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    A genetic improvement programme for New Zealand dairy goats : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Institute of Veterinary, Animal and Biomedical Sciences (IVABS), Massey University, Palmerston North, New Zealand
    (Massey University, 2014) Solis-Ramirez, Jose
    The establishment of genetic improvement programmes is an important aspect of any modern animal production industry. The New Zealand dairy goat industry has no national genetic improvement programme aimed at improving performance in economically important traits. A survey of dairy goat farmers was undertaken to collect information about their farming systems. Does were kept under indoor conditions and averaged (and standard deviation) of 2.8±0.2 litres of milk per day. Information on herd structure, reason for culling and death, milk-solids concentration and production, cost of production, revenue and management was collected. Four mathematical models were evaluated using random regression models to estimate lactation yields from test-day records. The Wilmink model (WK) was chosen as the best model based on AIC fit statistic. Does which were 75% Saanen and 25% other breeds or Toggenburg produced the highest milk yield (MY), fat yield (FY) and protein yield (PY), while Toggenburg does produced the lowest yields. Information from the survey was used to develop a deterministic bio-economic model to estimate economic values (EVs) for four payment scenarios. The breeding objective included seven traits: MY, FY, PY, lactose yield (LY), liveweight (LW), longevity (LGTY) and Somatic cell score (SCS). For the Current payment system in New Zealand (payment on milk-solids) the EVs were NZ$11.64, NZ$12.27, NZ$12.39, NZ$-0.10, NZ$-2.15, NZ$0.04 and NZ$-8.22, respectively. Heritabilities and repeatabilities were estimated using uni- and bivariate animal model analyses with two random variables (animal for additive genetic component and doe for animal permanent environmental component). Heritabilities for MY, FY and PY were all 0.21 and 0.22 for SCS with similar standard errors. Repeatabilities ranged from 0.40 for MY, FY and PY to 0.49 for SCS. Genetic and phenotypic correlations between milk traits were positive and high, while between milk traits and SCS were from positive low to low negative. These parameters suggest moderate favourable responses to selection for increased milk solids and reduced SCS. Genetic gain and responses in the traits in the breeding objective were estimated for pedigree and progeny testing selection schemes using a selection index for one (MS) or three traits (MY, FY and PY). Results suggested that higher genetic gain and responses in individual traits occurred using a progeny test scheme. The information generated from this research should be applied to the New Zealand dairy goat industry to improve farm profit per milking doe.
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    Epidemiological study of removals in New Zealand dairy goats : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Studies at Massey University
    (Massey University, 2012) Gautam, Milan
    This thesis provides a description of the demography, production and reproductive characteristics of dairy goats on commercial dairy goat farms in New Zealand. In addition, it quantifies the influence of individual animal-level characteristics on the length of productive life (LPL). A secondary set of data provided by the New Zealand Dairy Goat Co-operative formed the basis of the analyses presented in this thesis. Details were available for 23,771 does from 38 herds which were born between 1 January 2000 and 31 December 2009. Survival analyses were used to describe the pattern of removal of does as a function of age and within a lactation cycle, as a function of days in milk and days dry. A piece-wise Cox model was used to quantify the effect of individual doe level characteristics on LPL. The median age of does at first kidding was 394 days (Q1 369 days, Q3 722 days). The median age at the time of removal was 3.7 years (Q1 2.5 years, Q3 4.9 years). On average does completed less than three lactation cycles at the time they were removed from the herd. Within a lactation cycle the majority of removals took place soon after dry off date. We found that the majority of does were removed as culls as opposed to those removed by sale or death. Compared to dairy cows, does were removed for a wide range of reasons, the majority of which comprised various infectious and non-infectious health disorders. This indicates that those managing animal health on dairy goat farms require detailed knowledge on the control and prevention of a wide range of caprine health disorders. The effect of first lactation milksolids yield (MSL1) on LPL varied over time. During the first two years following the date of second kidding, high MSL1 yields had a protective effect on removal whereas beyond two years from the date of second kidding, does with high MSL1 yields were at a greater risk of removal compared to average producers. These findings indicate that high MSL1 producers should be preferentially managed beyond two years from the date of second kidding, in order to avoid preventable losses. In turn this should ensure longer LPLs among a more profitable sub-group of the herd.