The role of genetic variability of the host on the resistance to Neospora caninum infection in cattle.

Neospora caninum is one of the most frequently diagnosed abortifacient pathogens in cattle. There is abundant genomic information about the parasite itself, but very little is known about the genetic variability of resistance in the most common intermediate host. The aim of this review was to compile all the available information about the genetic variability associated with the resistance to N. caninum both between and within cattle breeds. We systematically searched for published studies that investigated the influence of genetics of the host on the prevalence of N. caninum and risk of abortion. Beyond the potential confounding effects of feeding systems, management and animal density, some lines of evidence suggest that Holstein, the most popular breed for milk production, has a comparatively higher risk of abortion due to infections by N. caninum, whereas some beef breeds from Continental Europe seem to be more resistant. It is still not clear if different genetic mechanisms of resistance are involved in the two known routes of infection: postnatal ingestion of oocysts or transplacental transmission from the infected dam to the fetus. Genomic information associated with susceptibility to infection and risk of abortion in different cattle breeds is still scarce. The information reported here could be useful to identify new research alternatives and to define novel strategies to deal with this major problem of animal production.

A randomized controlled trial evaluating the effect of providing a rest period during long-distance transportation of surplus dairy calves: Part II. Impact on hematological variables.

The objective of this randomized controlled trial was to determine if providing a rest stop including provision of feed and water between periods of continuous transportation mitigates the impact of long-distance transportation on markers of energy status and hydration in calves transported by road for 16 h. This study was conducted between September 2022 to January 2023 and included male and female Holstein and crossbred dairy calves ≥7 d old from 2 commercial dairy farms in Ontario, Canada (n = 96). On the day before transportation, calves were enrolled and randomly assigned to one of 2 treatment groups: 1) continuous transportation by road for 16 h or 2) 8 h of transport, 8 h of rest, and a further 8 h of transport to a single calf-raising facility. Calves that received a rest stop were fed 2 L of milk replacer at the time of unloading for the rest period and again immediately before reloading for the second leg of the journey. Blood samples were collected before and after transportation as well as daily for 3 d following arrival to the calf-raising facility. Serum was analyzed for concentrations of ß-hydroxybutyrate (BHBA), nonesterified fatty acid (NEFA), haptoglobin, and creatine kinase, while acid-base disturbances were evaluated within 1 h of collection of whole blood to assess glucose, sodium, potassium, ionized calcium, hematocrit, hemoglobin, pH, base excess, pO2, TCO2, HCO3, pCO2, and sO2. Mixed linear regression models with repeated measures were built to assess the effect of treatment group, age at transportation, breed, and sex on these parameters. Immediately after transportation, calves that received the rest period had lower BHBA (-68.04 µmol/L, 95% CI: -99.59 to -36.49), NEFA (-0.14 mmol/L, 95% CI -0.22 to -0.07), and sodium (-1.10 mmol/L, 95% CI = -2.18 to -0.02), and higher glucose (0.48 mmol/L, 95% CI = 0.21 to 0.74), potassium (0.27 mmol/L, 95% CI = 0.11 to 0.43), ionized calcium (0.06 mmol/L, 95% CI = 0.03 to 0.08), and sO2 (8.76%, 95% CI = 1.61 to 15.91) compared with calves that were continuously transported for 16 h. Additionally, calves transported between 11 and 12 d old had lower hematocrit (-1.22%, 95% CI = -2.19 to -0.25), hemoglobin (-3.07 g/L, 95% CI = -5.70 to -0.43), haptoglobin (-0.13 g/L, 95% CI = -0.23 to -0.02), and potassium (-0.13 mmol/L, 95% CI = -0.22 to -0.04) and higher sodium (0.83 mmol/L, 95% CI = 0.03 to 1.63) than 7-8 d old calves. Furthermore, calves that were 13-24 d old at transport had lower haptoglobin (-0.16 g/L, 95% CI = -0.27 to -0.06) and potassium (-0.14 mmol/L, 95% CI = -0.23 to -0.05), and higher sodium (1.02 mmol/L, 95% CI = 0.22 to 1.82) and ionized calcium (0.02 mmol/L, 95% CI = 0.002 to 0.035) compared with calves transported at 7-8 d old. The results of this trial demonstrate that a rest period improves energy status upon arrival to a calf-raising facility, suggesting that the benefit of a rest period may be mostly related to the provision of mid-journey milk meals.

A randomized controlled trial evaluating the effect of providing a rest period during long-distance transportation of surplus dairy calves: Part I. Impact on health, growth, and activity.

The objective of this randomized controlled trial was to determine if providing a rest period (RP) to surplus calves transported for 16 h reduced the impact of long-distance transportation on health, growth, and activity after arrival to a calf-raising facility. Between September 2022 to January 2023, 6 to 24 d old surplus calves were randomly assigned to one of 2 treatment groups: 1) continuous transportation by road for 16 h (n = 86) or 2) 8 h of transport, 8 h RP, then a further 8 h of transport to a single commercial calf-raising facility in Ontario, Canada (n = 84). Calves that received the RP were fed 2 L of milk replacer at the time of unloading for the RP and again before reloading for the second leg of transportation. Calves were weighed before and after transportation and once weekly until they left the calf-raising facility at 11 weeks after arrival. Additionally, fecal consistency and respiratory health were assessed immediately before and after transportation, as well as twice daily following arrival. The odds of abnormal fecal and respiratory scores were assessed with mixed effects logistic regression models, whereas cox proportional hazards models were used to evaluate the hazard of treatment for diarrhea and respiratory disease. To evaluate weight loss during transportation, average daily gain, lying bouts, and steps, mixed linear regression models were used. Furthermore, mixed logistic regression models with repeated measures were built to assess associations with the odds of having a sunken flank and prolonged skin tent. There were no statistical differences in the odds of abnormal fecal or respiratory scores or the treatment for diarrhea between treatment groups; however, there was evidence that calves that received a rest period had a higher hazard of treatment for respiratory disease. Calves >10 d old had reduced odds of having an abnormal respiratory score and calves 13-24 d old had lower odds of arriving with a prolonged skin tent, lower odds of abnormal fecal score, and reduced hazard of treatment for diarrhea compared with calves 6-8 d old at transportation. During transportation, calves that received a rest period lost less weight than continuously transported calves. With respect to ADG over the 77-d study, an interaction between age at transport and treatment group was identified where calves aged 9 to 10 d old and received a rest period had higher ADG compared with calves that were 9 to 10 d old and did not receive a rest period. As for calf activity, calves receiving an RP spent more time lying on the day after transportation compared with calves that were continuously transported. The results of this trial show few differences in the health and growth of calves having a RP compared with those that underwent continuous transport. Furthermore, calves receiving a rest period may arrive more fatigued than calves who arrive to their destination in a shorter period of time overall. Transporting calves at older ages presents an opportunity to reduce the impact of long-distance transportation on subsequent health, growth, and activity.

Fertility in seasonal-calving pasture-based lactating dairy cows following timed artificial insemination or timed embryo transfer with fresh or frozen in vitro-produced embryos.

The objective was to compare pregnancy per service event (P/S) in lactating dairy cows following timed artificial insemination (AI) or timed embryo transfer (ET) using either fresh or frozen in vitro-produced embryos. Oocytes were collected once per week for up to 9 wk using transvaginal ovum pick-up from elite dairy donors (ET-DAIRY; n = 40; Holstein-Friesian and Jersey) and elite beef donors (ET-ELITE-BEEF; n = 21; Angus). Both ET-DAIRY and ET-ELITE-BEEF donors consisted of heifers and cows. In addition, oocytes were collected from the ovaries of beef heifers of known pedigree following slaughter at a commercial abattoir (ET-COMM-BEEF; n = 119). Following in vitro maturation and fertilization, presumptive zygotes were cultured in vitro to the blastocyst stage. Grade 1 blastocysts were either transferred fresh or frozen for on-farm thawing and direct transfer. A total of 1,106 recipient cows (all lactating, predominantly Holstein-Friesian) located on 16 herdlets were blocked based on parity, calving date, and Economic Breeding Index, and randomly assigned to receive AI (n = 243) or ET (n = 863) after estrous synchronization with a 10-d Progesterone-synch protocol. Cows assigned to ET were further randomized to receive fresh (n = 187) or frozen (n = 178) ET-ELITE-BEEF embryos, fresh (n = 169) or frozen (n = 162) ET-DAIRY embryos, or fresh (n = 80) or frozen (n = 87) ET-COMM-BEEF embryos. Pregnancy was diagnosed using transrectal ultrasound on d 32 to 35 after synchronized ovulation and confirmed on d 62 to 65, at which time fetal sex was determined. Pregnancy per service event at d 32 was not different between AI (48.8%) and ET (48.9%) and did not differ between dairy and beef embryos (50.3% vs. 48.1%, respectively). However, P/S was less on d 32 following transfer of frozen embryos (41.6%) compared with fresh embryos (56.1%). Pregnancy loss between d 32 and 62 was greater for ET (15.1%) compared with AI (4.7%), with greater losses observed for frozen beef (18.5%), fresh beef (17.3%), and frozen dairy (19.2%) compared with fresh dairy (6.0%) embryos. Serum progesterone (P4) concentration on d 7 was associated with P/S at d 32 and 62. Cows in the quartile with the least serum P4 concentrations (quartile 1) had less probability of being pregnant on d 32 (33.4%) compared with cows in the 3 upper quartiles for serum P4 (45.7%, 55.6%, and 61.2% for quartile 2, quartile 3, and quartile 4, respectively). Sex ratio (male:female) at d 62 was skewed toward more male fetuses following ET (61.1:38.9) compared with AI (43.2:56.8) and was consistent with the sex ratio among in vitro blastocysts (61.2:38.8). In conclusion, P/S was similar for AI and ET, although pregnancy loss between d 32 and 62 was greater for ET than for AI.

Association of morbidity, mortality, and average daily gain with transfer of passive immunity in dairy-beef crossbred calves up to 60 days of life.

Adequate transfer of passive immunity (TPI) is a cornerstone for a proper health status of calves. In the literature, there is limited information on the prevalence of failure of TPI in dairy-beef crossbred calves and its effect on morbidity, mortality, and ADG during the preweaning period. Therefore, this study aimed to evaluate the association between TPI with morbidity, mortality, and ADG in preweaning dairy-beef crossbred calves. A total of 1,055 newborn dairy-beef crossbred calves were enrolled upon arrival at a calf-raising facility in California from January to August 2021. Farm of origin, genetic breed group, sex, and BW were recorded upon arrival. Blood was collected at 24 ± 1 h after arrival to evaluate serum IgG concentration, serum total protein (TP), and packed cell volume. Morbidity (diarrhea and respiratory treatment records) and mortality were recorded daily until 60 d of life. Calves were grouped into 2 genetic breed groups: Holstein × Beef (Ho × Be, 49.6%) and Jersey × Beef crossbred calves (Je × Be, 50.4%). Descriptive statistics and Cox proportional hazard models were created to evaluate the association of TPI categories for serum IgG (TPI-IgG: poor: <10.0 g/L, fair: 10.0-17.9 g/L, good: 18.0-24.9 g/L, and excellent: ≥25.0 g/L) and TP (TPI-TP: poor: <5.1 g/dL, fair: 5.1-5.7 g/dL, good: 5.8-6.1 g/dL, and excellent: ≥6.2 g/dL), sex, and genetic breed group with morbidity and mortality. Additionally, a mixed linear regression was performed to evaluate the association of sex, genetic breed group, and TPI categories with ADG. Overall morbidity and mortality were 84.8% (n = 895) and 2.5% (n = 26). Calves classified as TPI-IgG excellent were associated with the lowest (43.2% less) hazard of being treated compared with TPI-IgG poor calves. For mortality, dairy-beef crossbred calves with TPI-IgG excellent were associated with a reduction of 82.0% in the hazard of dying compared with TPI-IgG poor. The TPI-IgG poor and TPI-IgG fair calves were associated with a decreased ADG of 101.0 and 98.8 g/d, respectively, in comparison with TPI-IgG good calves. Average daily gain of TPI-IgG good and TPI-IgG excellent calves were not different. In our study, dairy-beef crossbred calves enrolled may have endured challenging conditions that increased morbidity. This reinforces the importance of high IgG levels to decrease morbidity and mortality and maximize ADG in dairy-beef crossbred calves raising systems. Further research should evaluate the long-term effects of TPI categories on the health and performance of dairy-beef crossbred calves.

The effects of colostrum consumption and feed restriction during marketing and transportation of male dairy beef calves: Impact on pre-transport nutritional status and on farm recovery.

The aim of this study was to evaluate the effects of colostrum consumption and feed restriction on biomarkers of stress, nutritional and health status, gut functionality, and behavior in male dairy beef calves being marketed and transported. A total of 82 male Holstein calves (42 ± 1.2 kg of body weight and 14 ± 0.9 d of age) were used to study the amount of colostrum given at birth at the dairy farm of origin, the degree of feed restriction suffered at an assembly center simulation (d -4 to d -1), and the effects of a 19 h transportation (d -1). Treatments were as follows: control calves (CTRL; n = 16) were fed 10 L of colostrum at the dairy farm of origin, milk replacer (MR) and concentrate at the assembly center, and were not transported; calves fed high colostrum and milk replacer (HCMR; n = 17) were given 10 L of colostrum at the dairy farm of origin, MR at the assembly center, and transported; calved fed high colostrum and rehydrating solution (HCRS; n = 16) were given 10 L of colostrum at the dairy farm of origin, a rehydrating solution (RS) at the assembly center, and transported; calves fed low colostrum and milk replacer (LCMR; n = 17) were given 2 L of colostrum at the dairy farm of origin, MR at the assembly center, and transported; and calves fed low colostrum and rehydrating solution (LCRS; n = 16) were given 2 L of colostrum at the dairy farm of origin, RS at the assembly center, and transported. Transported calves mimic a 19-h transportation. After transport, all calves were fed 2.5 L of MR twice daily and had ad libitum access to concentrate, straw, and water. Calves' recovery was followed for 7 d. Concentrate intake and health records were collected daily from d -4 until d 7 and body weight (BW) and blood samples were collected on d -4, -1, 0, 1, 2, and 7 of the study. Results showed that the feeding regimen provided at the assembly center reduced BW for the HCRS and LCRS calves compared with the CTRL, HCMR, and LCMR calves. Concentrate intake peaked on d 0 in the transported calves, followed by a reduction of intake on d 1 after transportation. Concentrate intake recovery was lower for the LCRS and LCMR calves. On d -1, nonesterified fatty acids and ß-hydroxybutyrate concentrations were greater for the HCRS and LCRS calves compared with the CTRL, HCMR, and HCRS calves. After transportation, serum Cr-EDTA concentration was greater for the HCRS and LCRS calves than the HCMR, LCMR, and CTRL calves. The LCRS calves had the lowest serum concentration of citrulline. Finally, health scores were greater for the LCRS calves from d 0 to 7. In summary, both the greatest degree of feed restriction during the assembly center and the low colostrum consumption at birth negatively affected the recovery of concentrate consumption and BW, gut functionality, health status, and behavior in calves after arrival at the rearing farm.

Cull cow carcass traits and risk of culling of Holstein cows and 3-breed rotational crossbred cows from Viking Red, Montbéliarde, and Holstein bulls.

Culled dairy cows represent a considerable source of meat production, but their carcasses may vary greatly in quality because of the wide variation in the age, stage of lactation, breed, body condition, and other characteristics of the cows at slaughter. However, the effect of crossbreeding on the value of culled cows has so far received little investigation. The aim of this observational study was to compare a range of carcass attributes of cull cows from 3-breed rotational crossbreeding using Viking Red, Montbéliarde (MO), and Holstein (HO) bulls with those of HO purebred cows. Data on 1,814 dairy cows were collected. Cows were reared together in one herd and slaughtered in 4 slaughterhouses. The carcass weight, fleshiness, and fatness scores, the total value, and the price (€/kg) of each cow carcass were recorded. The culling of a few cows in the sample (n = 86) was classified by the farm manager as "urgent" following a diagnosis of injury or sickness, and this information was recorded. Carcass traits were analyzed with a mixed model which included the fixed effects of parity, days in milk, genetic group (purebred HO, 787 cows, and crossbred cows, classified according to the breed of sire within crossbreds, with 309, 428, and 290 cows sired by Viking Red, MO, and HO bulls, respectively), and interactions, and the random effects of month × year of the date of slaughter, and slaughterhouse. Logistic regression was used to investigate the association of parity, days in milk and purebred or crossbred origin with unplanned, "urgent" culling compared with regular culling. Average carcass weight across genetic groups was 297 ± 65 kg, average price €2.03 ± 0.53/kg, and average value €631 ± 269. Compared with HO, crossbred carcasses were 7 to 12% heavier depending on the breed of sire, were graded + 0.12 to + 0.28 units higher for fleshiness and + 0.26 to + 0.30 units higher for fatness, and fetched an 8 to 11% higher price. As a consequence, compared with purebred HO, carcasses from crossbreds had 15 to 24% higher value (€84 to €133 more per cow), with crossbred cows sired by MO showing the greatest values. Moreover, compared with the HO cows, the crossbred cows had a 37% lower risk of being urgently removed from the herd, which raises welfare concerns and may reduce the salvage value of cull cows. Because cull cows represent a supplemental source of income for dairy farmers, the greater overall value of crossbred cull cows should be taken into account in evaluating the economic effectiveness of crossbreeding schemes.

Evaluation of potential biomarkers to determine adequate colostrum provision in male dairy-beef calves upon arrival at the rearing facility beyond 14 days of age.

Colostrum consumption is crucial for passive immunization and development of the newborn calf. However, the incidence on failed transfer of passive immunity in male calves destined to dairy-beef production remains high to date. In addition, the lack of an automated procedure to validate the immunization status upon arrival at rearing facilities in calves beyond 14 d of age impedes the identification of failed transfer of passive immunity, and therefore, of those calves at high risk of suffering diseases. For this study, 82 newborn male Holstein calves (43.3 ± 0.86 kg of body weight; mean ± standard error) from a commercial dairy farm were used to investigate potential serum biomarkers of colostrum provision. The potential biomarkers selected were IgG, IgG1, cholesterol, alkaline phosphatase, gamma-glutamyl transferase (GGT), and total protein (TP). Treatments were as follows: high-colostrum (HC; n = 49), in which calves received 4 L of colostrum within the first 2 h after birth and 2 L of colostrum in the next 3 feedings within the first 24 h after birth, for a total of 10 L of colostrum; and low-colostrum (LC; n = 33), in which calves received only 2 L of colostrum within the first 2 h after birth. After colostrum consumption, calves were allocated to individual hutches and fed 2 L of milk replacer twice daily at a concentration of 125 g/L as fed. Starter feed and water were offered ad libitum. At approximately 14 d of age (14.2 ± 0.81 d of age; mean ± standard error) calves were transported 2.5 h to a research unit at IRTA (Torre Marimon, Spain) simulating the arrival to a rearing facility. Blood samples were collected before feeding at birth, 48 h after birth, and at arrival to the rearing facility. Results on the serum concentrations of the potential biomarkers at arrival to the rearing facility showed that IgG, IgG1, GGT, and TP were greater for the HC calves compared with the LC calves. Serum concentrations of cholesterol and alkaline phosphatase did not show differences between treatment groups. Additionally, body weight losses from birth until arrival to the rearing facility were greater for the LC treatment compared with the HC. Because of their low cost, quickness, and ease of measurement, GGT and TP were good indicators of colostrum intake in calves arriving at rearing facilities beyond 14 d of age.

Invited review: Use of assisted reproduction techniques to accelerate genetic gain and increase value of beef production in dairy herds.

The contribution of the calf enterprise to the profit of the dairy farm is generally considered small, with beef bull selection on dairy farms often not considered a high priority. However, this is likely to change in the future as the rapid rate of expansion of the dairy herd in some countries is set to plateau and improvements in dairy herd fertility combine to reduce the proportion of dairy breed calves required on dairy farms. This presents the opportunity to increase the proportion of beef breed calves born, increasing both the value of calf sales and the marketability of the calves. Beef embryos could become a new breeding tool for dairies as producers need to reassess their breeding policy as a consequence of welfare concerns and poor calf prices. Assisted reproductive technologies can contribute to accelerated genetic gain by allowing an increased number of offspring to be produced from genetically elite dams. There are the following 3 general classes of donor females of interest to an integrated dairy-beef system: (1) elite dairy dams, from which oocytes are recovered from live females using ovum pick-up and fertilized in vitro with semen from elite dairy bulls; (2) elite beef dams, where the oocytes are recovered from live females using ovum pick-up and fertilized with semen from elite beef bulls; and (3) commercial beef dams (≥50% beef genetics), where ovaries are collected from the abattoir postslaughter, and oocytes are fertilized with semen from elite beef bulls that are suitable for use on dairy cows (resulting embryo with ≥75% beef genetics). The expected benefits of these collective developments include accelerated genetic gain for milk and beef production in addition to transformation of the dairy herd calf crop to a combination of good genetic merit dairy female calves and premium-quality beef calves. The aim of this review is to describe how these technologies can be harnessed to intensively select for genetic improvement in both dairy breed and beef breed bulls suitable for use in the dairy herd.

Short communication: The beef merit of the sire mated to a dairy female affects her subsequent performance.

Much of the research to date on dairy × beef matings has focused only on the greater revenue attainable from these beef-cross calves. The objective of the present study was to quantify the mean effect on cow performance following the birth of calves differing in beef merit; all calves were born without calving assistance. Beef merit in the present study was based on the breed of the sire but also its genetic merit for carcass weight and conformation. The cross-sectional study used up to 346,765 calving events from 230,255 Holstein-Friesian cows in 3,604 herds. Performance traits of interest were those associated with milk production, including somatic cell count, as well as female reproductive performance. Sire breed was associated with all yield traits, somatic cell count, and both pregnancy rate and the interval from calving to first service; no association existed with either submission rate or number of services. Relative to a Holstein-Friesian sire, the mean 305-d milk yield (in kg) was 45.22 (standard error, SE = 4.0), 62.0 (SE = 36.8), 65.4 (SE = 9.6), 101.1 (SE = 31.6), 36.7 (SE = 4.9), 51.5 (SE = 10.7), 53.3 (SE = 31.5), and 43.3 (SE = 23.4) less for cows that gave birth to Angus-, Aubrac-, Beligan Blue-, Charolais-, Hereford-, Limousin-, Saler-, or Simmental-sired calves, respectively. Service sire accounted for only 1% of the phenotypic variation in all 3 milk production traits when fitted as a random effect in the model. The regression coefficients of phenotypic milk, fat, and protein yields on sire (of calf) predicted transmitting ability for carcass weight were -1.84 (SE = 0.17), -0.10 (SE = 0.01), and -0.08 kg (SE = 0.01), respectively. The respective regression coefficients on sire (of calf) predicted transmitting ability for carcass conformation (scale of 1 to 15; 1 = poor and 15 = excellent) were -23.46 (SE = 1.81), -1.20 (SE = 0.08), and -1.05 units (SE = 0.06). The biological significance of the sire breed effects or the measure of sire genetic merit on the reproductive traits was either not different from zero or biologically small. Although statistically significant associations existed between sire beef merit and both milk and reproductive performance of the mate, the actual size of the associations was biologically small.

Short communication: Animal-level factors associated with whether a dairy female is mated to a dairy or beef bull.

When serving a female, the producer must decide whether to mate her to a dairy or beef bull. Tools assisting in this decision could be a useful component of the decision process. A database of 2,283,100 artificial inseminations from 806,725 dairy females was used to investigate what factors were associated with servicing a given female to a beef bull. The probability of being inseminated with a beef bull increased with each service and as the breeding season progressed. An older cow had greater odds of being served with a beef bull, as did cows that calved later in the year, had recently experienced dystocia, were a longer time calved, or were of a poor overall genetic merit compared with herdmates. Cows with low somatic cell count in the previous lactation compared with herdmates were less likely to be mated to a beef bull, as were cows that yielded relatively higher milk solids in the previous lactation. Relative to a first-parity cow, the odds of a fifth-parity cow being mated to a beef bull were 1.35, whereas those of a tenth-parity cow were 2.11. The odds of a female in the worst 10% for total genetic merit being mated to a beef bull were 2.90 times those of a female in the top 10%. Although dystocia was associated with the likelihood of being mated to a beef bull, the actual likelihood did not vary much by level of dystocia experienced. Relative to the first service, the odds of the third and fifth services being to a beef bull were 2.23 and 3.71, respectively. These probability estimates can form the back-end system supporting decisions on mating type for a female within a sire mating advice system but also in risk analysis of farm management.

Choice of artificial insemination beef bulls used to mate with female dairy cattle.

Understanding the preferences of dairy cattle producers when selecting beef bulls for mating can help inform beef breeding programs as well as provide default parameters in mating advice systems. The objective of the present study was to characterize the genetic merit of beef artificial insemination (AI) bulls used in dairy herds, with particular reference to traits associated with both calving performance and carcass merit. The characteristics of the beef AI bulls used were compared with those of the dairy AI bulls used on the same farms. A total of 2,733,524 AI records from 928,437 females in 5,967 Irish dairy herds were used. Sire predicted transmitting ability (PTA) values and associated reliability values for calving performance and carcass traits based on national genetic evaluations from prior to the insemination were used. Fixed effects models were used to relate both genetic merit and the associated reliability of the dairy and beef bulls used on the farm with herd size, the extent of Holstein-Friesian × Jersey crossbreeding adopted by the herd, whether the herd used a technician insemination service or do-it-yourself, and the parity of the female mated. The mean direct calving difficulty PTA of the beef bulls used was 1.85 units higher than that of the dairy bulls but with over 3 times greater variability in the beef bulls. This 1.85 units equates biologically to an expectation of 1.85 more dystocia events per 100 dairy cows mated in the beef × dairy matings. The mean calving difficulty PTA of the dairy AI bulls used reduced with increasing herd size, whereas the mean calving difficulty PTA of the beef AI bulls used increased as herd size increased from 75 cows or fewer to 155 cows; the largest herds (>155 cows) used notably easier-calving beef bulls, albeit the calving difficulty PTA of the beef bulls was 3.33 units versus 1.67 units for the dairy bulls used in these herds. Although we found a general tendency for larger herds to use dairy AI bulls with lower reliability, this trend was not obvious in the beef AI bulls used. Irrespective of whether dairy or beef AI bulls were considered, herds that operated more extensive Holstein-Friesian × Jersey crossbreeding (i.e., more than 50% crossbred cows) used, on average, easier calving, shorter gestation-length bulls with lighter expected progeny carcasses of poorer conformation. Mean calving difficulty PTA of dairy bulls used increased from 1.39 in heifers to 1.79 in first-parity cows and to 1.82 in second-parity cows, remaining relatively constant thereafter. In contrast, the mean calving difficulty PTA of the beef bulls used increased consistently with cow parity. Results from the present study demonstrate a clear difference in the mean acceptable genetic merit of beef AI bulls relative to dairy AI bulls but also indicates that these acceptable limits vary by herd characteristics.

Observed progeny performance validates the benefit of mating genetically elite beef sires to dairy females.

While several studies in cattle have confirmed the improved performance achievable from selection on total merit indexes, these studies have solely been confined to specific-purpose beef or dairy total merit indexes. Validation studies of total merit indexes used to select beef sires for use on dairy females are lacking. The objective here was to fill this void by quantifying the performance of beef × dairy progeny where the sire excels in either a total merit index encompassing calving performance and beef performance traits (dairy-beef index; DBI) or excels in a subindex based solely on calving performance (CLV); for comparative purposes, these beef × dairy progeny were also compared with dairy × dairy progeny. A total of 123,785 calving records from 101,773 dairy cows calving in 3,065 dairy herds were used; of these, 48,875 progeny also had carcass information. The beef sires were stratified into 5 equally sized groups based separately on their DBI or CLV. Linear and threshold mixed models were used to compare calving and carcass performance of all 3 sire genotypes. Of the 415 sires that ranked in the highest of the 5 strata on the CLV subindex, only 52% of them ranked in the highest stratum for the DBI. The percentage of primiparae requiring any assistance at calving was 2 to 3 percentage units greater for the higher DBI sires relative to both the higher CLV beef sires and the dairy sires (not ranked on anything); no difference existed in multiparae. The extent of calving difficulty in primiparae was, however, less in higher DBI beef sires relative to both the higher CLV beef sires and the dairy sires, although the differences were biologically small. Perinatal mortality was greatest in the beef sires relative to the dairy sires, but no difference existed between the high CLV or high DBI beef sires. No difference in progeny gestation length was evident between the high DBI or high CLV beef sires, although both were >2 d longer than progeny from dairy sires. The higher DBI sires produced progeny with heavier, more conformed carcasses relative to the progeny from both high CLV beef sires and dairy sires. No differences existed between the progeny of the beef sires ranked highly on the CLV versus those ranked highly on the DBI for the probability of achieving the specification for carcass weight (between 270 and 380 kg) or fat score; the higher DBI animals, however, had a 4 to 10% greater probability of achieving the minimum carcass conformation required. In all instances, the beef sires had a greater probability of achieving all specifications relative to the progeny from the dairy sires with the difference for conformation being particularly large. Results indicate that more balanced progeny can be generated using a DBI, helping meet the requirements of both dairy and beef producers. Ignoring market failure across sectors, using higher DBI sires could increase dairy herd profit by 3 to 5% over and above the status quo approach to selection in dairy (i.e., CLV subindex).

Maintaining production while reducing local and global environmental emissions in dairy farming.

While milk is a major agricultural commodity, dairy farming also supports a large share of global beef production. In Life Cycle Assessment (LCA) studies of dairy farming systems, dairy-beef production is often ignored or 'allocated off', which may give a distorted view of production efficiencies. This study combines LCA with Data Envelopment Analysis (DEA) to develop an indicator of eco-efficiency for each of 738 UK dairy farms (3624 data points in 15 years) that aggregates multiple burdens and expresses them per unit of milk and dairy-beef produced. Within the DEA framework, the importance (weight) of dairy-beef relative to milk is iteratively increased to quantify the environmental losses from heavily focussing on milk-production, via e.g. higher yields per cow, with consequent lower burdens per unit of milk, yet with lower dairy-beef production levels, where burdens for beef production are externalized. Then, the relationship between DEA eco-efficiency and a series of indicators of dairy farming intensity at animal- and farm-levels was studied with Generalized Additive Models (GAM). For all sets of DEA weights (proportion of deviance explained ranged between 68% and 82%) indicate that milk yield per cow and forage area, and larger dairy herds all have a positive effect on eco-efficiency, while concentrate fed per unit of milk and the forage area both have a negative effect (p < 0.05 for all modelled relationships). These findings suggest that more intensive and consolidated dairy farms can positively impact on eco-efficiency. However, as the DEA weight for dairy-beef relative to milk increases, the relationship between environmental efficiency and farming specialization (expressed as L milk per kg dairy-beef produced) reverses from positive to negative. In conclusion, dairy-beef production is pivotal in determining the wider environmental efficiency of dairy (and ruminant food) systems, and its under-representation in efficiency studies has generated a misleading approach to meeting emission targets.

A breeding index to rank beef bulls for use on dairy females to maximize profit.

The desire to increase profit on dairy farms necessitates consideration of the revenue attainable from the sale of surplus calves for meat production. However, the generation of calves that are expected to excel in efficiency of growth and carcass merit must not be achieved to the detriment of the dairy female and her ability to calve and re-establish pregnancy early postcalving without any compromise in milk production. Given the relatively high heritability of many traits associated with calving performance and carcass merit, and the tendency for many of these traits to be moderately to strongly antagonistic, a breeding index that encompasses both calving performance and meat production could be a useful tool to fill the void in supporting decisions on bull selection. The objective of the present study was to derive a dairy-beef index (DBI) framework to rank beef bulls for use on dairy females with the aim of striking a balance between the efficiency of valuable meat growth in the calf and the subsequent performance of the dam. Traits considered for inclusion in this DBI were (1) direct calving difficulty; (2) direct gestation length; (3) calf mortality; (4) feed intake; (5) carcass merit reflected by carcass weight, conformation, and fat and the ability to achieve minimum standards for each; (6) docility; and (7) whether the calf was polled. Each trait was weighted by its respective economic weight, most of which were derived from the analyses of available phenotypic data, supplemented with some assumptions on costs and prices. The genetic merit for a range of performance metrics of 3,835 artificial insemination beef bulls from 14 breeds ranked on this proposed DBI was compared with an index comprising only direct calving difficulty and gestation length (the 2 generally most important characteristics of dairy farmers when selecting beef bulls). Within the Angus breed (i.e., the beef breed most commonly used on dairy females), the correlation between the DBI and the index of genetic merit for direct calving difficulty plus gestation length was 0.74; the mean of the within-breed correlations across all other breeds was 0.87. The ranking of breeds changed considerably when ranked based on the top 20 artificial insemination bulls excelling in the DBI versus excelling in the index of calving difficulty and gestation length. Dairy breeds ranked highest on the index of calving difficulty and gestation length, whereas the Holstein and Friesian breeds were intermediate on the DBI; the Jersey breed was one of the poorest breeds on DBI, superior only to the Charolais breed. The results clearly demonstrate that superior carcass and growth performance can be achieved with the appropriate selection of beef bulls for use on dairy females with only a very modest increase in collateral effect on cow performance (i.e., 2-3% greater dystocia expected and a 6-d-longer gestation length).

Growth, carcass characteristics, and profitability of organic versus conventional dairy beef steers.

Bull calves (n=49), born at the University of Minnesota West Central Research and Outreach Center (Morris) between March and May 2011, were used to compare growth measurements and profitability of conventional and organic dairy steers. Calves were assigned to 1 of 3 replicated groups at birth: conventional (CONV; n=16), organic (pasture and concentrate; ORG; n=16), or organic grass only (GRS; n=17), and analysis of variables was on a pen basis. Breed groups of calves were Holstein (HO; n=9); Holsteins (n=11) maintained at 1964 breed average level; crossbreds (n=19) including combinations of HO, Montbéliarde, and Swedish Red; and crossbreds (n=10) including combinations of HO, Jersey, Swedish Red, and Normande. The CONV steers were fed a diet of 80% concentrate and 20% forage. The ORG steers were fed a diet of organic corn, organic corn silage, and at least 30% of their diet consisted of organic pasture during the grazing season. The GRS steers grazed pasture during the grazing season and were fed high-quality hay or hay silage during the nongrazing season. Intakes of a total mixed ration were recorded daily with herd management software. A profit function was defined to include revenues and expenses for beef value, feed intake, pasture intake, health cost, and yardage. The GRS (358.6 kg) steers had lesser total gains from birth to slaughter than ORG (429.6 kg) and CONV (534.5 kg) steers. Furthermore, the GRS (0.61 kg/d) steers had lesser average daily gain from birth compared with ORG (0.81 kg/d) and CONV (1.1 kg/d) steers. The GRS and ORG steers had smaller rib eye area (49.5 and 65.8 cm(2), respectively) compared with CONV (75.4 cm(2)) steers. For profitability, GRS steers had 43% greater profit than CONV steers due to organic beef price premiums and lower feed costs. On the other hand, ORG steers had substantially less profit than CONV steers. The higher cost of production for the ORG steers is due to the extreme high value of organic corn. The results of the current study illustrate the economic potential of alternative strategies for growing and marketing male offspring of organic dairy cattle in the Midwest.

Dairy cow handling facilities and the perception of Beef Quality Assurance on Colorado dairies.

A survey was conducted on Colorado dairies to assess attitudes and practices regarding Dairy Beef Quality Assurance (DBQA). The objectives were to (1) assess the need for a new handling facility that would allow all injections to be administered via DBQA standards; (2) establish if Colorado dairy producers are concerned with DBQA; and (3) assess differences in responses between dairy owners and herdsmen. Of the 95 dairies contacted, 20 (21%) agreed to participate, with a median herd size of 1,178. When asked to rank the following 7 traits--efficiency, animal safety, human safety, ease of animal handling, ease of operation, inject per Beef Quality Assurance (BQA) procedures, and cost--in order of priority when designing a new handling facility, human and animal safety were ranked highest in priority (first or second) by the majority of participants, with ease of animal handling and efficiency ranked next. Interestingly, the administration of injections per BQA standards was ranked sixth or seventh by most participants. Respondents estimated the average annual income from the sale of cull cows to be 4.6% of all dairy income, with 50% receiving at least one carcass discount or condemnation in the past 12 mo. Although almost all of the participating dairy farmers stated that the preferred injection site for medications was the neck region, a significant number admitted to using alternate injection sites. In contrast, no difference was found between responses regarding the preferred and actual location for intravenous injections. Although most participating producers are aware of BQA injection guidelines, they perceive efficiency as more important, which could result in injections being administered in locations not promoted by BQA. Dairy owners and herdsmen disagreed in whether or not workers had been injured in the animal handling area in the last 12 mo. Handling facilities that allow for an efficient and safe way to administer drugs according to BQA guidelines and educational opportunities that highlight the effect of improved DBQA on profitability could prove useful. Dairy producers play a key role in ensuring that dairy beef is safe and high quality, and just as they are committed to producing safe and nutritious milk for their customers, they should be committed to producing the best quality beef.

Effects of Cattle Breeds and Dietary Energy Density on Intake, Growth, Carcass, and Meat Quality under Thai Feedlot Management System.

This study determines the effects of varying dietary metabolizable energy densities on Holstein Friesian and Charolais crossbred beef cattle in fattening phases. The research focuses on nutrient utilization, ruminal fermentation, growth performance, carcass traits, and meat quality. Thirty-six steers were used in the feeding trial that lasted for six months according to a 2 × 3 factorial arrangement in a randomized complete block design (Factor A, cattle breeds (Holstein Frisian, Charolais crossbred); B, metabolizable energy density (10.5, 11.1 and 11.8 MJ/kg DM)) with six replications. The dietary energy density had no interaction with the cattle breeds (p > 0.05). Despite fewer carcass yields, Holstein Friesian crossbreds indicate superior eating quality to Charolais crossbreds on drip loss, meat iron content, and Warner-Bratzler shear force due to increased intramuscular fat content (p < 0.05) with similar meat color (p > 0.05). Increased dietary energy density positively impacts nutrient and energy intake and rumen fermentation (p < 0.05) but did not affect growth and carcass traits (p > 0.05). This research suggests the potential of Holstein Friesian crossbreds for intensive beef production, providing valuable insights into optimal feeding strategies for achieving quality meat outcomes. On-farm feeding trials are needed to develop a practical and economical Thai beef feedlot management system.

Chlorine dioxide may be an alternative to acidification and chlorination for drinking water chemical disinfection in dairy beef bulls.

Alternative water disinfectants to chlorination need to be identified because its effectiveness is limited by water pH and potentially carcinogen by-products resulted from chlorination and organic compound reaction. The first study aimed to evaluate the effect of different drinking water chemical disinfection treatments on water quality, its potential hazard effects on animal health, water and feed consumption, and apparent total tract digestibility in dairy beef bulls fed high-concentrate diets. For 224 days, 24 Holstein bulls (176 ± 16.3 kg BW, and 149 ± 5.8 days of age) were individually assigned to one of four treatments with different drinking water chemical disinfectants: without disinfection (CTR); acidification and chlorination (ACCHL; 0.65 mL/L H3PO4 and 0.14 mL/L NaClO 15%); hydrogen peroxide (PER; 0.15 mL/L); and chlorine dioxide (DIO; 2.50 mL/L). Data were analysed with a mixed-effects model. Treatments affected the chemical characteristics of the water: in ACCHL, pH was 6.60 and free residual chlorine was 0.75 mg/L; in PER, H2O2 was 10.6 mg/L; and in DIO, ClO2 was 0.52 mg/L. Water physicochemical quality parameters in all treatments were below maximal thresholds established for safe water consumption by the Water Safety Royal Decree (RD 140/2003). In addition, the total coliform count of treated waters was reduced (P = 0.01) compared with CTR; moreover, ACCHL and DIO treatments were more effective in reducing total coliform count than PER. Dry matter intake tended (P = 0.07) to increase in DIO compared with CTR. Treatments did not affect blood parameters nor apparent total tract digestibility. The second study aimed to evaluate the potential benefit on animal performance of two drinking water disinfectants under commercial conditions in dairy beef crossbred Holstein bulls fed high-concentrate diets. Ninety-six animals (307 ± 4.4 kg BW, and 224 ± 1.8 days of age) were allocated to six pens for 140 days and assigned to one of two treatments: ACCHL, most common water disinfectant, and DIO. Data were analysed with a mixed-effects model. Water total coliform count and water consumption were similar between treatments. Concentrate intake was greater (P = 0.02) in ACCHL for the last 14 study days. Growth performance and carcass quality were similar between treatments. In summary, acidification and chlorination, H2O2, and ClO2 as drinking water disinfectants in dairy beef bulls had good disinfecting activity without detrimental effects on health and nutrient digestibility, and performance.

Genomic and phenotypic comparison of two variants of multidrug-resistant Salmonella enterica serovar Heidelberg isolated during the 2015-2017 multi-state outbreak in cattle.

Salmonella enterica subspecies enterica serovar Heidelberg (Salmonella Heidelberg) has caused several multistate foodborne outbreaks in the United States, largely associated with the consumption of poultry. However, a 2015-2017 multidrug-resistant (MDR) Salmonella Heidelberg outbreak was linked to contact with dairy beef calves. Traceback investigations revealed calves infected with outbreak strains of Salmonella Heidelberg exhibited symptoms of disease frequently followed by death from septicemia. To investigate virulence characteristics of Salmonella Heidelberg as a pathogen in bovine, two variants with distinct pulse-field gel electrophoresis (PFGE) patterns that differed in morbidity and mortality during the multistate outbreak were genotypically and phenotypically characterized and compared. Strain SX 245 with PFGE pattern JF6X01.0523 was identified as a dominant and highly pathogenic variant causing high morbidity and mortality in affected calves, whereas strain SX 244 with PFGE pattern JF6X01.0590 was classified as a low pathogenic variant causing less morbidity and mortality. Comparison of whole-genome sequences determined that SX 245 lacked ~200 genes present in SX 244, including genes associated with the IncI1 plasmid and phages; SX 244 lacked eight genes present in SX 245 including a second YdiV Anti-FlhC(2)FlhD(4) factor, a lysin motif domain containing protein, and a pentapeptide repeat protein. RNA-sequencing revealed fimbriae-related, flagella-related, and chemotaxis genes had increased expression in SX 245 compared to SX 244. Furthermore, SX 245 displayed higher invasion of human and bovine epithelial cells than SX 244. These data suggest that the presence and up-regulation of genes involved in type 1 fimbriae production, flagellar regulation and biogenesis, and chemotaxis may play a role in the increased pathogenicity and host range expansion of the Salmonella Heidelberg isolates involved in the bovine-related outbreak.