Biosecurity award for M. bovis work
A small company which mobilised veterinarians around the country to deal with Mycoplasma bovis was one of the winners in this year's Biosecurity Awards, held at Parliament.
Their call, made in the May edition of the New Zealand Veterinary Journal, follows a study of calves that died or were condemned as unfit for processing at a Southland plant in 2011.
Report author Gareth Thomas told Dairy News that while it is disappointing any calves arrive in such a condition, the positive in the study is that the numbers were low. “It was only one premises and overall less than 1% died so the sample was a small number of a small number.”
However, of that sample, “a reasonable proportion” showed signs their handling hadn’t met best practice guidelines, he adds.
Of all calves delivered, 0.7% died pre-slaughter and 0.4% were condemned post slaughter, giving a total of 247 or 1.1%lost from production.
Analysis of those found digestive tract disorders were the biggest killer, accounting for 41% of deaths (see table), followed by unknown and omphalitis (navel infections).
The authors note the digestive tract disorders, particularly those resulting in severe diarrhoea, are one of the most common causes of death in other studies, ranging 14-58%.
Of the calves that died pre-slaughter at the Southland plant (as opposed to those that were condemned post slaughter due to, for example, omphalitis and septicaemia), 25% did not have curd in the abomasums.
“The absence of curd in this many calves prompts questions about the feeding practices used,” the report states. “Further evaluation of pre-transportation feeding practices is indicated to fully determine compliance with the welfare codes and the suitability of non-clotting milk replacements for bobby veal calves.”
Thomas points out calves should be fed no more than two hours prior to collection, except where explicit approval to do otherwise is gained, such as where it can be shown the calves will be delivered to the processing plant within an hour or two of leaving the farm.
The fact some calves born in the South Island are killed in the North Island indicates some of the transport distances involved, and with trucks sometimes collecting from 30-40 farms before delivery to a processor, the first calves loaded can be in transit for a long time, he adds.
“There should be no more than 28 hours from the last feed to being killed, and we like the transport component of that to be less than eight hours.”
Despite that time in transit, a quarter of the calves that died pre-slaughter were deemed immature, ie probably less than the required four days old, as they still had wet umbilical cords. However, there’s some uncertainty about the time the cord takes to dry in New Zealand conditions, the report notes.
Thomas’s message to dairy farmers likely to be selling bobby calves in a few months is simple: treat them as you would your replacement heifer calves, and don’t put them on the truck until they are at least four days old, and fit and healthy.
