Large Herds Research Articles

THE CONTRIBUTION OF GRASSLANDS IN THE MANNER OF LAND USE FROM THE HILL AREA OF BANAT IN RELATION TO LIVESTOCK

The meadows in the hill area of Banat can be defined as resources with multidimensional significance. In another context, grasslands can be considered one of the defining elements in livestock activities in rural areas. In this respect, the purpose of the research was to quantify the grassland resources in the area of interest and assess their potential in forage cover of local animals. The analysis of the area of interest was done by geospatial methods, applied with ArcGIS 10.4 software. Geospatial data, statistical and bibliographic data from the literature were used. The area of interest is characterized by complex and variable environmental conditions, which is also reflected in the use of the territory. In the five analyzed administrative units, grasslands occupy surfaces between 16.65% (UAT Balinţ) and 52.14% (UAT Secaş), these being interspersed with other categories of land use, respectively with arable land in the low areas and with forests in the areas located at higher altitudes. As far as animals are concerned, it was found that the largest herds were in ATU Brestovăţ, where per hectare of pasture has 0.72 LSU. Through the economic benefits offered, the meadows in the analyzed hill area constitute important natural resources for local and regional communities.

Kid mortality indicators based on census data in dairy goat herds in the Netherlands

Optimal young stock rearing benefits animal health and welfare and therefore contributes to a more sustainable herd. In order to be able to evaluate the rearing process, producers need insight into their kid rearing results, preferably based on key indicators. Although mortality is considered a useful parameter to assess animal health and welfare, little is known about the prevalence and factors influencing mortality in dairy goat farming. Calculating kid mortality risks may be further challenged by how and when producers record mortality after birth. This study aimed to develop key kid mortality indicators which can support producers in optimising their rearing system. Census data were available from 395 Dutch dairy goat herds from 2016 until and including 2020. Four mortality indicators were defined: mortality risk of neonatal kids, and mortality rates of postnatal, preweaning, and postweaning kids. Mortality percentages were determined for three subgroups of dairy goat herds depending on the quality of available data i.e. accuracy and completeness of data. The quality of mortality data was classified as good in 39 % (n = 153), fair in 49 % (n = 192), or poor in 13 % (n = 50) of the included herds. For each of the three quality groups, recorded kid mortality for all four mortality indicators was higher in herds with accurate animal registration. Kid mortality was significantly different (p 0.001) between all quality groups. Other factors affecting kid mortality levels included herd size as the 25 % largest herds had lower kid mortality (p = 0.005), and a decreasing trend was associated with the age of dairy kids. This study provided insight into kid mortality in Dutch dairy goat herds and showed that it is possible to monitor kid mortality based on routinely collected data. Nevertheless, data quality should be considered when communicating benchmark values and individual results back to farmers. It is therefore recommended that benchmark values are calculated on data from herds with the highest data quality.

Evaluation of multifactorial digestive disorders in a dairy herd at different stages of lactation.

The manager of a large dairy herd (total confinement, total mixed ration feeding, 10130 kg milk sold per cow and year) requested a workup of a digestive disorder problem that had been ongoing for several years. The cows were at all stages of lactation, and the incidence proportion (events/100 cows at risk) of digestive disorders was approximately 5 to 10%. The clinical picture included an abnormal demeanor of varying severity and signs that differed among the cows. The latter included decreased milk production and physical activity, low body condition score, abnormal rumen motility and stratification, small intestinal dilatation, diarrhea, undigested fiber particles in the feces, fever and abdominal pain.The following approach was used to investigate the digestive disorder problem:1. The herd was assessed for production levels, housing requirements, feeding protocols and animal health management. The latter comprised evaluation of different animal scores, metabolic profile analysis, diagnosis of disease, culling records and slaughter data. The results revealed risk factors concerning the feeding and animal health monitoring, (e. g. in dry matter intake and silage quality management, disease detection and diagnosis in fresh cows). The assessment also identified a high occurrence of digestive disorders of unknown origin.2. Fifteen cows that represented the ongoing digestive disorder problem were selected to undergo clinical examination, hematological analysis, urinalysis, and ultrasonography of the ventral abdomen. The clinical examinations revealed different digestive disorders, which were mainly inflammatory in nature, in all the cows. Eight cows had localized reticuloperitonitis and 13 had left displaced abomasum with different degrees of displacement and adhesions between the abomasum and reticulum attributable to reticuloperitonitis.Our results revealed a multifactorial problem caused by several risk factors relating to animal health and feeding management protocols that resulted in different types of digestive disorders. The wires from damaged tires used to hold the pit silo tarps in place were identified as a possible traumatic cause of the reticuloperitonitis. Treatment, prevention and follow-up of the different conditions were discussed.

Diagnosis of imminent placentitis in mares

Pregnancy loss and neonatal mortality have a significant economic impact on the equine industry. Placentitis is a common cause of abortion, stillbirths, and neonatal infections. Early diagnosis of placentitis allows prompt treatment and increases the chances of a pregnancy reaching term. Our study was designed to identify blood parameters that are diagnostic of imminent placentitis under natural conditions. We hypothesized that differences from physiological parameters of a healthy pregnancy indicate imminent placentitis. Blood sample collections and reproductive exams were prospectively performed, monthly, between 180 to 320 days of gestation, in a cohort of mares from 2 large broodmare herds in Lexington, KY. Twelve mares were diagnosed with placentitis based on rectal ultrasonographic examination (opening at the cervix, thickened placenta, fluid collection, placental edema, and/or placental separation). Blood samples collected on the day of placentitis diagnosis were designated as early onset, and the blood samples collected in the previous reproductive exam with no ultrasonographic abnormalities of the fetoplacental unit were named as pre-onset (before placentitis diagnosis). In addition, 12 gestion and age-matched control mares carrying healthy pregnancies based on the same parameters were paired to the mares with placentitis. We measured several immunological, inflammatory, and hormonal parameters (Table 1). Values were compared between groups within the same timepoint (placentitis vs control) and between timepoints (pre-onset vs early onset) using Paired Student's T test and Mann-Whitney U test, and significance set at p < 0.05. According to the gestational age, the interval between pre-onset timepoint and the diagnosis of placentitis (early onset) was around 40 days (227±6 days and 267±5 days, respectively).No differences were found between groups and timepoints for immunological and inflammatory parameters in the maternal circulation, including serum amyloid A (SAA) and alpha-fetoprotein (AFP). Both proteins have been shown to markedly increase in maternal circulation after experimental induction of placentitis. In the hormonal analyses, no differences were found in plasma progesterone levels and estradiol-17β/progesterone ratio. Plasma estradiol-17β concentration approached statistical difference (p=0.08) in mares at early onset of placentitis (408±35 pg/mL) compared to the control group (498±35 pg/mL). In conclusion, our data showed that early events of spontaneous placentitis do not increase inflammatory and immunological parameters in the maternal circulation. In addition, plasma estradiol-17β may be further investigated as an early indicator of placental dysfunction in mares with naturally occurring placentitis. Acknowledgments: We thank the Harry M. Zweig Memorial Fund for Equine Research for supporting our study.

Deep learning enables satellite-based monitoring of large populations of terrestrial mammals across heterogeneous landscape

New satellite remote sensing and machine learning techniques offer untapped possibilities to monitor global biodiversity with unprecedented speed and precision. These efficiencies promise to reveal novel ecological insights at spatial scales which are germane to the management of populations and entire ecosystems. Here, we present a robust transferable deep learning pipeline to automatically locate and count large herds of migratory ungulates (wildebeest and zebra) in the Serengeti-Mara ecosystem using fine-resolution (38-50 cm) satellite imagery. The results achieve accurate detection of nearly 500,000 individuals across thousands of square kilometers and multiple habitat types, with an overall F1-score of 84.75% (Precision: 87.85%, Recall: 81.86%). This research demonstrates the capability of satellite remote sensing and machine learning techniques to automatically and accurately count very large populations of terrestrial mammals across a highly heterogeneous landscape. We also discuss the potential for satellite-derived species detections to advance basic understanding of animal behavior and ecology.

Trends and factors associated with dairy calf early slaughter in Ireland, 2018-2022.

Dairy systems require that each cow calves annually to have an efficient milk production cycle. In systems where milk production is maximized, the male offspring from dairy breed sires tend to have poor beef production traits and, therefore, can be of low economic value. Few studies have been published on the factors impacting early slaughtering of calves in peer-reviewed literature. Here we present an analysis of national data on calves slaughtered from 2018 to 2022 in Ireland. Data (Jan 2018-May 2022) on all cattle <6 months of age were collated at a national level and were described at calf-, herd-, and county-levels. These data were statistically analyzed at per-capita slaughter rates (calves/calf born) using negative binomial regression models with an offset. There were 125,260 calves slaughtered early (1.09% of total births) recorded in the dataset from 1,364 birth herds during the study period, of which 94.8% (118,761) were male. 51.7% were classified as Friesian-cross (FRX), 11.5% Friesian (FR) and 32.1% Jersey-cross (JEX). The median age at slaughter was 16 days (Mean: 18.9 days; IQR: 13-22). The median calves/herd slaughtered was 16 (mean: 91.8); median calves/herd/year slaughtered was 21 (mean: 42.0). There was substantial variation in counts of calves slaughtered across herds, years, and counties. Herd calf slaughter rates and per capita calf slaughter rates increased significantly in 2022, with the highest rates over the time series. Calf slaughter rates varied significantly with herd size, year, and major breed (Jersey; JE). Herds which were more recently established tended to have higher calf slaughter rates. Herds that repeatedly slaughtered calves over 2 or more years tended to be larger and slaughtered more calves/herd/year. The slaughtering of calves is not widespread across the dairy industry in Ireland. The distribution of calves slaughtered per herd demonstrate that a small number of herds contributed disproportionately to calf slaughter numbers. Such herds tended to be very large (herd size), more recently established (2016 onwards), and have higher proportions of JE/JEX breed cattle. The outcomes of the present study provide an evidential base for the development of targeted industry-lead interventions with the aim of ending the routine early slaughter of calves.

Сучасне аерозольне обладнання для захисту великої рогатої худоби від гнусу та кліщів

Goal. To test modern aerosol equipment for individual and group treatment of cattle with insect-acaricides in the grazing period, and to analyze its technical characteristics. Methods. Information-bibliographic, parasitological, field, analytical. Results. Among the devices and instruments for individual treatment of cattle, mechanical hand-operated sprayers such as the “Rosynka” and its analog “Kvazar” with a capacity of 0.5 and 1 l had proved themselves well. This category also included hand-operated sprayers of “Dezinfal” type with a capacity of 2-3 liters, such as “Flo” and “Marolex”. For treatment of small groups of animals (about 50) during the grazing period, it is advisable to use mechanical shoulder sprayers of “Automax” type with a capacity of 5–2 liters, in particular, “Quartz Profi”, “Orion”, “Gardena”, and backpack ones of type “Tremas” with a capacity of 12-6 liters — “Lemira”, “Neptun Spray”, “Aqua Spray”. A larger number of animals (over 100) should be treated with electric sprayers of the battery type, for example, “Solo”, “Hyundai”, “Gerard”. The most suitable for treating a large grazing herd (more than 200) are motorized backpack sprayers of “Micronizer” type with a capacity of 12-14 liters - “Shtil”, “Solo Master”, “Oleo-Mak”. The lack of widespread use on pastures of aerosol generators with a capacity of 5–9 liters, in particular, “Longray”, “Stiff”, “Vectorfog”, “Pulsfog”, is caused by several technical difficulties. Conclusions. For individual treatment of cattle with insect-acaricides, it is recommended to use mechanical hand-operated sprayers of “Rosynka” and “Dezinfal” types. For the treatment of small groups of animals during the grazing period, it is advisable to use mechanical shoulder sprayers of “Avtomax” type and backpack ones of “Tremas” type, allowing them to pump without removing it from the shoulders. It is convenient to treat a larger number of animals with battery-type electric sprayers, which, unlike mechanical models, do not require much effort during operation. Motor backpack sprayers of “Micronizer” type, distinguished by lightness, compactness, and high productivity, are considered to be the most suitable for treating a large herd of cattle on pasture. Aerosol generators did not prove themselves to be promising for wide use on pastures.

Occurrence and control of equine strongyle nematode infections in Prince Edward Island, Canada.

Widespread overuse of anthelmintics has produced a growing population of intestinal parasites resistant to control measures. A paradigm shift in equine parasite control is warranted to prevent continued resistance development and maintain equine health. Small strongyles, which are ubiquitous in horses, are currently the most important intestinal parasites of adult horses. Sustainable management programs consider the variation in egg shedding by individual horses, and varied risks associated with age, use, density, climate, and environment. To develop regional recommendations for Prince Edward Island (PEI), Canada, it is important to first characterize strongyle egg shedding patterns and parasite management practices in use. Study objectives were to conduct a cross-sectional observational survey and risk factor analysis of parasite control programs, strongyle egg shedding and Strongylus vulgaris serology. A total of 339 horses from 40 PEI farms were sampled. Mean farm size was 8 horses and ranged from 2 to 30. Mean horse age was 11.6years (Std. Dev. =7.2) and ranged from 2months to 32years. Mean fecal egg count (FEC) was 322 eggs per gram (EPG) (Std. Dev. =648). On average, 32% (Std. Dev. =16%) of horses shed 80% of strongyle eggs across 32 eligible farms. When considering all horses (n=313) as one large herd, 18.7% of horses shed 80% of strongyle eggs. Use of FEC was identified in 4.6% of horses at 15% (n=6) of PEI farms. Reported deworming intervals included 37.4% (n=123) every 2-3months and 58% (n=191) every 3-4months. Positive S. vulgaris titers were identified in 60% of horses (n=200). Univariate analysis revealed that months since last deworming, age, and body condition score (BCS) were associated with strongyle shedding. The estimated odds of being in the high FEC category (>500 EPG) was 1.4 (95% CI, 1.1-1.8) times higher when last deworming increased by one month. Under-conditioned (BCS <4.5) horses had 3.6 (95% CI, 1.2-10.6) times odds of being in the higher FEC category than over-conditioned horses. Non-racing horses had 5.4 times odds of having a positive S. vulgaris titer than racehorses. This cross-sectional observational study is the first to report on the occurrence, risk factors and control of equine strongyle nematode infections in PEI, Canada. We conclude that the 80:20 rule can be used to develop control recommendations in PEI. Very few farms in PEI currently use FEC to guide parasite management. These findings provide a basis for future client education and investigations aimed at providing region specific recommendations.

Adaptive, multi-paddock, rotational grazing management alters foraging behavior and spatial grazing distribution of free-ranging cattle

Sustainable management of grazinglands depends upon understanding how management practices influence livestock movements in space and time. We conducted a ranch-scale (2,600-ha) social-ecological experiment to examine how foraging behavior of cattle differs between a single large herd rotated adaptively among paddocks (collaborative, adaptive rangeland management; CARM) versus continuous, season-long grazing of paddocks by small non-rotational herds (traditional rangeland management; TRM). We analyzed how differences in cattle movement patterns may be linked to reductions in cattle growth rates and diet quality in the CARM treatment, relative to TRM. Cattle in the CARM treatment exhibited more linear grazing pathways, moved at lower velocity while grazing, and exhibited longer grazing bouts early in the growing season compared to TRM cattle. Grazing time within any given 10 × 10 m area was distributed more unevenly across TRM vs. CARM paddocks in years with average or above-average precipitation, but not in dry years. In all years, areas of high and low grazing intensity were more spatially clustered in TRM than CARM paddocks. Movement patterns of cattle managed using adaptive, multi-paddock rotations at high stock density (CARM) are consistent with less selective foraging. Such cattle form a “grazing front” that moves across the paddock and distributes grazing pressure in a more spatially homogeneous fashion. In years with substantial forage production, TRM cattle spent more time than CARM cattle in preferred areas of the paddock and foraged in more circular patches. In dry years, however, both treatments resulted in similarly even grazing distribution, likely due to limited intra-paddock variation in forage quality and quantity. At the ranch scale, these different intra-paddock movement patterns led to reductions in animal growth rates and no overall effect of grazing management on forage production.

Controlling bovine leukemia virus in a large dairy herd by selective culling based on diagnostic testing

This intervention field trial aimed to reduce bovine leukemia virus (BLV) from a large dairy herd using a new diagnostic test to identify the most infectious cows for segregation or culling. Bovine leukemia virus infects over 40% of all dairy cattle in the United States. Similar prevalence has been reported in many other countries. Previously hidden economic impacts of BLV on the industry have only recently been recognized. The traditional method of controlling this disease was by culling all antibody-positive cattle. The availability of a new diagnostic test can identify the most infectious cows for removal. A 3,000-cow dairy farm conducted a 4-yr BLV disease control program using blood lymphocyte count (LC), BLV ELISA antibody test, and quantitative-PCR proviral load (PVL) to identify the most infectious animals for segregation or culling. The percentage of cows with a high LC was significantly decreased from 4.22 to 1.04% after the first year of selective culling of cows with high LC. Thereafter, BLV ELISA screening with PVL followup assays were used to target segregation and culling of cows with the highest PVL. After 3 yr, only 0.85% of the tested cows were BLV ELISA positive. The prevalence of animals with detectable PVL decreased from 284 to zero animals. When coupled with the results of an intervention trial in 3 small dairy farms, our findings from a large dairy herd demonstrate that BLV may be eradicated without the simultaneous culling of all ELISA-positive cows.

Staphylococcus aureus, Escherichia coli, and Klebsiella spp. prevalence in bulk tank milk of Colombian herds and associated milking practices.

Bovine mastitis is one of the most costly and prevalent diseases in dairy herds, which can be prevented and controlled through proper milking practices, diagnosis, and elimination of chronic animals, among others. Contagious pathogens such as Staphylococcus aureus and environmental pathogens such as Escherichia coli and Klebsiella spp. can affect cows and milk for human consumption, generating a public health risk. This study aimed to estimate the prevalence of herds with somatic cell count (SCC) ≥200,000 cells/mL, S. aureus, E. coli, and Klebsiella spp., in bulk tank milk (BTM) and its associated risk factors in Colombian dairy cow herds. A cross-sectional probabilistic study was carried out in 150 dairy herds located in the north of the Antioquia province. A single visit per herd was conducted, during which three BTM samples were aseptically collected. General data and milking practices were collected through an epidemiological survey applied in each herd. The prevalence of S. aureus, E. coli, and Klebsiella spp. were 14% (21/150), 2% (3/150), and 8% (12/150), respectively. Moreover, 95% of the herds presented an SCC of ≥200,000 cells/mL. Practices such as in-paddock milking, change of milker during the last month, use of disposable gloves, and hand disinfection were associated with increased prevalence of S. aureus, whereas proper dipping was a protective factor. Proper washing and disinfection of the milking machine, use of chlorinated disinfectants for hand hygiene, and use of disposable gloves decreased the prevalence of E. coli and Klebsiella spp. Bulk tank SCC increased in herds with 30-60 milking cows, herds with >60 milking cows, and herds with a change of milker during the last month. Hand disinfection and dipping decreased the SCC. Staphylococcus aureus, E. coli, and Klebsiella spp. were prevalent in BTM from dairy cow herds. The risk of S. aureus isolation was higher in herds with an in-paddock milking system. The risk of E. coli and Klebsiella spp. isolation were higher in herds with >60 milking cows, with a change of milker during the last month. Processes such as avoiding changing the milker and greater control in medium and large herds could improve the SCC in BTM.

A large-scale study on the seroprevalence of small ruminant lentiviral infection in the Polish goat population

A large-scale study was carried out in a Polish goat population in 2014-2022 to determine the herd-level (between-herd) and within-herd seroprevalence of small ruminant lentivirus (SRLV) infection. A total of 8354 adult goats (aged >1 year) from 165 herds located in various regions of Poland were serologically tested using a commercial ELISA. One hundred twenty eight herds were randomly selected while 37 were enrolled based on convenience non-random sampling. At least 1 seropositive result was obtained in 103 / 165 herds. For all these herds the probability that they were truly positive (herd-level positive predictive value) was calculated. It was ≥90% in 91 seropositive herds and 73% to <90% in 12 herds in which only 1-4 goats were seropositive (22 goats in total). The seropositive goats in the latter herds were retested using a different commercial ELISA and 14 goats (9 males and 5 females) from 9 herds were confirmed to be seropositive (serial testing). The true herd-level seroprevalence was estimated at 61% (95% confidence interval [CI 95%]: 53%-68%). It differed significantly between herd size classes (p=0.003): the highest prevalences were found in the medium (51 - 100 adult goats) and large herds (>100 adult goats) - 72% (CI 95%: 56-84%) and 86% (CI 95%: 67%-95%), respectively, while prevalences in very small (≤20 adult goats) and small herds (21 - 50 adult goats) were 46% (CI 95%: 34%-59%) and 57% (CI 95%: 43%-70%), respectively. The true herd-level seroprevalence differed significantly also between geographical regions of Poland (p=0.003), with the highest values in the north-western and the lowest in the southern region of the country. The true within-herd seroprevalence estimated using a Bayesian approach ranged from 0.7% to 100% with the median (IQR) of 42% (17%-84%), and did not vary significantly between herd size classes (p=0.393) or geographical regions of Poland (p=0.570). Concluding, SRLV infection is widespread in the Polish goat population, the north-western region of Poland is most extensively infected, and herds counting >50 adult goats are more often infected.

Colonization of Extramammary Sites with Mastitis-Associated S. aureus Strains in Dairy Goats.

Staphylococcus aureus (S. aureus), a major mastitis pathogen in dairy goats, is classified as a contagious pathogen. Although previous research has shown that extramammary body sites can be colonized with S. aureus, it is unknown whether these sites are reservoirs for intramammary infections. The aim of this research was to determine whether extramammary sites can be colonized with mastitis-associated S. aureus strains in dairy goats. Milk samples were collected from 207 primiparous goats and from 120 of these goats, extramammary site samples (hock, groin, nares, vulva and udder) were collected from a large commercial dairy goat herd in the Netherlands during four sampling visits. Extramammary site swabs and milk samples were (selectively) cultured and S. aureus isolates were spa genotyped. The prevalence of colonization of the extramammary sites at goat level was 51.7% and the prevalence of S. aureus intramammary infections was 7.2%. The nares were colonized most frequently (45%), while the groin area was colonized the least (2.5%). Six spa genotypes were identified in this herd and there was no significant difference in the distribution of spa genotypes between the milk or the extramammary sites (p = 0.141). Both in the extramammary sites and in the milk, spa genotypes t544 (82.3% and 53.3%) and t1236 (22.6% and 33.3%) were the dominant genotypes. These results show that in goats, extramammary sites, particularly the nares, are frequently colonized with mastitis-associated S. aureus strains. Extramammary sites may, thus, be a source of S. aureus intramammary infections that are not targeted by the intervention measures aimed at preventing transmission from infected udder glands.

Characterization of semen type prevalence and allocation in Holstein and Jersey females in the United States

Our objective was to characterize semen type prevalence and allocation to inseminate US Holstein and Jersey females by year, parity, service number, and herd size. A secondary objective was to identify the prevalence of beef breed sires selected to create beef × Holstein and beef × Jersey crossbred calves. The final data set included 8,244,653 total inseminations of 4,880,752 Holstein females across 9,155 herds, and 435,267 total inseminations of 266,058 Jersey females across 2,759 herds from October 2019 to July 2021. This data set represents approximately 42 and 27% of the total dairy cows and heifers, respectively, across approximately 40% of the total licensed dairy herds in the continental United States. Holstein and Jersey females were inseminated with 1 of 4 semen types: (1) beef, (2) conventional, (3) sexed, or (4) other dairy. The top 4 beef breeds used to produce beef × Holstein and beef × Jersey crossbred calves, respectively, were Angus (55.1 and 39.1%), Limousin (13.9, and 23.5%), Simmental (11.7 and 20.5%), and Crossbreed Beef (11.3 and 4.8%). From 2019 to 2021, the use of sexed semen to inseminate Holstein and Jersey females increased from 11.0 and 24.5% to 17.7 and 32.1%, respectively, and the use of beef semen to inseminate Holstein and Jersey females increased from 18.2 and 11.4% to 26.1 and 21.2%, respectively. The use of beef semen to inseminate Holstein and Jersey females increased with increasing parity and service number, whereas the use of sexed semen decreased with increasing parity and service number supporting that farmers used sexed semen more aggressively in higher fertility and younger females with greater genetic merit. Overall, the increase in sexed and beef semen inseminations was driven primarily by larger herds. In conclusion, sexed and beef semen inseminations in US Holstein and Jersey females increased from 2019 to 2021 and was allocated differentially based on parity and service number. This increase was driven primarily by larger dairy herds possibly due to differences in reproductive performance and economies of scale.

Genetical analysis of mastitis and reproductive traits in first-parity Holstein cows using standard and structural equation modelling

The present study aimed to investigate the causal relationships between clinical mastitis and some reproductive traits, including success at first insemination (SFI), the number of inseminations to pregnancy (INS), the interval from calving to first service (CTFS), first and last service interval (IFL), and open days (OD) in first-parity Holstein cows. For this purpose, the records of 58 281 first parity Holstein cows were analysed. These data sets were collected from 17 large dairy herds from 2008 to 2017. Recursive Mixed Models (RMMs) were applied and compared with the estimations under Standard Mixed Models. Then, one trivariate and three bivariate Gaussian-threshold models were used for the analyses. Recursive models were applied, considering that clinical mastitis can influence fertility traits. Mastitis is considered a covariate for the reproductive traits to determine their causal relationship. The results of this study indicated that causal effects of mastitis on SFI (on the observed scale, %), CTFS, IFL, OD, and INS were −5.7%, 3.3 days, 12.27 days, seven days, and 0.26 services, respectively. The estimated structural coefficients of the recursive models in the first parity imply that mastitis significantly lengthened the fertility interval and decreased the conception rate. In addition, genetic, residual, and phenotypic correlations between mastitis and the reproductive traits under both models were statistically significant. Results of genetic correlations between mastitis and fertility traits suggest that more incidence of mastitis during lactation is related to the delays in the heat show and pregnancy rate after insemination. In summary, considering the causal effects under RMMs may be advantageous to comprehend complicated relationships between complex traits better.

Incidental mortality of dolphins in the eastern Pacific Ocean purse-seine fishery: correlates and their spatial association

A zero-inflated Poisson model was used to identify typical fishing practices that contributed to incidental mortality of dolphins in the eastern Pacific purse-seine fishery between 1993 and 2001. The presence of hazardous net conditions (net canopies and net collapses), the duration of the backdown procedure (the primary method of releasing dolphins from the net), the size and species composition of the encircled dolphin herd and the amount of tuna encircled, were all found to consistently contribute to increased dolphin mortality per set. In particular, the presence of net canopies and large biomass in the net contributed to both the development of problematic situations in which mortality could occur and to the mean mortality per set, once a problematic situation had developed. On the other hand, lengthy backdown procedures and the presence of net collapses contributed to the development of problematic situations, but had less effect on the mean mortality per set once a problematic situation had developed. Because some of these variables are partially correlated, the overall conclusion of this analysis is that one of the primary causes of dolphin mortality continues to be the encirclement of large herds. Dolphin mortality can increase with the number of dolphins encircled because: (1) the more animals encircled, the greater the likelihood of entanglement and mortality while confined in the net; and (2) the duration of the backdown procedure increases with the number of animals encircled. The duration of the backdown procedure may, in turn, contribute to increased dolphin mortality by: (1) keeping dolphins in close contact with the net for longer periods of time, thereby increasing the chances for entanglement; and (2) leading to the formation of net canopies. Dolphin mortality increases in the presence of net canopies because animals can be trapped below the sea surface in the areas of canopies. Spatial distributions of encircled herd size, duration of the backdown procedure, presence of net canopies and presence of dolphin mortality show similar patterns. Encircled herd size tended to be greatest south of the equator and north of the equator along the offshore margin of the fishery. In these areas, the duration of the backdown procedure tended to be longer and there was often an increased probability of net canopies and dolphin mortality, but also larger catches of tuna. These consistent spatial patterns suggest that reallocation of fishing effort to other areas may be an effective means of reducing the current level of dolphin mortality. Predictive models could be developed to assess tradeoffs between dolphin mortality and tuna catches at varying levels of fishing effort in areas where large herds are targeted by fishermen and different strategies for reallocation of fishing effort to other areas or to purse-seine sets on unassociated tunas.

Associations of Eliminating Free-Stall Head Lock-Up during Transition Period with Milk Yield, Health, and Reproductive Performance in Multiparous Dairy Cows: A Case Report

The objective of this retrospective case study was to understand the effects of eliminating free-stall lock-up time during 21 days postpartum on milk yield, reproductive performance, and health events at a large dairy herd. A group of 200 cows were selected as the treatment (TRT) group, which did not receive a lock-up time during early lactation, and a separate group of 200 cows served as the control (CON) group, which received on average 2 h/day of lockup time. The TRT group had greater milk yield (mean ± SE) on the third monthly milk test day (33.1 ± 0.75 vs. 29.9 ± 1.22; p = 0.04) and tended to have greater milk yield on the second test day (38.3 ± 1.55 vs. 39.1 ± 0.79; p = 0.06) compared to the CON cows. Milk fat% (mean ± SE) was greater in the TRT group than in the CON group on the first monthly milk test (3.65 ± 0.06 vs. 3.31 ± 0.12, p = 0.01). The TRT group had lower linear somatic cell scores on the first monthly milk test day compared to the CON group (2.6 ± 0.24 vs. 3.2 ± 0.11; p = 0.01). Cows in the TRT group had lower days in milk at first breeding (DIMFB) (66.2 ± 3.7 vs. 76.7 ± 2.9; p = 0.02) and were confirmed pregnant earlier as indicated by smaller days in milk to pregnancy (DIMPREG) (96.9 ± 12.32 vs. 112.1 ± 5.5; p &lt; 0.01). Cows in the TRT group also had fewer incidences of all health events combined (13% vs. 30.5%; p &lt; 0.001), lameness (3% vs. 9.5%; p = 0.01), and mastitis (3% vs. 16%; p &lt; 0.001). We conclude that eliminating the stall lockup may have contributed to the increased milk yield, health, and reproductive performance of dairy cows in this dairy herd. Future prospective cohort studies are needed to further assess the potential effect of eliminating lock up time on cow performance.

Effects of non-genetic factors on growth traits and survival rate in Karacabey Merino lambs.

This study was conducted with the aim of determining the growth characteristics and survival rate of Karacabey Merino lambs, as well as the non-genetic factors affecting these traits. The study included data from a total of 17659 lambs and 12263 ewes raised in 30 herds between the years 2011 and 2016 as part of the National Sheep and Goat Improvement Project. The average birth weight of the lambs was determined as 3.73±0.05 kg, the average 45th day live weight was 18.43±0.58 kg, the average weaning (average 91.8 days) weight was 31.83±0.24 kg, and the average daily live weight gain until weaning was 289.1±3.91 g. The average survival rate of lambs at weaning was calculated to be 95.67% ± 1.15. The effects of the factors herd, birth year, birth type, birth season and sex were found significant for all traits (p<0.01). It was established that the mortality rate in lambs in large herds was higher during 6 years in which the project was carried out. Due to the high twinning rate in large herds, the number of lambs per worker is increased, and as a result, they cannot be adequately cared for. For this reason, large farms may be encouraged to increase workmanship services in addition to being provided with protective health practices for lambs throughout the birth period. On the other hand, it was determined that the twinning rate was low in small farms. On farms with fewer sheep populations, it may be advised to flush or administer exogenous hormone treatments to ewes in order to increase fertility and help them bear twins.

Seroprevalence and Factors Associated with Toxoplasma gondii, Neospora caninum, and Besnoitia besnoiti Infections in Cattle and Goats in Selangor, Malaysia.

Apicomplexan parasites such as Toxoplasma gondii, Neospora caninum, and Besnoitia besnoiti are widely recognized as causes of production diseases in ruminants. This study aimed to investigate the serological occurrence of T. gondii, N. caninum, and B. besnoiti in cattle and goats from smallholder farms in Selangor, Malaysia. A cross-sectional study was conducted on 19 farms by collecting 404 bovine (n = 225) and caprine (n = 179) serum samples, which were then essayed for T. gondii, N. caninum, and B. besnoiti antibodies using commercially available ELISA test kits. Farm data and animal characteristics were documented, and the data were analyzed using descriptive statistics and logistic regression models. The seroprevalence of T. gondii at animal and farm levels in cattle was 5.3% (95% CI 1.2-7.4%) and 36.8% (95% CI 22.4-58.0%), respectively. Animal-level seropositivity for N. caninum was 2.7% (95% CI 0.4-4.2%) and 5.7% for B. besnoiti (95% CI 1.3-9.4%) with corresponding farm-level seropositivity of 21.0% and 31.5%, respectively. For the goat samples, a high animal- (69.8%; 95% CI 34.1-82.0%) and farm-level (92.3%) seropositivity was recorded for T. gondii, but was relatively lower for N. caninum antibodies, at 3.9% (95% CI 1.5-6.2%) and 38.4% (5/13). The factors associated with T. gondii seropositivity were older animals (above 12 months) (OR = 5.3; 95% CI 1.7-16.6), semi-intensive farms (OR = 2.2; 95% CI 1.3-6.2), the presence of either dogs or cats (OR = 3.6; 95% CI 1.1-12.3), a large herd size (>100 animals) (OR = 3.7; 95% CI 1.4-10.0), and a single source of replacement animals (OR = 3.9; 95% CI 1.6-9.6). These findings are vital in developing effective control measures against these parasites in ruminant farms in Selangor, Malaysia. More national epidemiological research is required to elucidate the spatial distribution of these infections and their potential impact on Malaysia's livestock industry.

Search for additional variability in the herd of Holstein cows

Relevance. When breeding a large herd of the Holstein breed, the improvement of traits in the selection system is reflected, the integral basis (part of the basis) of which was belonging to the line. Against the background of a reduction in the number of lines, the selection of a limited number of sires related to each other into the herd, and the breeding of daughters from them by various types of rebounds, an increase in milk yield and mass fraction of protein (MPF) over three generations is reflected.Methods. The indices of the genetic value of sires in the population were evaluated according to the author's method, while taking into account the indicators of mothers and peers of the same herd. Comparison of the levels of variability of milk productivity traits in terms of standard deviations (±s) in breeding groups.Results. The relative increase in milk yield per generation for the highest lactations was 8.9–15.4% (P &lt; 0.001), and MDL – 1.3–3.2% (P &lt; 0.01). A comparison was made of groups of peer-daughters obtained by targeted selection of homo- and heterozygous fathers according to genetic markers of controlled EAB loci. Another aspect was the high standard deviation of milk yields in the group of daughters of homozygous fathers by 19% against the group of heterozygous, and among the crossed offspring – by 8.6% against intraline. It is assumed that this happened due to the introduction of new and rare alleles with sires into the herd.