Exploring the impact of sexed semen on the structure of the dairy industry

Comparative study of reproductive and estrus characteristics of sexed and conventional semen in crossbred cows under field conditions

Background and Aim

Sexed semen (SS), a reproductive biotechnology tool, can alter the sex ratio of offspring in bovines. This study elucidates a comparative analysis of estrus-related parameters influencing conception rate and pregnancy losses under field conditions between conventional and SS.

Materials and Methods

In the present study, artificial insemination with (SS; n = 143) and conventional semen (CS; n = 143) was performed at spontaneous estrus, i.e., 16-18 h after the onset of estrus signs, to analyze their comparative evaluation in terms of conception rates in crossbred cows under field conditions. Different parameters such as age, parity, body condition score (BCS), estrus duration, inter-estrus interval (IEI), diameter of pre-ovulatory follicle (DPOF) at estrus, and cervical mucus properties (pH and spinnbarkeit [SBK]) were recorded for each cow.

Results

The first insemination conception rates for sexed and conventional semen were 55.24% and 63.63% whereas the overall conception rates were 49.14% and 57.37% on days 35 and 75 post-insemination, respectively, with no significant difference (p > 0.05). Conception rates between sexed and CS inseminations were statistically significant (p < 0.01), whereas factors such as age, parity, BCS, DPOF, IEI), and SBK value exhibited no substantial variance (p > 0.05) for both types of semen straw.

Conclusion

SS straws yielded a conception rate equivalent to CS straws, with estrus duration being the key factor affecting conception under field conditions.

Semen sexing and its impact on fertility and genetic gain in cattle

Semen sexing is among one of the most remarkable inventions of the past few decades in the field of reproductive biotechnology. The urge to produce offspring of a desired sex has remained since traditional times. Researchers have tried many methods for accurate semen sexing, but only the flow cytometry method has proved to be effective for commercial utilization. However, there were always concerns about the effects of sexed semen, especially on fertility and the rate of genetic gain. Some concerns were genuine because of factors such as low semen dosage in sexed semen straws and damage to sperm during the sorting process. Various researchers have conducted numerous studies to find out the effect of sexed semen on fertility and, in this article, we reflect on their findings. Initially, there were comparatively much lower conception rates (∼70% of conventional semen) but, with refinement in technology, this gap is bridging and the use of sexed semen will increase over time. Concerning genetic gain with use of sexed semen, a positive effect on rate of genetic progress with the use of sexed semen has been observed based on various simulation studies, although there has been a mild increase in inbreeding.

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.

Sustainable animal production: exploring the benefits of sperm sexing technologies in addressing critical industry challenges

The sex of the animals is of paramount importance in many animal production systems. This is particularly evident in the production of milk or in breeding programs focused on the production of female animals. In some cases, slaughter or euthanasia of animals of the unwanted sex becomes the only solution, highlighting ethical and economic concerns. As global demand for food continues to rise, the importance of addressing these issues becomes more evident. Reproductive technologies, such as sperm sexing techniques, may hold the key to addressing both animal welfare and the sustainability of animal production. The use of semen enriched with sperm capable of producing offspring of the desired sex can serve as a valuable tool for producers to exert greater control over production outcomes, not only helping to mitigate welfare issues related to the unnecessary premature death of unwanted offspring but also providing a possible ally in the face of stricter animal welfare guidelines. In addition, sexed semen can also contribute to financial gains and reduce greenhouse gas emissions and food waste associated with the less profitable part of the herd. This paper explores the positive impacts that sperm sexing can have on animal welfare, economy, and environment. It also discusses currently available options and strategies for more successful implementation of sexed semen. Partnerships between companies and scientists will be essential to find innovative ways to adapt current production systems and develop sperm sexing technologies that apply to most livestock industries.

The effect of different implant programs on beef × dairy steer feedlot growth performance and carcass characteristics

The objective of this study was to evaluate potency and timing of trenbolone acetate (TBA) administration on live performance and carcass characteristics of beef × dairy steers. A total of 6,895 beef × dairy steers [initial body weight (BW) = 157 ± 5.2 kg] were allotted into 30 pens, with pen as the experimental unit. Each pen was randomly assigned one of three implant treatments: 1) Revalor-IS (IS) at d 0, IS at d 80, and Revalor-XS (XS) at d 160 (IS/IS/XS); 2) Ralgro at d 0, IS at d 80, and XS at d 160 (Ral/IS/XS); or 3) Encore at d 0 and XS at d 160 (Enc/XS). Steers were blocked by arrival date, each pen was terminally sorted in three ways at 257 ± 22 days on feed and harvested at 329 ± 25 days on feed. For live and carcass outcomes, fixed effect of implant treatment and random effect of block was evaluated. Data are reported on a deads and removals out basis. Removals, morbidity, and mortality were similar (P ≥ 0.45). Steers administered TBA prior to d 160 were 5.8 kg heavier (P = 0.03) than Enc/XS steers at d 160. Final BW was not different (P = 0.78). Early administration of a TBA-containing implant resulted in an increased prevalence of bullers [2.40%, 5.18%, 6.86% (for Enc/XS, Ral/IS/XS, and IS/IS/XS) respectively; P < 0.01]. Dry matter intake (DMI) was 2.3% greater (P < 0.01) in steers administered Enc/XS compared to IS/IS/XS; however, DMI as a percentage of BW, average daily gain, and feed efficiency were not different (P ≥ 0.12). Dressing percentage, hot carcass weight, heavy carcass occurrence, Longissimus muscle area, and 12th rib fat thickness were similar among all steers (P ≥ 0.28). Marbling score tended to be greatest for Enc/XS and Ral/IS/XS (P = 0.09). Enc/XS graded a greater proportion of USDA Prime and fewer USDA Select carcasses than IS/IS/XS (P < 0.05). Enc/XS and Ral/IS/XS tended (P = 0.09) to have more USDA Yield Grade (YG) 1 carcasses. While delayed administration or decreased total potency of TBA-containing implants may decrease buller incidence and improve Quality Grade, few differences were observed in live or carcass outcomes.

Development of feeding and reproduction technology in dairy cattle breeding based on the use of digital technologies

A study on the study of the qualitative assessment of the behavior of dairy cattle according to the VAS system (visual analog scale) was conducted in the LLP "Agrofirme "AKAS", located in the West Kazakhstan region of the Republic of Kazakhstan. According to research, it follows that different seasons of time affect the conditions of detention in different ways. So, for the maintenance of cows in the summer, the distance of avoidance at the feeding site according to test 1 and 2 is within 3 meters, whereas in spring and autumn it was 2 meters. The difference between the reference norm and the household ration has been determined, from which it follows that the feeding ration of the farm corresponds to the norm of 12 kg of milk yield per head per day. The vitamin and mineral premix developed by us includes vitamins, minerals, including macro-microelements. The premix also includes components in the following ratio: phosphorus (P) - 5% of monocalcium phosphate, vitamin A - 1.2% of rovimix A 1000, vitamin D3 - 0.64% of rovimix D3, vitamin E - 16% of rovimix E-50, manganese (Mn) - 22.2%, copper (Cu) - 9%, zinc (Zn) - 19%, iodine (I) - 0.28%, selenium (Se) - 7.65 and cobalt (Co) - 0.14%, and feed chalk - 5% and chickpea flour - 13.89% are used as fillers as a source of calcium (Ca).. The average daily milk yield at the beginning of the experiment in both study groups was in the range of 10.6-10.8 kg. At the end of the experiment, the average daily milk yield in animals receiving premix exceeded their peers from the control group by 1.4 kg or 1.6%. According to the chemical composition of milk, the indicators of fat, protein and lactose were higher in the cows of the experimental group compared with the peers of the control group (for fat - 3.92>3.37, for protein - 3.32>3.23, for lactose - 4.16>4.01).

Evaluation of pregnancy per artificial insemination of dairy animals detected in estrus during the synchronization protocol and assigned to conventional or sexed semen

Three experiments were designed to evaluate the effects of conventional and sexed-semen on reproductive performance of dairy females detected in estrus. In Exp. 1, 978 lactating Holstein cows and 116 Holstein heifers were used. Cows or heifers were randomly assigned to receive conventional (CONV) or sexed (SEXD) semen on day 0 of a TAI protocol. The TAI was performed using commercial CONV or SEXD frozen-thawed semen from the same 6 Holstein bulls, and SEXD semen was sexed through fluorescence cytometry. In Exp. 2, 390 lactating Holstein × Gir dairy cows and 344 Holstein × Gir heifers were used. Cows and heifers were randomly assigned to receive CONV or SEXD semen on day 0 with frozen-thawed semen from 5 Holstein × Gir bulls. The SEXD was sorted through the Sexcel™ methodology. In Exp. 3, 789 primiparous lactating Holstein cows were enrolled. Cows were randomly assigned to receive CONV or SEXD semen from 5 Holstein bulls, and the SEXD semen was sexed using the same semen allocation methodology described in Exp. 2. All data were analyzed using SAS. Regardless of the experiment, no treatment × bull interaction was observed for any of the variables analyzed herein (P ≥ 0.20). In Exp. 1, multiparous cows assigned to CONV had a greater P/AI vs. cohorts assigned to SEXD (P < 0.01) and a similar response tended to be observed for secundiparous cows (P = 0.10). No treatment effects were further observed when the effects of semen on day 60 P/AI were stratified by heat stress, milk yield, and CL at the beginning of the protocol. In Exp. 2, no P/AI differences between treatment were detected either on days 32 (P = 0.32) or 60 of pregnancy (P = 0.20). In Exp. 3, cows assigned to SEXD had reduced P/AI on day 32 (P = 0.03) and tended to have a reduced P/AI on day 60 of pregnancy (P = 0.06). No further treatment effects or interactions were observed herein (P ≥ 0.13). Overall P/AI of SEXD semen was 78% of the CONV (P < 0.01), but the variation of these results requires some attention. Moreover, an additional analysis was performed considering the median value of P/AI in bulls assigned to CONV and SEXD, and bulls that had a greater P/AI in CONV also had a greater P/AI in SEXD (P = 0.03). In summary, although not directly comparable, the sexing technologies herein provided similar results in heifers, but not in other categories (primiparous, secundiparous, and multiparous cows). Additionally, the P/AI of a sexed semen is associated to its performance on the conventional semen counterpart. Moreover, in the present experiment, no other parameters were shown to impact fertility of dairy females assigned to conventional or sexed-semen.

Applications and world-wide use of sexed semen in cattle

Successful sorting of sperm based on presence of the X- or Y-chromosome was first reported in the early 1980's with the first live births reported in rabbits in 1988. Subsequent development of technological efficiencies resulted in commercialization of sex-sorted semen to cattle producers in 2003-2005. At product launch, low throughput dictated that reasonable prices to the producer could only be accomplished with extremely low sperm number dosages (2 × 10⁶). Furthermore, conception rates were 70%-75% of those achieved by conventional unsorted product. Refinements in sorting equipment have enhanced the number of sperm that can be sorted from a semen sample and (or) aliquot of time, which translates into reduced production costs, while modifications to other aspects of sperm processing and freezing have facilitated maintenance of a conception potential more similar to that of conventional semen. More recently, strategic use of sex-sorted semen coupled with genomic technologies to identify superior females to satisfy replacement female needs has, by default, led to identification of a population of dairy cows from which replacements are not desired, leading to a tremendous increase in use of beef semen in dairy herds. Though exact numbers are unavailable, estimates indicate sex-sorted semen is rapidly approaching 30% of the total AI market share in North America. Though the primary application of sex-sorted semen is to accelerate genetic progress while enhancing biosecurity through in-house production of replacement animals, numerous other potential applications are evolving or are under consideration.

Welfare of cattle during transport

In the framework of its Farm to Fork Strategy, the Commission is undertaking a comprehensive evaluation of the animal welfare legislation. The present Opinion deals with protection of cattle (including calves) during transport. Welfare of cattle during transport by road is the main focus, but other means of transport are also covered. Current practices related to transport of cattle during the different stages (preparation, loading/unloading, transit and journey breaks) are described. Overall, 11 welfare consequences were identified as being highly relevant for the welfare of cattle during transport based on severity, duration and frequency of occurrence: group stress, handling stress, heat stress, injuries, motion stress, prolonged hunger, prolonged thirst, respiratory disorders, restriction of movement, resting problems and sensory overstimulation. These welfare consequences and their animal-based measures are described. A variety of hazards, mainly relating to inexperienced/untrained handlers, inappropriate handling, structural deficiencies of vehicles and facilities, poor driving conditions, unfavourable microclimatic and environmental conditions, and poor husbandry practices leading to these welfare consequences were identified. The Opinion contains general and specific conclusions relating to the different stages of transport for cattle. Recommendations to prevent hazards and to correct or mitigate welfare consequences have been developed. Recommendations were also developed to define quantitative thresholds for microclimatic conditions within the means of transport and spatial thresholds (minimum space allowance). The development of welfare consequences over time was assessed in relation to maximum journey duration. The Opinion covers specific animal transport scenarios identified by the European Commission relating to transport of unweaned calves, cull cows, the export of cattle by livestock vessels, the export of cattle by road, roll-on-roll-off ferries and 'special health status animals', and lists welfare concerns associated with these.

Public attitudes toward different management scenarios for "surplus" dairy calves

As awareness grows, some traditional management practices used by the dairy industry will be questioned by members of the public. Therefore, to maintain its social license to operate, the industry needs to account for public perspectives when developing future directions. Our aims were to assess attitudes of members of the public toward the management of surplus calves not needed for milk production on dairy farms, and to assess how specific calf management practices might influence these attitudes. A mixed-methods questionnaire was developed and distributed online in the United States and in Canada. After reading an introductory paragraph stating that surplus calves are generally used for meat production, participants were randomly allocated into groups and read 1 of 4 scenarios that described different surplus calf management practices in more detail. The scenarios followed a 2 × 2 factorial design, and the factors that differed were the calf's age at slaughter (≤2 wk vs. ≥12 mo), and whether the calf was separated from the cow at birth or sometime later. Data representative of key census demographics from 998 participants were analyzed. Quantitative data analysis included descriptive statistics, nonparametric tests, generalized partial credit models, and linear regression models. For qualitative data, we used reliability thematic analysis. Overall, participants were slightly positive in their attitudes toward the introductory paragraph, and participants in the groups in which the calf was slaughtered after 12 mo of age often specifically linked their acceptance of the practice to the fact that the calves' lives had a purpose (i.e., contributing meaningfully to the beef supply). In contrast, only 3% of the participants regarded a slaughter age of <1 mo as appropriate. Participants in the groups in which calves were slaughtered within 2 wk after birth had more negative attitudes, and these attitudes declined even further when the calf was separated from the cow soon after birth. Besides the 2 main factors (age at slaughter and cow-calf separation), information on pasture access, the healthiness of the meat from the calves, and the exact age of slaughter were also considered important by participants to make a more informed decision about their view on surplus calf management. Overall, our results indicate that failure by the dairy industry to provide assurances that excess dairy calves have a reasonable length of life and that this life has purpose (i.e., contributes to the beef supply chain) places the industry at odds with public values. Also, as awareness grows, the practice of early cow-calf separation will be increasingly questioned by the public; failure to begin discussions on this topic will increase the risk that future decisions about this topic will be made in the absence of the farmer.

Preparing Male Dairy Calves for the Veal and Dairy Beef Industry

Surplus male dairy calves experience significant health challenges after arrival at the veal and dairy beef facilities. To curb these challenges, the engagement of multiple stakeholders is needed starting with improved care on some dairy farms and better management of transportation. Differing management strategies are also needed if calves arrive at veal and dairy beef facilities under poor condition.

Economics of timed artificial insemination with unsorted or sexed semen in a high-producing, pasture-based dairy production system

This study used a stochastic simulation model to estimate the potential economic benefit of using timed artificial insemination (TAI) in combination with conventional unsorted (TCONV) and sexed (TSEX) semen in heifers only (TCONV-H, TSEX-H) and in both heifers and lactating cows (TCONV-HC, TSEX-HC) in a high-producing, pasture-based production system. The scenarios were compared with a conventional reproductive policy (CONV) in which heifers and cows were inseminated with conventional unsorted semen after estrus detection. Sensitivity analysis was also used to estimate the effect of hormone costs from TAI use on the profitability of each program relative to CONV. The mean annual (± standard deviation) profit advantage (ΔPROF) over CONV for TCONV-H, TCONV-HC, TSEX-H, and TSEX-HC scenarios were €3.90/cow ± 4.65, €34.11/cow ± 25.69, €13.96/cow ± 6.83, and €41.52/cow ± 42.86, respectively. Combined application of both technologies was shown to return a greater annual ΔPROF on average compared with that achievable from TAI alone. However, the risk of not returning a positive annual ΔPROF varied across the scenarios with higher risk in TCONV-H and TSEX-HC. Specifically, TCONV-H and TSEX-HC had a 24 and 18% chance, respectively, of not returning a positive annual ΔPROF. Sensitivity analysis showed that when hormone costs increased by €10/cow TCONV-H and TSEX-HC had a 38 and 23% chance, respectively, of not returning a positive annual ΔPROF. The range in ΔPROF for TCONV policies was most sensitive to the TAI pregnancy rate and TSEX policies were most sensitive to the relative fertility achieved with sexed compared with unsorted semen. This study has shown TAI and sexed semen are complementary technologies that can increase genetic gain and profitability in a pasture-based, dairy production system.

Overview of common practices in calf raising facilities

In this literature review, we overview some of the common management practices associated with calf rearing in specialized operations of the United States. Given the growing importance of dairy-beef calves entering the beef production of the United States, we overview aspects related to housing, nutrition, and health events during the pre- and post-weaning period. Based on data on dairy animals, we hypothesize how early life experiences could impact the feedlot performances of dairy-beef animals. Most of the large calf raising operations, where the majority of dairy-beef animals are raised, are located in the Central Great Plains and West regions of the United States. Approximately 80% of calves are individually housed, but the type of housing (e.g., outside hutch, inside a barn) varies based on location of calf-raising facilities. Milk-replacer is fed in more than 80% of operations, while milk (saleable or nonsaleable) is fed in approximately 30% of calf raising facilities (some operations fed more than one type of liquid diet). In addition to liquid feed, water and calf starter are offered ad libitum to calves. Adequate starter intake at weaning is crucial for feed transition from pre- to post-weaning period, which occurs at approximately 2 months of age. Then, calves are mainly housed in group pens and transition from calf-starter to total mixed ration (TMR). Health challenges such as scours and bovine respiratory disease (BRD) can hinder the performance of calves and are major causes of morbidity and mortality in calf ranches. Transportation at a very young age and comingling with animals from other dairies can increase the risk of diseases. Current research efforts are focusing on determining individual factors such as body weight (BW) at arrival or biomarkers of inflammation and stress that can be predictive of disease morbidity, mortality, and performance of calves. Future research should focus on how to utilize this information to optimize management and to develop targeted preventative strategies to reduce incidence of diseases and mortality and improve performance during the pre-weaned period. Also, more research is needed to understand how colostrum management, housing, and nutrition can impact the adult performance of dairy-beef animals.

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.

Pregnancy and offspring sex ratio following insemination with SexedULTRA and conventional semen in cows in a commercial beef operation

Pregnancy rate per AI (PR/AI) and breeding season pregnancy rates between insemination with sexed semen (SS; at 18 hr after the onset of oestrus) and conventional semen (CS; at 12 hr after the onset of oestrus,) and offspring gender ratio between two groups were compared. Angus cross cows (n = 686, during 2019 and 2020 breeding seasons) were oestrus-synchronized using Select-Synch + CIDR protocol and were observed thrice daily for oestrus until 72 hr after PGF2α administration. Cows expressed oestrus (n = 513) were inseminated with either SS (n = 246; SexedULTRA 4M™; y chromosome-bearing sperm) or CS (n = 267). Cows (n = 173) that failed to express oestrus at 72 hr after PGF2α received 100 μg of GnRH and CS insemination concomitantly. Two weeks later, cows were penned with natural service sires (bull:cow ratio 1:25) for 45 days. Pregnancy was diagnosed 30 days after bull removal. Calves' gender was determined at birth. For cows that expressed oestrus, PR/AI did not differ (p > .1) between SS (65.0%) and CS (66.7%) groups. The overall PR/AI differed (p < .05) between SS (65.0%) and CS (56.4%) groups. The natural service PR differed (p < .001) but breeding season PR (p > .05) did not differ between SS vs. CS groups. Bull:heifer gender ratio following AI was 88:12 and 52:48 for SS and CS groups, respectively, with an overall 66:34 ratio. Bull:heifer gender ratio for the two breeding seasons was 79:21 and 52:48 for SS and CS groups, respectively, with an overall 62:38 ratio. In conclusion, the fertility of SS insemination at 18 hr after onset of oestrus was 97% of CS insemination at 12 hr after onset of oestrus. Though breeding season pregnancy did not differ between SS and groups, preferred calf gender was 25 percentage points greater for SS over CS application. The gender accuracy was 88%.

Exploring farmers' attitudes and determinants of dairy calf welfare in an expanding dairy sector

The 2015 European Union milk quota abolition initiated considerable expansion in the dairy sector in many European Union countries, most significantly in Ireland. However, this major production increase also had wider societal implications, such as negative environmental and animal welfare consequences. In this article, we used survey data of 441 Irish dairy farmers to assess farmers' attitudes toward the welfare of farmed animals and dairy calves, as well as the reputation of the Irish dairy sector. We also explored how expansion, breeding, calf management, and farmer characteristics relate to calf welfare outcomes (i.e., calf mortality, calf export, and premature culling). In relation to attitudes, farmers expressed a general concern toward animal welfare, while views toward dairy calves and industry reputation were mixed. We used Ward's linkage hierarchical cluster analysis to group farmers based on their attitudes. The cluster analysis revealed 3 distinct groups relating to high, medium, and low animal welfare concern. Herd expansion was negatively associated with being in a higher animal welfare concern cluster, whereas beef trait-focused breeding was positively associated with it. In relation to dairy calf welfare outcomes, our econometric analyses based on multiple regression and binary choice models revealed that expansion was positively associated with calf mortality, whereas improved breeding and calf management factors had a negative association. In addition, being in the high animal welfare concern cluster was negatively associated with calf mortality. Furthermore, breeding decisions were significantly associated with whether calves were exported, and being in the high animal welfare concern cluster was negatively associated with the probability that calves were sent for live export. Finally, farmers' breeding and calf management decisions were associated with premature culling of calves. Overall, this article revealed strategies worth promoting to improve dairy calf welfare, such as beef trait-focused breeding leading to greater dairy-beef integration.

Gene Editing for Improved Animal Welfare and Production Traits in Cattle: Will This Technology Be Embraced or Rejected by the Public?

Integrating technology into agricultural systems has gained considerable traction, particularly over the last half century. Agricultural systems that incorporate the public’s concerns regarding farm animal welfare are more likely to be socially accepted in the long term, a key but often forgotten component of sustainability. Gene editing is a tool that has received considerable attention in the last five years, given its potential capacity to improve farm animal health, welfare, and production efficiency. This study aimed to explore the attitudes of Brazilian citizens regarding the applications of gene editing in cattle that generate offspring without horns; are more resistant to heat; and have increased muscle tissue. Using a mixed-methods approach, we surveyed participants via face-to-face, using in-depth interviews (Study 1) and an online questionnaire containing closed-ended questions (Study 2). Overall, the acceptability of gene editing was low and in cases where support was given it was highly dependent on the type and purpose of the application proposed. Using gene editing to improve muscle tissue growth was viewed as less acceptable compared to using gene editing to reduce heat stress or to produce hornless cattle. Support declined when the application was perceived to harm animal welfare, to be profit motivated or to reinforce the status quo of intensive livestock systems. The acceptability of gene editing was reduced when perceptions of risks and benefits were viewed as unevenly or unfairly distributed among consumers, corporations, different types of farmers, and the animals. Interviewees did not consider gene editing a “natural” process, citing dissenting reasons such as the high degree of human interference and the acceleration of natural processes. Our findings raised several issues that may need to be addressed for gene editing to comply with the social pillar of sustainable agriculture.

Game-Changing Approaches in Sperm Sex-Sorting: Microfluidics and Nanotechnology

Simple Summary

Sexing of sperm cells, including the capacity to preselect the sex of offspring prior to reproduction, has been a major target of reproductive biotechnology for a very long time. The advances in molecular biology, biophysics, and computer science over the past few decades, as well as the groundbreaking new methods introduced by scientists, have contributed to some major breakthroughs in a variety of branches of medicine. In particular, assisted reproduction is one of the areas in which emerging technologies such as nanotechnology and microfluidics may enhance the fertility potential of samples of sex-sorted semen, thus improving the reproductive management of farm animals and conservation programs. In human medicine, embryo sex-selection using in vitro fertilization (IVF) and preimplantation genetic testing (PGT) is accepted only for medical reasons. Using sex-sorting before IVF would enable specialists to prevent sex-linked genetic diseases and prevent the discharge of embryos which are not suitable for transfer due to their sex.

Abstract

The utilization of sex-sorted sperm for artificial insemination and in-vitro fertilization is considered a valuable tool for improving production efficiency and optimizing reproductive management in farm animals, subsequently ensuring sufficient food resource for the growing human population. Despite the fact that sperm sex-sorting is one of the most intense studied technologies and notable progress have been made in the past three decades to optimize it, the conception rates when using sex-sorted semen are still under expectations. Assisted reproduction programs may benefit from the use of emergent nano and microfluidic-based technologies. This article addresses the currently used methods for sperm sex-sorting, as well as the emerging ones, based on nanotechnology and microfluidics emphasizing on their practical and economic applicability.

Exploring the Opinions of Irish Dairy Farmers Regarding Male Dairy Calves

Background: There has been very little previous research in Ireland on the farmers' opinions regarding calf welfare issues. Calf welfare, particularly for male dairy calves, has assumed greater importance in Ireland in recent years due, in part, to an increase in the number of dairy cattle over the past decade. The objective of this study was to explore dairy farmers' views on a broad range of issues related to the expansion in the dairy herd.

Methods: A survey was developed to capture the views of farmers regarding male dairy calves. The majority of questions were quantitative, and a final open-ended question collected qualitative data. The survey was distributed to ~2,900 dairy farmers via text message and 881 responses were received.

Results: The sample was composed almost entirely of dairy farmers, although ~20% also had a beef enterprise on their farm. Fifty eight percent of the farmers were concerned with the increase in the number of male dairy calves in recent years. The EU's abolition of milk quotas, the profitability of dairy farming compared to other farm types, and guidance from farm advisors were the three highest ranked drivers behind the increase in the number of male dairy calves. The three highest ranked options for managing the number of male dairy calves were to increase exports, encourage greater use of sexed semen, and improve the beef merit of these calves. Eighty five percent of respondents stated that individual farmers had responsibility for making changes to the number of male dairy calves. The main themes arising from analysis of the responses to the open-ended question, seeking any additional comments, were breed, beef price, live exports, and sexed semen.

Conclusions: Dairy farmers recognized the responsibility they have for making changes in respect of male dairy calves, and many demonstrated a willingness to make changes in this regard. The important role of other stakeholders, particularly suckler (system where reared from calf to beef) farmers, in rearing male dairy calves for beef production was also recognized. However, the issues of who bears the risks and costs associated with greater integration will have to be carefully considered.

Factors Affecting the Welfare of Unweaned Dairy Calves Destined for Early Slaughter and Abattoir Animal-Based Indicators Reflecting Their Welfare On-Farm

In many dairy industries, but particularly those that are pasture-based and have seasonal calving, "surplus calves," which are mostly male, are killed at a young age because they are of low value and it is not economically viable to raise them. Such calves are either killed on farm soon after birth or sent for slaughter at an abattoir. In countries where calves are sent for slaughter the age ranges from 3-4 days (New Zealand and Australia; "bobby calves") to 3-4 weeks (e.g., Ireland); they are not weaned. All calves are at the greatest risk of death in the 1st month of life but when combined with their low value, this makes surplus calves destined for early slaughter (i.e., <1 month of age) particularly vulnerable to poor welfare while on-farm. The welfare of these calves may also be compromised during transport and transit through markets and at the abattoir. There is growing recognition that feedback to farmers of results from animal-based indicators (ABI) of welfare (including health) collected prior to and after slaughter can protect animal welfare. Hence, the risk factors for poor on-farm, in-transit and at-abattoir calf welfare combined with an ante and post mortem (AM/PM) welfare assessment scheme specific to calves <1 month of age are outlined. This scheme would also provide an evidence base with which to identify farms on which such animals are more at risk of poor welfare. The following ABIs, at individual or batch level, are proposed: AM indicators include assessment of age (umbilical maturity), nutritional status (body condition, dehydration), behavioral status (general demeanor, posture, able to and stability while standing and moving, shivering, vocalizations, oral behaviors/cross-sucking, fearfulness, playing), and evidence of disease processes (locomotory ability [lameness], cleanliness/fecal soiling [scour], injuries hairless patches, swellings, wounds], dyspnoea/coughing, nasal/ocular discharge, navel swelling/discharge); PM measures include assessment of feeding adequacy (abomasal contents, milk in rumen, visceral fat reserves) and evidence of disease processes (omphalitis, GIT disorders, peritonitis, abscesses [internal and external], arthritis, septicaemia, and pneumonia). Based on similar models in other species, this information can be used in a positive feedback loop not only to protect and improve calf welfare but also to inform on-farm calf welfare management plans, support industry claims regarding animal welfare and benchmark welfare performance nationally and internationally.

Perspectives on the Management of Surplus Dairy Calves in the United States and Canada

The care of surplus dairy calves is a significant issue for the United States and Canadian dairy industries. Surplus dairy calves commonly experience poor welfare as evidenced by high levels of mortality and morbidity, and negative affective states resulting from limited opportunities to express natural behaviors. Many of these challenges are a result of a disaggregated production system, beginning with calf management at the dairy farm of origin and ending at a calf-raising facility, with some calves experiencing long-distance transportation and commingling at auction markets or assembly yards in the interim. Thus, the objectives of this narrative review are to highlight specific challenges associated with raising surplus dairy calves in the U.S. and Canada, how these challenges originate and could be addressed, and discuss future directions that may start with refinements of the current system, but ultimately require a system change. The first critical area to address is the management of surplus dairy calves on the dairy farm of origin. Good neonatal calf care reduces the risk of disease and mortality, however, many dairy farms in Canada and the U.S. do not provide sufficient colostrum or nutrition to surplus calves. Transportation and marketing are also major issues. Calves can be transported more than 24 consecutive hours, and most calves are sold through auction markets or assembly yards which increases disease exposure. Management of calves at calf-raisers is another area of concern. Calves are generally housed individually and fed at low planes of nutrition, resulting in poor affective states and high rates of morbidity and mortality. Strategies to manage high-risk calves identified at arrival could be implemented to reduce disease burden, however, increasing the plane of nutrition and improving housing systems will likely have a more significant impact on health and welfare. However, we argue the current system is not sustainable and new solutions for surplus calves should be considered. A coordinated and holistic approach including substantial change on source dairy farms and multiple areas within the system used to market and raise surplus dairy calves, can lead to more sustainable veal and beef production with improved calf outcomes.

Spermatological parameters of immunologically sexed bull semen assessed by imaging flow cytometry, and dairy farm trial

This study compared the quality parameters of bull semen sexed using an immunological method with those of conventional semen by imaging flow cytometry and applied this semen in dairy farm trials. Semen samples were collected from ten ejaculates from five bulls. Each sample was divided into two treatments: conventional semen (CON) and semen sexed using monoclonal male-specific antibodies combined with the complement system for cytotoxicity reaction (IC-sexed). After obtaining frozen-thawed semen, we used imaging flow cytometry to assess acrosome integrity, sperm sex ratio and viability. Sperm morphology was evaluated using eosin-nigrosin staining. The percentage acrosome integrity did not differ between IC-sexed and CON semen (P = 0.313). The sperm sex ratio showed that the percentage of live X-chromosome-bearing sperm was higher than that of live Y-chromosome-bearing sperm in IC-sexed semen (P = 0.001). IC-sexed semen showed a higher percentage of head and tail defects than did CON semen (P = 0.019). In field trials, 585 cows were subjected randomly to AI with CON or IC-sexed semen. The pregnancy rate of the IC-sexed group did not differ from that of the CON group (P = 0.535). However, IC-sexed semen produced a significantly higher percentage of female calves than did CON semen (P = 0.031). Thus, immunological sexing did not adversely affect the acrosome integrity of sperm. Furthermore, a female calf birth rate of over 74 % can potentially be achieved using IC-sexed semen. These findings could help farmers to replace heifers in their herds.

Effects of herd fertility on the economics of sexed semen in a high-producing, pasture-based dairy production system

This study used a stochastic simulation model to estimate the potential economic benefit of using sexed semen in heifers only and in heifers and lactating cows in a high-producing, pasture-based system under 3 fertility scenarios. Three breeding strategies were modeled: (1) only heifers inseminated with sexed semen and cows inseminated with conventional unsexed semen (SSH); (2) both heifers and cows inseminated with sexed semen (SSHC); and (3) a reference scenario in which all females were inseminated with conventional, unsexed semen (CONV). Each scenario was evaluated under 3 herd fertility states: high (HF), medium (MF), and low (LF), which, under the reference scenario, corresponded to herd replacement rates of 21, 25, and 31%, respectively. The model estimated the economic profit, including the net present value of the genetic gain from selection intensity. The economic return from adoption of sexed semen strategies declined, with reduced levels of baseline herd fertility turning negative in the LF state. The mean (±SD) sexed semen advantage (SSA) per cow for HF-SSH, MF-SSH, and LF-SSH scenarios were €30.61 ± 8.98, €27.45 ± 7.19, and €14.69 ± 11.06, respectively. However, the SSA per cow for HF-SSHC, MF-SSHC, and LF-SSHC scenarios were €49.14 ± 15.43, €18.46 ± 30.08, and -€19.30 ± 57.11. The range in economic profit for SSA for SSH was most sensitive to calf prices in HF-SSH and the pregnancy rate of sexed semen as a percentage of conventional unsorted semen in MF-SSH and LF-SSH. The range in economic profit for SSA for SSHC scenarios was most sensitive to the pregnancy rate of sexed semen as a percentage of conventional unsorted semen in HF-SSHC, MF-SSHC, and LF-SSHC. This study highlights the effect of baseline herd fertility state on the financial advantage of adopting sexed semen in a pasture-based dairy production system.

Effect of delaying the time of insemination with sex-sorted semen on pregnancy rate in Holstein heifers

The objective of the study was to evaluate the interval from onset of oestrus to time of artificial insemination (AI) to obtain the optimum pregnancy rate with sex-sorted semen in Holstein heifers. Heifers in oestrus were detected and inseminated only by using heat-rumination neck collar comprised electronic identification tag at the age of 13-14 months. Heifers (n = 283) were randomly assigned to one of three groups according to the timing of insemination at 12-16 hr (G1, n = 97), at 16.1-20 hr (G2, n = 94) and at 20.1-24 hr (G3, n = 92) after reaching the activity threshold. The mean duration of oestrus was 18.6 ± 0.1 hr, and mean peak activity was found at 7.5 ± 0.1 hr after activity threshold. The mean interval from activity threshold to ovulation was 29.4 ± 0.4 hr. The overall pregnancy per AI (P/AI) was 53.0% at 29-35 days and 50.9% at 60-66 days after AI. There was a significant reduction between G1 (13.8 ± 1.4 hr) and G3 (7.9 ± 1.4 hr) related to the intervals from AI to ovulation time. Sex-sorted semen resulted in significantly higher P/AI at 29-35 days when heifers inseminated in G3 (60.9%) after oestrus than those inseminated in G1 (49.5%) and G2 (48.9%). In terms of fertility, when the temperature-humidity index (THI) was below the threshold value (THI ≤65) at the time of AI, there was a tendency (≤65; 57.2% vs. > 65; 47.1%) for high pregnancy rate. There was no effect of sire on P/AI. In addition, the interaction of the technician with the time of AI was found significant, and three-way interaction of technician, sire and time of AI was tended to be significant on pregnancy rate. Thus, in addition to delaying the time of insemination (between 20.1 and 24 hr) after oestrous detection, THI and experienced technician were also found to be critical factors in increasing fertility with the use of sex-sorted semen in Holstein heifers.

Economic opportunities of using crossbreeding and sexing in Holstein dairy herds

With the increasing availability of sexed semen, farms have the opportunity to select genetically superior dams to produce their replacement animals and to produce crossbred calves for beef production of higher economic value than the remainder of the herd. However, higher costs and reduced fertility of sexed semen complicate the decision of when and to what extent sexed semen should be applied in a herd. The objective of this study was to explore the economically optimal utilization of sexed semen and crossbreeding among North Rhine-Westphalian dairy farms in a holistic single-farm model. For the analysis, we derived a representative sample of farms from Latin Hypercube sampling based on the observed distribution of farm characteristics from official North Rhine-Westphalian Farm Structure Survey data. Market- and technology-related input parameters such as output prices and sexed semen accuracy and fertility were included in the sampling procedure. Modeling results of the systematic sensitivity analysis were evaluated in a statistical meta-model. We found that the profit-maximizing utilization of sexed semen and crossbreeding was highly heterogeneous among the farms. Farms with lower stocking densities, <2 livestock units (LU)/ha, were generally found to produce excess heifers for sale, whereas farms with stocking densities >2 LU/ha were producing crossbred calves and using sexed semen only to produce replacement animals. On average, female-sexed dairy semen was used on 25.3% of all inseminations. Beef semen (both sexed and conventional) for producing crossbred calves was used in an average of 21.5% of the inseminations. The combination of sexed semen and crossbreeding increased profits from €0 to €568 per cow per year, with an average of €79.42 per cow per year. Farms characterized by low stocking densities (<2 LU/ha) and above-average replacement rates (>40%) were found to have higher profit increases as a result of selling more heifers from the use of sexed semen. Overall, sexed semen and crossbreeding adoption were most sensitive to stocking density and average cow longevity, as well as to additional costs for sexed semen and sexed semen accuracy. Our results show the potential of modern breeding technologies to improve dairy farm profits and the need to judge their profitability in the light of farm-specific production settings.

Symposium review: An abundance of replacement heifers: What is the economic impact of raising more than are needed?

Historically, most dairy producers raised every heifer born, to ensure a supply of future replacements. However, advancements in transition and reproductive management, coupled with widespread use of sex-sorted semen in dairy heifers and cows, have led to an oversupply of dairy replacement heifers in the United States. With current market values for prepartum heifers at $1,300 and estimated raising costs ranging from $1,700 to $2,400, dairies that continue to produce quantities of heifers in excess of anticipated needs with plans of selling the extras on the open market are likely to experience significant economic loss. Adult cow herd turnover is the key driver behind the number of heifers needed to calve; however, mortality, disease, fertility, and elective culling losses throughout the heifer-raising period determine the total number of heifers that must be retained and raised to meet anticipated needs. A convenience sample of 50 US dairy herds revealed an average heifer inventory of 102% of total milking and dry cows. In this data set, the mean annualized adult herd turnover was 39%. With a mean stillbirth risk of 5.7% in calving heifers, a culling risk of 10.2% by 13 mo of age, a reproductive failure risk of 6.8% in breeding heifers, and an additional culling risk of 6.4% in pregnant heifers, only 74% of calving events with a heifer birth yielded a heifer that entered the lactating herd. Much of this heifer removal was elective, and making the correct culling decisions at the appropriate time yields the best return for the herd. To demonstrate how a herd might approach the elective culling issue, a records-based exercise with 2 large Holstein herds was performed to estimate the cost versus benefit of 3 different elective culling approaches, using a combination of genetic potential and growth performance as the selective criteria. However, the culling of heifers results in economic losses, because the revenue received is less than the cost incurred during raising. Selective culling of heifers soon after weaning yielded the best results in both herds, but despite the predicted improvement in lactation performance of the retained group, the cost associated with removal was greater than the benefit predicted. Culling a group early and then culling a second group just before calving yielded the largest loss. Moving forward, herds should breed more carefully to produce better-quality heifers from more superior dams and sires and consider the use of beef semen in inferior animals. However, to reduce the risk of not producing an adequate supply of replacement heifers, dairies should add an additional buffer to their anticipated needs. Using the assumptions within this project, having 10% extra calving events with a heifer birth would allow the annualized adult herd turnover to rise from 39 to 43% in case economic conditions or health status of the herd should change. If these heifers are not needed, the selection criteria outline could be used to help identify more valuable animals to retain.

The complex relationship between welfare and reproduction in cattle

Using reproduction parameters as indicators for cattle welfare has limitations and, at best, these parameters should only be viewed as indirect indicators of welfare. On a farm level, measures such as fertility rates emphasize biological performance of the herd but fail to consider the welfare of individual animals. Even on an individual level, the relationship between reproductive effectiveness and animal welfare is complex. Good reproductive performance does not automatically signify good welfare, as domestication and targeted breeding programmes have led to prioritization of high productive and reproductive performance in most modern farm animal species. In this review, we synthesize literature regarding cattle husbandry, reproduction, welfare and their multidimensional relationships. We argue that practices such as artificial insemination or the use of sexed semen may provide potential welfare advantages as these practices reduce the risk of disease transmission and injury or enable selection of specific beneficial traits. Furthermore, they may offer a solution to current practices jeopardizing welfare, such as the management of surplus bull calves in the dairy industry. Conversely, the animals' ability to perform natural behaviours such as oestrous expression, an aspect arguably contributing to welfare, is often limited on commercial farms; this limitation is particularly evident in housing systems such as tie stalls where movement is restricted. Moreover, common management practices such as oestrus manipulation may lead to negative attitudes in citizens who often regard naturalness as important element of animal welfare.

The effects of improved performance in the U.S. dairy cattle industry on environmental impacts between 2007 and 2017

The U.S. dairy industry considerably reduced environmental impacts between 1944 and 2007, primarily through improved dairy cow productivity. However, although milk yield per cow has increased over the past decade, whole-system environmental impact analyses have not been conducted over this time period, during which environmental modeling science has improved considerably. The objective of this study was to compare the environmental impact of U.S. dairy cattle production in 2007-2017. A deterministic model based on population demographics, metabolism, and nutrient requirements of dairy cattle was used to estimate resource inputs, nutrient excretion, and greenhouse gas (GHG) emissions per 1.0 × 106 t (one million metric t or MMT) of energy-corrected milk (ECM) produced in 2007 and 2017. System boundaries extended from the manufacture and transport of cropping inputs to milk at the farm gate. Milk transport, processing, and retail were not included. Dairy systems were modeled using typical management practices, herd population dynamics, and production data from U.S. dairy farms. Cropping data were sourced from national databases. The resources required to produce 1.0 MMT ECM in 2017 were considerably reduced relative to those required in 2007, with 2017 production systems using 74.8% of the cattle, 82.7% of the feedstuffs, 79.2% of the land, and 69.5% of the water as compared to 2007. Waste outputs were similarly reduced, with the 2017 U.S. dairy industry producing 79.4%, 82.5%, and 85.7% of the manure, N, and P excretion, respectively. Dairy production in 2017 emitted 80.9% of the CH4 and 81.5% of the N2O per 1.0 MMT ECM compared to 2007. Enteric and manure emissions contributed the major proportion (80%) of GHG emissions per unit of milk, with lesser contributions from cropping (7.6%) and fertilizer application (5.3%). The GHG emissions per 1.0 MMT ECM produced in 2017 were 80.8% of equivalent milk production in 2007. Consequently, although total U.S. ECM production increased by 24.9% between 2007 and 2017, total GHG emissions from this milk production increased by only 1.0%. In line with previous historical analyses, the U.S. dairy industry has made remarkable productivity gains and environmental progress over time. To maintain this culture of continuous improvement, the dairy industry must build on gains made to date and demonstrate its commitment to reducing environmental impacts while improving both economic viability and social acceptability.

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).

Effects of use of conventional and sexed semen on the conception rate in heifers: A comparison study

Conception rate with the use of sexed semen is lower than that with the use of conventional semen, posing a major problem in the dairy industry. The aim of this study was to understand the risk factors that affect the conception rate after artificial insemination (AI) with conventional and sexed semen using field data. The records of the first insemination in Holstein heifers with conventional (n = 41,857) and sexed semen (n = 45,465) in Hokkaido, Japan were analyzed. The mean conception rate after AI from 2012 to 2016 was 56.9% with conventional semen and 47.3% with sexed semen. A multivariable logistic regression model including the effects of year, heifer age, time of the year, semen type, service sire, and their interactions was used to evaluate the interaction effect of heifer age and time of the year by semen type on the conception rate. In the analysis using heifer age, we found that heifers inseminated with sexed semen were approximately 21 days younger than those inseminated with conventional semen. Interestingly, in early, warmer months (Jun, Jul, and Aug), the conception rate after AI with sexed semen significantly decreased compared with that after AI with conventional semen (P < 0.01). Our results showed that more careful implementation of AI is required for a stable conception using sexed semen, particularly during warmer months.

Health parameters and their association with price in young calves sold at auction for veal operations in Québec, Canada

The veal calf industry in Québec depends on young calves' availability at auction. Most of these calves come from dairy farms. The aim of this cross-sectional study was to determine the effect of clinical anomalies and other calf characteristics on their sale price. A total of 3,820 calves from 5 different auctions were included in this observational study. The calves were examined by a veterinarian on arrival at the auction and screened for umbilical anomalies, the presence of nasal or eye discharge, joint abnormality, diarrhea, appearance of neonatal characteristics (compatible with age less than 1 wk), and general health status mainly based on the presence of depression and dehydration. The final multivariable model included 5 different variables (calf weight, sex, breed, abnormal joints, and general health status) and the interaction between sex and general health status. The presence of abnormal joints and unhealthy characteristics was negatively associated with standardized price. Female calves and mixed breed beef calves were positively associated with standardized price. Finally, the calves' weight was associated with standardized price in a quadratic fashion. Ongoing or previous diarrhea had no effects on standardized price. This study will be helpful for both dairy and veal producers for improving the quality of calves sold to the Québec auction market.

Bovine sperm sex-selection technology in Japan

BACKGROUND

In Japan, Livestock Improvement Association of Japan started commercially producing sexed bovine semen 10 years ago, and sexed bovine semen is currently used for the artificial insemination (AI) in the farms. In this review, the authors introduce the technology for sperm sexing by flow cytometry, the efforts at commercializing sexed semen in Japan, and recent field data on artificial insemination of the cattle with sexed semen.

METHODS

In the procedures of the flow cytometric method, X-chromosome-bearing sperm and Y-chromosome-bearing sperm were fluorescently stained, separated from each other by analyzing the difference in the DNA content, and cryopreserved. The authors surveyed the conception rates after AI with these sperm and sex ratios of the offspring with the cooperation from livestock associations, AI technicians, and farmers.

MAIN FINDINGS RESULTS

Although AI with sexed semen was associated with lower conception rates in comparison with AI with conventional semen, the accuracy of sex selection using AI with sexed semen was beyond >90%.

CONCLUSION

Sexed semen produced by flow cytometry has the potential to produce offspring of the preferred sex with high accuracy and reliability. Thus, it is expected that sexed semen is used for AI more frequently in the farms.

Impact of applying sex sorted semen on the selection proportion of the sire of dams selection pathway in a nucleus program

Objective

In a nucleus breeding scheme, the sire of dam’s pathway plays an important role in producing genetic improvement. Selection proportion is the key parameter for predicting selection intensity, through truncating the normal distribution. Semen sexing using flow cytometry reduces the number of vials of sperm that can be obtained from a proved bull. In addition, a lower fertility of this kind of sperm is expected because of the lower sperm dosage in sex sorted semen. Both of these factors could affect the selection proportion in the sire of dam’s pathway (p_SD).

Methods

In the current study, through a deterministic simulation, effect of utilizing sex sorted semen on selection (p_SD) was investigated in three different strategies including 1: continuous use of sex sorted semen in heifers (CS), 2: the use of sex sorted semen for the first two (S2) and 3: the first (S1) inseminations followed by conventional semen.

Results

Results indicated that the use of sex sorted semen has a negative impact on the sire of dams (SD) pathway due to increase in selection proportion. Consequently selection intensity was decreased by 10.24 to 20.57, 6.38 to 8.87 and 3.76 to 6.25 percent in the CS, S2, and S1 strategies, respectively.

Conclusion

Considering the low effect of sexed semen on genetic improvement in dam pathways, it is necessary to consider the joint effect of using sex sorted semen on the sire and dams pathway to estimate about the real effect of sexed semen on genetic improvement in a nucleus breeding scheme.

Effect of health status evaluated at arrival on growth in milk-fed veal calves: A prospective single cohort study

The objective of this prospective single cohort study was to determine the effect of health status at arrival on growth in milk-fed veal calves. Upon arrival at the veal facility, calves were evaluated using a standardized health scoring system and weighed, and the supplier of the calf was recorded. The calves were followed until slaughter, when the hot carcass weight (HCW) was reported. To calculate average daily gain (ADG), the HCW was transformed into an estimated live weight, weight at arrival was subtracted, and this value was divided by the number of days on feed. A mixed linear regression model was created to evaluate the association of health status on arrival with the ADG throughout the production period. A total of 4,825 calves were evaluated at arrival; however, due to inconsistent HCW data from one slaughter plant, and 357 calves dying during the production period, 2,283 calves were used for analysis. In the final model, 7 variables were significantly associated with ADG. Housing location within the farm, method of calf procurement (drover or auction-derived calves versus direct delivery from local farms) and having a higher body weight at arrival were associated with a higher ADG. The season of arrival (summer or fall compared with winter) and being dehydrated at arrival were associated with a lower ADG. Days on feed was also significant in the multivariable model and had a quadratic relationship with ADG. The associations identified suggest that there may be value in scoring dehydration and body weight at arrival to a veal facility.

Economic evaluation of sexed semen use in Iranian dairy farms according to field data

In this study, at first, the reproductive consequences of sexed semen use were quantified and then the cost-benefit of sexed semen use on Iranian commercial dairy farms was evaluated. Retrospective data collected during 2006 to 2013 from four large dairy farms in the Isfahan province of Iran were used for this study. These data included of 13,003 heifers records, from which 11.2% used sexed semen from 33 different bulls. All data were analysed using a multivariable logistical regression model, GENMOD procedure from SAS software. The analyses included economic values (EVs) when sexed semen was used in 1, 2 and 3 consecutive services compared with conventional semen use for all insemination. Results showed that rates of female born from sexed semen (86.3%) were 1.8 times higher than those from conventional semen (48.5%). Conception rates were 43.8% for sexed and 59.2% for conventional semen (p < 0.0001). Abortion (4.4% vs. 5.4%) and stillbirth (8.4% vs. 7.2%) rates were not significantly different between sexed and conventional semen (p = 0.09). Dystocia rates were 15.5% for sexed and 19.6% for conventional semen (p = 0.002). Sexed semen use showed negative EVs through all investigated scenarios. The EVs from the implementation of 1, 2 and 3 sexed semen breedings were estimated to be $-6.69, $-14.01 and $-19.08, respectively. Total insemination cost and increased cost of age at first calving were the most important components associated with negative EV for sexed semen. Sensitivity analysis showed that proportion of conception rates of sexed semen to conventional semen and female calf value were the most important biological and economic factors influencing on the EV of sexed semen, respectively. Breakeven would be obtained with 77.4%-79.3% conception rates or female calf value of $719.5-$754.7 through investigated breeding scenarios when all other factors remained the same.

Review: Applications and benefits of sexed semen in dairy and beef herds

The use of sexed semen in dairy and beef cattle production provides a number of benefits at both farm and industry levels. There is an increasing demand for dairy and beef products across the globe, which will necessitate a greater focus on improving production efficiency. In dairy farming, there is surplus production of unwanted male calves. Male dairy calves increase the risk of dystocia compared with heifer calves, and as an unwanted by-product of breeding with conventional semen, they have a low economic value. Incorporating sexed semen into the breeding programme can minimise the number of unwanted male dairy calves and reduce dystocia. Sexed semen can be used to generate herd replacements and additional heifers for herd expansion at a faster rate from within the herd, thereby minimising biosecurity risks associated with bringing in animals from different herds. Furthermore, the use of sexed semen can increase herd genetic gain compared with use of non-sorted semen. In dairy herds, a sustainable breeding strategy could combine usage of sexed semen to generate replacements only, and usage of beef semen on all dams that are not suitable for generating replacements. This results in increased genetic gain in dairy herd, increased value of beef output from the dairy herd, and reduced greenhouse gas emissions from beef. It is important to note, however, that even a small decrease in fertility of sexed semen relative to conventional semen can negate much of the economic benefit. A high fertility sexed semen product has the potential to accelerate herd expansion, minimise waste production, improve animal welfare and increase profitability compared with non-sorted conventional semen.

Bioeconomics of sexed semen utilization in a high-producing Holstein-Friesian dairy herd

A bioeconomic, stochastic spreadsheet model, that included calculation of the net present value of the additional value of all future descendants resulting from increased selection intensity, was developed to study the profitability of using sexed semen in a high input-high output dairy herd. Three management strategies were modeled: (1) only heifers inseminated with sex-sorted semen and cows inseminated with unsorted semen; (2) both heifers and cows inseminated with sex-sorted semen; and (3) a reference scenario, in which all breeding females were inseminated with unsorted semen. A Monte Carlo simulation (@risk software, Palisade Corp., Ithaca, NY) was run to study the sensitivity of net profit and sexed semen advantage to key input parameters. Most input parameters were given truncated normal distributions, whereas the maximum numbers of inseminations in heifers and cows were given discrete distribution functions. The calculated intensity of selection accounted for the different numbers of dairy females born for each of the 100,000 iterations. Using sexed semen (X-sorted, female) was shown to be profitable, with insemination of both heifers and cows being most profitable. The returns on assets were higher when only heifers were inseminated with sexed semen (8.54% ± 2.94; ±SD) or all females were inseminated with sexed semen (8.85% ± 2.93) than when all females were inseminated with unsexed semen (8.38% ± 2.95). The range in net profit was most sensitive to the assumed distributions of milk protein price (€/kg), milk fat price (€/kg), cow pregnancy rate, fertilizer price (€/t), and concentrate price (€/t) when unsorted semen was used. When only heifers or both heifers and cows were inseminated with sex-sorted semen, the range in net profit was most sensitive to the same distributions, with fertilizer price and cow pregnancy rate in reverse order of sensitivity. However, the range in sex-sorted semen advantage (in net profit) when only heifers were inseminated with sex-sorted semen was most sensitive to the assumed distributions of cow pregnancy rate, sex-sorted semen pregnancy rate as a percent of unsorted semen rates, standard deviation of index, additional cost of sex-sorted semen (€/dose), dairy bull calf price (€/head), and dairy heifer calf price (€/head). When both heifers and cows were inseminated, the order of importance of the last 2 inputs was reversed. This study highlights the relatively high effect of pregnancy rate and the genetic value of dairy bulls in determining the level of financial advantage from using sex-sorted semen in a dairy herd.

Deep insemination with sex-sorted Cashmere goat sperm processed in the presence of antioxidants

Flow cytometrically sex-sorted sperm have been widely used for improving reproductive management in the dairy industry. However, the industrial application of this technology in other domestic species is largely limited by the lower fertility after insemination. The aim of this study was to investigate effects of antioxidant supplementation during the sex-sorting and freezing process on the quality and functions of sorted sperm from Liaoning Cashmere goats. We tested the effects of antioxidant supplementation during sex-sorting and freezing process, including ascorbic acid-2-glucoside AA-2G, glutathione, melatonin and vitamin C (VC), on the quality and functions of sex-sorted fresh and frozen-thawed sperm. Based on these experiments, we performed deep insemination with sex-sorted sperm using our improved strategy, in comparison to unsorted sperm. In Experiment 1, compared with control group and other antioxidants, AA-2G supplementation significantly alleviated the degradation of motility and viability of fresh sperm after sorting and showed the highest percentage of sperm with normal morphology. In addition, AA-2G supplementation showed an evident protection against the sorting process-induced membrane and acrosome damage. In Experiment 2, AA-2G supplementation was most effective in protecting motility, while melatonin supplementation appears to facilitate the degradation of quality of frozen-thawed sex-sorted sperm. In Experiment 3, we performed deep insemination with sperm that were sorted and frozen in the presence of AA-2G and obtained a satisfying pregnancy rate comparable to that from unsorted sperm. The results showed that AA-2G supplementation efficiently protects quality and function of both fresh and frozen-thawed sex-sorted sperm of Cashmere goats, thus obtaining a satisfying pregnancy outcome.

Economic and genetic performance of various combinations of in vitro-produced embryo transfers and artificial insemination in a dairy herd

The objective of this study was to find the optimal proportions of pregnancies from an in vitro-produced embryo transfer (IVP-ET) system and artificial insemination (AI) so that profitability is maximized over a range of prices for embryos and surplus dairy heifer calves. An existing stochastic, dynamic dairy model with genetic merits of 12 traits was adapted for scenarios where 0 to 100% of the eligible females in the herd were impregnated, in increments of 10%, using IVP-ET (ET0 to ET100, 11 scenarios). Oocytes were collected from the top donors selected for the trait lifetime net merit (NM$) and fertilized with sexed semen to produce IVP embryos. Due to their greater conception rates, first ranked were eligible heifer recipients based on lowest number of unsuccessful inseminations or embryo transfers, and then on age. Next, eligible cow recipients were ranked based on the greatest average estimated breeding values (EBV) of the traits cow conception rate and daughter pregnancy rate. Animals that were not recipients of IVP embryos received conventional semen through AI, except that the top 50% of heifers ranked for EBV of NM$ were inseminated with sexed semen for the first 2 AI. The economically optimal proportions of IVP-ET were determined using sensitivity analysis performed for 24 price sets involving 6 different selling prices of surplus dairy heifer calves at approximately 105 d of age and 4 different prices of IVP embryos. The model was run for 15 yr after the start of the IVP-ET program for each scenario. The mean ± standard error of true breeding values of NM$ of all cows in the herd in yr 15 was greater by $603 ± 2 per cow per year for ET100 when compared with ET0. The optimal proportion of IVP-ET ranged from ET100 (for surplus dairy heifer calves sold for ≥$300 along with an additional premium based on their EBV of NM$ and a ≤$100 embryo price) to as low as ET0 (surplus dairy heifer calves sold at $300 with a $200 embryo price). For the default assumptions, the profit/cow in yr 15 was greater by $337, $215, $116, and $69 compared with ET0 when embryo prices were $50, $100, $150, and $200. The optimal use of IVP-ET was 100, 100, 62, and 36% of all breedings for these embryo prices, respectively. At the input price of $165 for an IVP embryo, the difference in the net present value of yr 15 profit between ET40 (optimal scenario) and ET0 was $33 per cow. In conclusion, some use of IVP-ET was profitable for a wide range of IVP-ET prices and values of surplus dairy heifer calves.

Effect of spermatozoa motility hyperactivation factors and gamete coincubation duration on in vitro bovine embryo development using flow cytometrically sorted spermatozoa

The aim of the present study was to evaluate the effects of sperm motility enhancers and different IVF times on cleavage, polyspermy, blastocyst formation, embryo quality and hatching ability. In Experiment 1, sex-sorted X chromosome-bearing Bos taurus spermatozoa were incubated for 30 min before 18 h fertilisation with hyperactivating factors, namely 10 mM caffeine (CA), 5 mM theophylline (TH), 10 mM caffeine and 5 mM theophylline (CA + TH); and untreated spermatozoa (control). In Experiment 2, matured B. taurus oocytes were fertilised using a short (8 h) or standard (18 h) fertilisation length, comparing two different fertilisation media, namely synthetic oviducal fluid (SOF) fertilisation medium (SOF-FERT) and M199 fertilisation medium (M199-FERT). Cleavage and blastocyst formation rates were significantly higher in the CA + TH group (77% and 27%, respectively) compared with the control group (71% and 21%, respectively). Cleavage rates and blastocyst formation were significantly lower for the shortest fertilisation time (8 h) in M199-FERT medium (42% and 12%, respectively). The SOF-FERT medium with an 8 h fertilisation time resulted in the highest cleavage rates and blastocyst formation (74% and 29%, respectively). The SOF-FERT medium produced the highest embryo quality (50% Grade 1) and hatching rate (66%). Motility enhancers did not affect polyspermy rates, whereas polyspermy was affected when fertilisation length was extended from 8 h (3%) to 18 h (9%) and in M199-FERT (14%) compared with SOF-FERT (6%). We conclude that adding the motility enhancers CA and TH to sex sorted spermatozoa and Tyrode’s albumin lactate pyruvate (TALP)-Sperm can improve cleavage and embryo development rates without increasing polyspermy. In addition, shortening the oocyte–sperm coincubation time (8 h) resulted in similar overall embryo performance rates compared with the prolonged (18 h) interval.

A new device to inseminate cows at the base of the uterine horns

A new device (Chapingo device) to deposit semen at the base of the uterine horns of cattle was developed at Universidad Autonoma Chapingo, Mexico. Nine Holstein heifers were inseminated by transvaginal laparoscopy, using a laparoscope for cattle and the Chapingo device. A dose of sexed semen (2.1 × 10⁶ spermatozoa) was deposited at the base of the uterine horn ipsilateral to the ovary where the preovulatory follicle was identified. Insemination was achieved in all the heifers, taking on average 13.7 ± 3.1 min per animal. In all cases, it was possible to see both ovaries, the base of the uterine horns and the oviducts. After the procedure, none of the heifers showed any type of complications such as haemorrhage, adhesions or trauma. On days 21 and 22 after insemination, four of the nine heifers (44.4%) returned into oestrus; on day 30 after insemination, one heifer was found to be pregnant by ultrasound. The results show the feasibility of generating pregnancies by transvaginal laparoscopy in heifers inseminated with sexed semen.

Mortality risk factors for calves entering a multi-location white veal farm in Ontario, Canada

Mortality in preweaned dairy-breed calves, whether they are replacement dairy heifers, veal animals, or dairy beef animals, represents both a welfare issue and a source of economic loss for the industries involved. Studies describing morbidity and mortality in veal calves have illustrated different management practices and requirements in terms of housing and nutrition around the world. Studies examining the rearing of replacement dairy heifers have shown that rates of morbidity and mortality can vary dramatically between farms, perhaps reflecting differences in management strategies. It has been over 2 decades since morbidity and mortality in veal calves in Ontario were described. The objective of this retrospective population cohort study was to describe mortality and determine whether on-arrival information could be used to predict mortality risk. Predictors could be used to both better classify and group calves on arrival and provide feedback to suppliers about the characteristics of the highest- and lowest-risk calves. We collected data from 10,910 calves entering 7 barns of a single white veal farm, all in Ontario, from January 1 to December 31, 2014. Calves were followed until death or marketing (typically 140 to 150 d). We developed logistic regression models to determine the effects of weight on arrival, season of arrival, supplier, sex, barn, and purchase price on the risk of total mortality, early mortality (0-21d after arrival), and late mortality (>21d after arrival). We identified significant associations between season, barn, supplier, weight, and total mortality risk, with lighter-weight calves arriving in winter being at increased risk. Early mortality was significantly associated with weight, season, barn, and supplier, and tended to be associated with standardized price; lighter-weight calves arriving in winter at lower prices were at increased risk. Late mortality was significantly associated with season of arrival, barn, and supplier. On-arrival measures better predicted early mortality compared with late or total mortality. A further exploration of risk factors from the dairy farm of origin for veal calf mortality would serve to improve the productivity and welfare of calves of both sexes born on dairy farms.

Expanding the dairy herd in pasture-based systems: The role of sexed semen within alternative breeding strategies

A simulation model was developed to determine the effects of sexed semen use in heifers and lactating cows on replacement heifer numbers and rate of herd expansion in a seasonal dairy production system. Five separate artificial insemination (AI) protocols were established according to the type of semen used: (1) conventional frozen-thawed semen (CONV); (2) sexed semen in heifers and conventional semen used in cows (SS-HEIFER); (3) sexed semen in heifers and a targeted group of cows (body condition score ≥3 and calved ≥63 d), with conventional semen used in the remainder of cows (SS-CONV); (4) sexed semen in heifers and a targeted group of cows, with conventional semen in the remainder of cows for the first AI and conventional beef semen used for the second AI (SS-BEEF); or (5) sexed semen in heifers and a targeted group of cows, with conventional semen in the remainder of cows for the first AI and short gestation length semen used for the second AI (SS-SGL). Each AI protocol was assessed under 3 scenarios of sexed semen conception rate (SS-CR): 100, 94, and 87% relative to that of conventional semen. Artificial insemination was used on heifers for the first 3 wk and on cows for the first 6 wk of the 12-wk breeding season. The initial herd size was 100 cows, and all available replacement heifers were retained to facilitate herd expansion, up to a maximum herd size of 300 cows. Once maximum herd size was reached, all excess heifer calves were sold at 1 mo old. All capital expenditure associated with expansion was financed with a 15-yr loan. Each AI protocol was evaluated in terms of annual farm profit, annual cash flow, and total discounted net profit. The SS-CONV protocol generated more replacement heifers than all other AI protocols, facilitating faster expansion, and reached maximum herd size in yr 9, 9, and 10 for 100, 94, and 87% SS-CR, respectively. All AI protocols, except SS-BEEF and SS-SGL at 87% SS-CR, reached maximum herd size within the 15-yr period. Negative profit margins were experienced for SS-CONV in the first 5, 4, and 3 yr of expansion for 100, 94, and 87% SS-CR, respectively. Total discounted net profit was greater in all sexed semen AI protocols compared with CONV. This study demonstrated that, for each SS-CR, the greatest rate of expansion is achieved when using sexed and conventional semen (SS-CONV). The combined use of sexed semen and beef (SS-BEEF) or SGL (SS-SGL) semen resulted in greater discounted net profit at 100, 94, and 87% SS-CR compared with CONV, but a similar net worth change at 87% SS-CR due to a lower inventory change because SS-BEEF and SS-SGL reached maximum herd size within 15 yr.