Veterinary Clinical Sciences - Theses
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ItemEnsuring dairy cow welfare with increasing scale of production( 2018)Animal welfare is important to the general public and dairy consumers and the dairy industry is coming under increasing scrutiny. There is the potential for community concern arising from perceived intensification of the industry with an increasing number of large herds, and producers adopting a mix of grazing and confined feeding strategies. This thesis examines the particular welfare challenges associated with increased herd size in Australian pasture-based dairy herds including how they might be measured and managed. A survey of Australian dairy farmers was conducted to assess relationships between herd size and known or proposed risk factors for adverse animal welfare outcomes in Australian dairy herds in relation to increasing scale of production. Increasing herd size was associated with increases in stocking density, stock per labour unit and grain fed per day – all of which could reasonably be hypothesized to increase the risk of adverse welfare outcomes unless carefully managed. However, increasing herd size was also associated with an increased likelihood of staff with formal and industry-based training qualifications. Herd size was not associated with reported increases in mastitis or lameness. Large herds were more likely to use monitoring systems such as electronic identification in the dairy, computerised records, daily milk yield or cell count monitoring and pedometers or activity meters. Increasing herd size was related to increased herd milking time, increased time away from the paddock and increased distance walked. Animal welfare assessments were conducted on 50 Australian pasture-based dairy farms of varying herd sizes. Findings were generally consistent with the previous survey. Major challenges included heat stress, mastitis, lameness, and longer milking duration. All cows had access to water for more than 12 h in a 24 h period. More larger farms had water points on the farm tracks or at the dairy. Skin and joint lesion prevalence was not related to herd size and they were uncommon. All farms had some form of cooling strategy. Shade in all paddocks was more common on smaller farms than others while sprinklers were more common on large/very large farms. There was wide variation in the avoidance distance of humans but this was not related to farm size. Lameness scoring was conducted on 19154 cows from 50 farms as they left the dairy after being milked. We compared our Results with farmer estimates of lameness prevalence. Farmers detected only 24% of the cows observed/scored as lame. Whilst lameness scoring of the entire herd was necessary to detect all the lame cows, scoring just the last 200 cows milked could be used to estimate the prevalence of lame cows on a given day. In large Australian dairy herds, it is common for cows to be collected from the paddock as a group, to wait as a group in the dairy yard to be milked and to return individually to the paddock or feed pad immediately after milking. We demonstrated that even in these large herds there is consistency in the order cows are milked. This may have welfare implications for cows that are regularly milked last because they may spend several hours per day less in a paddock grazing. Lying is a high priority behaviour for cows. We used activity monitors to show that cows in large Australian dairy herds spend an average of 9.5 hours lying each day. Even in large herds, where milking can take up to 4 hours, the time taken to milk the cows did not affect their welfare by significantly impacting on their ability to lie down.