 2003 EPD for weaning BW, yearling BW, and milk of 552 available AI beef sires were used. Seven breeds from four AI semen providers were evaluated, and sires were ranked by NPV from both the crossbred and purebred producer perspective. The analysis examined the impact on ranking of various production goals and management situations faced by producers. The 20 most profitable sires in each ranking offered substantial genetic improvement at less than the cost of average genetic improvement. The average NPV of the most profitable sires was substantially greater than the average NPV of all sires in the analysis. Substantial differences in rankings were found for different production goals and management situations. Thus, proper specification of production goals and risk tolerance is important in accurately selecting AI service sires to maximize profit.

Carcass value of the progeny of tested beef bulls

In the study focused on the estimation of the efficiency of beef cattle in the conditions of the Czech Republic, 361 half-carcasses of the offspring of crossbred bulls of tested young beef sires were dissected. The bulls were fattened together and slaughtered at the age of 500 &amp;plusmn; 30 days. The tested breeds were Aberdeen Angus (AA), Blonde d&amp;rsquo;Aquitaine (BA), Belgian Blue (BB), Charolais (CH), Hereford (HE), Limousine (LI), and Piemontese (PI). The control groups were bulls of the Czech Pied (C) and Holstein (H) breeds. The best commercial class according to the SEUROP system was found in the offspring of Charolais sires (3.17). The fat content was the highest in the BB group (2.45) and the lowest (P &amp;lt; 0.01) in the PI group (1.50). The average hot carcass weight was 332.54 kg and was significantly (P &amp;lt; 0.05) the lowest in bulls of the HE group (290.50 kg). After dissection the dressing percentage of meat, bone, separable fat, and the meat/bone ratio were calculated. The average meat percentage in the carcass was 78.47%. The dressing percentage of meat of PI group was 80.33% and was the highest of all the groups (P &amp;lt; 0.01). H group showed the highest proportion of bones (19.79%), which was by 2% higher than in PI group. The content of separable fat ranged between 1.29 and 3.68%. &amp;nbsp;

Should genetic groups be fitted in BLUP evaluation? Practical answer for the French AI beef sire evaluation

Should genetic groups be fitted in BLUP evaluation? Practical answer for the French AI beef sire evaluation

The relationship between beef sire carcass EPD and progeny phenotype

Carcass data from purebred steer (n = 207) and heifer (n = 66) progeny of 15 Charolais sires with carcass expected progeny differences (EPD) were used to quantify the relationship between sire EPD and progeny phenotype for hot carcass weight, fat thickness, muscle area, marbling score, and percent lean yield. The model included six slaughter date × sex subclasses, the linear effect of age at harvest (434 ± 18 d), and the appropriate sire EPD for each trait of interest. Differences of the regression coefficients from their theoretical expectation of one were tested using general linear models procedures. Sire EPD was positively (P &lt; 0.0001) associated with progeny performance for hot carcass weight, fat thickness, muscle area, marbling score, and percent lean yield. For all traits, the regression coefficients were not different (P &gt; 0.27) from one. Regression coefficients were 1.16 ± 0.41 kg, 1.27 ± 0.27 mm, 1.23 ± 0.23 cm2, 1.26 ± 0.23 score, and 0.84 ± 0.19% for hot carcass weight, fat thickness, muscle area, marbling score, and percent lean yield, respectively. These results suggest that carcass EPD for hot carcass weight, fat thickness, muscle area, marbling score, and percent lean yield were related to progeny differences at or near theoretical expectations. Selection for carcass merit using appropriate EPD would be expected to be successful. Key words: Beef cattle, carcass, expected progeny difference

The identification of beef sires that produce calves of above average conformation from dairy cows

AbstractThe Ministry of Agriculture, Fisheries and Food routinely publishes price information for 3-week-old beef + dairy calves sold at major livestock auction centres in England and Wales. For the period 1993/94 to 1996/97, there were average price premiums of £51 for male and £38 for female calves classed as ‘first quality’. We have shown previously that choosing an easy calving beef sire for use on dairy cows will generally lead to calves which are smaller in size and of poorer conformation. To enable dairy producers to maximize returns from calf sales, we propose that beef sires be evaluated for the predicted incidence of first quality’ calves, which can be derived from the sire’s evaluation for calf conformation and the breed incidence of first quality’ calves. Dairy farmers may then jointly consider a bull’s predicted merit for calving ease and calf quality when choosing a sire for use in their herd.

The genetic evaluation of beef sires used for crossing with dairy cows in the UK 2. Genetic parameters and sire merit predictions for calving survey traits

AbstractGenetic parameters were estimated for traits recorded in a calving survey for beef sires used in commercial dairy herds in England and Wales. The five traits included in the survey were calving difficulty score, calf mortality to 48 h after birth, gestation length, and subjectively assessed calf size and conformation. The data file examined included over 88 000 records, on 323 sires of eight beef sire breeds, namely Aberdeen Angus, Belgian Blue, Blonde d'Aquitaine, Charolais, Hereford, Limousin, Piedmontese and Simmental.Estimates of heritability and genetic and phenotypic correlations were obtained for all traits by REML procedures using a sire model. The effects of cow age, calf sex, year and season of the calving and sire breed were included in the model, together with interactions.Heritability estimates were 0·09 (s.e. 0·01) for calving difficulty score, 0·32 (s.e. 0·03) for gestation length, 0·02 (s.e. 0·003) for mortality, 0·09 (s.e. 0·01) for calf size and 0·06 (s.e. 0·01) for calf conformation.Heritability estimates for the scored categorical and binomial (mortality) traits were also obtained using threshold model analysis. As expected, these estimates were higher than the REML estimates; 0·16 (s.e. 0·01) for calving difficulty score, 0·08 (s.e. 0·01) for mortality, 0·14 (s.e. 0·01) for calf size and 0·09 (s.e. 0·01) for calf conformation. Calving difficulty score was strongly correlated genetically with calf size (-0·84), mortality (0·74) and calf conformation (-0·72), and moderately correlated with gestation length (0·26). Calf size and conformation were very highly correlated genetically (0·86), and both were also strongly correlated with mortality (-0·63 and -0·52 respectively). In all cases, the genetic correlations were stronger than the phenotypic correlations.Sire genetic merit was predicted for all traits and the distribution of these predictions is described. Sire predictions of genetic merit for calving difficulty score on the underlying scale were backtransformed to predict the expected incidence of serious difficulties in future calvings and these predictions are illustrated for the major sire breeds.

The genetic evaluation of beef sires used for crossing with dairy cows in the UK 1. Sire breed and non-genetic effects on calving survey traits

AbstractAn analysis has been carried out of over 88000 calving survey records for bulls of eight beef breeds tested in commercial dairy herds in England and Wales. The data were collected from 1981 to 1993. The traits analysed were the degree of difficulty at calving, assessed from no difficulty to serious difficulty, calf mortality to 48 h, gestation length, and subjective assessments of calf size and conformation.Major sire breeds in the survey were the Hereford (30070 records, 93 sires), Charolais (25816 records, 105 sires) and the Limousin (15420 records, 55 sires). Other sire breeds were Belgian Blue (5391 records, 24 sires), Simmental (3864 records, 19 sires), Aberdeen Angus (2886 records, 12 sires), Piedmontese (2423 records, 7 sires) and the Blonde d'Aquitaine (2271 records, 8 sires).Information was routinely recorded on cow age (heifer or mature), sex of the calf, and the year and month of the calving, while cow size and the regional location of the herd were also recorded in later years.Heifers had more difficult calvings, higher calf losses and shorter gestations than mature cows (all P &lt; 0·05) Seriously difficult calvings and calf mortality were higher for male calves, which were also larger and had better conformation than heifer calves (P &lt; 0·05).Sire breed effects were significant for all traits, although sire breed ranking for calving ease was different for cow and heifer calvings and some interactions involving sire breed were also significant. For cow calvings, the easiest calving breeds were the Hereford (1·1%) and the Aberdeen Angus (1·4%), while the Charolais (4·3%), Blonde d'Aquitaine (3·7%) and Simmental (3·1%) had most difficult calvings.Gestation length differed between sire breeds, from Aberdeen Angus (281·0 days) and Hereford (282·7 days) up to the Limousin (288·1 days) and the Blonde d'Aquitaine (289·0 days). For calf size and conformation, the Simmental, Charolais and Blonde d'Aquitaine were the best.In general, summer months were associated with lower incidences of difficult calvings, lower losses and shorter gestations.Large cows had calves which were larger and of better conformation than small or medium cows, but large cows also had longer gestations, more difficult calvings and poorer calf survival (all P &lt; 0·05).Statistical models are discussed that should be used for the genetic evaluation of calving survey traits, when beef bulls are to be used in dairy herds in the United Kingdom.

Economic values for carcase traits in UK commercial beef cattle

The economic importance of carcase weight, carcase conformation score and carcase fat score, when making selection decisions for terminal beef sires in the UK, is quantified. A framework based on asset replacement theory is first described for the estimation of economic weights for meat production and slaughter traits. A biological growth model that describes growth, conformation and fatness in the carcase over time is used within the economic framework to establish a profit-maximising slaughter point. The economic values, computed by comparing optimum profit per animal before and after genetic improvement of each trait, varied with the crossbreed and production system modelled. Carcase weight economic values were most robust, ranging between 1.88 and 2.31 £ kg −1. Carcase conformation score economic values ranged between 2.11 and 5.33 £ pt −1 with the highest values occurring in situations where conformation was relatively poor at the optimal slaughter time. Economic values for reductions in carcase fat score were low (≤1.30 £ pt −1) for bulls in intensive production systems, but potentially much higher (> 5 £ pt −1) for steers and heifers of British crossbreeds in 16- and 24-month systems without immediate replacement of animals in the finishing facilities. Economic values are also shown to be sensitive to changes in the food price and carcase price penalties.

Economic values for reproduction traits in beef suckler herds based on a calving distribution model

Economic values for the genetic improvement of gestation length, post partum anoestrus interval, conception rates at first or later post partum oestrus and calving day (relative to the first day of the calving season) in seasonal calving beef suckler herds were estimated. The approach used combines partial budgeting of the economic cost of a barren cow with a model of the herd calving distribution which is driven by assumed levels of reproductive parameters. Economic values for all traits were shown to be highly variable across farms and are also likely to vary across years. For an increase in gestation length and equivalently in post partum anoestrus interval, estimates of economic values ranged between −0.2 and −2.77 £/day with higher values apparent in herds with a wide calving spread. Economic values for conception rates were higher at later (0.25 to 1.28 £ per % increase) than at first (0.1 to 0.7 £ per % increase) post partum oestruses. For calving day, economic values were approximately half of those derived using an alternative method from the literature which assumes calving day to be normally distributed. Implications for establishing selection criteria to choose terminal beef sires and suckler beef cows are discussed.