The biostimulation of exposure to a male can improve postpartum reproductive performance in females of many species. The aim of this research was to examine the biostimulatory effects of fenceline bull exposure during the early postpartum period in lactating dairy cows on the resumption of ovulatory activity, subsequent conception and calving interval, either in naturally cycling or oestrus syncronised cows. Three experiments were carried out in which Holstein-Friesian cows were allocated after parturition between two groups: cows that had unlimited time of access to fenceline bull exposure (BC) and a control group that was not exposed to a bull (NBC). Experiment 1, assessing the effects of bull exposure on cows at varied stages post partum, showed that the interval from start of exposure to resumption of ovarian activity, assessed by milk progesterone concentration, was not significantly affected by bull presence. Cows showed generally poor visible indicators of oestrus making correct insemination timing difficult consequently prolonged the calving interval. Experiment 2, investigating the biostimulation approach for freshly calved cows, showed an increase in pregnancy rate to the first service and consequent reduction in calving interval. This was especially marked in those cows previously treated with a progesterone intra-vaginal device (PRID). The average number of services per conception was lower in biostimulated cows, though there was no significant improvement of oestrus detection in these cows. Experiment 3, investigating cows that were freshly calved and then syncronised for oestrus using PRID treatment, showed a similar improvement in conception rate to first service, though compromised by generally poor reproductive performance. Similarly, oestrus detection rate was low even with PRID treatment. The outcomes from this study highlight the potential effects of a biostimulation approach as a strategy to improve reproductive performance in postpartum anoestrus dairy cows raised in intensive farming systems.

Four desktop studies were conducted to investigate the effects of animal and dietary factors on metabolisable energy (ME) requirement for maintenance (MElli)' efficiency of utilisation of ME for lactation (kl), and enteric methane (CH4) emission rates in lactating dairy cows at the Agri-Food and Biosciences Institute, Hillsborough. The data used in these studies involved nearly 1000 observations of Holstein-Friesian (HF), Norwegian and HF crossbred with Jersey or Norwegian (Fl hybrid) dairy cows, and were collated from 32 respiration calorimeter experiments between 1992 and 2010. Study 1, 3, and 4 evaluated the effect of animal factors and dietary forage proportion on energy metabolism. Study 2 focused on the examination of cow genetic merit influencing the enteric CH4 emission rates. In Study 1, 670 observations of lactating HF dairy cows with various genetic merit indexes were collated. Cow genetic merit in the United Kingdom (UK) is described using two economic indexes, Profit Index (PIN) and Profitable Lifetime Index (PLI). The PIN is based solely on milk production (n = 736, -£30 to +£63), PLI includes milk production and a number of other functional traits including health, fertility and longevity (n = 548, -£131 to +£184). The MEm for individual cows was calculated from heat production (HP) minus energy losses from inefficiencies of ME use for lactation, energy retention and pregnancy, and the kl was obtained from milk energy output (EI) adjusted to zero energy balance (EI(o») divided by ME available for production. Analysis of variance (ANOVA) and linear mixed regression technique were used to examine the effects of cow genetic merit on the MEm and the lq, As there was no significant relationship between cow genetic merit and calculated values of MEm (MJ per kg metabolic body weight, MJ/kgo.7S) or kl using the whole PIN and PLI data set, further analysis was conducted by dividing each dataset of PIN « £3, £3 to £15 and> £15) and PLI « £23, £23 to £67 and> £67) into three sub-groups categorising as low, medium and high genetic groups. Linear relationships between cow genetic merit and energetic parameters were developed to evaluate if there was any significant difference among the coefficients or constants when a common constant or coefficient was used. No significant relationship was found between ME intake (MJ/kgo.7s) and MEm (MJ/kgo.7s), EI(o) (MJ/kgo.7s) or HP (MJ/kgo. 7S) within PIN or PLI sub-groups. These results indicated that cow genetic merit may have no effects on maintenance metabolic rate or energetic efficiency for lactation and high yielding HF cows need more nutrient supply to maximise the production potential. The following study (Study 2) was conducted to investigate the effect of cow genetic merit on the enteric CH4 emissions rates using the same dataset as used in Study 1. The animals had a large range of days in milk (18 to 354), energy corrected milk yields (16.0 to 45.6 kg/d), and CH4 emissions (138 to 598 g/d). The data were analysed using the same programmes as used in Study 1 (AN OVA and regression technique) with the effects of a number of animal and diet factors removed. Within the PIN and PLI datasets there were no significant difference among the three sub-groups in terms of CH4 emission per kg feed intake, energy corrected milk yield, or CH4 energy (CH4-E) output as a proportion of energy intake (P > 0.05). Linear mixed regression using the whole PIN and PLI datasets also demonstrated that there was no significant relationship between either PIN or PLI, and CH4 emission per kg of feed intake or CH4-E output as a proportion of energy intake (P > 0.05). These results indicate that cow genetic merit has little effect on enteric CH4 emissions as a proportion of feed intake. Enteric CH4 production may mainly relate to total feed intake and dietary nutrient composition. effects of a number of animal and diet factors removed. Within the PIN and PLI datasets there were no significant difference among the three sub-groups in terms of CH4 emission per kg feed intake, energy corrected milk yield, or CH4 energy (CH4-E) output as a proportion of energy intake (P > 0.05). Linear mixed regression using the whole PIN and PLI datasets also demonstrated that there was no significant relationship between either PIN or PLI, and CH4 emission per kg of feed intake or CH4-E output as a proportion of energy intake (P > 0.05). These results indicate that cow genetic merit has little effect on enteric CH4 emissions as a proportion of feed intake. Enteric CH4 production may mainly relate to total feed intake and dietary nutrient composition.

Dark, Firm and Dry (DFD) beef is a major meat quality defect that is produced by animals' subjected to pre-slaughter stress and is considered to be one of the main meat quality defects resulting in significant economic losses. Conflicting views have been reported surrounding the use of conventional markers of pre-slaughter stress and their association to meat quality and subsequently the prevalence of DFD beef remains. The overall aim of this research was to utilise targeted and untargeted analytical approaches to enhance the understanding of the physiological pre-slaughter stress response in cattle and its association to downstream meat quality. Two animal studies were conducted; one investigated the stress response of young bulls (n=298) reared and slaughter in a commercial setting and the second assessed the social disruption of young bulls (n=27) maintained under controlled experimental conditions. Studies demonstrated that conventional markers of pre-slaughter stress (urinary/blood cortisol and cortisone) were unable to differentiate between varying intensities of pre-slaughter stress and showed no clear association to meat quality (as measured by ultimate pH (pHu)) In contrast, untargeted high resolution-mass spectrometry based metabolomic profiling of bovine urine from corresponding animals revealed 15 new urinary metabolites (9 up- and 6 down-regulated) that discriminated between the different levels of pre-slaughter stress. Based on the development of a predictive model these urinary metabolites were shown to relate to carcass pHu, suggesting potential for use as a means of predicting downstream meat quality. Furthermore, metabolomic profiling of longissimus dorsi muscle tissue extracts revealed 6 up-regulated metabolites that differentiated between normal and high pHu meat. Findings from this research has revealed new metabolites that can distinguish between animals exposed to a combination of psychological and physiological stress, which will aid in mitigating against associated meat quality losses, thus leading to improved sustainability and profitability of the meat industry.

Bovine Parainfluenza Virus-3 (BPIV-3) is a major viral pathogen of the Bovine Respiratory Disease (BRD) complex, which is considered to be one of the most significant causes of economic loss in intensively reared cattle worldwide. Current diagnostic tests for BPIV -3 infection provide limited information on the health status of infected animals. This study was designed to address major limitations in BRD management, using Bovine Parainfleunza Virus-3 (BPIV -3) as a model virus to investigate whether screening tools based on biomarkers could be employed to successfully aid in the identification of infected animals and to understand the processes of successful immune response to vaccination. Through the application of in vitro and in vivo biomarker screening tools, this study demonstrated the potential for proteomic and metabolomics marker screening approaches to provide more accurate diagnosis of BPIV -3 infected animals and assess immune responses at the metabolite level. The application of these markers to diagnostic testing could provide numerous benefits for the management of BPIV -3 infection at the herd level. This research highlights the potential for metabolomic and proteomic biomarker approaches to be applied to the improved management and diagnosis of agricultural diseases.

Mastisis, an inflamatory disease of the mammary gland is of major importance in cattle in all milk producing countries. The development of mastitis is a dynamic process involving the external environment and management of the animals their susceptibility to the disease and the efficiency of their defence mechanisms once the disease has established. There are numerous factors associated with the disease which have been incriminated as predisposing factors. Many of these are really, just opinions, and consequently difficult to investigate experimentally. Even if this were possible, to investigate one in isolation from all the, rest would be unlikely to provide an unequivocal result. From the view of satisfactory statistical analysis, it, is impossible, without very great resources, to investigate management, hereditary and all other factors as a whole.

In commercial dairy cattle farming, stressful disease conditions, such as high somatic cell count (SCC), poor body condition score (BCS) or lameness, are associated with subfertility. The objective of this thesis is to identify key areas in the reproductive cycle associated with each condition which contribute to this subfertility. Cows 30-80 days post partum from two commercial dairy farms were scored for SCC, BCS and lameness over a 5 week period prior to the implementation of an oestrous synchronization programme. Blood and milk sampling, trans-rectal ultrasonography and oestrus behaviour monitoring were conducted. Follicular development from emergence to deviation was unaffected as all cows produced a dominant follicle, which continued to grow beyond lOmm. In the following period, mean follicular growth, maximum follicular diameter and time to ovulation were not influenced by any of the 3 conditions (p> 0.05). In the animals that ovulated (irrespective of clinical status), follicles grew faster and achieved a greater diameter than in the animals that failed to ovulate (p< 0.05). Fewer lame animals ovulated compared to healthy animals (p< 0.05) and fewer high SCC animals with concurrent lameness ovulated than cows with only high SCC (p< 0.05) In cows with high SCC, progesterone concentrations prior to PG injection, over the peri-ovulatory period, on Days 5 and 7 or during the mid luteal phase after ovulation were unaffected, as was mean oestradiol concentration prior to ovulation. In the cows that ovulated, the dominant follicle grew at the same rate and ovulated at a similar size and at the same time regardless of high SCC, lameness or both. High SCC cows tended to (p< 0.07) and lame cows did express an oestrus of lower intensity and had a lower maximum intensity score than healthy animals (p< 0.05). High SCC cows started displaying oestrus signs and stood to be mounted (STBM) later than their healthy counterparts (p< 0.05) while lame animals displayed oestrus and STBM earlier than non lame cows (p< 0.05).

No description available.

The desire to develop national greenhouse gas (OHO) emission inventories and mitigation strategies to reduce carbon footprint of cattle production systems, has prompted interest to fill the knowledge gap of OHO emission from young cattle in the UK. The current UK government funded study was undertaken over a two-year period to evaluate the effects of gender (steers vs. heifers) of growing Holstein cattle (6 to 22 months of age) on enteric methane emissions and energy and nitrogen utilisation and then to use these data to develop prediction models for quantification of carbon footprint of the dairy production sector. Twenty 5-month old Holstein cattle (10 steers and 10 heifers) were used in successive 28 d feeding period, with measurements undertaken at age of 6, 12, 18 and 22 months, to investigate the effects on feed intake, live weight gain, energy and nitrogen (N) utilisation and enteric methane (CH4) emission. Throughout the study, cattle were offered a diet for ad libitum intake containing a single perennial ryegrass silage mixed with concentrates. In the first period, the concentrate supplement was offered at a ratio of 550 g/kg of dry matter (DM), while it was given at a fixed rate of 2 kg DM daily in other 3 periods. During each measurement period, the cattle were housed as a single group in cubicle accommodation for the first 20 d, then individually in metabolism units for the next 3 d, and then in indirect open-circuit respiration calorimeter chambers for the final 5 d with feed intake, faeces and urine outputs and gaseous exchange measured during the last 4 d.

Health challenges that lead to subclinical or clinical diseases can increase treatment costs, reduce performance and affect animal welfare. These impacts can be reduced by starting treatment early. Since behaviour is known to be affected by the health status of an animal, an early diagnosis by monitoring changes in behaviour is a possibility. The objective of this thesis was to quantify the changes in behaviour that take place as a consequence of health challenges and to asses them for their suitability to be used for the early detection of (sub) clinical disease. The behaviours looked at were: feeding; drinking; activity; and posture. In two experiments an acute health challenge was used, in the form of either a vaccination or a lipopolysaccharide bolus. These acute challenges, due to their transient nature, did not manifest as substantial changes in behaviour. A gastro-intestinal parasite (Ostertagia ostertagi) was used as a chronic challenge in three experiments. This health challenge affected several aspects of the behaviours measured. Due to its prolonged nature these effects increased over time, but were reversed after the challenge had been removed. The challenge also showed a dose dependency, demonstrating a threshold, rather than a gradient, when affecting behaviour for different levels of parasitic infection. From the overall results it was concluded that activity, posture and in some cases feeding behaviour, were affected by the parasitic (O. ostertagi) health challenge. From these, activity and posture were found to have the greatest magnitude of change and to be the most consistently affected across experiments. These behavioural changes, however, started at the same time as a rise in faecal egg counts and pepsinogen levels. Nonetheless, due to the magnitude of the behavioural changes, behaviour could still be used as an indicator of health status, predominantly in animals that receive little visual monitoring.

Bovine viral diarrhoea virus (BVDV) is an important pathogen that causes infectious disease of cattle worldwide and results in significant economic losses. Vaccination has long been used as a tool for control of BVDV but inadequacies of existing vaccines have hampered eradication efforts. Attempts to develop sub-unit vaccines have focused on the structural envelope protein E2, which is a dominant target of neutralising antibodies and as well as CD4 T cell responses. This study aimed to rationally address the development of more efficacious vaccines by characterising the kinetics and specificity of T cell responses to a BVDV type 1 peptide library in calves rendered immune to BVDV following recovery from experimental infection. Upon identification of E2 and NS3 as the dominant targets of CD4 T cell responses, we assessed whether T cells induced by one virus genotype were capable of responding to a heterologous virus genotype and to identified E2 and NS3 as targets of genotype-specific and genotype transcending responses, respectively. This finding strengthened the argument for inclusion of both antigens in a subunit vaccine formulation. A nanoparticulate formulation of E2 and NS3 adjuvanted with poly(I:C) was shown to induce protective responses comparable to a commercial available BVDV vaccine in a vaccination and challenge experiment. It is hoped that the data generated will have implications for the design of improved vaccines against BVD.