The behaviour and health of dairy lambs reared artificially with and without early access to meal : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University.

Many large-scale dairy sheep producers use lamb-rearing systems and provide lambs with milk replacer (MR) ad libitum and grain-based meal to accelerate rumen development to support early weaning methods. Lambs are raised inside for three weeks before being relocated to a pasture paddock and weaned off MR, followed by weaning off meal 3-4 weeks later onto a pasture-only diet. The potential to replace the early provision of meal with early access to good quality pasture before weaning has not been evaluated and may have effects on the development of feeding behaviour. Studies on feeding behaviour in lambs have focused on differences between restricted and ad libitum quantities of MR, with little research on differences in use of solid feed before weaning. Sixty East Friesian crossbred ewe lambs aged 3-4 days were randomly allocated to one of two treatment groups; MR ad libitum with access to meal (M) or MR ad libitum without meal (NM). Both groups had access to pasture at the beginning of week 4, and were abruptly weaned off MR at week 6 and gradually weaned off meal (M lambs only) beginning in the middle of week 8 until the end of week 10. It was hypothesised that; (1) while lambs were being reared inside, M lambs would initiate rumination earlier due to their early access to meal. (2) There would be no difference in the milk feeding behaviour between lambs on the two diets. (3) There would be no difference in the health of the lambs and lastly (4), once outside, M lambs would spend more time grazing and subsequently ruminating as a result of their earlier rumen development. All lamb behaviours were visually recorded during weeks 2, 3, 5, 7, 10 and 12 (nine hours/week). Milk feeding behaviour traits were automatically recorded hourly through the automatic MR dispenser while being reared inside for 23 days. Health scores were recorded twice daily and total days health incidences were recorded. Meal access accelerated onset of rumination, while NM lambs spent more time consuming wood shavings during week 3 (P<0.001). Once outside, NM lambs spent more time grazing during weeks 5 (P<0.05), 7 and 12 (P<0.001), and increased rumination time compared to M lambs by week 12 (P<0.001). Lambs with meal access on average had a greater number of rewarded meals (meals in which lambs consumed more than 1 ml), with a greater intake of MR per meal than lambs without meal access (P<0.001). There were no mortalities of lambs fed either diet. Loose faeces (mild scours), pink eye and navel infections were observed in both M and NM lambs. These findings may allow refinement of lamb-rearing practices by adjustments to the provision of meal to lambs since no adverse behavioural or health effects were observed in lambs without meal access

Teacher Perspectives on Co-teaching in a Content Classroom with English Language Support

This study explores co-teachers’ valuations on four aspects of best-practice, which were administrative support, planning time and preparation, training for co-teachers, and the co-teacher relationship. It uses correlative analysis to compare these valuations and coteachers’ perceived feelings of effectiveness as individuals and as partnerships. Data was gathered through a survey of both ESL and mainstream teachers via a university listserv. The results showed administrative support was perceived as the least important of four aspects of co-teaching best-practice, but correlative analysis showed a strong link between perceived effectiveness of administrator support for co-teaching and teachers’ feelings of effectiveness as both individual co-teachers and in co-teaching partnerships

A recessive genetic screen for host factors required for retroviral infection in a library of insertionally mutated Blm-deficient embryonic stem cells.

BACKGROUND: Host factors required for retroviral infection are potential targets for the modulation of diseases caused by retroviruses. During the retroviral life cycle, numerous cellular factors interact with the virus and play an essential role in infection. Cultured embryonic stem (ES) cells are susceptible to retroviral infection, therefore providing access to all of the genes required for this process to take place. In order to identify the host factors involved in retroviral infection, we designed and implemented a scheme for identifying ES cells that are resistant to retroviral infection and subsequent cloning of the mutated gene. RESULTS: A library of mutant ES cells was established by genome-wide insertional mutagenesis in Blm-deficient ES cells, and a screen was performed by superinfection of the library at high multiplicity with a recombinant retrovirus carrying a positive and negative selection cassette. Stringent negative selection was then used to exclude the infected ES cells. We successfully recovered five independent clones of ES cells that are resistant to retroviral infection. Analysis of the mutations in these clones revealed four different homozygous and one compound heterozygous mutation in the mCat-1 locus, which confirms that mCat-1 is the ecotropic murine leukemia virus receptor in ES cells. CONCLUSION: We have demonstrated the feasibility and reliability of this recessive genetic approach to identifying critical genes required for retroviral infection in ES cells; the approach provides a unique opportunity to recover other cellular factors required for retroviral infection. The resulting insertionally mutated Blm-deficient ES cell library might also provide access to essential host cell components that are required for infection and replication for other types of virus

Generation of an inducible and optimized piggyBac transposon system.

Genomic studies in the mouse have been slowed by the lack of transposon-mediated mutagenesis. However, since the resurrection of Sleeping Beauty (SB), the possibility of performing forward genetics in mice has been reinforced. Recently, piggyBac (PB), a functional transposon from insects, was also described to work in mammals. As the activity of PB is higher than that of SB11 and SB12, two hyperactive SB transposases, we have characterized and improved the PB system in mouse ES cells. We have generated a mouse codon-optimized version of the PB transposase coding sequence (CDS) which provides transposition levels greater than the original. We have also found that the promoter sequence predicted in the 5'-terminal repeat of the PB transposon is active in the mammalian context. Finally, we have engineered inducible versions of the optimized piggyBac transposase fused with ERT2. One of them, when induced, provides higher levels of transposition than the native piggyBac CDS, whereas in the absence of induction its activity is indistinguishable from background. We expect that these tools, adaptable to perform mouse-germline mutagenesis, will facilitate the identification of genes involved in pathological and physiological processes, such as cancer or ES cell differentiation

A time-implicit numerical method and benchmarks for the relativistic Vlasov–Ampere equations

We present a time-implicit numerical method to solve the relativistic Vlasov–Ampere system of equations on a two dimensional phase space grid. The time-splitting algorithm we use allows the generalization of the work presented here to higher dimensions keeping the linear aspect of the resulting discrete set of equations. The implicit method is benchmarked against linear theory results for the relativistic Landau damping for which analytical expressions using the Maxwell-Juttner distribution function are derived. We note that, independently from the shape of the distribution function, the relativistic treatment features collective behaviours that do not exist in the nonrelativistic case. The numerical study of the relativistic two-stream instability completes the set of benchmarking tests

Four-field Hamiltonian fluid closures of the one-dimensional Vlasov-Poisson equation

We consider a reduced dynamics for the first four fluid moments of the one-dimensional Vlasov-Poisson equation, namely, the fluid density, fluid velocity, pressure and heat flux. This dynamics depends on an equation of state to close the system. This equation of state (closure) connects the fifth order moment—related to the kurtosis in velocity of the Vlasov distribution—with the first four moments. By solving the Jacobi identity, we derive an equation of state which ensures that the resulting reduced fluid model is Hamiltonian. We show that this Hamiltonian closure allows symmetric homogeneous equilibria of the reduced fluid model to be stable

Efficiency in the further education sector in England

Further education in England is a diverse sector which typically provides education for the 16 - 19 age group. This study investigates efficiency levels by subject of study within further education (FE) colleges. Mean overall technical efficiency is found to vary from 75% to 86% in the worst- and best-performing subject areas, respectively. Statistical analysis of efficiency reveals that, while student and teacher composition and regional characteristics affect efficiency in each subject, the strength of these effects can vary by subject. This has the clear policy implication that strategies to improve efficiency in English FE must be devised and operated at subject rather than provider level

Olfactory bulb hypoplasia in Prokr2 null mice stems from defective neuronal progenitor migration and differentiation.

New neurons are added on a daily basis to the olfactory bulb (OB) of a mammal, and this phenomenon exists throughout its lifetime. These new cells are born in the subventricular zone and migrate to the OB via the rostral migratory stream (RMS). To examine the role of the prokineticin receptor 2 (Prokr2) in neurogenesis, we created a Prokr2 null mouse, and report a decrease in the volume of its OB and also a decrease in the number of bromodeoxyuridine (BrdU)-positive cells. There is disrupted architecture of the OB, with the glomerular layer containing terminal dUTP nick-end labeling (TUNEL) -positive nuclei and also a decrease in tyrosine hydroxylase-positive neurons in this layer. In addition, there are increased numbers of doublecortin-positive neuroblasts in the RMS and increased PSA-NCAM (polysialylated form of the neural cell adhesion molecule) -positive neuronal progenitors around the olfactory ventricle, indicating their detachment from homotypic chains is compromised. Finally, in support of this, Prokr2-deficient cells expanded in vitro as neurospheres are incapable of migrating towards a source of recombinant human prokineticin 2 (PROK2). Together, these findings suggest an important role for Prokr2 in OB neurogenesis

The length of homology required for gene targeting in embryonic stem cells

Homologous recombination has been used to introduce site-specific mutations into murine embryonic stem (ES) cells with both insertion and replacement vectors. In this study, we compared the frequency of gene targeting with various lengths of homology and found a dramatic increase in targeting with an increase in homology from 1.3 to 6.8 kb. We examined in detail the relationship between the length of homology and the gene-targeting frequency for replacement vectors and found that a critical length of homology is needed for targeting. Adding greater lengths of homology to this critical length has less of an effect on the targeting frequency. We also analyzed the lengths of homology necessary on both arms of the vector for gene replacement events and found that 472 bp of homology is used as efficiently as 1.2 kb in the formation and resolution of crossover junctions

Can Who-Edits-What Predict Edit Survival?

As the number of contributors to online peer-production systems grows, it becomes increasingly important to predict whether the edits that users make will eventually be beneficial to the project. Existing solutions either rely on a user reputation system or consist of a highly specialized predictor that is tailored to a specific peer-production system. In this work, we explore a different point in the solution space that goes beyond user reputation but does not involve any content-based feature of the edits. We view each edit as a game between the editor and the component of the project. We posit that the probability that an edit is accepted is a function of the editor's skill, of the difficulty of editing the component and of a user-component interaction term. Our model is broadly applicable, as it only requires observing data about who makes an edit, what the edit affects and whether the edit survives or not. We apply our model on Wikipedia and the Linux kernel, two examples of large-scale peer-production systems, and we seek to understand whether it can effectively predict edit survival: in both cases, we provide a positive answer. Our approach significantly outperforms those based solely on user reputation and bridges the gap with specialized predictors that use content-based features. It is simple to implement, computationally inexpensive, and in addition it enables us to discover interesting structure in the data.Comment: Accepted at KDD 201