Herd Performance Research Articles

Selection and implementation of single nucleotide polymorphism markers for parentage analysis in crossbred cattle population

Crossbreeding is an essential way of improving herd performance. However, frequent parentage record errors appear, which results in the lower accuracy of genetic parameter estimation and genetic evaluation. This study aims to build a single nucleotide polymorphism (SNP) panel with sufficient power for parentage testing in the crossbred population of Simmental and Holstein cattle. The direct sequencing technique in PCR products of pooling DNA along with matrix-assisted laser desorption/ionization time-of-flight MS method for genotyping the individuals was applied. A panel comprising 50 highly informative SNPs for parentage analysis was developed in the crossbred population. The average minor allele frequency for SNPs was 0.43, and the cumulative probability of exclusion for single-parent and both-parent inference met 0.99797 and 0.999999, respectively. The maker-set for parentage verification was then used in a group of 81 trios with aid of the likelihood-based parentage-assignment program of Cervus software. Reconfirmation with on-farm records showed that this 50-SNP system could provide sufficient and reliable information for parentage testing with the parental errors for mother–offspring and sire–offspring being 8.6 and 18.5%, respectively. In conclusion, a set of low-cost and efficient SNPs for the paternity testing in the Simmental and Holstein crossbred population are provided.

187 Protocols, standard operating procedures, and employee training to improve milk safety and quality

Abstract Dairy farm employees play a key role in ensuring the highest quality milk being delivered to manufacturers. Major concerns associated with milk quality on dairies include the number of clinical mastitis cases, elevated somatic cell counts, elevated bacteria count, and presence of residues in raw milk. All these factors are impacted by the knowledge, skills, and performance of dairy employees working in the milking parlor and other areas of the operation. Exemplary performance on dairies is driven by effective training, motivation, and communication between various team members. Standard operating procedures (SOPs) provide a basis for training employees, improving consistency between and within shifts, and conducting performance evaluations with valuable feedback. SOPs also have the potential to improve milk quality, herd performance, and herd health. SOPs should be specific to the dairy operation and developed with detailed instructions on completing a task. These procedures need to be written in the employees’ native language in addition to English and should be easy to read and understand. The font used should be large and when appropriate, photos should be used to explain or highlight step by step procedures. Once developed, SOPs need to be evaluated at least once a year and revised as needed. Regular trainings are also important for prevention of procedural drifts. Hybrid learning models combining classroom/online and hands-on activities should be considered and implemented. This approach ensures that dairy employees are engaged and appropriately trained, independent of their literacy and reading proficiency. Dairies should also strive to provide a positive, safe, and comfortable work environment for their employees. A positive environment can lead to improvements in employee morale, performance, and retention. Finally, it is important to establish clear and firm expectations on producing the highest quality of milk while providing specific, timely, and constructive feedback.

PSXII-23 Identification and evaluation of novel fertility traits using automated activity monitor data from commercial dairy herds

Abstract The reproductive performance of dairy herds is a determinant factor in their production efficiency and long-term profitability. While the genetic improvement of fertility in cows has been a top breeding objective, its success has been constrained by the low heritability of current traits and the negative impact of management practices on trait measurement accuracy. The recent development and adoption of automated sensor technologies, such as activity monitors, within dairy production systems have provided new opportunities to identify relevant and cost-effective phenotypes of fertility. To date, several activity-based measurements of estrus expression have been associated with fertility outcomes and may, therefore, be suitable predictors of female fertility. The objective of this study was to identify and evaluate novel estrus-related fertility traits using automated activity monitor (AAM) data from commercial dairy herds. A total of 8,730,987 records consisting of 10,529 estrus events were collected between January 2019 and March 2020 from 2,434 cows and 689 heifers of two U.S. commercial herds, where cows were fitted with collar-mounted accelerometers (Heatime, SCR Engineers Ltd., Netanya, Israel). The AAM dataset contained individual bi-hourly activity and rumination patterns, as well as computed fertility index scores, which were used to derive fertility traits related to estrus duration and intensity. The mean number of estrus events per cow and heifer was 4.06 ± 0.04 and 2.63 ± 0.07, respectively, with 1,408 of estruses resulting in pregnancy. Traditional fertility traits were calculated from the breeding record information of 3,255 animals. An estimation of the heritabilities along with genetic and phenotypic correlations between the novel estrus-related fertility traits and traditional fertility traits was undertaken using the program AIREML. Outputs from this project are expected to provide further insight on how to best use AAM measurements to improve selection for reproductive performance in commercial dairy herds.

PSVIII-35 Late-Breaking Abstract: Administration of an appeasing substance at castration improves performance of pre-conditioned beef crossbred steers

Abstract Alternatives that alleviate stress-related responses and improve performance of the beef cattle herd are imperative and deserve further investigation. In previous trials, administration of the bovine appeasing substance (BAS) has improved performance of newly-weaned and feedlot received beef animals, as well as reduced the risk of dark, firm, and dry (DFD) cuts in carcass obtained from Bos indicus cattle. Therefore, this study was designed to evaluate the effects of BAS administration at castration on pre-conditioning performance of crossbred beef animals. On day 0, 390 crossbred Angus × Nellore animals were ranked by initial shrunk BW (255 ± 21.1 kg) and assigned to receive or not (CON) 5 mL/head of BAS (SecureCattle; Nutricorp, Araras, SP, Brazil) immediately before castration. From d 0 to 30, animals within treatments were maintained in 2 feedot pens with a minimum distance (300 m) to avoid contact between treatment groups and received a grass hay-based diet (70:30 roughage:concentrate ratio) ad libitum. On day 30, animals were individually weighed following 16 hours of feed and water restriction. Hence, a descriptive analysis was performed to evaluate pen dry matter intake (DMI) and feed efficiency (FE). Animal was considered the experimental unit and all data were analyzed using the PROC MIXED procedure of SAS (version 9.4; SAS Inst. Inc., Cary, NC). Bovine appeasing substance administration at castration improved ADG and BW change (P < 0.0001) compared with CON cohorts (0.983 vs. 1.155 kg/d and 29.5 vs. 34.6 kg for ADG and BW change, respectively). Total DMI was similar among treatments when reported as kg/d (6.70 vs. 6.75 kg) or % of BW (2.48 vs. 2.48%), whereas FE was dramatically improved in BAS-administered animals (146 vs. 172 g/kg for CON and BAS, respectively). In summary, BAS administration improved performance of crossbred beef animals for 30 days post-castration.

Epidemiological study of the association between bovine gammaherpesvirus type 4 and reproductive disease in dairy cattle from northwestern Spain

Bovine gammaherpesvirus 4 (BoHV-4) has controversially been related with cattle reproductive disease. In the present study we analyze the relationship between exposure to BoHV-4 and reproductive performance in dairy cattle from northwestern Spain. A total of 2022 sera from 50 farms were examined to detect anti-BoHV-4 antibodies. Herd and individual reproductive records were collected to analyze association with exposure to BoHV-4. In addition, 52 abortion cases were examined to detect BoHV-4 DNA. An individual seroprevalence of 66.6 % and a herd prevalence of 98 % were found. Exposure to BoHV-4 increased with age, particularly in individuals between 26−36 months old (OR = 2.7; CI 95 %: 1.2−5.0, compared to animals < 26 months). Seroprevalence was not associated with herd fertility and herd abortion rate, but seropositive animals between 26−36 months presented prolonged calving to fertilizing insemination intervals (HR: 1.4; CI 95 %: 1.2–2.0) as well as higher odds of an unsuccessful 1st insemination (OR: 2.5; CI 95 %: 1.2−5.0). In abortion cases, BoHV-4 DNA was found in 12 vaginal swabs from 5 farms but not in any fetal tissue. Our results reveal an endemic, high and widespread exposure to BoHV-4 among dairy cattle from NW Spain with a limited impact in the reproductive performance of herds. The significantly worse reproductive performance of seropositive animals of 26−36 months of age may be the consequence of the establishment of primo-infections when moving heifers to lactation lots. Our findings may be useful to understand the potential population impact of BoHV-4.

Mycoplasma species in vaginas of dairy cows before and after exposure to bulls and their association with conception

Mycoplasma species can colonize the urogenital tract of dairy cattle. However, interrelationships between Mycoplasma spp. and reproductive performance in dairy herds are unclear. In this study, we measured apparent prevalences of Mycoplasma spp. in the vaginas of dairy cows (n = 629) pre- and post-bull exposure in dairy herds with and without Mycoplasma bovis clinical disease (n = 5 herds), and assessed associations between variables describing reproductive performance and consequent Mycoplasma spp. isolation. Mycoplasma spp. were infrequently isolated from the vagina pre- (1.9%; 12/629) and post-bull (3.2%; 20/629) exposure. Of the mycoplasmas isolated, Mycoplasma bovigenitalium was isolated most frequently (87.5%; 28/32), followed by Mycoplasma californicum (9.3%; 3/32). Mycoplasma bovis was only isolated from one cow. We were unable to provide any evidence of venereal transmission of M. bovis in cows in M. bovis-infected herds that use natural service bulls. There was an insufficient number of cows with Mycoplasma spp. in the vagina pre-bull exposure to assess effects on subsequent reproductive performance. Cows that had not conceived before post-bull exposure sampling had much greater odds (odds ratio 14.8; 95% confidence interval 4.2 to 52.3) of having a Mycoplasma sp. isolated from the vagina at this time compared with those that had conceived. Also, within those that had conceived, delayed conception increased the odds of having a Mycoplasma spp. isolated from the vagina at the post-bull exposure sampling by a factor of 1.62 for every additional week not pregnant. The likely cause of these findings is that cows that remain not pregnant for longer are more likely to be served by a bull (likely repeatedly) and subsequently become colonized with a Mycoplasma sp. (mostly M. bovigenitalium) through venereal transmission. In dairy herds that use bulls, there is a greater chance of isolating a Mycoplasma sp. (mostly M. bovigenitalium) after a period of bull breedings from the vaginas of cows that have remained nonpregnant for longer during the bull breeding period.

Evaluation of performance and carcass traits for a five-cohort All Heifer, No Cow beef production system demonstration herd.

The All Heifer, No Cow (AHNC) beef production system is an alternative to conventional cow/calf production that involves insemination of nulliparous heifers with sexed semen to produce female calves that are early weaned at 3 mo of age. Dams are finished on a high-concentrate diet and harvested before reaching 30 mo of age. Objectives of this research were to document reproductive, feedyard, calf, and carcass performance of an AHNC herd; evaluate effects of carcass maturity on carcass quality; and determine if performance of initial cohorts (i.e., cohorts 1 and 2) differed from sustaining cohorts (i.e., cohorts 3–5). A total of 272 heifers were enrolled in the AHNC system via five annual cohorts. The system was initiated with 51 yearling, Angus-based heifers, and a replicate set (n = 56) was started 12 mo after. Heifers in cohorts 3 (n = 53), 4 (n = 56), and 5 (n = 56) were primarily offspring of prior cohorts (i.e., cohort 3 heifers born to cohort 1 females), but some were purchased to maintain inventory. Angus replacement heifers were purchased in cohorts 3 (n = 26), 4 (n = 26), and 5 (n = 28). Mean (±standard deviation) pregnancy rate at 30 d after fixed-time artificial insemination (AI) with sexed semen was 50.8% ± 9.4%, and 140-d pregnancy rate was 93.0% ± 1.5%. With AHNC, 61.0% ± 6.5% of females replaced themselves with a heifer. During finishing, average daily gain (ADG) was 1.9 ± 0.4 kg • d−1 and dry matter intake (DMI) was 14.9 ± 1.9 kg • d−1. Hot carcass weight (HCW) was 367 ± 35 kg. The USDA grading system classified 20.5% of all carcasses (n = 220) as C maturity (A00 = 100, B00 = 200, etc.), 62.4% ± 29.1% of carcasses as USDA Choice. USDA yield grade (YG) was 2.6 ± 0.7. Based on cohorts 1 and 2, there were no differences (P = 0.96) in Warner–Bratzler shear force values between A and B maturity vs. C maturity carcasses. Across all cohorts, there were no differences in USDA YG, marbling score (MA), and lean maturity between A and B maturity vs. C maturity carcasses; there were differences in age (P < 0.001), bone maturity (P < 0.001), and overall maturity (P <0.001). A comparison of initial vs. sustaining cohorts showed that initial cohorts had lower (P < 0.001) DMI, heavier (P < 0.001) HCW, and more advanced (P < 0.05) bone maturity. However, there were no differences for 30- and 140-d pregnancy rates, ADG, USDA YG, and MA between initial and sustaining cohorts. The AHNC beef production system can effectively produce female calves and quality carcasses for harvest.

An economic framework to evaluate alternative management strategies for beef enterprises in northern Australia

Context Beef producers in northern Australia are continually presented with new technologies and opportunities to enhance beef production. They need to be able to accurately and efficiently assess the potential impact of alternative strategies on profitability, risk and the period of time before benefits can be expected. Aims Our aim was to demonstrate the value of the farm-management economics framework for assessing alternative management strategies applicable to beef cattle enterprises in northern Australia. Methods Beef cattle herd models incorporated into a farm-level partial discounted cash-flow framework were used to evaluate the potential effects of alternative management strategies on the performance of enterprises. This was undertaken using constructed, representative beef enterprises developed for the following three regions in Queensland: Central, Northern Downs and Northern Gulf, and the Katherine region of the Northern Territory. The analysis considered the expected response to change in the management of the base herd. Strategies that targeted (1) overall herd or property performance, (2) breeder reproductive performance, (3) steer growth rates, (4) alternative beef cattle marketing options, or (5) enterprise expansion were assessed. All of the changes considered to the current management strategy of the base herd and property were put forward by industry participants as potentially positive. Key results The framework efficiently identified substantial differences in net benefits among strategies and allowed ranking of the alternatives at the property level. Strategies that improved profitability also generally increased management complexity and financial risk. While strategies that could substantially improve profitability were identified, many other strategies were likely to reduce profitability at the property level. Key insights were gained into the time taken to implement the strategies, the complexity of implementation, and the level of financial risk incurred. Conclusions This study (1) demonstrated the appropriate framework to compare management options and support decision making, (2) efficiently indicated the potential range of outcomes, and (3) provided insight into the risks associated with development processes and technology adoption. Implications This farm-management economics framework could be used to assess alternative strategies for individual beef enterprises and to guide appropriate adoption of technology.

Data driven decision making

When I began my veterinary career in the late 1990s there was a lot of talk about production medicine in food animal medicine. And while the profession has been evolving since it began, I think at that time there was a real struggle to establish just what production medicine was. As many veterinarians described what they did as herd advisors or consultants, it was common to declare our role was to assist with establishing herd health protocols, such as vaccination or treatment protocols, and then help analyze whether those protocols were effective or not. The only problem was our evidence of whether something was working on-farm was slim to non-existent. Or, our evidence was either statistically irrelevant or incorrectly interpreted.&#x0D; In the early 2000s several production medicine-oriented veterinarians began working towards improving the data we had available to evaluate herd performance and improving our ability to make good management recommendations. This started with improving our farm records systems and then developing additional analytical programs to improve the efficiency of analyzing farm records. The final step to using data to make decisions is to improve our knowledge of statistics and our ability to accurately interpreting farm data.

A survey on sensor systems used in Italian dairy farms and comparison between performances of similar herds equipped or not equipped with sensors

Sensor systems (SS) were developed over the last few decades to help dairy farmers manage their herds. Such systems can provide both data and alerts to several productive, behavioral, and physiological indicators on individual cows. Currently, there is still a lack of knowledge on both the proportion of dairy farms that invested in SS and type of SS installed. Additionally, it is still unclear whether the performances of herds equipped with SS differ from those of similar herds managed without any technological aid. Therefore, the aims of this study were (1) to provide an insight into SS spread among Italian dairy farms and (2) to analyze the performances of similar herds equipped or not equipped with SS. To reach the former goal, a large survey was carried out on 964 dairy farms in the northeast of Italy. Farmers were interviewed by the technicians of the regional breeders association to collect information on the type of SS installed on farms and the main parameters recorded. Overall, 42% of the surveyed farms had at least 1 SS, and most of them (72%) reared more than 50 cows. Sensors for measuring individual cow milk yield were the most prevalent type installed (39% of the surveyed farms), whereas only 15% of farms had SS for estrus detection. More sophisticated parameters, such as rumination, were automatically monitored in less than 5% of the farms. To reach the latter goal of the study, a subset of 100 Holstein dairy farms with similar characteristics was selected: half of them were equipped with SS for monitoring at least individual milk yield and estrus, and the other half were managed without any SS. Average herd productive and reproductive data from official test days over 3 yr were analyzed. The outcomes of the comparison showed that farms with SS had higher mature-equivalent milk production. Further clustering analysis of the same 100 farms partitioned them into 3 clusters based on herd productive and reproductive data. Results of the Chi-squared test showed that the proportion of farms equipped with SS was greater in the cluster with the best performance (e.g., higher milk yield and shorter calving interval). However, the presence of a few farms equipped with SS in the least productive cluster for the same parameters pointed out that although the installation of SS may support farmers in time- and labor-saving or in data recording, it is not a guarantee of better herd performance.

How to manage cows yielding 20,000 kg of milk: technical challenges and environmental implications

The world cow milk production will reach between 810 and nearly 1,000 Mt in 2050, implying changes in dairy farm management as well implications in environmental impact, especially as far as greenhouse gases (GHG) emissions, and nitrogen and phosphorus excretions are concerned. The future dairy farms will need to become smarter, profitable, and high yielding to continuously improve the sustainability of milk production. Among western countries, the Italian dairy industry has good performances both for milk yield and quality. Most of its milk is used to produce highly exported PDO cheeses with high added value. It could represent a model to study the impact of accelerated phenotypic trend on technical and environmental challenges. Assuming a constant average increase of milk yield equal to the actual phenotypic trend (+128 kg per cow and per year), the production of the current best cows (20t/head year−1) will become the average herd performance of the intensive dairy farms in 2030. Thus, maintaining the current Italian milk production (equal to 12.1 Mt), the higher milk production per head would cause a reduction of the environmental impact of 11.4% and 60.1% for GHG, 9.1% and 36.0% for N, 15.8% and 52.6% for P considering two scenarios of present phenotypic trend or 20t/head year−1, respectively. To cope with this challenge, technical suggestions for breeding and feeding the 20t dairy cow are given. Highlights Current top Italian cows represent the 2030 average of dairy herds Genomics and management will drive the productivity success Efficiency will reduce dairy environmental impact

Incorporating Diversity Into Animal Production Systems Can Increase Their Performance and Strengthen Their Resilience

Animal production systems (APSs) have long been transformed through intensification, specialization and geographical concentration, leading them to become major anthropogenic drivers of pollution, climate change, and biodiversity loss. Agroecology, organic farming and sustainable intensification have been proposed as alternative models to invert those trends. Diversity is highly valued in agroecology and organic farming, in which it is assumed not only to increase farm performance but also to strengthen farm resilience. Here, we examine how the diversity of system components and interactions among these components can increase productivity, resource-use efficiency and farm resilience in aquaculture, rabbit, monogastric and ruminant systems. In doing so, we reveal that the same processes can occur in very different systems. For instance, the higher performance of multi-species aquaculture or ruminant grazing systems results from (i) the complementary feeding habits of animal species that exploit resources from different ecological niches more efficiently; and (ii) facilitation or competitive exclusion, which results in a species increasing or decreasing resource availability for another species. The benefits of diversity are observed not only in relatively extensive systems but also in intensive indoor systems. For instance, genetic diversity is associated with herd and social immunity in rabbit production, while trade-offs between life functions play a major role in dairy herd performance. In the last section, we discuss how management options nested in system component diversity and their interactions can enhance system resilience. Strategic and tactical management of APS diversity can promote farm buffering and adaptive capabilities, respectively, via the abovementioned processes. By stabilizing the farm financial situation and facilitating access to short supply channels, transformative changes, such as a diversification of the animal species bred or development of a processing enterprise on farm, expand options for increasing the resilience of APSs to market price fluctuations and climatic shocks. However, the need for new technical skills and sometimes high initial investments can act as strong inhibitors of farm diversification. We conclude with a description of some of the research or action that is needed for these principles to be more widely implemented in commercial farms.

Estimating prevalence of endometritis in smallholder zero-grazed dairy cows in Rwanda.

Endometritis is a postpartum uterine disease of cows that interrupts reproductive cycles resulting in suboptimal fertility, reduced performance and profitability of the dairy herd. The objective of the study was to estimate the perceived and observed prevalence of endometritis among zero-grazed dairy cows in smallholder farms in Rwanda. A snowball sampling method was applied in cross-sectional survey to obtain data from 370 farms on 466 cows within their 21-60days postpartum (dpp). The survey, conducted from September 2018 to March 2019, simultaneously examined cows using the Metricheck Device (MED) to determine the presence and type of vaginal mucus (VMC) based on a score scale of 0 to 3. Cows scoring VMC ≥ 1 were recorded as clinical endometritis (CLE)-positive. Cytotape (CYT) was used to determine the percentages of polymorphonuclear cells (PMN)in endometrial cytology sample. Cows with ≥ 5% PMN were recorded subclinical endometritis (SCLE)-positive, whereas cows with VMC-0 and < 5% PMN were considered healthy cows. At cow-level, endometritis prevalence was 70.2% with 67.2% CLE and 31.8% SCLE while at the herd-level, prevalence was 71.1% with 68.1% CLE and 34.4% SCLE. The differences between the diagnostic performance of the MED and CYT were significant (p < 0.001). Perceived prevalence by farmers was much lower (3.2%) and without agreement with the observed prevalence (kappa = - 0.02, p > 0.05). The highly observed prevalence and farmer underestimation of endometritis prevalence indicate knowledge gaps about endometritis. The extension service therefore needs to increase awareness and education among smallholder farmers about detection and management of endometritis.

Reproductive performance following a modified Presynch-Ovsynch, Double-Ovsynch, or conventional reproductive management program in Korean dairy herds

We aimed to compare the reproductive performance of dairy cattle following a modified Presynch-Ovsynch, Double-Ovsynch, or conventional reproductive management program (CRMP). On Day 30 (±5) after calving (calving = Day 0), 960 lactating cows were assigned randomly to one of two presynchronization treatments, before the synchronization of ovulation (Ovsynch) or CRMP without presynchronization. Cows were administered prostaglandin F2α (PGF2α) on Days 38 (±5) and 52, and gonadotropin-releasing hormone (GnRH) on Day 55 (Presynch-G-Ovsynch group, n = 333); or GnRH on Day 45 (±5), PGF2α on Day 52, and GnRH again on Day 55 (Double-Ovsynch group, n = 307). Thereafter, each cow underwent Ovsynch 7 days later: GnRH on Day 62, PGF2α on Day 69, and GnRH again 56 h later, followed by timed artificial insemination (AI) 16 h later. The remaining cows underwent AI when estrus was detected or Ovsynch (CRMP group, n = 320). In a subset of cows (each n = 40) in the two presynchronization groups, blood collections and ovarian ultrasonography were performed on Days 30 (±4), 52, 62, and 69, and uterine cytology on Days 30 (±4) and 52. The probabilities of pregnancy per AI 32 and 60 days after the first AI were higher in the Presynch-G-Ovsynch (odds ratio [OR]: 1.89 and 1.81, P < 0.01) and Double-Ovsynch (OR: 1.63 and 1.60, P < 0.05) groups than in the CRMP group. The likelihood of pregnancy by 210 days postpartum was higher (P < 0.05) in Presynch-G-Ovsynch (hazard ratio [HR]: 1.29) and Double-Ovsynch (HR: 1.31) groups than in the CRMP group, whereas the least square mean number of inseminations per conception was lower (P < 0.05) in Presynch-G-Ovsynch (1.8) and Double-Ovsynch (1.8) groups than in the CRMP group (2.1). The percentages of cows with serum progesterone concentrations ≥1.0 ng/mL or with a corpus luteum (CL) did not differ between the groups (P > 0.1) on Days 30, 62, and 69, but were lower (P < 0.05) on Day 52 in the Presynch-G-Ovsynch than in the Double-Ovsynch groups. However, the diameter of the dominant follicles, the proportion of neutrophils in uterine cytological samples, and the prevalence of an accessory CL on Day 69 did not differ (P > 0.1) between the two groups. In conclusion, both the Presynch-G-Ovsynch and Double-Ovsynch programs improved reproductive performance vs. CRMP in smallholder Korean dairy herds, and there were no differences in the ovarian endocrine and structural dynamics, or uterine health, between the two programs involving presynchronization.

Una revisión de los sistemas de apareamiento para el trópico

Los sistemas de producción de ganado de carne a pastoreo difieren en materia de utilización de recursos, grado de intensificación, roles culturales, entre otros. En relación con la eficiencia y la productividad de los sistemas de producción de ganado bovino de carne a pastoreo, se podría hacer grandes progresos en lo relativo a la adopción de procedimientos de manejo mejorados. Se realizó una investigación bibliográfica sobre los Sistemas de Apareamiento en los sistemas de producción de ganado bovino de carne y su aplicación en el Trópico Americano, con énfasis en Venezuela. En ella se revisan las condiciones y prácticas de manejo requeridas para lograr la expresión de los potenciales genéticos, los requerimientos, ventajas y desventajas de las alternativas al sistema rotativo para compararlos y recomendar en consecuencia. El sistema de apareamiento intersé para la generación de Compuestos y el [F1] modificado tienen similitudes, pero se han evidenciado algunas diferencias: El uso de sementales F1 impide la pérdida de heterosis debido a la renovación de la consanguinidad, amplía la retención de la heterosis, no interfiere con la selección de caracteres aditivos y capitaliza el progreso genético en las razas progenitoras. En conclusión, unos toros F1 capaces de prosperar en condiciones adversas, sobre una población de vacas cruzadas, en generaciones sucesivas, podrían ser una forma viable de superar las limitaciones de otros sistemas de apareamiento, combinar la adaptabilidad con un mayor desempeño en rebaños pequeños, manteniendo al mismo tiempo un manejo sencillo, capacidad de ajuste y adaptación a las nuevas restricciones y oportunidades generadas por el entorno cambiante.

Impact of age at first calving on performance and economics in commercial dairy herds in Argentina

Dairy herd efficiency depends on an adequate replacement program, and one of the main management factors affecting the replacement cost is age at first calving (AFC). The primary objective of this study was to evaluate the impact of AFC on performance and economic results in commercial dairy herds in Argentina. A retrospective study was conducted to analyze data from a total of 26,614 first lactation cows from 290 argentinian dairy farms calved for the first time during the calendar year 2016. Milk yield for first lactation cows having at least 5 milk test days was used to analyze production (n=15,181). Records were stratified by AFC into 5 groups: 1) 18–21 mo (n=202), 2) 22-25 mo (n=5,569), 3) 26-29 mo (n=5,579), 4) 30-33 mo (n=2,389), 5) 34-37 mo (n=1,442). The overall median of AFC was 27 mo. Although milk yield at the beginning of the lactation was lower for lower AFC categories, the differences between categories 2, 3, and 4 disappeared by the fourth test day at approximately 113 days in milk. No effect of AFC category was detected for milk fat and protein content and for SCC. Considering AFC categories, cows calving for the first time at 22–25 mo of age needed the shortest period after calving to conceive. The lower income associated with the mild milk losses may be compensated by the cost of more than 80 extra d in the rearing period and the increment in days open estimated for the upper categories.

Development and evaluation of a dynamic simulation model of reproductive performance in pasture based suckler beef systems

The reproductive performance of a beef cow herd is largely a factor of efficient animal management strategies and genetics. The complex and cumulative nature of individual management decisions on a farm system's performance over multiple years mean that robust evaluation is time consuming and costly. A dynamic deterministic simulation model (Grange Reproductive Management Model; GReMM) with the capacity to replicate herd inventory dynamics over multiple reproductive cycles was developed using the Stella Architect dynamic modelling platform. The model is representative of a pasture-based spring calving suckled beef cow herd and is initialised by specifying individual farm parameters with respect to reproductive management, such as the breeding season duration, nutrition and management of the cow and calf postpartum. The focus was on the key factors which affect the duration of the postpartum anoestrus interval (PPAI); body condition score of the cow at calving (BCSc), postpartum nutrition (PPN), access of the suckling calf to the dam and, exposure of the dam to a fertile male. Model output was displayed in the form of a shift in calving distribution, the number of calves produced per cow bred per year and, percentage of cows culled due to barrenness. Three management scenarios were investigated to represent a herd implementing current industry best practice (BASE), a herd implementing intensive levels of reproductive management (Intensive reproductive management; IRM) and a herd implementing poor levels of reproductive management (Poor reproductive management; PRM). When evaluated in terms of calving distribution over six production cycles, both PRM and IRM showed a shift in the calving spread with a higher proportion of animals calving earlier and later, respectively, in the calving season compared to the BASE. This resulted in a 5% increase and a 14% decrease in six-week calving rates relative to BASE by year six, for IRM and PRM, respectively. Correspondingly, culling rates due to barrenness reduced by 0.9% and increased by 3.3% relative to BASE for IRM and PRM, respectively. The model developed offers a realistic and intuitive dynamic simulation model capable of investigating practical on-farm management decisions on herd reproductive performance.

Associations between On-farm Welfare, Milk Production, and Reproductive Performance in Dairy Herds in Northwestern Spain

ABSTRACT This study was conducted to evaluate the relationship between on-farm welfare, milk production, and reproductive performance in dairy herds in northwestern Spain. Data on the welfare status from 31 herds were collected using the Welfare Quality® protocol. Linear regression was applied to assess associations between WQ criteria/principle scores on farm average 305-d milk production and calving to conception interval (CCI). Results indicated that milk production was associated with the absence of prolonged hunger criterion (average increase of 22.33kg per unit score). Each one unit increase in the score for good feeding was also associated with a26.49kg increase in milk production. A10 unit increase in the scores for the absence of pain (by management procedures), expression of social behaviors, and absence of injuries was associated with reductions in CCI by 1.77, 0.8, and 0.29 days. CCI also decreased by 1.08 and 0.53 days when the principles of good health and appropriate behavior increased by 10 units. This study points out associations which can help encourage the dairy cattle sector to adopt practices that promote animal welfare.

An assessment of the production, reproduction, and functional traits of Holstein-Friesian, Jersey × Holstein-Friesian, and Norwegian Red × (Jersey × Holstein-Friesian) cows in pasture-based systems

Pasture-based production systems typically require highly fertile, healthy, and robust genetics, with greater emphasis on milk solids (MSo; kg of fat + protein) production as opposed to milk yield. This study assessed milk production, production efficiency, reproductive performance, body weight (BW), body condition score, and functional traits in 3 different dairy cow genotypes: Holstein-Friesian (HF), Jersey × Holstein-Friesian (JEX), and Norwegian Red × (Jersey × Holstein-Friesian) (3-way). The 3 genotypes were rotationally grazed on 4 different grazing treatments after calving in spring and were stocked at a rate of 2.75 cows/ha. Holstein-Friesian cows produced higher daily and total milk yields compared with JEX and 3-way cows (5,718 vs. 5,476 and 5,365 kg/cow, respectively). However, JEX and 3-way cows had higher milk fat and protein contents (4.86 and 4.75%, respectively, for JEX and 3.87 and 3.88%, respectively, for 3-way) compared with HF (4.52 and 3.72%), resulting in similar MSo yield for JEX and HF (469 and 460 kg/cow) and slightly lower MSo yield for 3-way (453 kg/cow) compared with JEX. As parity increased, milk and MSo yield per cow increased. Reproductive performance was not significantly different between the 3 genotypes, which had similar 24-d submission rates, 6-wk pregnancy rates, and overall pregnancy rates over the 4-yr period. No difference in calving difficulty, incidence of mastitis, or incidence of lameness was observed among the 3 genotypes. Body weight was significantly different among all 3 genotypes, with HF being the heaviest followed by 3-way and JEX (530, 499, and 478 kg, respectively), and 3-way cows had a higher body condition score throughout lactation compared with HF and JEX cows. The differences in BW coupled with similar MSo production resulted in JEX cows having the highest production efficiency (4.58 kg of MSo/kg of metabolic BW), 3-way cows being intermediate (4.30 kg of MSo/kg of metabolic BW), and HF cows having the lowest (4.16 kg of MSo/kg of metabolic BW). In conclusion, HF herds with poor reproductive performance and low milk fat and protein contents are likely to benefit considerably from crossbreeding with Jersey, and all herds are likely to benefit in terms of production efficiency. However, where herd performance, particularly in relation to reproductive performance, is comparable with HF in the current study, crossbreeding with Jersey or Norwegian Red is unlikely to lead to significant improvements in overall herd performance.

Farming smarter with big data: Insights from the case of Australia's national dairy herd milk recording scheme

Digitalization and the use of Smart Farming Technologies are considered a major opportunity for the future of agriculture. However, realisation of full benefits is constrained by: (1) farmers' interest in and use of big data to improve farm decision making; (2) issues of data sovereignty and trust between providers and users of data and technology; (3) institutional arrangements associated with the governance of data platforms. This paper examines the case of Australia's dairy herd milk recording system, arguably one of agriculture's first cases of ‘big data’ use, which collects, analyses and uses farm-level data (milk production, lactation and breeding records) to provide individual cow and herd performance information, used by individual farmers for farm management decisions. The aim of this study was to 1) examine the use of big data to add value to farm decision making; and 2) explore factors and processes, including institutional arrangements, which influence farmer engagement with and use of big data. This paper traces the Australian history of the organisation of dairy herd recording (established in 1912 and digitalized in late 1970s) and then uses findings from a longitudinal study of 7 case study dairy farms, which were incentivised to become involved in herd recording in 2015. Applying a conceptual framework linking path dependency in farm decision making and collaborative governance capacity, we find three new important dimensions of the farm user context influencing farmer demand for big data applications: 1) the transition to a new business stage; 2) the additionality farmers seek from data generated in one component of the farm system to other subsystems, and 3) the use of data in long term or strategic decision making. Further, we identified critical attributes of support services in addressing digital literacy, capacity and capability issues at farm level, including diversity in data presentation formats and facilitation of the on-farm transition process through intermediary herd test organisations. The role of farmers as governance actors, or citizens in the decisions of the trajectory of big data applications, adds to understanding of the nature of collaborative governance arrangements that support farm engagement.