Browsing by Author "Sneddon, NW"

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    Brief communication: Do different grazing strategies affect pre-weaning calf growth rates?
    (The New Zealand Society of Animal Production, 2016) Back, PJ; Hickson, RE; van Bouwel, K; de Cock, H; Verdurman, J; Sneddon, NW; Laven, RA
    Rearing replacement heifer calves is a labour-intensive and expensive component of dairy systems (Drackley 2008). Large numbers of replacement heifers are not meeting target live weights in New Zealand (McNaughton & Lopdell 2012) which has implications for future milk production, fertility and subsequent longevity in the herd (Van Amburgh & Tikofsky 2001). This paper reports results from the second year of a long-term experiment being conducted at Massey University that examines the impact of colostral status and liveweight gain of heifer calves fed different diets on subsequent milk production, fertility and longevity in the herd. Previous work (Cardoso et al. 2015) demonstrated no difference in pre-weaning liveweight gain of calves fed different levels of milk. The calves in that study ate surprisingly little meal. It was surmised that the exposure to frequent shifts onto fresh pasture stimulated intake of pasture, and removed the advantage of feeding calves higher levels of milk and supplementation with meal. Anecdotally, many calves when removed from rearing sheds to pasture are kept on the same paddocks as they are not a high priority for pasture allocation. Therefore, the aim of this experiment was further collection of colostral and Brix data as described by Coleman et al. (2015), and to compare pre-weaning growth rates of calves that are continually offered fresh pasture to those that are set stocked.
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    Grazing behaviour and species selection of heifer calves fed different forages
    (The New Zealand Society of Animal Production, 2016) Back, PJ; Hickson, RE; Lilly, VM; Coleman, LW; Sneddon, NW; Laven, RA
    The aim of this experiment was to determine whether there was a difference in the behaviour of calves grazing different forages. Weaned dairy heifer calves (n = 64) were assigned to two different forage feeding treatments: ryegrass pasture and a clover-herb mix. Behavioural observations were recorded every 10 minutes over a 72 h period. Behaviours recorded were standing, walking, lying or sitting, grazing, ruminating, drinking/grooming, playing and various combinations of these. Calves grazing pasture spent more time lying and ruminating compared to calves grazing the clover-herb mix (34.6% vs 16.7%), and less time standing and grazing (17.2% vs 32.2%). Calves were less active from late evening and early morning and more likely to be ruminating earlier in the day and grazing later in the day. Plant selection (measured as plant disappearance rate) was determined in calves grazing the clover-herb mix. Red clover had the highest disappearance rate on all days compared to other species (P<0.05). Plantain, chicory and white clover eaten on day one did not differ in proportions eaten, but by day three less red clover and chicory remained compared to plantain and white clover (P<0.05).
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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.