Relationship between dairy cow genetic merit and profit on commercial spring calving dairy farms

peer-reviewedBecause not all animal factors influencing profitability can be included in total merit breeding indices for profitability, the association between animal total merit index and true profitability, taking cognisance of all factors associated with costs and revenues, is generally not known. One method to estimate such associations is at the herd level, associating herd average genetic merit with herd profitability. The objective of this study was to primarily relate herd average genetic merit for a range of traits, including the Irish total merit index, with indicators of performance, including profitability, using correlation and multiple regression analyses. Physical, genetic and financial performance data from 1131 Irish seasonal calving pasture-based dairy farms were available following edits; data on some herds were available for more than 1 year of the 3-year study period (2007 to 2009). Herd average economic breeding index (EBI) was associated with reduced herd average phenotypic milk yield but with greater milk composition, resulting in higher milk prices. Moderate positive correlations (0.26 to 0.61) existed between genetic merit for an individual trait and average herd performance for that trait (e.g. genetic merit for milk yield and average per cow milk yield). Following adjustment for year, stocking rate, herd size and quantity of purchased feed in the multiple regression analysis, average herd EBI was positively and linearly associated with net margin per cow and per litre as well as gross revenue output per cow and per litre. The change in net margin per cow per unit change in the total merit index was h1.94 (s.e.50.42), which was not different from the expectation of h2. This study, based on a large data set of commercial herds with accurate information on profitability and genetic merit, confirms that, after accounting for confounding factors, the change in herd profitability per unit change in herd genetic merit for the total merit index is within expectations

Development of an avian tuberculosis vaccine for wildfowl

The Wildfowl and Wetlands Trust maintain a large and comprehensive collection of captive wildfowl at Slimbridge in Gloucestershire, Avian tuberculosis caused by Mycobacterium avium, has been enzootic since 1948 and is now the main cause of death, accounting for over a third of post fledgling mortalities. There is a grave risk of spreading infection to the enormous number of wild birds that use the grounds. The introductory chapters review the disease in both wild and captive wild birds. The particular susceptibility of the rarest duck in the world: the White-winged Wood Duck Cairina scutulata, and the effect of the disease on its captive breeding programme, are discussed. The disease situation at Slimbridge is assessed in an epizootiological study which is carried out on adult post mortem data of the years 1980-1989. This study shows both genetic and environmental factors greatly influencing incidence of the disease. However, it also suggests that there are definite levels of immunity to M.avium in some groups and individuals. The main experiments in the thesis investigate the possibility of immunoprophylaxis in the form of a vaccine as a possible method of controlling the disease. Past attempts at vaccination are reviewed, as is the current knowledge of the wildfowl immune system. Conditions for the immunological tests used to assess immune responses throughout the vaccine studies had to be optimised. These tests included: wildfowl lymphocyte transformation test (LTT) which has been made to work in the presence of antigen for the first time; a method for skin testing, previously not done in wildfowl; and an enzyme linked immunosorbence assay (ELISA). The main study chapters report the use of intradermal BCG and M.vaccae as potential vaccines. Studies with Mallard Anas platyrhynchos platyrhynchos indicate killed M.vaccae administered at one day old as an immunopotentiating agent. Studies with Mandarin ducks Aix galericulata confirm the optimum age for vaccination to be one day old. An optimum dose of this vaccine has been elucidated in studies using Gadwall Anas strepera and Hawaiian Geese or Nenes Branta sandvicensis. No protection was afforded to White-winged Wood Ducks when vaccinated with killed M.vaccae in adult life. A bacteriological study of strains of M.avium isolated from tuberculous birds at post mortem is also reported. Strains were isolated from birds from both Slimbridge and Arundel Wildfowl and Wetlands Trust centres, and also from several wild birds. These strains were subjected to lipid and DNA analysis, and studies were made of their protein patterns using SDS-polyacrylamide gel electrophoresis. The current vaccination programme at Slimbridge and The Wildfowl and Wetlands Trust centre at Llanelli, South Wales, is discussed. Results from tuberculous birds in the vaccine trials indicate the potential for the development of a diagnostic test

Carcass characteristics of cattle differing in Jersey proportion

peer-reviewedComparison of alternative dairy (cross-)breeding programs requires full appraisals of all revenues and costs, including beef merit. Few studies exist on carcass characteristics of crossbred dairy progeny originating from dairy herds as well as their dams. The objective of the present study was to quantify, using a national database, the carcass characteristics of young animals and cows differing in their fraction of Jersey. The data set consisted of 117,593 young animals and 42,799 cows. The associations between a combination of sire and dam breed proportion (just animal breed proportion when the dependent variable was on cows) with age at slaughter (just for young animals), carcass weight, conformation, fat score, price per kilogram, and total carcass value were estimated using mixed models that accounted for covariances among herdmates of the same sex slaughtered in close proximity in time; we also accounted for age at slaughter in young animals (which was substituted with carcass weight and carcass fat score when the dependent variable was age at slaughter), animal sex, parity of the cow or dam (where relevant), and temporal effects represented by a year-by-month 2-way interaction. For young animals, the heaviest of the dairy carcasses were from the mating of a Holstein-Friesian dam and a Holstein-Friesian sire (323.34 kg), whereas the lightest carcasses were from the mating of a purebred Jersey dam to a purebred Jersey sire which were 46.31 kg lighter (standard error of the difference = 1.21 kg). The young animal carcass weight of an F1 Holstein-Friesian × Jersey cross was 20.4 to 27.0 kg less than that of a purebred Holstein-Friesian animal. The carcass conformation of a Holstein-Friesian young animal was 26% superior to that of a purebred Jersey, translating to a difference of 0.78 conformation units on a scale of 1 to 15. Purebred Holstein-Friesians produced carcasses with less fat than their purebred Jersey counterparts. The difference in carcass price per kilogram among the alternative sire-dam breed combinations investigated was minimal, although large differences existed among the different breed types for overall carcass value; the carcass value of a Holstein-Friesian animal was 20% greater than that of a Jersey animal. Purebred Jersey animals required, on average, 21 d longer to reach a given carcass weight and fat score relative to a purebred Holstein-Friesian. The difference in age at slaughter between a purebred Holstein-Friesian animal and the mating between a Holstein-Friesian sire with a Jersey dam, and vice versa, was between 7.0 and 8.9 d. A 75.8-kg difference in carcass weight existed between the carcass of a purebred Jersey cow and that of a Holstein-Friesian cow; a 50% Holstein–Friesian-50% Jersey cow had a carcass 42.0 kg lighter than that of a purebred Holstein-Friesian cow. Carcass conformation was superior in purebred Holstein-Friesian compared with purebred Jersey cows. Results from this study represent useful input parameters to populate simulation models of alternative breeding programs on dairy farms, and to help beef farmers evaluate the cost-benefit of rearing, for slaughter, animals differing in Jersey fraction.This publication arose from research supported in part by a research grant from Science Foundation Ireland (Dublin) and the Department of Agriculture, Food and Marine on behalf of the Government of Ireland under the Grant 16/RC/3835 (VistaMilk; Dublin, Ireland) as well as funding from the Research Stimulus Fund (BreedQuality and GREENBREED; Dublin, Ireland) and Meat Technology Ireland (MTI; Dublin, Ireland), a co-funded industry/Enterprise Ireland project (TC 2016 002)

Accuracy of predicting milk yield from alternative milk recording schemes

peer-reviewedThe effect of reducing the frequency of official milk recording and the number of recorded samples per test-day on the accuracy of predicting daily yield and cumulative 305-day yield was investigated. A control data set consisting of 58 210 primiparous cows with milk test-day records every 4 weeks was used to investigate the influence of reduced milk recording frequencies. The accuracy of prediction of daily yield with one milk sample per test-day was investigated using 41 874 testday records from 683 cows. Results show that five or more test-day records taken at 8-weekly intervals (A8) predicted 305-day yield with a high level of accuracy. Correlations between 305-day yield predicted from 4-weekly recording intervals (A4) and from 8-weekly intervals were 0.99, 0.98 and 0.98 for milk, fat and protein, respectively. The mean error in estimating 305-day yield from the A8 scheme was 6.8 kg (s.d. 191 kg) for milk yield, 0.3 kg (s.d. 10 kg) for fat yield, and −0.3 kg (s.d. 7 kg) for protein yield, compared with the A4 scheme. Milk yield and composition taken during either morning (AM) or evening (PM) milking predicted 24-h yield with a high degree of accuracy. Alternating between AM and PM sampling every 4 weeks predicted 305-day yield with a higher degree of accuracy than either all AM or all PM sampling. Alternate AM-PM recording every 4 weeks and AM + PM recording every 8 weeks produced very similar accuracies in predicting 305-day yield compared with the official AM + PM recording every 4 weeks

Promoter and Riboswitch Control of the Mg2+ Transporter MgtA from Salmonella enterica

The MgtA protein from Salmonella enterica serovar Typhimurium mediates Mg(2+) uptake from the periplasm into the cytoplasm. Here we report that the PhoP/PhoQ two-component regulatory system, which responds to periplasmic Mg(2+), governs mgtA transcription initiation at all investigated Mg(2+) concentrations and that the Mg(2+)-sensing 5′ leader region of the mgtA gene controls transcription elongation into the mgtA coding region when Salmonella is grown in media with <50 μM Mg(2+). Overexpression of the Mg(2+) transporter CorA, which is believed to increase cytoplasmic Mg(2+) levels, decreased mgtA transcription in a manner dependent on a functional mgtA 5′ leader