Browsing by Author "Sneddon NW"

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    Does the age of milk affect its mid-infrared spectrum and predictions
    (Elsevier Ltd, 2024-05-30) Magro S; Sneddon NW; Costa A; Chiarin E; Penasa M; De Marchi M
    Milk of dairy species commonly undergo standardized official analyses, these that may require chemical preservation and transportation to a certified laboratory. In this context, storage duration is an important factor that can potential affect both milk chemical analyses and its mid-infrared spectrum. We analysed milk samples at different time points/ages to assess repeatability and reproducibility of mid-infrared predicted traits (e.g., fat and protein). Using spectral data, we also evaluated the ability of spectroscopy coupled with chemometrics to discriminate samples according to their age. Although the main components of milk remained consistently reproducible across age (days), changes in the spectrum due to sample aging and deterioration of the matrix were detectable. Using a discriminant analysis, we achieved a classification accuracy of 77% in validation. Predicting milk age using mid-infrared spectra is feasible, allowing for sample monitoring within circuits where maximum reliability is needed, e.g., bulk or individual milk samples for legal/official use or payment systems.
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    Effects of yard weaning and human contact compared to paddock weaning on the liveweight gain and stress reactivity of beef cattle
    (Taylor and Francis Group, 2023-09-03) Cranston LM; Ramsay BA; Schoorl J-AAJ; Stayton KM; Greaves A; Shanks RD; van Kampen CJ; Cockrem JF; Beausoleil NJ; Morris ST; Sneddon NW; Hickson RE
    In New Zealand beef herds, calves undergo ‘paddock weaning’ by separating calves and cows into different paddocks. Anecdotal evidence indicates ‘yard weaning’ whereby calves are yarded and receive regular human contact during weaning may improve long-term stress reactivity and growth rates. Calves were allocated to one of three treatments for seven days post-separation from dams: paddock weaned with minimal human interaction (PN), paddock weaned with daily human interaction (PV), yard weaned with daily human interaction (YV). Calf liveweight, behavioural and physiological measures of stress reactivity and faecal corticosterone concentration were measured. Until day seven, YV calves lost less liveweight than PV or PN calves (0.5 kg vs. 3.5 and 4.8 kg P < 0.05). On day seven, PN calves had a 23% greater heart rate compared to YV calves and a greater faecal corticosterone concentration than PV and YV calves (in cohort 2 only) (P < 0.05). This indicates, regular non-aversive human contact during weaning may reduce stress associated with the weaning process itself and reduced stress reactivity to subsequent handling and restraint. However, this effect was transient with no consistent longer-term benefits over traditional paddock weaning, in terms of growth or stress reactivity to human handling.
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    Wool shedding and lamb fleece weights: first-cross and backcross Wiltshire–Romney sheep scored at lamb, hogget and two-tooth ages
    (Taylor and Francis Group, 2024-05-03) Sneddon NW; Handcock RC; Corner-Thomas RA; Kenyon PR; Burnham DL; Garrick DJ; Littlejohn MD; Blair HT; Morris ST
    With decreasing wool values, interest is increasing regarding shedding sheep. To investigate this, two long-term studies introducing Wiltshire genes into Romney flocks were initiated. Data from these two studies provide phenotypic relationships between a range of shedding scores at different ages. The data included shedding scores (on a 0–5 scale) repeated on lambs (∼5 months), hoggets (∼14–18 months) and two-tooths (∼27 months), and lamb fleece weights. Positive relationships between shedding scores on the same animals were observed. Lamb fleece weight was negatively correlated with all shedding scores. Lamb shedding score in February had a correlation of 0.54 (P < 0.001) with the February score as a hogget at Riverside farm. Scoring wool shedding is a laborious activity requiring individual animals to be scored in the shearing position. Therefore, lamb fleece weight was investigated for its relationship with shedding scores, as a potentially easier alternative. Lamb fleece weight had a greater correlation with February hogget shedding score than with the lamb shedding score (−0.76 vs −0.52, P < 0.001). This study indicated that February scores are an accurate predictor of future shedding phenotypes, and when used in conjunction with fleece weight, are a good predictor of phenotypes expressed at later ages.