Browsing by Author "Lopez-Villalobos, N"

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    The current state of the New Zealand goat industry
    (New Zealand Society of Animal Production, 30/06/2017) Scholtens, MR; Smith, RMC; Lopez-Lozano, SR; Lopez-Villalobos, N; Burt, D; Harper, L; Tuohy, M; Thomas, DG; Carr, AJ; Gray, DI; Tozer, PR; Schreurs, NM
    Goat farming in New Zealand has a lower profile compared to dairy, sheep and beef systems. The goat industry is small in New Zealand (Stafford & Prosser, 2016) and there has been limited consideration of the potential for the industry to expand (Shepard & O’Donnell, 1979). The environmental and commodity market constraints currently impacting pastoral systems in New Zealand provide an opportunity for the goat industry to have a greater economic contribution to New Zealand’s agricultural production. In New Zealand, goats are farmed for milk, meat and fibre production and also act as a mechanism for controlling excess pasture growth, enhancing clover in mixed pasture and controlling weeds (Batten, 2014). The aim of this paper was to present an overview of the goat industry to provide background knowledge for consideration when deciding the direction of the goat industries in New Zealand. As part of the overview, farmers, processors and industry bodies were contacted to obtain an estimate of the number and location of goats farmed in New Zealand. Although some of the sources of information for the goat industry are not perfect, this research is an attempt to bring together information that has not been consolidated in nearly 40 years (Shepard & O’Donnell, 1979) and was achieved as part of a three-part study with companion papers being produced (Lopez-Lozano et al. 2017; Smith et al. 2017). Information from this study were used in conjunction with the value of the goat industry (Lopez-Lozano et al. 2017) to project the potential of the New Zealand goat industry (Smith et al. 2017).
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    Genetics of alternative definitions of feed efficiency in grazing lactating dairy cows
    (NZSAP, 7/07/2016) Hurley, AM; Lopez-Villalobos, N; McParland, S; Lewis, E; Kennedy, E; O'Donovan, M; Burke, JL; Berry, DP
    The objective of this study was to estimate genetic parameters for measures of energy conversion efficiency (ECE), energy balance (EB), net energy intake (NEI), net energy of lactation (NEL) and body weight (BW), within lactation stages in grazing dairy cows. Individual measurements of NEI (n=7,675) from 2,445 lactations on 1,245 grazing cows were available. Residual energy intake (REI) was defined as NEI minus predicted energy requirements; residual energy production (REP) was defined as net energy of lactation (NEL) minus predicted energy requirements. Energy conversion efficiency was defined as NEL divided by NEI; EB was defined as the difference between intake and energy required for maintenance plus lactation. Lactation was divided into three stages (8-90, 91-180, and >180 days in milk [DIM]). Genetic and phenotypic (co)variances for EB, NEL and BW were estimated using univariate and bivariate animal repeatability models. The models included the fixed effects of contemporary group (treatment and test-date), parity, DIM, as well as a random additive genetic effect of animal, a within-lactation stage random permanent environmental effect and an across-lactation permanent environmental effect. Heritability across-lactation stages varied from 0.13 (8-90 DIM) to 0.28 (91-180 DIM) for NEI, from 0.16 (8-90 DIM) to 0.33 (91-180 DIM) for NEL, from 0.04 (8-90 DIM) to 0.10 (91-180 and >180 DIM) for EB, from 0.03 (8-90 DIM) to 0.11 (>180 DIM) for REI, and from 0.04 (8-90 DIM) to 0.18 (>180 DIM) for ECE. A strong genetic association between REI and EB was evident when average BW change was close to zero. These genetic parameters from Holstein-Friesian dairy cows fed predominantly grazed grass imply that genetic improvement in selected efficiency traits is achievable.
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    Milk composition and productive and reproductive performance of cows from A1 and A2 β-casein variants, milked once or twice a day
    (2020) Lu, Y; Hickson, R; Gedye, K; Correa-Luna, M; Donaghy, D; Lopez-Villalobos, N
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    Persistency and lactation curves modelled using nonlinear random regression in dairy cows milked once a day
    (2020) Jiang, H; Hickson, R; Woods, O; Morandeau, M; Burke, J; Correa-Luna, M; Donaghy, D; Lopez-Villalobos, N
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    Supply curves for yields of dairy products from first-lactation Holstein Friesian, Jersey and Holstein Friesian-Jersey crossbred cows accounting for seasonality of milk composition and production
    (New Zealand Society of Animal Production (INC), 2016) Sneddon, NW; Lopez-Villalobos, N; Davis, SR; Hickson, RE; Shalloo, L; Garrick, DJ
    The economic efficiency of a milk-processing system is influenced by seasonality of the milk supply, and changes to milk composition, influences the product potential of that milk. Lactation curves for milk yield and composition for seasonal calving first-lactation Holstein Friesian (F), Jersey (J) and Holstein Friesian-Jersey crossbred (FxJ) cows were used as inputs in a deterministic simulation model to produce seasonal curves for daily yields of dairy products. The dairy products were whole milk powder, skim milk powder, cheese, or butter. Dairy product potential was estimated for each animal from a population of 4333 mixed-breed, first-lactation cows. Lactation lengths differed (P<0.0001), among F, FxJ, and J, which averaged 219, 222 and 221 days respectively. Total-lactation milk yield was different (P<0.0001) among breeds and averaged 3257, 3092 and 2902 litres for F, FxJ and J cows, respectively. Whole-milk powder potential (yield per 1000 L of milk) was greatest at the start of the season and least at the end of the season, whereas cheese-production potential (yield per 1000 L of milk) followed the opposite pattern. Total-lactation whole-milk powder yield was different among breeds (P<0.0001) at 366, 338 and 312 kg of whole-milk powder for F, FxJ and J cows, respectively. Total-lactation cheese yield was also different among breeds (P<0.0001), and was 371, 375 and 361 kg for F, FxJ and J cows, respectively. The supply curves indicate that milk is best processed into whole or skim milk powder during peak season, and cheese and butter at the end of lactation. However, seasonal production of specific products would limit the use of by-product lactose from cheese manufacture in the production of milk powders, and thus negate the efficiency gains from changes to processing priorities.