Milk recording consists in the regular, usually monthly, collection of a milk sample from all the lactating cows of a dairy herd. A large sample of milk recording data collected in England and Wales between 2004 and 2006 was used in this thesis. A sample of 8,211,988 recordings in 2,128 herds, representing 16 % of the dairy herds in activity in December 2006, were described and analysed. Calvings followed a seasonal pattern with 80 % more calving in September than in May. Milk production was highest in May (26.5 kg) and lowest in October (24.1 kg). Butterfat was stable, close to 4 % from October to March and reached a minimum at 3.7 % in June and July. Protein stayed between 3.2 and 3.3 % all the year. Geometric mean somatic cell count was between 177 and 180 between October and March and reached 205,000 cells/mL in July and August. At the individual cow level, the mean milk yield, percentage of butterfat, percentage of protein, fat to protein ratio and somatic cell count (geometric mean) were 26.4 kg, 3.96 %, 3.29 %, 1.21 and 90,000 cells/mL, between 5 and 305 days in milk. Changes in individual cow somatic cell counts around a threshold of 200,000 cells/mL between consecutive recording dates were used to predict bulk milk somatic cell count at both the herd-year and test-day levels. The main contributors to bulk milk somatic cell counts were cows staying above the threshold for 2 consecutive test-days. Milk yields and composition at the start of lactation were used to predict the calving to conception interval. Higher milk yield, lower percentage of protein, lower percentage of lactose, higher somatic cell count and higher percentage of butterfat were associated with lower probabilities of conception before 145 days in milk.

Routinely collected herd management data in a variety of formats were collated from 468 dairy herds, and novel objective measures of data recording quality were developed and applied. This revealed that there was a substantial amount of variation in data quality between herds, and the vast majority of herds failed to meet the threshold level for at least one of the data quality measures used. Analysis of trends in reproductive performance across the herds with good quality fertility event recording suggested that their fertility was generally declining through the first half of the 2000s, but there was some evidence that improvements in submission rate were beginning to reverse this decline in the later years studied (up to 2007). Associations between reproduction and two endemic diseases common in dairy cattle (mastitis and lameness) were explored using multilevel discrete time survival modelling, and probabilistic sensitivity analysis (PSA) used to contextualise and illustrate the results. In both cases, statistical modelling revealed significant and sizeable associations between disease events and reproductive outcomes at lactation level. However, simulation and application of PSA showed that a herd’s incidence rate of either disease was highly unlikely to influence its overall reproductive performance to a clinically relevant degree when other inputs to herd fertility were also considered. Factors associated with the proportion of serves leading to a pregnancy (pregnancy rate) were explored using multilevel logistic regression modelling. This revealed that relatively little of the variation in herd pregnancy rate is explainable by routinely recorded milk recording data (including constituent concentration in early lactation as well as daily and lactation yields). A large amount of the unexplained variation was revealed to be at herd level and very little at cow level, suggesting that investigation of herd management practices associated with pregnancy rate would be rewarding.

The aim of this work is to better understand the structuring processes in low fat dairy emulsions. Model sodium caseinate-galactomannan aqueous two-phase systems (NaCAS-GM ATPS) differing in GM-type (locust bean gum (LBG), tara gum (TG), guar gum (GG), fenugreek gum (FG)) and added sugar (trehalose, sucrose, glucose and fructose) were studied by the phase-volume ratio method, rheooptics, and droplet retraction method on phase equilibria, flow behaviour and interfacial properties, respectively, at pH 5.8 and 20°C. The results revealed that the presence of sugar in concentrations 5-40 wt% resulted in an increase in cosolubility of the phases and a decrease in interfacial tension (σ). Sugar concentrations > 40 wt% decreased cosolubility. Based on the mannose:galactose ratio of GM and type of sugar (added in concentration 15 wt%) the best cosolubility and corresponding smallest σ was attributed to FG and trehalose, respectively. The flow of ATPS depended on quiescent microstructure, the shear and physical properties of the phases. In polysaccharide-continuous ATPS, the occurrence of a shear-induced phase inversion event was observed for 0- 20 wt% sugar. A further increase in sugar concentration >20 wt% was found to suppress this phenomenon due decreased viscosity ratio and formation of thread like structures in flow.

Periparturient milk fever is a widespread metabolic disease within the dairy industry, with a number of potential impacts on the affected animals’ health and productivity in the subsequent lactation that can have a considerable economic impact on farmers. This thesis aimed to investigate current attitudes of both UK dairy farmers and veterinarians towards milk fever and subclinical hypocalcaemia, as well as investigating the feeding of rumen-protected rice bran during the dry period as a milk fever preventative, due to its reported potential as a calcium binder, within a commercial UK dairy herd. A retrospective study was also carried out in order to investigate associations between recorded milk fever events and other outcomes from farm records obtained from 78 UK dairy herds. The levels of agreement between three different blood sample types (serum, lithium heparin plasma, and lithium heparin whole blood) were also considered with regard to testing for concentrations of calcium, magnesium and phosphorous. Questionnaires were distributed to UK dairy farmers and veterinarians in order to assess current attitudes towards milk fever and its prevention. When choosing a prevention strategy, farmers were most concerned with its efficacy, with its ease of use being their second priority. Veterinarians placed a greater importance on metabolic disease than farmers, and it appears that vets may have an important role in education on the subject of hypocalcaemia. A retrospective study of over 59,000 lactations from 78 UK dairy herds found associations between recorded events of milk fever and an increased risk of dystocia, and an increased risk of a cow exiting the herd during the first 30 days of the lactation. Twin pregnancies were associated with a 30% reduction in the risk of milk fever. Rumen-protected rice bran was trialled against a control feed on a UK dairy herd during the dry period as a potential milk fever preventative. Serum calcium concentrations in the control group were significantly higher pre-calving than in the group that received rumen-protected rice bran. Cows fed rumen-protected rice bran were more likely to experience an elevated NEFA concentration post-calving than the control group. No feed-related differences were found in the subsequent 100 day yields. Limits of agreement were examined to investigate whether bovine serum, plasma and whole blood samples can be interchangeably used for the analysis of calcium, phosphorous and magnesium concentrations. Serum and plasma results appeared to show high levels of agreement for all three of the analytes. Whole blood results were more variable. In conclusion, the findings of this thesis provide an insight into the current attitudes within the UK dairy industry towards hypocalcaemia and its prevention. This thesis has also provided information on the effects and practicalities of feeding rumen-protected rice bran during the dry period in a commercial dairy herd and highlights the need for further research on the subject.

No description available.

No description available.

The recent increase in intensification of the UK dairy industry has led to the majority of cattle in the UK being housed in large, dynamic groups. Proposals for two large-scale dairies intending to house between 3,000 and 8,000 head of cattle have been met with considerable opposition by both producers and the public alike. Recent reports by both the Farm Animal Welfare Council and European Food Safety Authority have highlighted the continued welfare issues relating to dairy cattle, especially those housed in such large, dynamic groups. Conversely, with the current economic challenges being imposed on the UK dairy industry, there are many who see these systems as the future of dairying and discount the welfare concerns being highlighted. This project aimed to address one of the main welfare issues that receives scarce consideration when designing such systems; the social bonds of dairy cattle. A herd of 400 Holstein-Friesian cattle, plus followers, were observed in cubicle housing under commercial conditions. Through the identification of preferential relationships using an association index, important social bonds between individuals were identified. The majority of relationships between dyads were however weak, short term associations appearing together no more than once throughout the observation period. These bonds were significantly stronger in younger cattle demonstrated through the closer proximity maintained and the higher association index scores between dyads. Between the ages of 7 & 11 months animals performed the most positive social behaviour and had the strongest dyad relationships. In order to assess the strength of these positive relationships between dyads and to investigate the importance of these relationships to cattle, a short term (30 minutes) separation test from the remainder of the herd was carried out. Cattle’s responses to the challenge were assessed both physiologically and behaviourally. A significantly lower heart rate (p<0.01) during the separation period was observed when cattle were separated with their preferred partner compared to the non-preferred partner, and significantly lower levels of behaviour suggestive of agitation (p<0.05) were observed when they were with their preferred partner compared to when they were with the non-preferred partner. These results suggest that cattle were receiving social support from their preferred partners allowing them to have a reduced stress response to the social isolation test. As cattle aged and experienced regrouping, positive social bonds tended to disappear and cattle were more likely to have only weak associations. During long term separation (two weeks) from preferred partners, cattle showed significant behavioural, physiological and milk production changes. Upon subsequent reunion of preferred partners and consequential regrouping of individuals no further changes in behaviour, biology and milk production were observed, suggesting that separation rather than regrouping elicited a stress response. The bonds that had previously been evident between dyads were no longer present after the two weeks of separation. Subsequent relationships were also significantly weaker in focal cattle after separation of preferred partners and regrouping of animals. These results highlight the importance of relationships to the welfare of cattle and in particular the psychological well-being of cattle in commercial dairies. There is a significant need to reduce regrouping where possible and promote a more stable grouping system that enhances social bonds and positive social behaviour such as allogrooming; a behaviour which is currently rare in commercial systems. This will improve the quality of life for dairy cattle and increase their ability to cope with environmental challenge such as at times of regrouping and separation. In conclusion, social bonds do occur in domesticated dairy cattle and can be found when living in large dynamic group systems, but they are significantly affected by separation at the time of regrouping. These social bonds are important to the welfare and well-being of cattle; practices that promote stability and positive associations will be beneficial to the welfare of animals.

No description available.

Calving is an essential event in dairy production, as lactation only begins after calving and cows must give birth at regular intervals in order to maintain milk production. Careful management is important during the weeks around calving as this is when dairy cows most frequently experience health problems. Experienced stockmen use judgements based on physical and behavioural changes in order to recognise when cows may be about to calve, and subsequently be available to offer assistance when required. With increasing herd sizes and large numbers of cows per stockman, individual attention is often difficult. An automated system that monitors behavioural or physiological changes before calving could potentially be used to predict the time of calving, and help improve supervision by farm staff. Data comprising two years of records from Langhill Farm were used to identify any variables which could be used for calving prediction or as risk factors for various calving problems. Records kept by stockmen detailing the signs of calving and time of observation were compared with quantitative behavioural data. Observations from video recordings were used to identify any consistent behavioural changes occurring the day before calving that could be used to predict the onset of calving. The frequencies of lying and tail raises proved to be the most useful indicators, as they showed consistent changes in the final six hours before calving. Differences between heifers and cows, and between those experiencing calving difficulties and those which did not, were also investigated. Differences between heifers and cows were shown which should be taken into account when predicting calving times. However, no early-warning signs of difficulties were identified for cows and heifers assisted with a calving jack. Cows were also fitted with collars containing accelerometers to investigate if features in tri-axial accelerometer data could be shown to correspond to specific behaviours. Some success was achieved in identifying eating behaviour and postural changes, demonstrating that there is potential for monitoring behaviour using this method. Weekly heart rate recordings were also taken to establish if there was a change in the heart rate or heart rate variability during the final six weeks of gestation. Changes were found but, although they were statistically significant, they were considered too subtle for any practical application. Consistent changes in behaviour were observed in the six hours before calving, some of which could be measured using accelerometers. These changes have the potential to be used as the basis of an automated monitoring system to predict calving.

La carne de pollo y los huevos constituyen excelentes materias primas para desarrollar nuevos alimentos de alto valor añadido. El objetivo principal de este trabajo fue el de aplicar los efectos de la alta presión isostática sobre las macromoléculas de estas materias primas para obtener un gel modelo, con alto contenido de proteínas, bajo en grasas, sal y fosfatos, que sirva como base para elaborar diversos alimentos. También, el de evaluar la aplicación de la alta presión y la transglutaminasa microbiana en las pastas cárnicas para mejorar las características fisicoquímicas de los geles. A la carne de pollo se le adicionó albumen como sustituto de grasa en diferentes proporciones (0 a 20%), yema de huevo (10%) y transglutaminasa (0.3%), se disminuyó el contenido de sal hasta 1% y se eliminaron los fosfatos. Las pastas cárnicas se sometieron a diferentes tratamientos: por calor a presión atmosférica (75 ºC/30 min) y (20 y 40 ºC/30 min), y por alta presión (400 a 500 MPa, a 40 y 60 ºC/30 min) y (500, 700 y 900 MPa/40 ºC/30 min). La adición de albumen (10%) a la carne de pollo repercutió favorablemente en las características de retención de agua y en las propiedades texturales de los geles obtenidos por calor y por alta presión y mostró un efecto protector frente al cambio de color de los geles. A presión atmosférica, la adición de 0.3% de transglutaminasa disminuyó notablemente las pérdidas de agua, mejoró la textura de los geles aún con un bajo contenido en NaCl (1.0%) y se obtuvo una microestructura más compacta originada por la formación de enlaces covalentes ?-(?-glutamil)lisina. Se desarrolló actividad enzimática entre 500 y 700 MPa y se observó un efecto sinérgico de la aplicación simultánea de la transglutaminasa y de la alta presión en las características texturales y de retención de agua, cuyo incremento fue muy significativo en relación con el efecto de la enzima o de la presión aplicados en forma independiente. Se concluye que unas condiciones adecuadas para elaborar productos tipo salchicha libres de fosfatos y bajos en grasa y sal, son las siguientes: 700 MPa/40 ºC/30 min con adición de 0.3% de transglutaminasa microbiana. / Chicken meat and eggs constitute excellent commodities to develop new high value foods. The main objective of this study was to apply the effects of high isostatic pressure on the macromolecules of these raw materials in order to obtain a model gel, with high protein content, low fat, low salt and low-phosphates, which work as initial point for developing diverse foods. Moreover, to improve the gels characteristics by means of high pressure and microbial transglutaminase to the meat pastes. Albumen as fat replacement was added to the chicken meat in different proportions (0 to 20%), egg yolk (10%) and transglutaminase (0.3%), the salt content was diminished to 1% and phosphates were eliminated. The meat pastes were submitted to different processing: by heat (75 ºC/30 min) and (20 and 40 ºC/30 min) at atmospheric pressure and by high pressure (400 to 500 MPa, to 40 and 60 ºC/30 min, and 500, 700 and 900 MPa/40 ºC/30 min). The addition of albumen (10%) to the meat improved the water retention characteristics and the textural properties of the gels obtained by heat and by pressure and showed a protective effect in front of the colour change. Under atmospheric pressure, the addition of 0.3% transglutaminase diminished notably the water loss and improved the texture gels still with a reduction in NaCl content (1.0%) and, also, a more compact microstructure was obtained by the formation of ?-(?-glutamil)lysine bonds. It was demonstrated an enzymatic activity between 500 and 700 MPa and a synergistic effect was observed for the simultaneous application of transglutaminase and pressure in the textural characteristics and water holding capacity, which increment was very significant in relation to the enzyme or to the pressure independently applied. It is concluded that an adequate conditions for developing low fat and low salt and phosphates-free sausage type products are the following:700 MPa/40 ºC/30 min with addition of 0.3% of microbial transglutaminase.