Occurrence of preterm calving in Great Britain and associations with milk production and reproductive performance in dairy cattle

This study describes the occurrence of preterm calving in Great Britain and evaluates its associations with subsequent milk production and reproductive performances and survival on farm of dairy cows. A total of 53 British dairy farms and 5759 animals with detailed breeding and milk recording data available were used to form two study groups: preterm calving (calving occurring between days 266 and 277 of gestation) and full-term calving (calving occurring at 278 days of gestation and over). Mixed effects models were implemented to compare milk production, clinical cases of mastitis and number of services per conception between groups. Kaplan-Meier curves and Cox regression analyses compared time from calving to conception, calving interval and survival on farm between groups. Preterm calving cows showed significantly lower milk yield (P<0.01) and butter fat per cent (P=0.02), increased milk protein per cent (P=0.01), longer survival on farm (P<0.01), and a tendency for shorter calving to conception intervals and fewer services per conception, although other factors were involved in the reproduction outcomes. Experiencing a preterm calving is associated with lower milk production and longer survival times on farm. Potential risk factors for preterm calving, such as infectious diseases, diet and husbandry practices, should be further investigated

Major management factors associated with the variation in reproductive performance of Irish dairy herds

End of project reportThe results highlight the importance of BCS in achieving good reproductive performance. The likelihood of reproductive success was best predicted by BCS around the time of breeding and, for cows calving in good BCS (3.0 or greater) the level of BCS loss between calving and first service. A low BCS pre-calving (3.5) results in excessive BCS loss (>0.5) post-calving. On the basis of these findings a pre-calving BCS of no greater than 3.25 is a sensible target for pasture-based spring calving systems in Ireland. It is necessary to maintain BCS at 2.75 or greater during the breeding season, and loss of body condition between calving and first service should be restricted to 0.5 BCS units.National Development Plan (NDP

Reproductive performance parameters in a large population of game-ranched white rhinoceroses (Ceratotherium simum simum)

The population of free-roaming white rhinoceroses (Ceratotherium simum) is under serious threat. Captive breeding of this species is therefore becoming more important, but this is challenging and often not successful. Obtaining reproductive reference values is a crucial aspect of improving these breeding results. In this study performed between 2008 and 2016, reproductive performance was analysed in 1,354 animals kept in a 8000 hectares game-ranched environment. Descriptive statistics of this captive population showed an average annual herd growth (%) of 7.0 +/- 0.1 (min -9-max 15). Average calving rates were calculated as an annual calving rate of 20% and biennial calving rate of 37% adult females calving per year. Females had a median age of 83.2 months at first calving (IQR 72.9-110.7) and inter-calving intervals of 29.2 (IQR 24.6-34.8) months. Furthermore, translocations of animals did not interfere with reproductive success in terms of inter-calving periods or age at first calving. Multivariate models showed a clear seasonal calving pattern with a significant increase of the number of calvings during December-April when compared to April-December. Our results did not show any significant skewed progeny sex ratios. Weather observations showed no significant influence of rain or season on sex ratios of the calves

Fertility and fertility management in thirteen well-established organic dairy herds in the UK

This report was presented at the UK Organic Research 2002 Conference of the Colloquium of Organic Researchers (COR). Milk production and breeding records from thirteen organic dairy herds were collected between January 1997 and December 1999. Mean lactation yields in the herds ranged from 5127 kg to 7031 kg. Whilst seasonality of calving varied widely between herds, a majority of them (6/13) were autumn calving. Mean calving to first service interval was 80 days (range 68 to 97), and mean calving interval was 385 days (range 370 to 413). The mean number of services per conception was 2.3 (range 1.6 to 3.1). Overall culling rates and culling rates for fertility related problems were at 15.8% and 5.4%, respectively. A preliminary study of selected breeding periods of cows that had a subsequent calving revealed no significant differences in calving interval between high or low yielding cows or between cows with different calving month or parit

Effects of daily herbage allowance and stage of lactation on the intake and performance of dairy cows in early summer

peer-reviewedThis research was part-funded by European Union Structural Funds (EAGGF).The aim of this study was to investigate the relationship between daily herbage allowance (DHA) and the performance of dairy cows at two stages of lactation. Spring-calving (n=42, mean calving date 17 February) and autumn-calving (n=42, mean calving date 22 September) Friesian cows were divided into three equal groups and assigned to three levels of DHA (above a cutting height of 35 mm), 17 (L), 20 (M) and 23 (H) kg of dry matter (DM) per head, from late April to late June, 1996. The spring-calving cows grazed to sward heights (mm) of 47, 56 and 65 (s.e. 0.6) and residual herbage organic matter (OM) masses (above 35 mm) of 294, 408 and 528 (s.e. 12.1) kg/ha for L, M and H, respectively. The autumn-calving cows grazed to corresponding sward heights of 51, 60 and 69 (s.e. 1.1) mm and leftresidual herbage OM masses of 364, 445 and 555 (s.e. 12.9) kg/ha for L, M and H, respectively. Pastures were mechanically topped post grazing. Spring-calving cows consumed 13.3, 14.7 and 15.5 kg OM (s.e. 0.47) per day, and autumn-calving cows consumed 13.3, 13.8 and 14.9 kg OM (s.e. 0.43) per day for L, M and H, respectively. Mean daily solids-corrected milk yield was 23.1, 23.8 and 24.8 (s.e. 0.34) kg for the spring-calving cows, and 17.5, 18.4 and 18.7 (s.e. 0.35) kg for the autumncalving cows, for L, M and H, respectively. Milk yield could be predicted from preexperimental yield (PMY) and daily herbage organic matter allowance (DOMA, kg) according to the following equation: y = −1.13 + 0.76 (s.e. 0.030) PMY + 0.22 (s.e. 0.057) DOMA (r.s.d. 1.32, R2 0.89). The results indicate that high individual cow and herd production levels can be achieved from high quality herbage alone during early summer at a DHA of 23 kg DM for spring-calving cows and 20 kg DM for autumn-calving cows.European Unio

Classification of calving fronts around Antarctica

Iceberg calving is the largest loss term in Antarctic mass balance. The iceberg areas vary from a few square meters (growler) to several hundred square kilometres (huge tabular icebergs or ice islands) and their shape (blocky, domed or tabular) depends on the morphology of their calving front. The Antarctic coastline has a length of about 18 000km and is characterized by a large spectrum of morphological properties. In contrast to the Greenland ice sheet, Antarctica is surrounded by a variety of large, medium and small sized ice shelves, besides of glacier tongues and parts without offshore floating ice masses. With the aid of synthetic aperture radar (SAR) images all ice shelves and glacier tongues around Antarctica were mapped. The mosaic of the RADARSAT-1 Antarctica Mapping Project (RAMP) Antarctic Mapping Mission 1 (AMM) was used at a 100 m x 100 m image resolution and the ice shelves were extracted by using the grounding line of the MODIS Mosaic of Antarctica (MOA) Project and the RAMP1-AMM coastline. An automated detection of crevasses was used as a first calving front classification. On the basis of the orientation of the crevasses to one another and relative to the calving front, and the distance between them, an estimation of the dominant size of potentially calving icebergs was made. Other parameters (e.g. shape of the calving front itself, pinning points) were used to make a clearer distinction between calving sites. The Antarctic coast is classified into several groups of calving sites e.g. no floating ice offshore (e.g. Mawson Coast), large ice shelf (e.g. Filcher-Ronne-Ice Shelf) or large glacier tongue (e.g. Mertz Glacier). The resulting map of the classified calving fronts around Antarctica and their description will be used to achieve a detailed picture of crevasse formation and propagation within a co-operation with material scientists and ice shelf modelers

'Calving laws', 'sliding laws' and the stability of tidewater glaciers

A new calving criterion is introduced, which predicts calving where the depth of surface crevasses equals ice height above sea level. Crevasse depth is calculated from strain rates, and terminus position and calving rate are therefore functions of ice velocity, strain rate, ice thickness and water depth. We couple the calving criterion with three 'sliding laws', in which velocity is controlled by (1) basal drag, (2) lateral drag and (3) a combination of the two. In model 1, velocities and strain rates are dependent on effective pressure, and hence ice thickness relative to water depth. Imposed thinning can lead to acceleration and terminus retreat, and ice shelves cannot form. In model 2, ice velocity is independent of changes in ice thickness unless accompanied by changes in surface gradient. Velocities are strongly dependent on channel width, and calving margins tend to stabilize at flow-unit widenings. Model 3 exhibits the combined characteristics of the other two models, and suggests that calving glaciers are sensitive to imposed thickness changes if basal drag provides most resistance to flow, but stable if most resistance is from lateral drag. ice shelves can form if reduction of basal drag occurs over a sufficiently long spatial scale. In combination, the new calving criterion and the basal-lateral drag sliding function (model 3) can be used to simulate much of the observed spectrum of behaviour of calving glaciers, and present new opportunities to model ice-sheet response to climate change.</p

Analysis of the Management and Costs Associated with Rearing Pregnant Dairy Heifers in the UK from Conception to Calving

Good management of the pregnant heifer is crucial to ensure that she is well grown and healthy and calves down easily before joining the milking herd. This study collected primary data on all aspects of heifer management on 101 UK farms during heifer pregnancy from conception to calving including farm factors and associated costs of system inputs. A cost analysis workbook was developed to calculate the cost of rearing per heifer for each of the study farms. Associations between cost of rearing and farms factors were determined using linear regression and analysis of variance. Heifers had a mean age of conception of 509 d (range 365 - 700 d) and an age at first calving of 784 d (range 639 - 973 d). The mean total cost of rearing during pregnancy was £450.36 (range £153.11 to £784.00) with a mean daily cost of £1.64 (range £0.56 to £2.86). The inputs contributing the most to cost were feed (32.7%), labour (23.8%) and slurry disposal (11.2%). Total purchased and homegrown feed and grazing contributed between 25.5% and 65.4% of total costs with a mean contribution of 43.6%. The cost of rearing was lowest in spring calving herds and highest in all year round calving herds with intermediate values in autumn and multi block calving herds. The main variables influencing the cost were the number of days spent at grass, age at first calving, calving pattern, breed, herd size and region. Each extra day in age at first calving increased the mean cost of rearing during pregnancy by £0.33/d whereas every extra day at grass reduced the cost by £1.75/d

Machine-learning-based calving prediction from activity, lying, and ruminating behaviors in dairy cattle

The objective of this study was to use automated activity, lying, and rumination monitors to characterize prepartum behavior and predict calving in dairy cattle. Data were collected from 20 primiparous and 33 multiparous Holstein dairy cattle from September 2011 to May 2013 at the University of Kentucky Coldstream Dairy. The HR Tag (SCR Engineers Ltd., Netanya, Israel) automatically collected neck activity and rumination data in 2-h increments. The IceQube (IceRobotics Ltd., South Queensferry, United Kingdom) automatically collected number of steps, lying time, standing time, number of transitions from standing to lying (ly-. ing bouts), and total motion, summed in 15-min increments. IceQube data were summed in 2-h increments to match HR Tag data. All behavioral data were collected for 14 d before the predicted calving date. Retrospective data analysis was performed using mixed linear models to examine behavioral changes by day in the 14 d before calving. Bihourly behavioral differences from baseline values over the 14 d before calving were also evaluated using mixed linear models. Changes in daily rumination time, total motion, lying time, and lying bouts occurred in the 14 d before calving. In the bihourly analysis, extreme values for all behaviors occurred in the final 24 h, indicating that the monitored behaviors may be useful in calving prediction. To determine whether technologies were useful at predicting calving, random forest, linear discriminant analysis, and neural network machine -learning techniques were constructed and implemented using R version 3.1.0 (R Foundation for Statistical Computing, Vienna, Austria). These methods were used on variables from each technology and all combined variables from both technologies. A neural network analysis that combined variables from both technologies at the daily level yielded 100.0% sen-sitivity and 86.8% specificity. A neural network analysis that combined variables from both technologies in bihourly increments was used to identify 2-h periods in the 8 h before calving with 82.8% sensitivity and 80.4% specificity. Changes in behavior and machine-learning alerts indicate that commercially marketed behavioral monitors may have calving prediction potential

Risk factors and prevention strategies for mastitis in New Zealand dairy heifers : this thesis is completed as a partial requirement for the Masters of Veterinary Studies (Epidemiology) from Massey University, Palmerston North, New Zealand

The aims of this thesis were to investigate herd level risk factors for heifer clinical mastitis and to test the efficacy of a pre-calving intervention on prevalence of post-calving IMI, incidence of clinical mastitis and somatic cell count (SCC) in heifers. Materials and methods A prospective survey (chapter 3) was used to collect data concerning farmers' management practices for rearing heifers and mastitis management. A proportion of herd-owners (n=250) subsequently provided data on the clinical mastitis cases in their herd occurring in the first 120 days of the subsequent lactation. A pilot quarter level intervention study (n=1000 quarters; chapter 4) investigated the effect of pre-calving infusion of a teat sealant. Glands were randomly assigned to one of 4 treatment groups (no treatment; mammary gland secretion collection; infusion of a teat sealant; or sample collection with infusion of teat sealant) to identify the risk of each of these treatments on post-calving IMI and clinical mastitis. A heifer level intervention study (n=1000 heifers; chapter 5, 6) investigated the pre-calving use of teat sealant infused into all four quarters and/or treatment with the injectable antibiotic tylosin. Analysis was undertaken at quarter level (chapter 5) and heifer level (including SCC data; chapter 6). Results The survey identified that the cumulative incidence of heifers with clinical mastitis was higher in herds with a higher per cow milk production, with more cows milked per person, in herds with a higher stocking rate, and in herds with a higher cumulative incidence of clinical mastitis in their multiparous cows. The cumulative incidence of heifers in a herd with clinical mastitis was lower in herds that managed the lactating cows in multiple groups. The pilot study found that the presence of an IMI pre-calving increased the risk of an IMI post-calving and the incidence of clinical mastitis, relative to no IMI pre-calving. Infusion of the teat sealant reduced the risk of post-calving IMI due to Streptococcus uberis and the incidence of clinical mastitis. Sampling the glands pre-calving had no effect on post-calving IMI or on incidence of clinical mastitis. The large-scale intervention study found that neither infusion of a teat sealant nor treatment with the injectable antibiotic increased the risk of cure of pre-calving IMI. Infusion of the teat sealant reduced the risk of quarter level new IMI. At both quarter and heifer level teat sealant reduced the risk of the prevalence of post-calving IMI, incidence of clinical mastitis. At heifer level the SCC was decreased throughout lactation following the use of a teat sealant. Tylosin had no effect on prevalence of IMI, incidence neither of clinical mastitis nor on SCC. Conclusions It was concluded that the risk of heifer clinical mastitis was associated with a number of herd level management factors and that further studies are required to elucidate the mechanisms behind these associations. Hence, it may be possible to reduce the incidence of clinical mastitis in heifers by modification of herd level management practices. Intervention with an intramammary teat sealant pre-calving decreased the incidence of new infections over this high-risk peripartum period, and may provide a useful tool for reducing the risk of subclinical and clinical mastitis in heifers