A 10% mortality rate in calves less than one week old was investigated. The problem occurred in a 320 cow spring block calving herd in Hampshire. The herdsman, who had only recently joined the unit, reported that calves were scouring and dying (Fig. 1). He had recently returned from working in New Zealand, and, based on his experiences there, had a somewhat indifferent attitude to calf health, attributing low value to them. No effort was made to ensure good colostrum intake, particularly in bull calves, which were left untreated if signs of diarrhoea were observed. The herdsman was assisted by the farm owner's wife, who was an enthusiastic novice, and a part-time calf rearer, employed on a seasonal basis.
The farm suffered a severe outbreak of Salmonella Dublin in the spring of 2004, resulting in widespread calf mortality and the loss of two periparturient heifers. In view of past history, faecal samples were submitted to the local AHVLA laboratory, together with a dead calf.
Post mortem examination revealed pus in joints; omphalophlebitis; pleurisy and pericarditis. Zinc sulphate turbidity testing revealed a blood level of 4.6 (reference level > 20 units). Rotavirus antigen was detected, but no Salmonellae were isolated. Faecal samples from other calves in the group showed the presence of Cryptosporidium and rotavirus, again with no Salmonellae.
Total protein measurement of other calves in the group, using a refractometer revealed serum proteins of < 50 g/L. Optimum levels are generally defined, using refractometry, as > 55 (Dobelaar et al., 1987).
Following the diagnosis of septicaemia and enteritis due to poor colostrum intake, the herdsman was instructed to force feed all calves with 2 – 4 litres of colostrum as soon as possible after calving, where possible from the calf's dam. Review of calving accommodation revealed a very intensively stocked straw yard, which, due to the pressure of the seasonal calving, was not being cleaned out. This was felt to be a significant source of neonatal infection for the calves, and a weekly routine of cleaning out was instigated.
Sick calves were treated with a long acting amoxycillin injection (Betamox LA, Norbrook), oral halofuginone lactate (Halocur, MSD) and treated with electrolyte solution (Rehydion, CEVA) in milk. Affected calves were removed to a sheltered hospital pen, until recovered. A heat lamp, creep feed and ad lib electrolytes were available to the calves. The herdsman was instructed to completely clean out and disinfect the housing, and where possible calves were housed in other pens. All calves born subsequently were treated with halofuginone lactate after calving. The above management protocols resulted in an immediate improvement in neonatal calf health.
The herd staff were instructed in the importance of personal hygiene (wearing of disposable gloves, changing overalls after handling calves, cleaning and disinfection of footwear; not eating or drinking until hands had been washed), but despite this advice, the owner's wife suffered a severe enteritis, suspected to be due to Cryptosporidia. Fortunately her four-month-old son did not contract the infection.
Review of the calves two weeks later revealed that they were still in poor health. They appeared to be stunted, hunched, were very hairy, and several exhibited a pasty diarrhoea, often with faecal tenesmus (Fig. 2).
The stronger calves were by that time out at grass, with a temporary building (a canvas pig roundhouse) available for shelter, and being fed milk replacer from a New Zealand style milk bar (Fig. 3). The calves were unwilling to leave the roundhouse, except for their twice daily milk feed, despite good weather.
Younger and weaker calves were still indoors. However, they were by that time housed in a large straw yard, which was extremely draughty due to the funnelling effect of surrounding buildings. The herdsman was instructed to construct a wind barrier, which took the form of a large cross arrangement of big straw bales. This has the advantage of giving the calves different options for shelter, depending on the prevailing wind.
Two calves had died that day. Coccidiosis was suspected, due to the straining, so the carcasses were again submitted to AHVLA for investigation. Post mortem showed no evidence of coccidiosis, but unusually, in view of the age of the calves, Cryptosporidia and rotavirus were still present. No Salmonellae were isolated. In view of the ongoing diarrhoea and general ill-health, both groups of calves were treated with doxycycline hyalite (Soludox, Eurovet) incorporated in the milk replacer feed, at a dosage rate of 1 g/100 kg for five days. The concentration of milk powder was reviewed, and found to be correct, to ensure that this was not a factor in causing diarrhoea. A regime of cleaning and disinfection of the milk bar was advised, to minimise cross infection between the groups if possible. The calves showed a dramatic recovery, and there were no further problems during the year. The herdsman was dismissed in May 2011.
Protocols were established to ensure no repetition occurred in 2012. New calving accommodation was allocated, to reduce the infection challenge to new born calves. Ventilation and shelter in calf pens was greatly increased, by altering the roof of the calf house, and by providing sheets on gates to reduce draughts. Purchase of a pasteuriser for colostrum was suggested, but not implemented. Vaccination of cows with a rotavirus vaccine, to increase colostral antibodies, was recommended, but, again, not implemented.
All calves were force fed colostrum with a stomach tube. Where possible, colostrum from the dam was fed, although beef calves received pooled colostrum. All calves were treated with halofuginone lactate after birth. Apart from a few isolated mild cases of diarrhoea, which were managed using electrolyte treatment, no problems with calves were seen this year.